Mechanical reusable auto injector

Abstract

The invention relates to a mechanical reusable auto injector for delivery of medicament from a cassette inserted in the mechanical reusable auto injector.

Description

Mechanical Reusable Auto InjectorThe invention relates to a mechanical reusable auto injector for delivery of medicament froma cassette inserted in the mechanical reusable auto injector.5 BackgroundAuto injectors for the delivery of medicament to a patient comes in many varieties dependingon the type of medicament, which is to be delivered to the patient. When the auto injector is are-usable injector part into which a disposable cassette is inserted, there are some mainrequirements, which need to be fulfilled for each of the two parts. For the auto injector, it needs10 to be ensured that all operational parts in the auto injector stay full functional in order to prolongthe lifetime of the auto injector. For the cassette, there need to be mechanical stability, but atthe same time, a minimum of material use in the disposable cassette is often also desired inorder to keep production costs and the environmental impact low.15 Patent application WO 2021 / 069106 A1 discloses an example of a system comprising areusable auto injector and a disposable cassette, where the disposable cassette is absent ofmajor electronic parts and spring systems. The auto injector comprises a number of injectorpins, which moves into the cassette after assembly of the two parts thereby releasing a skinsensor and initiating a medicament delivery sequence. For releasing the skin sensor, flexible20 arms on the skin sensor deflects when the injector pins move into the cassette.SummaryThroughout this description, all references to the proximal direction or proximal surfaces referto parts, surfaces and similar oriented in the direction of the injector site. Thus, by proximal25 end is meant the end of a part, which points towards the injection site. By proximal movementis meant a movement in a direction towards the injection site along / parallel with the longitudinalaxis.The distal end is the opposite end compared to the proximal end. Thus, all references to the30 distal direction or distal surfaces refer to parts, surfaces and similar oriented in the directionaway from the direction of the injector site, i.e. in the direction of the user. Thus, distalmovement is a movement in the opposite direction of the proximal movement. Proximalsurfaces are surfaces pointing in the proximal direction, and distal surfaces are surfacespointing the in distal direction.35WO 2025 / 109058 PCT / EP2024 / 0830892Both the proximal and distal surfaces may be found at the distal end, the proximal end, orsomewhere there in between, since the wording only refers to the direction in which thesurfaces are oriented and not the position of the surfaces in the individual part.5 Disclosed herein in a first aspect is a reusable auto injector for administration of medicament,the auto injector being configured for receiving a cassette comprising a syringe containing themedicament.The auto injector is extending from a proximal end to a distal end along a longitudinal axis (L).10 The cassette is configured for being removable received in the auto injector in a longitudinaldirection along the longitudinal axis (L).The auto injector normally comprises a cassette receiver configured for receiving the cassette.In one or more examples, the auto injector comprises a plunger rod configured for proximal15 movement of a stopper inside the syringe for medicament delivery. A plunger rod resettingpart connected to and protruding radially from the plunger rod may be part of the auto injector.In one or more examples, the auto injector comprises a drive spring adapted for moving theplunger rod in a proximal direction, i.e. a forward direction, such as a first longitudinal direction.The auto injector comprises a resetting sleeve rotatable relative to the cassette receiver in a20 first rotational direction (DR1). The resetting sleeve may be comprising a resetting threadnormally located on an inner surface of the resetting sleeve, wherein the plunger rod resettingpart engages with the resetting thread such that a rotation of the resetting sleeve in a firstrotational direction (DR1) moves the plunger rod in a distal direction for resetting the plungerrod.25Thus, in one or more examples the auto injector comprises:e acassette receiver configured for receiving the cassette;e a plunger rod configured for proximal movement of a stopper inside the syringe formedicament delivery;30 e a plunger rod resetting part connected to and protruding radially from the plungerrod;e a drive spring adapted for moving the plunger rod in a proximal direction; ande a resetting sleeve rotatable relative to the cassette receiver in a first rotationaldirection (DR1), the resetting sleeve comprising a resetting thread located on an35 inner surface of the resetting sleeve, wherein the plunger rod resetting part engageswith the resetting thread such that a rotation of the resetting sleeve in a first rotationalWO 2025 / 109058 PCT / EP2024 / 0830893direction (DR1) moves the plunger rod in a distal direction for resetting the plungerrod.Disclosed herein in a second aspect is a reusable auto injector for administration of5 medicament. The auto injector may be comprising:e a cassette receiver configured for receiving a removable cassette containing themedicament;e a plunger rod configured for movement of a stopper inside the cassette in a firstlongitudinal direction for medicament delivery;10 e aplunger rod resetting part connected to and protruding radially from the plunger rod;e adrive spring adapted for moving the plunger rod in the first longitudinal direction; ande aresetting sleeve rotatable relative to the cassette receiver in a first rotational directionDR1, the resetting sleeve comprising a resetting thread, wherein the plunger rodresetting part engages with the resetting thread such that a rotation of the resetting15 sleeve in a first rotational direction DR1 moves the plunger rod in a second longitudinaldirection opposite the first longitudinal direction for resetting the plunger rod.By resetting thread is meant a thread or a channel in which the plunger rod resetting parttravels, or which supports / abuts / comes in contact with the plunger rod resetting part during20 rotation in the first direction. The resetting thread is normally positioned on an inner surface ofthe resetting sleeve, but may also be positioned on an outer surface depending on the plungerrod and the resetting sleeve design.By the plunger rod resetting part protruding radially from the plunger rod is meant that the25 plunger rod resetting part extends from the plunger rod in an outwards direction. In general,by radially outwards is meant that the direction in which an object extend is outwards from acenter point, i.e. the object it extends from. Often, an item will be extending radially outwardsfrom an outer surface. By radially inwardly is in general meant that an object extends towardsa center. Often, an item will be extending radially inwards from an inner surface towards a30 center. The radial directions are often perpendicular from the longitudinal axis / the longitudinaldirection.The reusable auto injector disclosed herein is therefore a spring-driven alternative to themotor-driven auto injector described in WO 2021 / 069106 A1. Including electronical35 components in the auto injector increases productions costs compared to auto injectors absentof / with only a limited number of electronical components. However, controlling the movementof the individual parts in the auto injector in relation to each other, e.g. controlling a plungerWO 2025 / 109058 PCT / EP2024 / 0830894rod movement for medicament delivery, and controlling reloading and / or resetting of the autoinjector after medicament delivery normally becomes more complicated without the use ofelectronical elements. By the reusable auto injector disclosed herein is therefore obtained aninjector with an easy resetting function, which only requires the rotation of the resetting sleeve5 in the first rotational direction for resetting the plunger rod thereby preparing the auto injectorfor use for delivery of a new medicament portion. The reusable auto injector disclosed hereinis further a cost-attractive alternative to the auto injector described in WO 2021 / 069106 A1.In one or more examples, the cassette receiver is configured for receiving the cassette10 releasably in the cassette receiver. The cassette may thereby be a disposable cassetteinserted into the auto injector prior to use and removable after medicament delivery. The autoinjector may thus be reused multiple times with a new cassette each time. This is in contrastto the reloadable auto injector disclosed in patent application US 2014 / 221974 A1, which isable to provide only one additional dose of medicament after reloading. The auto injector is15 not reusable with a new cassette, since the syringe containing the medicament is a nonreplaceable part of the reliable auto injector.In one or more examples, rotation of the resetting sleeve in the first rotational direction DR1moves the plunger rod in a distal direction for resetting the plunger rod relative to the cassette20 receiver. By movement of the plunger rod in the distal direction, the plunger rod may be resetto its original position. This is further in contrast to the reloadable auto injector disclosed inpatent application US 2014 / 221974 A1, where the syringe assembly and the plunger rod movetogether during reloading.25 In one or more examples, the plunger rod is configured for proximal movement between aretracted plunger rod position and an extended plunger rod position. The proximal movementmay be seen as a movement along the first longitudinal direction. The resetting sleeve maybe configured for moving the plunger rod from the extended plunger rod position to theretracted plunger rod position by rotation of the resetting sleeve in the first rotational direction30 DR1 a predefined amount of degrees relative to the cassette receiver. Thus, in one or moreexample, the resetting sleeve is configured for moving the plunger rod from the extendedplunger rod position to the retracted plunger rod position by rotation of the resetting sleeve inthe first rotational direction DR1 a predefined amount of degrees relative to the cassettereceiver. The movement of the plunger rod from the extended plunger rod position to the35 retracted plunger rod position may be seen as a movement along the second longitudinaldirection, such as a rearward movement.WO 2025 / 109058 PCT / EP2024 / 0830895In one or more example, the resetting sleeve is configured for moving the plunger rod from theextended plunger rod position to the retracted plunger rod position by rotation of the resettingsleeve in the first rotational direction DR1 a predefined number of degrees relative to thecassette receiver. The predefined amount / number of degrees relative to the cassette receiver5 may correspond to a full resetting of the auto injector. By full resetting is normally meant aresetting of the plunger rod to a retracted plunger rod position corresponding to the positionwhich the plunger rod was in prior to activation of the auto injector, i.e. prior to the auto injectorreceiving a cassette. The reloadable auto injector of patent application US 2014 / 221974 A1does not disclose reloading or resetting to an original position.10In one or more examples, the predefined amount / number of degrees relative to the cassettereceiver is between 150 degrees and 210 degrees, such as between 160 degrees and 200degrees, such as between 170 degrees and 190 degrees, such as 180 degrees.15 In one or more examples, the predefined amount / number of degrees relative to the cassettereceiver is between 150 degrees and 360 degrees, such as between 160 degrees and 340degrees, such as between 170 degrees and 320 degrees, such as between 175 degrees and300 degrees, such as between 175 degrees and 280 degrees, such as between 175 degreesand 260 degrees, such as between 175 degrees and 240 degrees, such as between 17520 degrees and 220 degrees, such as between 175 degrees and 200 degrees, such as between175 degrees and 190 degrees, such as between 175 degrees and 185 degrees.If the auto injector has an outer surface design constituting an oval shape, a 180 degreesrotation may be preferred as it maintains the outer oval shape. If the auto injector has an outer25 surface design constituting a round shape, a 180 degrees rotation may not be preferred as itis not required for maintaining an outer round shape.In one or more examples, the plunger rod is non-rotatable relative to the cassette receiver.This ensures that the plunger rod may be able to travel in and out of a cassette without30 experiencing rotational friction between the plunger rod and the stopper in the syringe. Theplunger rod may be in contact with the stopper at a proximal end, such as a first end, of theplunger rod.In one or more examples, the plunger rod resetting part extends from a distal end, such as a35 second end, of the plunger rod. Alternatively, the plunger rod could be extending the from theproximal end of the plunger rod or from a position between the distal end and the proximalend.WO 2025 / 109058 PCT / EP2024 / 0830896In one or more examples, the plunger rod resetting part comprises two pin parts positionedopposite another. Alternatively, only one plunger rod pin resetting part could be envisioned.Yet alternatively, more than two pin parts could also be imagined. The expression “pin part” is5 not to be understand as limiting to the structural formation of the plunger rod resetting part.Hooks, tabs or other alternative shapes could also be used as plunger rod resetting part aslong as they interact with the resetting thread during rotation of the resetting sleeve in a firstrotational direction.10 In one or more examples, the resetting thread comprises two helical threads positionedopposite each other, normally inside the resetting sleeve. Each of the two helical threads maybe interfacing with each of the two oppositely positioned pin parts extending from a distal endof the plunger rod. When the resetting sleeve is rotated relative to the cassette receiver in thefirst rotational direction, the helical threads inside resetting sleeve forces the plunger rod15 resetting part to move in the distal direction, such as the second longitudinal direction. Thismoves the plunger rod distally towards its initial position, i.e. a ready for use with a newcassette position.In one or more examples, the reusable auto injector further comprises a distal injector housing.20 The distal injector housing may be surrounding the resetting sleeve. The distal injector housingmay be rotatable relative to the cassette receiver. The distal injector housing may berotationally locked to the resetting sleeve. The rotational locking may be obtained by the distalinjector housing or the resetting sleeve having protruding parts engaging into channels oropenings in the other of the distal injector housing or the resetting sleeve. The distal injector25 housing may form an outer housing part surrounding the resetting sleeve and providing aneasy user-friendly grip for performing the rotation of the resetting sleeve relatively to thecassette receiver.In one or more examples, the distal injector housing comprises at least one rotational stop30 surface. The at least one rotational stop surface may be protruding from a distal injectorhousing plate of the distal injector housing. The at least one rotational stop surface is normallypreventing further rotation of the resetting sleeve than a predefined amount of degrees relativeto the cassette receiver.35 In one or more examples, the rotational stop surface abuts the plunger rod resetting part whenthe resetting sleeve has been rotated the predefined amount of degrees relative to the cassettereceiver. Further rotation of the resetting sleeve relative to the cassette receiver is therebyWO 2025 / 109058 PCT / EP2024 / 0830897normally prevented. The predefined amount of degrees may be 180 degrees. Alternatively,other predefined amount of degrees, such as 80 degrees, such as 90 degrees, such as 100degrees, such as 110 degrees, such as 120 degrees, such as 130 degrees, such as 140degrees, such as 150 degrees, such as 160 degrees, such as 170 degrees, such as 1905 degrees, such as 200 degrees, such as 210 degrees, such as 220 degrees, such as 230degrees, such as 240 degrees, such as 250 degrees, such as 260 degrees, such as 270degrees, such as 280 degrees, such as 290 degrees, such as 300 degrees, such as 310degrees, such as 320 degrees, such as 330 degrees, such as 340 degrees, such as 350degrees, or such as 360 degrees may also be imagined.10In one or more examples, the reusable auto injector further comprises a distal housing cap.The distal housing cap may be attached to a distal end of the distal injector housing.In one or more examples, the rotation of the resetting sleeve in the first rotational direction15 (DR1) compresses the drive spring. When the drive spring is fully compressed, it is reloadedand ready for the auto injector to be used again when inserting a new cassette in the autoinjector. The resetting of the plunger rod may be set to be occur concurrently with thecompressing of the drive spring. This optimizes the process.20 In one or more examples, the plunger rod comprises a plunger rod cavity. The plunger rodcavity may be extending into the plunger rod. The drive spring may be positioned at least partlyinside the plunger rod cavity. By cavity is meant an opening inside the plunger rod. Theopening may extend from the distal end of the plunger rod and to the proximal end of theplunger rod. Normally, the proximal end of the plunger rod will be closed, whereas the distal25 end will be open allowing the drive spring to extend outside the distal end of the plunger rod.The drive spring thereby normally extends outside the plunger rod cavity when the drive springrelaxes by pushing the plunger rod in the proximal direction for medicament delivery.In one or more examples, the reusable auto injector comprises a spring guide. At least a distal30 end of the drive spring may extend around the spring guide. The drive spring may be biasedbetween a proximal end surface inside the plunger rod cavity and a distal end surface of thespring guide. The spring guide may support the drive spring and ensure that the drive springdoes not boggle.35 In one or more examples, the spring guide extends into the plunger rod opening. The springguide is normally longitudinally fixed to the resetting sleeve such that the parts do not moverelative to each other in the longitudinal direction. The spring guide and the resetting sleeveWO 2025 / 109058 PCT / EP2024 / 0830898are normally relatively rotatable. The spring guide is normally rotationally fixed in relation tothe cassette receiver.In one or more examples, the reusable auto injector as described in any of the previous5 examples and aspects further comprises a first damper assembly. The first damper assemblymay be configured for dampening at least part of the proximal movement of the drive springduring medicament delivery.Disclosed herein in a third aspect is a reusable auto injector for administration of medicament.10 The auto injector is configured for receiving a cassette comprising a syringe containing themedicament, wherein the auto injector is extending from a proximal end to a distal end alonga longitudinal axis. The auto injector is comprising a plunger rod configured for proximalmovement of a stopper inside the syringe for medicament delivery. The plunger rod may beconfigured for moving a total plunger rod movement length. The total plunger rod movement15 length may be from an initial distal plunger rod position to a proximal delivery plunger rodposition. The auto injector may comprise a drive spring adapted for moving the plunger rod ina proximal direction. The auto injector may further comprise a first damper assemblyconfigured for dampening at least part of the proximal movement of the drive spring duringmedicament delivery. The first damper assembly may be configured for dampening a first part20 of the total plunger rod movement length or the entire total plunger rod movement length.Thus, in one or more examples, a reusable auto injector is disclosed, the auto injector beingconfigured for receiving a cassette comprising a syringe containing the medicament, whereinthe auto injector is extending from a proximal end to a distal end along a longitudinal axis,25 wherein the auto injector is comprising a plunger rod configured for proximal movement of astopper inside the syringe for medicament delivery, the plunger rod being configured formoving a total plunger rod movement length from an initial distal plunger rod position to aproximal delivery plunger rod position; a drive spring adapted for moving the plunger rod in aproximal direction; and a first damper assembly configured for dampening at least part of the30 proximal movement of the drive spring during medicament delivery, wherein the first damperassembly is configured for dampening a first part of the total plunger rod movement length orthe entire total plunger rod movement length.In one or more examples of any of the described examples and aspects, during medicament35 delivery, the plunger rod is configured for moving a total plunger rod movement length. Thetotal plunger rod movement length may be from an initial distal plunger rod position to aproximal delivery plunger rod position. The first damper assembly may be configured forWO 2025 / 109058 PCT / EP2024 / 0830899dampening a first part of the total plunger rod movement length or the entire total plunger rodmovement length. The first damper assembly may be configured for dampening only a firstpart of the total plunger rod movement length. The first part of total plunger rod movementlength may be less than 25%, such as less than 20%, such as less than 15% of the total5 __ plunger rod movement length.In one or more examples, the plunger rod is configured for moving between:e an initial distal plunger rod position where the plunger rod is not in contact with thestopper inside the cassette;10 e astopper contact position, wherein the plunger rod is in contact with the stopper insidethe cassette; ande a proximal delivery plunger rod position, where the stopper inside the syringe hasbeen moved proximally for medicament delivery.15 The first damper assembly may damper the movement of the plunger rod only from the initialdistal plunger rod position to the stopper contact position.In one or more examples, the first damper assembly comprises an O-ring. The O-ring may beextending around a first part of the spring guide extending inside the plunger rod cavity. The20 O-ring may be in contact with an inner surface of the plunger rod cavity. Contact between theO-ring and the plunger rod cavity upon proximal movement of the plunger rod introduces adampening effect. Frictional force between the O-ring and the plunger rod cavity upon proximalmovement of the plunger rod may introduce a linear dampening effect.25 In one or more examples, the plunger rod comprises an inner plunger rod tube. The innerplunger rod tube may be extending into the plunger rod cavity. At least part of the drive springmay be positioned around the inner plunger rod tube. At least a part of the spring guide maybe extending through the inner plunger rod tube. The O-ring may be movable into the innerplunger rod tube when the drive spring pushes the plunger rod proximally.30In one or more examples, the spring guide comprises a spring guide rod. The spring guide rodmay be comprising spring guide tracks for supporting the drive spring.In one or more examples, the plunger rod comprises at least a first plunger rod opening. In35 one or more examples, the auto injector comprises a plunger rod release element with aplunger rod release hook. The plunger rod release hook may be secured in the first plungerWO 2025 / 109058 PCT / EP2024 / 08308910rod opening. This may be preventing proximal movement of the plunger rod when the autoinjector is in an initial position ready for receiving the cassette.In one or more examples, the plunger rod release element comprises a chassis sleeve5 interacting rod. In one or more examples, the plunger rod release element comprises a chassissleeve interacting rod around which the plunger rod release element is tiltable moving theplunger rod release hook radially outwardly. In one or more examples, the plunger rod releaseelement comprises a push protrusion abutting a sloping surface on the injector skin sensordetector. Distal movement of the injector skin sensor detector relative to the plunger rod10 release element may push the plunger rod release hook radially outwardly by relativemovement of the sloping surface against the push protrusion. Thereby the plunger rod releasehook may be released from the first plunger rod opening releasing the plunger rod for proximalmovement.15 More plunger rod openings may be present. These are normally positioned distally of the firstplunger rod opening in which the plunger rod release hook is secured if the user removes thedevice from the skin before medicament delivery has been finalized. This ensures that themedicament delivery does not continue after the user has removed the injector during an earlylift.20In one or more examples, the auto injector comprises a push back spring. The push backspring may be positioned between the plunger rod release element and the injector skin sensordetector exerting a pressure on the plunger rod release hook radially inwardly.25 In one or more examples, the reusable auto injector further comprises a chassis sleeve. Thechassis sleeve may be positioned between the plunger rod and the resetting sleeve. Thechassis sleeve may be comprising a longitudinally extending channel through which theplunger rod resetting part extends. The chassis sleeve may be non-rotatable relative to thecassette receiver. The channel may be configured for preventing the plunger rod from rotating30 when the resetting sleeve is rotated in the first rotational direction (DR1). Thus, the chassissleeve may be seen as rotationally locking the plunger rod and preventing any rotation of theplunger rod during medicament delivery and / or resetting of the plunger rod.In one or more examples, the reusable auto injector further comprises a cassette interacting35 tab. The cassette interacting tab may be movable in the longitudinal direction (L) between aproximal cassette locking position (PD) and a distal cassette release position (PP). Prior toreceiving a cassette in the reusable auto injector, the cassette interacting tab may be in theWO 2025 / 109058 PCT / EP2024 / 08308911distal cassette release position (PP). The cassette interacting tab may be used for useractivation of the auto injector and locking of the cassette in the auto injector.In one or more examples, when the cassette is received in the reusable auto injector, user5 induced movement of the cassette interacting tab from the distal cassette release position(PP) to the proximal cassette locking position (PD) locks the cassette in the reusable autoinjector. Movement of the cassette interacting tab to the proximal cassette locking position(PD) may also allow for a subsequent unlocking of the cassette part inside the cassetteenabling the user to active the auto injector and cassette system for medicament delivery.10 Locking of the cassette in the auto injector may be prevented if the cassette is a used or partlyused cassette thereby ensuring that the user never tries to inject medicament from a half-filledor empty syringe, or a tampered syringe.In one or more examples, the reusable auto injector is configured for moving the cassette15 interacting tab from the proximal cassette locking position (PD) to the distal cassette releaseposition (PP) when resetting the reusable auto injector by rotation of the distal injector housingor the resetting sleeve in the first rotational direction (DR1). Thereby normally the cassette isunlocked and removeable from the reusable auto injector. The resetting of the plunger rod andpossibly also the drive spring may thus occur concurrently with the resetting of the cassette20 interacting tab. This optimizes the process in terms of steps needed by the user to perform.Alternatively, in one or more examples, the cassette interacting tab are moved from theproximal cassette locking position (PD) to the distal cassette release position (PP) prior toresetting the auto injector. This may seem more natural for the user wanting to remove and25 discharge of the cassette before resetting the auto injector. The movement of the cassetteinteracting tab from the proximal cassette locking position (PD) to the distal cassette releaseposition (PP) may be user controlled by movement of e.g. the cassette interacting tab.Overall, the resetting of the auto injector and the unlocking of the cassette for removal of the30 cassette may be performed in a number of different manners. Examples of different resettingand unlocking scenarios include:A) Simultaneously resetting and unlocking. In this scenario, resetting of the reusable autoinjector unlocks the cassette. The resetting of the auto injector is normally obtained by rotation35 of the distal injector housing or the resetting sleeve in the first rotational direction (DR1). Theplunger rod may be retracted by the rotation of the distal injector housing or the resettingsleeve in the first rotational direction (DR1). The drive spring may also be compressed by theWO 2025 / 109058 PCT / EP2024 / 08308912rotation of the distal injector housing or the resetting sleeve in the first rotational direction(DR1).B) Subsequent resetting and unlocking. In this scenario, resetting of the reusable auto injector5 does not unlock the cassette. The resetting of the auto injector is normally obtained by rotationof the distal injector housing or the resetting sleeve in the first rotational direction (DR1). Theplunger rod may be retracted by the rotation of the distal injector housing or the resettingsleeve in the first rotational direction (DR1). The drive spring may also be compressed by therotation of the distal injector housing or the resetting sleeve in the first rotational direction10 (DR1). The subsequent unlocking of the cassette may be obtained by the user manually afterthe resetting of the auto injector.C) Spring compression and simultaneously resetting and unlocking. In this scenario, the drivespring is not compressed in the initial delivery state. After insertion of a cassette in the auto15 injector and locking of the cassette in the auto injector, the user compresses the drive springby rotation of the distal injector housing or the resetting sleeve in the first rotational direction(DR1). After end of medicament delivery, manual unlocking of the cassette also retracts theplunger rod whereby the auto injector is reset to the original position. The resetting of the autoinjector is normally obtained by rotation of the distal injector housing or the resetting sleeve in20 the first rotational direction (DR1).D) Simultaneously spring compression and cassette locking and simultaneously resetting andunlocking. In this scenario, the drive spring is not compressed in the initial delivery state. Afterinsertion of a cassette in the auto injector, the user compresses the drive spring by rotation of25 the distal injector housing or the resetting sleeve in the first rotational direction (DR1). Thisalso locks the cassette in the auto injector. After end medicament delivery, resetting of theauto injector by rotation of the distal injector housing or the resetting sleeve in the first rotationaldirection (DR1) retracts the plunger rod and unlocks the cassette.30 Combinations of the above scenarios may also be imagined.In one or more examples, the cassette interacting tab is accessible for a user through achannel in the cassette receiver in which the cassette interacting tab is movable along thelongitudinal direction (L).35WO 2025 / 109058 PCT / EP2024 / 08308913In one or more examples, the reusable auto injector further comprises a pullback part. Thepullback part may comprise the cassette interacting tab. Alternative positionings of thecassette interacting tab may also be envisioned.5 In one or more examples, the reusable auto injector further comprises a cassette activationpart. The cassette activation part may be configured for moving in the longitudinal direction (L)relative to the cassette receiver. The cassette interacting tab may in an example be positionedon the cassette activation part. The cassette activation part may be adapted for moving in thelongitudinal direction into the cassette for interacting with parts in the cassette. The cassette10 activation part may release parts in the cassette allowing the user to delivery medicamentusing the auto injector and cassette system.In one or more examples, the cassette activation part comprises one or more injector releasemembers. In one or more examples, the one or more injector release members are configured15 for locking the cassette in the auto injector by proximal movement of the one or more injectorrelease members into the cassette.The one or more injector release members may also be configured for releasing a skin sensorin the cassette after securing the cassette in the auto injector. The skin sensor may be released20 by proximal movement of the one or more injector release members into the cassette.In one or more examples, the pullback part comprises at least one cassette activation part tabsurface. The cassette activation part may comprise at least one pullback interacting tab. Theat least one cassette activation part tab surface on the pullback part may engage the at least25 one pullback interacting tab on the cassette activation part such that the cassette activationpart can be moved in relation to the pullback part.The relative movement need not be relative longitudinal movement. In one or more examples,the cassette activation part and the pullback part are configured for moving together in the30 longitudinal direction. The cassette activation part and the pullback part may thereby belongitudinal locked.In one or more examples, the cassette activation part can be tilted in relation to the pullbackpart. The tilting of the cassette activation part relative to the pullback part may be seen as a35 rotational movement around the interaction point constituting the at least one cassetteactivation part tab surface on the pullback part and the at least one pullback interacting tab onthe cassette activation part.WO 2025 / 109058 PCT / EP2024 / 08308914In one or more examples, the cassette activation part can be tilted in relation to the pullbackpart around an interaction point constituting the at least one cassette activation part tab surfaceon the pullback part and the at least one pullback interacting tab on the cassette activation5 part.In one or more examples, the reusable auto injector further comprises a converter. Theconverter may comprise one or more converter pins selected from the group of a primaryconverter pin; a secondary converter pin; a tertiary converter pin; and quaternary converter10 pin. In one or more examples, the converter comprises a primary converter pin. In one or moreexamples, the converter comprises a secondary converter pin. In one or more examples, theconverter comprises a tertiary converter pin. In one or more examples, the convertercomprises a quaternary converter pin.15 In one or more examples, the cassette receiver comprises a tertiary converter pin receivingopening. The tertiary converter pin may be positioned in the tertiary converter pin receivingopening. The converter may be rotatable in a first rotational direction around the tertiaryconverter pin. The tertiary converter pin may thereby constitute a rotational axis.20 In one or more examples, the cassette activation part comprises a quaternary converter pinreceiving channel. The quaternary converter pin may be positioned in the quaternary converterpin receiving channel. The quaternary converter pin may be movable in the quaternaryconverter pin receiving channel.25 In one or more examples, rotation of the converter around the tertiary converter pin in the firstrotational direction moves the quaternary converter pin proximally. The proximal movement ofthe quaternary converter pin occurs when the converter rotates around the rotational axisdefined by the tertiary pin. The cassette activation part may thereby be moved proximally alongthe longitudinal direction. The proximal movement of the cassette activation part along the30 longitudinal axis is due to the quaternary converter pin positioned inside the quaternaryconverter pin receiving channel on the cassette activation part. Thus, a rotational movementof the converter may be converted to a longitudinal movement of the cassette activation part.In one or more examples, the reusable auto injector further comprises a user button. The user35 button may be movable relative to the auto injector housing. The user button may be an item,which the user moves and / or rotates in order to activate the locking of the cassette inside theauto injector. The user button may have a square shape, a round shape or any other shape.WO 2025 / 109058 PCT / EP2024 / 08308915The user button may comprise a user button tab on an outer surface of the button. The userbutton tab is normally what the user grabs when moving and / or rotating the user button.In one or more examples, the user button comprises a primary converter pin receiving opening.5 The primary converter pin may be positioned in the primary converter pin receiving opening.In one or more examples, the user button comprises a secondary converter pin receivingopening. The secondary converter pin may be positioned in the secondary converter pinreceiving opening. The converter and the user button may be rotationally locked to each other.10 In one or more examples, the user button is configured for rotating in the first rotationaldirection. The rotation in the first rotational direction may rotate converter in the first rotationaldirection. Thus, the user button and the converter may rotate together. The user button andthe converter may thereby be rotationally locked together.15 In one or more examples, the user button comprises a user button channel. The secondaryconverter pin may be configured to travel inside the user button channel. The user button maybe configured for moving sideways. By sideways movement is meant a movement in adirection opposite the longitudinal direction. Sideways movement normally does not involve amovement along the longitudinal direction. The sideways movement may be movement from20 a first side position to a second side position. Movement of the user button sideways mayrotate the converter in the first rotational direction.In one or more examples, the reusable auto injector further comprises a proximal injectorhousing.25In one or more examples, the proximal injector housing comprises a user button receivingopening. The user button receiving opening may be configured for receiving the user button.In one or more examples, the converter comprises a converter plate. The converter plate may30 comprise a primary converter plate surface. The converter plate may comprise a secondaryconverter plate surface. The converter pins normally protrude from either the primary converterplate surface or the secondary converter plate surface. In one or more examples, the primaryconverter pin and the secondary converter pin protrudes from the primary converter platesurface. In one or more examples, the tertiary converter pin and the quaternary converter pin35 protrudes from the secondary converter plate surface.WO 2025 / 109058 PCT / EP2024 / 08308916In one or more examples, the cassette activation part comprises an activation part plate. Theactivation part plate may comprise an activation part plate thread. The resetting sleeve maycomprise at least one resetting sleeve pin configured for traveling inside the activation partplate thread.5In one or more examples, during rotation of the resetting sleeve in the first rotational direction(DR) for resetting the auto injector, the at least one resetting sleeve pin travels inside theactivation part plate thread. The cassette activation part may thereby be moving from anextended to a retracted position.10In one or more examples, the resetting sleeve is configured for rotating relative to the cassettereceiver in a second rotational direction (DR) opposite the first rotational direction (DR).In one or more examples, the at least one resetting sleeve pin is configured for traveling inside15 the activation part plate thread when rotating the resetting sleeve in the second rotationaldirection (DR). The cassette activation part may thereby be moved proximally to the extendedposition.In one or more examples, the resetting sleeve comprises a first blocking pin. The first blocking20 pin may be configured for stopping the rotation of the resetting sleeve in the second rotationaldirection (DR) when abutting the activation part plate. This may thereby be limiting the rotationof the resetting sleeve in the second rotational direction to a predefined angle. The predefinedangle may be a rotational angle of between 150 degrees and 210 degrees, such as between160 degrees and 200 degrees, such as between 170 degrees and 190 degrees, such as 18025 degrees.In one or more examples, the resetting sleeve comprises a second blocking pin. The secondblocking pin may be configured for stopping the rotation of the resetting sleeve in the firstrotational direction when abutting the activation part plate. This may thereby be limiting the30 rotation of the resetting sleeve in the first rotational direction to a predefined angle. Thepredefined angle may be a rotational angle of between 150 degrees and 210 degrees, suchas between 160 degrees and 200 degrees, such as between 170 degrees and 190 degrees,such as 180 degrees.35 In one or more examples, the auto injector comprises a plunger rod support part. The plungerrod support part may comprise a spring guide connecting opening for supporting a distal endof the spring guide.WO 2025 / 109058 PCT / EP2024 / 08308917In one or more examples, the plunger rod comprises at least one plunger rod tab. The leastone plunger rod tab may be located on an outside surface of the plunger rod. The plunger rodsupport part may comprise a plunger rod release tab. The plunger rod release tab may abut5 the at least one plunger rod tab when the auto injector is in an initial position ready for receivingthe cassette. The plunger rod release tab may thereby be used for ensuring that the plungerrod is not released prior to mounting of a cassette and preparing the cassette for medicamentdelivery.10 In one or more examples, the auto injector comprises an injector skin sensor detector. Theinjector skin sensor detector may be configured for moving proximally into the cassette andfor moving distally again by a user pressing the cassette against an injection site.In one or more examples, the injector skin sensor detector comprises a converter blocking15 surface. The converter may comprise a skin sensor detector pin interaction surface. Theinjector skin sensor detector may be configured for being moved from an initial extendedposition to a distal position. In the initial extended position, the converter blocking surfacenormally abuts the skin sensor detector pin interaction surface thereby preventing rotation ofthe converter. When in the distal position, the converter blocking surface normally no longer20 abuts the skin sensor detector pin interaction surface thereby allowing rotation of theconverter.In one or more examples, the reusable auto injector comprises an unlock sledge element. Theunlock sledge element may be configured for moving between a proximal position (USP) and25 a distal position (USD). At the proximal position (USP), longitudinal movement of the cassetteactivation part may be prevented. At the a distal position (USD), longitudinal movement of thecassette activation part into the cassette may be permitted.In one or more examples, the cassette activation part comprises one or more plunger rod lock30 elements. In one or more examples, the plunger rod comprises a cassette activation lockelement. Prior to a cassette being received in the auto injector, the cassette activation lockelement may be secured by the one or more plunger rod lock elements preventing relativelongitudinal movement of the cassette activation part and the plunger rod.35 Alternatively, or in combination, a direct interface between the cassette activation part and thechassis sleeve may be used for preventing relative longitudinal movement of the cassetteactivation part and the plunger rod.WO 2025 / 109058 PCT / EP2024 / 08308918Alternatively, or in combination, a direct interface between the cassette activation part and theplunger rod support part may be used for preventing relative longitudinal movement of thecassette activation part and the plunger rod.5Alternatively, or in combination, a direct interface between the cassette activation part and thecassette receiver may be used for preventing relative longitudinal movement of the cassetteactivation part and the plunger rod.10 In one or more examples, the unlock sledge element comprises an unlock sledge release tab.Distal movement of the unlock sledge element relative to the cassette activation part maymove the unlock sledge release tab towards the one or more plunger rod lock elements.Thereby the cassette activation lock element may be released from the one or more plungerrod lock elements. Thereby relative longitudinal movement of the cassette activation part and15 the plunger rod may be allowed.The one or more plunger rod lock elements may flex outwardly when the unlock sledge releasetab moves distally. The grab on the plunger rod is thereby released.20 In one or more examples, the cassette activation part is configured for being moved proximally.This may be moving the one or more injector release members into the cassette.Movement of the one or more injector release members into the cassette normally also locksthe cassette in the auto injector. The cassette activation part may be moved proximally by the25 user. The cassette activation part may comprise the cassette interacting tab, which is the part,which the user moves proximally.In one or more examples, the unlock sledge element and the injector skin sensor detector arelongitudinal locked.30The unlock sledge element may comprise an injector skin sensor detector lock tab. The injectorskin sensor detector lock tab may be fixing the unlock sledge element in a sledge receivingchannel in the injector skin sensor detector. Alternatively, the unlock sledge element may bepart of the injector skin sensor detector. Splitting the unlock sledge element and the injector35 skin sensor detector into two parts may be done to facilitate easy assembly of the auto injectorparts. The unlock sledge element may be configured for moving distally when an unusedcassette is received in the auto injector thereby moving the injector skin sensor detectorWO 2025 / 109058 PCT / EP2024 / 08308919distally. If an already used cassette is received in the auto injector, the injector skin sensordetector is not moved distally whereby the unlock sledge is also not moved distally. Thecassette activation part is thereby not unlocked. This ensures that the auto injector cannot beactivated if a used cassette is inserted into the auto injector instead of an unused cassette.5In one or more examples, the plunger rod and the drive spring, being in a compressed state,are configured for being unlocked when the injector skin sensor detector is moved in the distaldirection. This may allow the compressed drive spring to push the plunger rod in the proximaldirection for medicament delivery as the drive spring expands. By expands may also be meant10 decompresses.In one or more examples, the injector skin sensor detector comprises a distal release endsurface. The distal release end surface may be configured for pushing the plunger rod releasetab radially outwardly when the user is pressing the cassette against an injection site. Thereby15 the plunger rod release tab normally no longer abuts the at least one plunger rod tab. Thismay allow the drive spring to move the plunger rod proximally for medicament delivery.In one or more examples, the reusable auto injector further comprises an injector skin sensordetector spring. The injector skin sensor detector spring may be configured for pushing the20 injector skin sensor detector proximally after removal of the cassette received in the autoinjector from the injection site.In one or more examples, the auto injector comprises a cassette detector. The cassettedetector may comprise a release surface. The plunger rod support part may comprise a25 proximal flexible part with a proximal protruding part. The cassette activation part maycomprise a support part lock tab abutting the proximal protruding part prior to inserting acassette in the auto injector. When the release surface is pushed against the proximalprotruding part, the proximal flexible part may flex radially. This may release the cassetteactivation part. This may enable locking of the cassette in the auto injector by proximal30 movement of the cassette activation part.In one or more examples, the cassette activation part further comprises a distal end protrusion.The plunger rod support part may comprise a cassette activation part stop protrusion. Theplunger rod may comprise a longitudinally extending bar. The cassette activation part stop35 protrusion may prevent distal movement of the cassette activation part after positioning acassette in the auto injector by the distal end protrusion being positioned between the cassetteactivation part stop protrusion and the longitudinally extending bar.WO 2025 / 109058 PCT / EP2024 / 08308920In one or more examples, the pullback part further comprises a second cassette interactingtab. The second cassette interacting tab may be moving with the cassette interacting tab inthe longitudinal direction. The second cassette interacting tab may be radially non-movable.5 The second tab is normally included to allow for more grip and better mechanical guidancewith the housing front, when sliding the first and the second tabs forward to lock the cassettein the auto injector. In some examples, the second tab may be omitted.In one or more examples, the reusable auto injector further comprises a rotational damper.10 The rotational damper may comprise a damper sleeve positioned between the chassis sleeveand the resetting sleeve. The damper sleeve may comprise one or more damper channels.The rotational damper may comprise a damper end surface. The plunger rod resetting partmay extend through the one or more damper channels and into the resetting thread in theresetting sleeve. The damper sleeve may be rotatable relative to the chassis sleeve.15 Movement of the plunger rod in the proximal direction normally rotates the damper sleeve dueto the plunger rod resetting part extending through the one or more damper channels in thedamper sleeve. The damper sleeve and the damper end surface may rotate relatively duringinjection. A speed of the plunger rod during injection in the proximal direction is therebynormally reduced.20In one or more examples, the damper sleeve is rotatable relative to the resetting sleeve duringproximal movement of the plunger rod. The relative rotation of the resetting sleeve and thedamper sleeve during proximal movement of the plunger rod is normally seen during injectionof medicament.25In one or more examples, the damper sleeve is non-rotatable relative to the resetting sleeveduring distal movement of the plunger rod. The non-rotation of the resetting sleeve and thedamper sleeve during distal movement of the plunger rod is normally seen during reloading ofthe auto injector, often after end medicament delivery.30In one or more examples, the one or more damper channels in the damper sleeve each has apitch in the first rotation direction being identical to a pitch of the resetting thread in the resettingsleeve in the first rotation direction. Rotation of the damper sleeve relative to the resettingsleeve may thereby be prevented. By identical pitch is meant that the two part rotate together.35 Normally, there is no damping during reloading, but only a damping effect during medicamentdelivery. Alternatively, by tweaking the thread it can be achieved that the damper is only activeduring specific parts of the injection, for example during the first part of the injector. To avoidWO 2025 / 109058 PCT / EP2024 / 08308921the damper being active during reloading of the auto injector, a decoupling feature may beused.In one or more examples, the damper end surface is positioned inside distal injector housing5 and connected to the distal injector housing. The damper end surface and the distal injectorhousing may be rotationally locked.In one or more examples, the reusable auto injector is configured for receiving a cassette. Thecassette may comprise a syringe holder for receiving the syringe containing the medicament.10 The cassette may comprise a skin sensor movable in the longitudinally direction relative to thesyringe holder between two or more longitudinal positions. The two or more longitudinalpositions may include at least a first locked position prior to securing the cassette in the autoinjector and an unlocked position after securing the cassette in the auto injector. The cassetteactivation part may comprise the one or more injector release members configured for15 releasing the skin sensor in the cassette after securing the cassette in the auto injector. Theskin sensor may be released by proximal movement of the one or more injector releasemembers into the cassette.In one or more examples, the reusable auto injector is configured for receiving a cassette20 comprising a cap positioned at the proximal end of the cassette. The injector skin sensordetector may be configured for moving proximally into the cassette after removal of the cap.In one or more examples, after removal of the cap, the skin sensor is configured for moving inthe distal direction by a user pressing the skin sensor towards the injector site. The injector25 skin sensor detector may be configured for moving in the distal direction when the skin sensoris pressed towards the injector site.In one or more examples, when the injector skin sensor detector spring pushes the injectorskin sensor detector proximally after removal of the cassette received in the auto injector from30 the injection site, the skin sensor of the cassette is configured for being moved into a finallocked position.In one or more examples, the pullback part further comprises a plunger rod engagementsurface. The plunger rod engagement surface may be configured for coming into contact with35 and abutting a distal end of the plunger rod during medicament delivery whereby the pullbackpart moves proximally with the plunger rod during at least a last part of the medicamentdelivery.WO 2025 / 109058 PCT / EP2024 / 08308922In one or more examples, disclosed is a system comprising a reusable auto injector accordingto the above and a cassette. The cassette may comprise a syringe holder for receiving thesyringe containing the medicament. The cassette may comprise a skin sensor longitudinally5 movable relative to the syringe holder between two or more longitudinal positions including atleast a first locked position prior to securing the cassette in the auto injector and an unlockedposition. One or more injector release members in the reusable auto injector may beconfigured for releasing the skin sensor in the cassette after securing the cassette in the autoinjector. The skin sensor may be released by proximal movement of the one or more injector10 release members into the cassette.Disclosed herein in a fourth aspect is a system comprising a reusable auto injector accordingto the above and a cassette. The cassette comprises:e asyringe holder for receiving the syringe containing the medicament;15 e askin sensor longitudinally movable relative to the syringe holder between two ormore longitudinal positions including at least a first locked position prior to securingthe cassette in the auto injector and an unlocked position;wherein one or more injector release members in the reusable auto injector is configured forreleasing the skin sensor in the cassette after securing the cassette in the auto injector,20 wherein the skin sensor is released by proximal movement of the one or more injector releasemembers into the cassette.In one or more examples, the skin sensor is movable in the longitudinally direction relative tothe syringe holder between two or more longitudinal positions. The two or more longitudinal25 positions may be selected from:o adistal position (LD);o a final locked position (LP3);© an initial locked position (LP1) between the final locked position (LP3) and the distalposition (LD); and30 o an intermediate position (LP2) between the initial locked position (LP1) and the finallocked position (LP3).In one or more examples, when the skin sensor is in the distal longitudinal position (LD), thesyringe outlet is exposed. The skin sensor may cover the syringe outlet when the skin sensor35 __ is in either of:e the initial locked position (LP1); ore the intermediate position (LP2); orWO 2025 / 109058 PCT / EP2024 / 08308923e the final locked position (LP3).In one or more examples, the skin sensor is in the initial locked position (LP1) prior to securingthe cassette in the reusable auto injector and movable to the intermediate position (LP2) after5 release of the skin sensor by the one or more injector release members.In one or more examples, the cassette further comprises an index ring. The index ring may berotatable relative to the skin sensor between two or more rotational positions. The two or morerotational positions may be selected from:10 o a first rotational position (R1);o a delivery rotational position (Rd) in which the skin sensor is moveable between thedistal position (LD) and the final locked position (LP3);© acap-release rotational position (Rcr) positioned between the first rotational position(R1) and the delivery rotational position (Rd).15The one or more injector release members may be configured for rotating the index ringbetween the two or more rotational positions when the one or more injector release membersmoves proximally and comes into contact with the index ring.20 In one or more examples, the cassette further comprises a syringe received in the syringeholder. The syringe may comprise a syringe medicament compartment. The syringe maycomprise an outlet at the proximal end of a syringe medicament compartment. The syringemay comprise a stopper positioned inside the syringe compartment. The stopper may bemovable from a distal end of the syringe compartment towards the proximal end of the syringe25 compartment for emptying the medicament in the syringe compartment through the outlet.In one or more examples, the index ring is configured for moving from the cap-releaserotational position (Rcr) to the delivery rotational position (Rd) preparing the reusable autoinjector for medicament delivery when the skin sensor is in the distal longitudinal position (LD).30In one or more examples, the index ring comprises a track extending in a sloping direction.The one or more injector release members may be configured for traveling inside the track.The index ring may be rotated when the injector release member travels proximally inside thetrack.35WO 2025 / 109058 PCT / EP2024 / 08308924In one or more examples, each of the one or more injector release members comprises atrack-guide protrusion. The track-guide protrusion may be configured for traveling inside thetrack.5 In one or more examples, the auto injector comprises one or more cassette locking parts. Theone or more cassette locking parts may be configured for engaging in a snap-fit connectionwith corresponding one or more cassette securing tabs on the cassette when the cassette isinserted into the auto injector. Proximal movement of the injector release member may preventa disengagement of the snap-fit connection thereby securing the cassette inside the auto10 _ injector.In one or more examples, the one or more injector release members are adapted for movingto the initial position after delivery of medicament. Thereby the cassette is normally unlockedfrom the auto injector for removal of the cassette after medicament delivery.15In one or more examples, the auto injector comprises an injector skin sensor detector. In oneor more examples, the auto injector comprises a skin sensor spring. The skin sensor springmay be adapted for pushing the injector skin sensor detector against a cassette skin sensorpin upon proximal movement of the injector release member after release of the skin sensor20 from the initial locked position.In one or more examples, the skin sensor spring is adapted for pushing the cassette skinsensor in a proximal direction to the proximal longitudinal position (L_P2) when the index ringis in the cap-release rotational position (Rer).25In one or more examples, the skin sensor spring is adapted for pushing the cassette skinsensor in a proximal direction to the proximal longitudinal position (LP3) when the index ringis in the delivery rotational position (Rd).30 In one or more examples, after medicament delivery and removal of the reusable auto injectorfrom the delivery site, the skin sensor spring is configured for keeping the skin sensor in thefinal longitudinal position (LP3) during distal movement of the injector release member.Thereby the index ring is normally rotated from the delivery rotational position (Ra) to the firstrotational position (R1).35In one or more examples, the index ring is in the first rotational position (R1) prior to use. Whenthe index ring is moved from the first rotational position (R1) to the cap-release rotationalWO 2025 / 109058 PCT / EP2024 / 08308925position (Rcer) by proximal movement of the one or more injector release members, the skinsensor spring reusable auto injector may be adapted for pushing the skin sensor to theintermediate position (LP2).5 In one or more examples, the cassette further comprises a cassette housing. The cassettehousing may comprise a cap holding part at a proximal end of the cassette housing. Thecassette housing may comprise a removable cassette cap comprising one or more locking capparts extending distally from a proximal end of the cassette cap. Prior to use, a cassette caplocking protrusion on each of the one or more locking cap parts may be secured inside the10 cassette housing. Upon proximal movement of the skin sensor from the initial locked position(LP1) to the intermediate position (LP2), the distal locking ends may move outside the cassettehousing.It is noted that all cassette and auto injector details described above applies to all described15 aspects of the cassette, auto injector and system comprising both parts.Brief description of the drawingsVarious examples are described hereinafter with reference to the figures. Like referencenumerals refer to like elements throughout. Like elements will, thus, not be described in detail20 with respect to the description of each figure. It should also be noted that the figures are onlyintended to facilitate the description of the examples. They are not intended as an exhaustivedescription of the claimed invention or as a limitation on the scope of the claimed invention. Inaddition, an illustrated example needs not have all the aspects or advantages shown. Anaspect or an advantage described in conjunction with a particular example is not necessarily25 limited to that example and can be practiced in any other examples even if not so illustrated,or if not so explicitly described.Figures 1A-B show an exploded view of an example of an auto injector (figure 1A) extendingalong a longitudinal direction L, and in a cut-through view (figure 1B).30Figures 2-16 show the different parts in the auto injector of figures 1A-B in close-up views.Figure 17A shows the plunger rod and the resetting sleeve during resetting of the auto injectorby rotation of the resetting sleeve.35WO 2025 / 109058 PCT / EP2024 / 08308926Figures 17B-C show the distal injector housing together with the plunger rod and the resettingsleeve in a view from the proximal direction during resetting of the auto injector by rotation ofthe resetting sleeve.5 Figures 18A-E show cut-through views inside the auto injector during resetting of the autoinjector by rotation of the resetting sleeve.Figures 19A-G show cut-throughs of the auto injector during a process of receiving a cassette,unlocking of the cassette, whereby the plunger rod can be unlocked, during medicament10 delivery and during resetting of the auto injector after medicament delivery.Figures 19H-| show the auto injector of figures 19A-G in a situation, where the user hasinterrupted the medicament delivery by removing the cassette and auto injector system fromthe injection site prior to completing the medicament delivery.15Figures 20A-B show the unlocking of the plunger rod by the user pushing the injector skinsensor detector into the auto injector 1000 after cap removal in close-up views of figure 19D.Figures 21A-D show the interaction of the plunger rod, the cassette activation part, and the20 __ plunger rod support part.Figures 22A-C show the cassette detector and cassette interaction for locking the cassette inthe auto injector.25 Figure 23 shows an exploded view of an example of a cassette extending along a longitudinaldirection L.Figures 24A-E show the locking of the cassette in the auto injector.30 Figure 25A show the plurality of longitudinal positions which the skin sensor may move intorelative to the syringe holder, and figure 25B shows the rotational positions which the indexring may be rotated between.Figures 26A-I show the syringe holder, the skin sensor, and the index ring of the cassette from35 figure 23, and the injector release member shown in figures 10A-C in different skin sensorlongitudinal positions and index ring rotational positions as the injector release member moveslongitudinally in the index ring track.RECTIFIED SHEET (RULE 91) ISA / EPWO 2025 / 109058 PCT / EP2024 / 08308927Figures 27A-| show a second example of the syringe holder, the skin sensor, and the indexring, and the injector release member in different skin sensor longitudinal positions and indexring rotational positions as the injector release member moves longitudinally in the index ring5 track.Figures 28A-B show a third example of the syringe holder, the skin sensor, and the index ring.Figure 28C shows the cassette housing in a third example of figures 28A-B.10Figures 29A-G show the syringe holder, the skin sensor, and the index ring of figures 28A-B,and the injector release member in different skin sensor longitudinal positions and index ringrotational positions as the injector release member moves longitudinally in the index ring track.15 Figures 29H-I show a cut-through of the cassette housing and the skin sensor of figures 29AG showing the skin sensor in non-locked position (figure 29H) and the final position LP3 (figure291).Figures 30A-D show the removal of the cassette cap from the cassette.20Figures 31A-G show perspective views of parts of a cassette and the auto injector during aprocess of unlocking of the cassette cap, removal of the cap, medicament delivery and duringresetting of the auto injector after medicament delivery25 Figures 32A-D show a damper included in the auto injector.Figures 33A-B show an exploded view of another example of an auto injector extending alonga longitudinal direction L (figures 33A), and in a cut-through view (figure 33B).30 Figures 34-40 show selected parts in the auto injector of figures 33A-B in close-up views.Figures 41A-D show selected parts of the auto injector of figures 33A-B during activation ofthe second auto injector.35 Figures 42A-H show cut-throughs of the auto injector of figures 33A-B during a process ofreceiving a cassette, unlocking of the cassette, whereby the plunger rod can be unlocked,WO 2025 / 109058 PCT / EP2024 / 08308928during medicament delivery, after end medicament delivery, and after reloading of the autoinjector.Figure 421 shows a cut-through of the auto injector of figures 33A-B during an early lift before5 medicament delivery has been finalized.Figures 43A-D show cut-throughs close-ups of the auto injector of figures 33A-B duringunlocking of the plunger rod allowing for medicament delivery.10 Figures 44A-B show a cut-throughs of the auto injector of figures 33A-B when receiving anunused cassette (figure 44A) and when receiving an already used cassette (figure 44B).Figures 45A-B show a linear damper inside the plunger rod cavity in close-ups.15 Figures 46A-B show an exploded view of a third example of an auto injector extending alonga longitudinal direction L (figures 46A), and in a cut-through view (figure 46B).Figures 47-55 show selected parts in the auto injector of figures 46A-B in close-up views.20 Figures 56A-C show selected parts of the auto injector of figures 46A-B during activation ofthe third auto injector.Figures 57A-B show an exploded view of a fourth example of an auto injector extending alonga longitudinal direction L (figures 57A), and in a cut-through view (figure 57B).25Figures 58A-61 show selected parts in the auto injector of figures 57A-B in close-up views.Figure 62 show an exploded view of a fifth example of an auto injector extending along alongitudinal direction L.30Figure 63 shows a selected part in the auto injector of figure 62 in close-up view.Description of examplesExemplary examples will now be described more fully hereinafter with reference to the35 accompanying drawings. In this regard, the present examples may have different forms andshould not be construed as being limited to the descriptions set forth herein. Accordingly, theexamples are merely described below, by referring to the figures, to explain aspects. As usedWO 2025 / 109058 PCT / EP2024 / 08308929herein, the term "and / or" includes any and all combinations of one or more of the associatedlisted items. Expressions such as "at least one of," when preceding a list of elements, modifythe entire list of elements and do not modify the individual elements of the list.5 In the drawings, thicknesses of a plurality of layers and areas are illustrated in an enlargedmanner for clarity and ease of description thereof. When a layer, area, element, or plate isreferred to as being “on” another layer, area, element, or plate, it may be directly on the otherlayer, area, element, or plate, or intervening layers, areas, elements, or plates may be presenttherebetween. Conversely, when a layer, area, element, or plate is referred to as being10 “directly on” another layer, area, element, or plate, there are no intervening layers, areas,elements, or plates therebetween. Further when a layer, area, element, or plate is referred toas being “below” another layer, area, element, or plate, it may be directly below the other layer,area, element, or plate, or intervening layers, areas, elements, or plates may be presenttherebetween. Conversely, when a layer, area, element, or plate is referred to as being15 “directly below” another layer, area, element, or plate, there are no intervening layers, areas,elements, or plates therebetween.The spatially relative terms “lower” or “bottom” and “upper” or “top”, "below", "beneath", "less","above", and the like, may be used herein for ease of description to describe the relationship20 between one element or component and another element or component as illustrated in thedrawings. It will be understood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation, in addition to the orientation depictedin the drawings. For example, in the case where a device illustrated in the drawings is turnedover, elements described as being on the “lower” side of other elements, or "below" or25 "beneath" another element would then be oriented on “upper” sides of the other elements, or"above" another element. Accordingly, the illustrative term "below" or “beneath” may includeboth the “lower” and “upper” orientation positions, depending on the particular orientation ofthe figure. Similarly, if the device in one of the figures is turned over, elements described as“below” or “beneath” other elements would then be oriented ”above” the other elements. The30 exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of aboveand below, and thus the spatially relative terms may be interpreted differently depending onthe orientations described.Throughout the specification, when an element is referred to as being “connected” to another35 element, the element is “directly connected” to the other element, or “electrically connected”to the other element with one or more intervening elements interposed therebetween.WO 2025 / 109058 PCT / EP2024 / 08308930The terminology used herein is for the purpose of describing particular examples only and isnot intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intendedto include the plural forms, including “at least one,” unless the content clearly indicatesotherwise. “At least one” is not to be construed as limiting “a” or “an.” It will be further5 understood that the terms “comprises,” "comprising," "includes" and / or "including," when usedin this specification, specify the presence of stated features, integers, steps, operations,elements, and / or components, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components, and / or groups thereof.10 It will be understood that, although the terms “first,” “second,” “third,” and the like may be usedherein to describe various elements, these elements should not be limited by these terms.These terms are only used to distinguish one element from another element. Thus, “a firstelement” discussed below could be termed “a second element” or “a third element,” and “asecond element” and “a third element” may be termed likewise without departing from the15 teachings herein."About" or "approximately" as used herein is inclusive of the stated value and means within anacceptable range of deviation for the particular value as determined by one of ordinary skill inthe art, considering the measurement in question and the error associated with measurement20 of the particular quantity (i.e., the limitations of the measurement system). For example,"about" may mean within one or more standard deviations, or within + 30%, 20%, 10%, 5% ofthe stated value.Unless otherwise defined, all terms used herein (including technical and scientific terms) have25 the same meaning as commonly understood by those skilled in the art to which this inventionpertains. It will be further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that is consistent with their meaningin the context of the relevant art and will not be interpreted in an idealized or overly formalsense unless expressly so defined in the present specification.30Exemplary examples are described herein with reference to cross track section illustrationsthat are schematic illustrations of idealized examples, wherein like reference numerals referto like elements throughout the specification. As such, variations from the shapes of theillustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be35 expected. Thus, examples described herein should not be construed as limited to the particularshapes of regions as illustrated herein but are to include deviations in shapes that result, forexample, from manufacturing. For example, a region illustrated or described as flat may haveWO 2025 / 109058 PCT / EP2024 / 08308931rough and / or nonlinear features. Moreover, sharp angles that are illustrated may be rounded.Thus, the regions illustrated in the figures are schematic in nature and their shapes are notintended to illustrate the precise shape of a region and are not intended to limit the scope ofthe present claims. Some of the parts which are not associated with the description may not5 be provided in order to specifically describe exemplary examples of the present disclosure.Figure 1A show an exploded view of an example of an auto injector 1000 extending along alongitudinal direction L. The auto injector 1000 is extending from a proximal end 1002 to adistal end 1004 and comprises a number of different parts as shown in close-up views in10 figures 2-16. The different parts in the auto injector 1000 includes a plunger rod 1020 with aplunger rod resetting part 1026, a drive spring 1040, a drive spring guide 1050, a cassettereceiver 1100, a resetting sleeve 1200, a plunger rod support part 1300, a chassis sleeve1400, a cassette activation part 1500, a pullback part 1600, an injector skin sensor detector1700, an injector skin sensor detector spring 1710, a cassette detector 1800, a cassette15 detector spring 1810, a proximal injector housing 2100, and a distal injector housing 2200. Theauto injector 1000 may possibly comprise a rotational damper 1900 as shown in figures 32AD. Figure 1B shows the assembled auto injector 1000. During loading and preparation of acassette 100 (an example of a cassette 100 is shown in figure 23) for medicament delivery,and during medicament delivery, there is no rotational movement between the different parts20 in the auto injector 1000. Instead, the different parts in the auto injector 1000 move relative toeach along the longitudinal direction L and some part flex and / or tilt relative to other parts asdescribed in the following. After medicament delivery and removal of the cassette 100, theauto injector 1000 is reloaded by rotation of the resetting sleeve 1200 and the distal injectorhousing 2200 relative to the other parts of the auto injector 1000. This retracts the plunger rod25 1020 to its initial distal position and reloads the drive spring 1040 as described in the following.Figures 2A-B show a closeup of the resetting sleeve 1200 as seen from both the proximal end1202 in figure 2A and the distal end 1204 in figure 2B. The resetting sleeve 1200 has a tubularform. The resetting sleeve 1200 comprises a resetting thread 1206 extending in a helical30 manner on an inner surface 1205 of the resetting sleeve 1200. The plunger rod resetting part1026 engages with the resetting thread 1206 such that a rotation of the resetting sleeve 1200moves the plunger rod 1020 along the longitudinal direction L (see details in figures 4A-B).On the outer surface 1208 of the resetting sleeve 1200 is a number of outer housing channels35 1209. The outer housing channels 1209 are configured for containing inner resetting sleevelocking parts 2209 on the distal injector housing 2200 (see figure 3). The interaction betweenthe outer housing channels 1209 and the inner resetting sleeve locking parts 2209 rotationallyWO 2025 / 109058 PCT / EP2024 / 08308932locks the two parts together. The resetting sleeve 1200 and distal injector housing 2200 shownin figures 2-3 have four sets of outer housing channels 1209 and the inner resetting sleevelocking parts 2209. Few or more could also be imagined. The locking of the resetting sleeve1200 and distal injector housing 2200 is shown in figures 17B-C.5At the proximal end 1202 of the resetting sleeve 1200 are two chassis sleeve interacting hook1210 configured for engaging with resetting sleeve interacting tabs 1410 on the chassis sleeve1400 (see figure 9B). During reloading of the auto injector 1000, the resetting sleeve 1200 isrotated in a first rotational direction DR1 relative to the chassis sleeve 1400. This brings the10 chassis sleeve interacting hooks 1210 in contact with the resetting sleeve interacting tabs 1410on the chassis sleeve 1400. The contact, when rotating in the first rotational direction DR1, isbetween sloping surfaces 1211, 1411 on both the chassis sleeve interacting hooks 1210 andthe resetting sleeve interacting tabs 1410. The chassis sleeve interacting hooks 1210 can flexradially outwardly. Thus, when the sloping surfaces 1211, 1411 coming into contact with each15 other when rotating the resetting sleeve 1200 in the first rotational direction DR1, the chassissleeve interacting hooks 1210 flex radially outwardly allowing the resetting sleeve 1200 tocontinue its rotation. However, if rotating in a direction opposite the first rotational directionDR1, steep surfaces 1212, 1412 on both the chassis sleeve interacting hooks 1210 and theresetting sleeve interacting tabs 1410 come into contact with each other. This prevents further20 relative rotation between the two parts.Figure 3 shows a closeup of the distal injector housing 2200. The distal injector housing 2200is positioned outside the resetting sleeve 1200 at the distal end 1004 of the auto injector 1000.The distal injector housing 2200 is extending from a proximal end 2202 to a distal end 2204.25 The distal injector housing 2200 has a cylindrical shape. In the shown example, the injectorhousing has a non-circular elliptic cylindrical shape. Alternative shapes, such as round,squared, triangular cylindrical shapes, or similar could also be imagined. On an inner surface2205 of the distal injector housing 2200 is found the number of inner resetting sleeve lockingparts 2209 for rotationally locking the resetting sleeve 1200 and the distal injector housing30 2200. On an outer surface 2208 of the distal injector housing 2200 are user grip lines 2206,which makes it easier for the user to hold and operate the auto injector 1000.The distal injector housing 2200 comprises a distal injector housing plate 2212 at the distalend 2204. On the distal injector housing plate 2212 of the distal injector housing 2200 is a35 rotational stop surface 2210. When the plunger rod resetting part 1026 comes in contact withthe rotational stop surface 2210 further relative rotation of the plunger rod 1020 and theresetting sleeve 1200, rotationally locked to the distal injector housing 2200, is prevented. TheWO 2025 / 109058 PCT / EP2024 / 08308933plunger rod resetting part 1026 comes in contact with the rotational stop surface 2210 afterthe plunger rod resetting part 1026 has moved along the resetting thread 1206. This is shownin figures 17B-C.5 Normally, there will be two sets of resetting thread 1206 and rotational stop surface 2210 onthe inner surface 1205 of the resetting sleeve 1200 and the distal injector housing plate 2212of the distal injector housing 2210. When two sets of resetting thread 1206 and rotational stopsurface 2210 are used, the relative rotation between the plunger rod resetting part 1026 andthe resetting thread 1206 will normally be approximately 180 degrees. If only one set of10 resetting thread 1206 and rotational stop surface 2210 is used, the relative rotation betweenthe plunger rod resetting part 1026 and the resetting thread 1206 may be larger, such as upto 360 degrees. Multiple rotational rounds could also be imagined.On the distal injector housing plate 2212 there are also plunger rod support part alignment15 tabs 2214, which rotationally and axially aligns the distal injector housing 2200 and the plungerrod support part 1300.Figures 4A-B show the plunger rod 1020 as seen from two different directions. The plungerrod extends from a proximal end 1022 to a distal end 1024. At the distal end 1024 is found the20 two plunger rod resetting parts 1026, which each travels along one of the two resetting threads1206 inside the resetting sleeve 1200 when the two parts rotate relatively. The plunger rodresetting parts 1026 are two pin parts positioned opposite another. Other configurations couldalso be imagined.25 The plunger rod 1020 has a plunger rod cavity 1030 (see figure 1B and figures 19A-l). Thus,the plunger rod 1020 is hollow. Inside the plunger rod cavity 1030 is found the drive spring1040.The plunger rod 1020 comprises a number of outer protrusions. The number of outer30 protrusions includes a pullback part stop part 1021 on the outside surface 1031 of the plungerrod 1020. A distally directed surface 1023 on the pullback part stop part 1021 engages aplunger rod engagement surface 1608 on the pullback part 1600 when the user resets theauto injector 1000 after medicament delivery by rotation of the resetting sleeve 1200 therebymoving the plunger rod 1020 and the pullback part 1600 distally.35The number of outer protrusions also includes a number of plunger rod tabs 1027 located onthe outside surface 1031 of the plunger rod 1020. The plunger rod tabs 1027 have a slopingWO 2025 / 109058 PCT / EP2024 / 08308934distal surface 1028 and a steep proximal surface 1029. The steep proximal surface 1029 onthe most proximally positioned plunger rod tab 1027a engages a plunger rod release tab 1310on the plunger rod support part 1300 when the auto injector 1000 is in an initial position readyfor receiving the cassette 100. This ensures that the plunger rod 1020 and the plunger rod5 spring 1040 are not allowed to move proximally for medicament delivery before the userinitiates medicament delivery. The initiation of medicament delivery — and thereby release ofthe plunger rod 1020 and the drive spring 1040 allowing the drive spring 1040 to expands / decompress thereby pushing the plunger rod 1020 in the proximal direction — is done by theuser pressing the cassette 100 against the injection site. This presses the injector skin sensor10 detector 1700 distally bringing a distal release end surface 1709 on the injector skin sensordetector 1700 into contact with the plunger rod release tab 1310. The distal release endsurface 1709 pushes the plunger rod release tab 1310 radially outwardly whereby contact withthe plunger rod tab 1027a is no longer present. The release of the plunger rod 1020 by theinjector skin sensor detector 1700 is shown in details in figures 20A-B.15The remaining plunger rod tabs 1027b ensures that if stopping mid medicament delivery, theplunger rod 1020 does not continue its movement to the most proximal position for fullmedicament delivery. Early lift of the cassette 100 from the injection site will result in theinjector skin sensor detector 1700 being pushed in the proximally due to the spring force of20 the injector skin sensor detector spring 1710. When the injector skin sensor detector 1700moves proximally, the distal release end surface 1709 no longer keeps the plunger rod releasetab 1310 flexes radially outwardly. This allows the plunger rod release tab 1310 to stop themovement of the plunger rod 1020, by coming into contact with one of the other plunger rodtabs 1027b. See also figures 19H-I.25The number of outer protrusions further includes a longitudinally extending bar 1033 locatedon the outside surface 1031 of the plunger rod 1020. The longitudinally extending bar 1033prevents distal movement of the cassette activation part 1500 after positioning a cassette 100in the auto injector 1000 as described in further details in figures 21A-D.30Figure 5 shows a closeup view of the drive spring 1040. The drive spring 1040 extends froma proximal end 1042 to a distal end 1044. The drive spring 1040 is adapted for moving theplunger rod 1020 in a proximal direction during medicament delivery. When the drive spring1040 is in a compressed state, it is confined inside the plunger rod cavity 1030 (see figure 1B35 and figures 19A-l). When the compressed drive spring 1020 relaxes, it pushes the plunger rod1020 in the proximal direction resulting in the distal end 1044 of the drive spring 1044extending outside the plunger rod 1020 at the distal end 1024 of the plunger rod 1020.WO 2025 / 109058 PCT / EP2024 / 08308935Inside the plunger rod cavity 1030, the proximal end 1042 of the drive spring 1040 abuts aspring proximal end surface 1032 (see figure 1B). The distal end 1044 of the drive spring 1040abuts a spring distal end surface 1056 located at a distal end 1054 of the drive spring guide5 1050 (see figure 1B and figure 6). The drive spring guide 1050 is shown in a closeup view inFigure 6. The drive spring guide 1050 extends from a proximal end 1052 to the distal end1054. The drive spring guide 1050 comprises a spring guide rod 1058 extending from theproximal end 1052 of the drive spring guide 1050 to the spring distal end surface 1056. Thedrive spring 1040 is positioned around the spring guide rod 1058 (see figure 1B).10Figures 7A-B show the plunger rod support part 1300 from two different directions. The plungerrod support part 1300 extends from a proximal end 1302 (view from proximal end in figure 7A)to a distal end 1304 (view from distal end in figure 7B). The plunger rod support part 1300 ispositioned between the plunger rod 1020 and a tubular chassis part 1401 of the chassis sleeve15 1400.At the distal end 1304 of the plunger rod support part 1300 is support part end plate 1303. Thedistal end 1054 of the drive spring guide 1050 is secured in a spring guide connecting opening1301 in the support part end plate 1303. From the support part end plate 1303, a first20 proximally extending arm 1305 and a second proximally extending arm 1308 are extending.On the first proximally extending arm 1305 is plunger rod support bar 1306 and a cassetteactivation part stop protrusion 1307. The plunger rod support bar 1306 supports and guidesthe plunger rod 1020 by its abutment with the longitudinally extending bar 1033 on the plunger25 rod 1020.Together with the longitudinally extending bar 1033 on the plunger rod 1020 and a distal endprotrusion 1510 on the cassette activation part 1500, the cassette activation part stopprotrusion 1307 prevents distal movement of the cassette activation part 1500 after positioning30 —_ a cassette 100 in the auto injector 1000. This is described in further details in figures 21A-D.On the second proximally extending arm 1308, there is a flexible side arm 1309, which is ableto flex radially outwardly. The flexible side arm 1309 comprises the plunger rod release tab1310 which abuts the steep proximal surface 1029 on the most proximally positioned plunger35 rod tab 1027a on the plunger rod 1020 prior to activation of the auto injector 1000. When theinjector skin sensor detector 1700 is pushed distally by the skin sensor 400 in the cassette100 (see figures 19A-G), the distal release end surface 1709 of the injector skin sensorWO 2025 / 109058 PCT / EP2024 / 08308936detector 1700 abuts the plunger rod release tab 1310 and causes the flexible side arm 1309to flex radially outwardly. When the flexible side arm 1309 flexes radially outwardly, the plungerrod release tab 1310 no longer abuts the steep proximal surface 1029 on the most proximallypositioned plunger rod tab 1027a on the plunger rod 1020. This allows the compressed drive5 spring 1040 to relax thereby forcing the plunger rod 1020 in the proximal direction formedicament delivery.At the proximal end 1302 of the plunger rod support part 1300 is a proximal protruding part1311. The proximal protruding part 1311 and a support part lock tab 1511 on the cassette10 activation part 1500 interact for locking the plunger rod support part 1300 in position prior tomounting of the cassette 100 in the auto injector 1000. The support part lock tab 1511 ispositioned against the distal end of the proximal protruding part 1311 on the plunger rodsupport part 1300. The proximal protruding part 1311 is positioned on a proximal flexible part1312 of the first proximally extending arm 1305. When a release surface 1806 on the cassette15 detector 1800 is pushed against the proximal protruding part 1311, the proximal flexible part1312 flexes radially, thereby releasing the cassette activation part 1500. This allows for lockingof the cassette 100 in the auto injector 1000 by proximal movement of the cassette activationpart 1500. See further specification for the situation where the user tries to insert a usedcassette in the auto injector 1000 in connection with figure 14.20Figures 8A-B shows the pullback part 1600 from two different directions. The pullback part1600 is extending from a proximal end 1602 to a distal end 1604. The pullback part 1600extends along the longitudinal direction L with a step type bend 1605 along the direction witha part extending in the radial direction. The pullback part 1600 has cassette activation part tab25 surfaces 1606 adapted for holding pullback interacting tabs 1506 on the cassette activationpart 1500 (see figures 10A-C and figures 19A-H). The pullback part 1600 is tillable relative tothe cassette activation part 1500 around connecting points constituting a cassette activationpart tab surface 1606 and a pullback interacting tab 1506.30 The pullback part 1600 comprises the plunger rod engagement surface 1608 at the distal end1604 of the pullback part 1600. The plunger rod engagement surface 1608 comes in contactwith the pullback part stop part 1021 on the plunger rod 1020 when the plunger rod 1020moves distally upon resetting of the auto injector 1000. This moves the pullback part 1600 andthe cassette activation part 1500 distally (see further description of the movement of the35 pullback part 1600 and the cassette activation part 1500 in connection with figures 10A-C).WO 2025 / 109058 PCT / EP2024 / 08308937The pullback part 1600 further comprises a cassette interacting tab 1601. The cassetteinteracting tab 1601 (and the pullback part 1600) is movable in the longitudinal direction Lbetween a proximal cassette locking position PP and a distal cassette release position PD(see figures 19A-B). Prior to receiving a cassette 100 in the reusable auto injector 1000, the5 cassette interacting tab 1601 is in the distal cassette release position PD.The cassette interacting tab 1601 is shown as being positioned on the pullback part 1600, butcould also be integrated into the cassette activation part 1500 instead.10 The pullback part 1600 and / or the cassette activation part 1500 may comprise a secondcassette interacting tab 1611 (see figures 32A-D) for structural stability.The cassette interacting tab 1601 is movable in the radial direction by the user pressing thecassette interacting tab 1601 downwards. This is due to the interaction with a flexible pullback15 arm 1507 on the pullback part 1500 (see figures 10A-C and figures 19A-H) and the tiltingconnecting point constituting the cassette activation part tab surfaces 1606 and the pullbackinteracting tabs 1506. When the user presses the cassette interacting tab 1601 downwards,the cassette activation part 1600 and the pullback part 1500 can be moved in the proximaldirection. Doing so moves injector release members 1508 on the pullback part 1500 into the20 cassette 100 for activation of the cassette 100 as described in connection with figures 19A-H,figures 26A-I, and figures 27A-I.Figures 9A-B show the chassis sleeve 1400. The chassis sleeve 1400 extends from a proximalend 1402 to a distal end 1404. Figure 9A shows the chassis sleeve 1400 from the proximal25 end 1402 and figure 9B shows the chassis sleeve 1400 from the distal end 1404.The chassis sleeve 1400 comprises a tubular chassis part 1401. The tubular chassis part 1401is positioned between the plunger rod 1020 and the resetting sleeve 1200.30 The tubular chassis part 1401 comprises a longitudinally extending channel 1403. Normally,as shown in figures 9A-B, two longitudinally extending channels 1403 positioned opposite oneanother on the tubular chassis part 1401 are present in the tubular chassis part 1401. Theplunger rod resetting part 1026 travels in the longitudinal direction inside the longitudinallyextending channel 1403.35WO 2025 / 109058 PCT / EP2024 / 08308938On the inside of the tubular chassis part 1401, a plunger rod support part coupling surface1408 is also found. The proximally extending arms 1305, 1308 on the plunger rod support part1300 are extending inside the plunger rod support part coupling surface 1408.5 The chassis sleeve 1400 comprises a chassis sleeve plate 1407. Extending in the proximaldirection from the chassis sleeve plate 1407 is a distal skin sensor spring support rod 1405.The distal skin sensor spring support rod 1405 supports a distal end 1714 of the injector skinsensor detector spring 1710. The injector skin sensor detector spring 1710 can move in thelongitudinal direction relative to the chassis sleeve 1400. The injector skin sensor detector10 spring 1710 can thereby extend at least partly into the tubular chassis part 1401 when in adistal position.Extending in the proximal direction from the chassis sleeve plate 1407 is also a distal cassettedetector spring support rod 1406. The distal cassette detector spring support rod 140615 supports a distal end 1814 of the cassette detector spring 1810 (see figures 22A-C). Thecassette detector 1800 can move in the longitudinal direction relative to the chassis sleeve1400.Extending proximally from the chassis sleeve plate 1407 are coupling surfaces 1409. The20 outside 1413 of the coupling surfaces 1409 extend inside chassis sleeve channels 2108 onthe proximal injector housing 2100 (see figure 16). The inside 1414 of the coupling surfaces1409 contains the outer coupling surfaces 1108 on the cassette receiver 1100 (see figures15A-B).25 The chassis sleeve 1400 further comprises a number of resetting sleeve interacting tabs 1410on a proximal outside end of the tubular chassis part 1401. The resetting sleeve interactingtabs 1410 has on one side a sloping surface 1411 and on the other side a steep surface 1412.As described in connection with figure 2, during reloading of the auto injector 1000, theresetting sleeve 1200 is rotated in a first rotational direction DR1 relative to the chassis sleeve30 1400. This brings the chassis sleeve interacting hooks 1210 in contact with the resetting sleeveinteracting tabs 1410. The contact, when rotating in the first rotational direction DR1, isbetween the sloping surfaces 1211, 1411 on the chassis sleeve interacting hooks 1210 andthe resetting sleeve interacting tabs 1410. When the sloping surfaces 1211, 1411 coming intocontact with each other, the chassis sleeve interacting hooks 1210 flex radially outwardly35 allowing the resetting sleeve 1200 to continue its rotation. However, if rotating in a directionopposite the first rotational direction DR1, the steep surfaces 1212, 1412 on the chassis sleeveWO 2025 / 109058 PCT / EP2024 / 08308939interacting hooks 1210 and the resetting sleeve interacting tabs 1410 come into contact witheach other. This prevents further relative rotation between the two parts.Figures 10A-C show the cassette activation part 1500 seen from three different directions. The5 cassette activation part 1500 extends from a proximal end 1502 to a distal end 1504. Thecassette activation part 1500 comprises injector release members 1508 extending proximally.The cassette activation part 1500 are movable into the cassette 100 for activation of thecassette 100 as described in connection with figures 19A-H, figures 26A-l, and figures 27A-l.Each injector release members 1508 comprises a track-guide protrusion 1509 at the proximal10 end of the cassette activation part 1500. The cassette activation part 1500 also comprises theflexible pullback arm 1507 interacting with the pullback part 1600 when the user presses thecassette interacting tab 1601 radially inwards (see figures 8A-B and figure 19A).The pullback part 1600 is tillable relative to the cassette activation part 1500 around15 connecting points constituting a cassette activation part tab surface 1606 and a pullbackinteracting tab 1506. The pullback part 1600 is locked to the cassette activation part 1500 atthe connecting points constituting a cassette activation part tab surface 1606 and a pullbackinteracting tab 1506 such that the two parts 1500, 1600 move together in the longitudinaldirection L.20The cassette activation part 1500 also comprises a distal end protrusion 1510, which togetherwith the longitudinally extending bar 1033 on the plunger rod 1020 and the cassette activationpart stop protrusion 1307 on the plunger rod support part 1300 prevents distal movement ofthe cassette activation part 1500 after positioning a cassette 100 in the auto injector 1000 as25 described in further details in figures 21A-D and plunger rod 1020 movement in the proximaldirection for medicament delivery.The cassette activation part 1500 further comprises the support part lock tab 1511. Thesupport part lock tab 1511 locks the plunger rod support part 1300 in position prior to mounting30 of the cassette 100 in the auto injector 1000. The support part lock tab 1511 is positionedagainst the distal end of the proximal protruding part 1311 on the plunger rod support part1300.The cassette activation part 1500 further comprises a guiding tab 1512 that slides inside a35 chassis sleeve 1103 in the cassette receiver.WO 2025 / 109058 PCT / EP2024 / 08308940Figure 12 shows the injector skin sensor detector 1700 and figure 11 the injector skin sensordetector spring 1710. The injector skin sensor detector 1700 extends from a proximal end1702 to a distal end 1704. The injector skin sensor detector spring 1710 extends from aproximal end 1712 to a distal end 1714. The injector skin sensor detector 1700 comprises a5 proximal skin sensor spring support rod 1705. The proximal end 1712 of the injector skinsensor detector spring 1710 is positioned around the proximal skin sensor spring support rod1705. The injector skin sensor detector spring 1710 is thereby positioned between the proximalskin sensor spring support rod 1705 on the distal skin sensor spring support rod 1405 and thedistal injector skin sensor detector support rod 1405 on the chassis sleeve 1400.10Extending proximally from the proximal skin sensor spring support rod 1705 is an injector skinsensor detector pin 1703, which is configured for entering the cassette 100 and interactingwith the cassette skin sensor 400 as described in connection with figures 26A-l, figures 27A-|and figures 29A-G.15The injector skin sensor detector 1700 comprises a plate part 1706 with a plate part channel1707 allowing the plunger rod tabs 1027 on the plunger rod 1020 to pass by duringmedicament delivery and reloading of the auto injector 1000.20 Figure 14 shows the cassette detector 1800 and figure 13 shows the cassette detector spring1810. The cassette detector 1800 extends from a proximal end 1802 to a distal end 1804. Thecassette detector spring 1810 extends from a proximal end 1812 to a distal end 1814. At thedistal end 1804 of the cassette detector 1800 is a proximal cassette detector spring supportrod 1805. The proximal end 1812 of the cassette detector spring 1810 is positioned around25 the proximal cassette detector spring support rod 1805. The cassette detector spring 1810 isthereby positioned between the proximal cassette detector spring support rod 1805 on thecassette detector 1800 and the distal injector cassette detector spring support rod 1406 on thechassis sleeve 1400 (see figures 22A-C).30 Extending proximally is a cassette detector pin 1803, which is configured for entering into andinteracting with the cassette 100. The cassette detector 1800 further comprises the releasesurface 1806, which unlocks the cassette activation part. When the cassette 100 is inserted inthe auto injector 1000, the release surface 1806 on the cassette detector 1800 is in contactwith the proximal protruding part 1311 on the plunger rod support part 1300 (see figure 22A).35 The cassette detector 1800 detects that a cassette 100 is positioned in the auto injector 1000when the cassette detector pin 1803 comes in contact with a proximal end 422 of a skin sensor400 in the cassette 100. This contact result in the cassette detector 1800 being pushed distally.WO 2025 / 109058 PCT / EP2024 / 08308941Thereby, the release surface 1806 is pushed against the proximal protruding part 1311 on theplunger rod support part 1300. The proximal flexible part 1312 flexes radially inwardly as aconsequence thereof, thereby releasing the cassette activation part 1500 from the plunger rodsupport part 1300 (see figure 22C). This allows for locking of the cassette 100 in the auto5 injector 1000 by further proximal movement of the cassette activation part 1500 (see figures26A-I and figures 27A-l).If a used cassette is inserted into the auto injector 1000, the cassette detector pin 1803 is notpushed distally by the proximal end 422 of the skin sensor 400 since the skin sensor is locked10 in a position being so proximal compared to the skin sensor position in a new cassette thatpushing the cassette detector pin 1803 distally is impossible. The cassette activation part 1500is therefore not released from the plunger rod support part 1300, and the used cassette is notlocked in the auto injector 1000 (see figure 22B).15 Figures 15A-C show the cassette receiver 1100. The cassette receiver 1100 extends from aproximal end 1102 to a distal end 1104. The cassette receiver 1100 comprises a tubular part1101 at its proximal end 1102. The cassette 100 is inserted inside the tubular part 1101 of thecassette receiver 1100 when received in the auto injector 1000. Inside the tubular part 1101are cassette locking parts 1109 for securing the cassette 100 inside the auto injector 1000 as20 described in figures 24A-E.Distally of the tubular part 1101 is a cassette receiver end plate 1110 against which thecassette 100 is positioned. Extending in the distal direction of the cassette receiver end plate1110 is a first spring support surface 1105 inside which the injector skin sensor detector spring25 1710 is positioned. The injector skin detector pin 1703 and the proximal skin sensor springsupport rod 1705 are further normally positioned inside the first spring support surface 1105.Also extending in the distal direction of the cassette receiver end plate 1110 is a second springsupport surface 1106 inside which the cassette detector spring 1810 is positioned. Themajority of the cassette detector 1800 is further normally positioned inside the second spring30 support surface 1106.The cassette receiver 1100 is positioned inside the proximal injector housing 2100 (see figure1B, and figure 16). Between the cassette receiver 1100 and the proximal injector housing 2100is the chassis sleeve 1400. The proximal injector housing 2100 and the cassette receiver 110035 are rotationally fixed by mutual interaction with the chassis sleeve 1400. The outer couplingsurfaces 1108 extends inside 1414 the coupling surfaces 1409 on the chassis sleeve 1400,WO 2025 / 109058 PCT / EP2024 / 08308942and the outside 1413 of the coupling surfaces 1409 extends inside the chassis sleevechannels 2108 of the proximal injector housing 2100.The cassette receiver 1100 comprises an activation part channel 1107 through which the5 cassette interacting tab 1601 extends.The cassette receiver end plate 1110 has a number of openings including a plunger rodopening 1120 through which the plunger 1020 can extend for medicament delivery. Theinjector skin sensor detector pin 1703 can extend into the cassette 100 through an injector10 skin sensor detector opening 1115 in the cassette receiver end plate 1110. The cassettedetector pin 1803 can extend into the cassette 100 through a cassette detector opening 1116in the cassette receiver end plate 1110. The injector release members 1508 can extend intothe cassette 100 through injector release member openings 1118 in the cassette receiver endplate 1110.15Figure 16 shows the proximal injector housing 2100. The proximal injector housing 2100extends from a proximal end 2102 to a distal end 2104. At the proximal end 2102, the proximalinjector housing 2100 comprises a first tubular part 2101 with a cassette view opening 2106through which the cassette 100 can be seen. At the distal end 2104, the proximal injector20 housing 2100 comprises a second tubular part 2109. The second tubular part 2109 comprisesa second activation part channel 2107 through which the cassette interacting tab 1601extends. Inside the second tubular part 2109 is chassis sleeve channels 2108 in which theoutside 1413 of the coupling surfaces 1409 on the chassis sleeve 1400 are found. In the shownexample, the first tubular part 2102 and the second tubular part 2109 have non-circular25 cylindrical shapes. Alternative shapes, such as round, elliptical, squared, triangular cylindricalshapes, or similar could also be imaginedFigure 17A shows the plunger rod 1020 and the resetting sleeve 1200 during a resetting ofthe auto injector 1000 by rotation of the resetting sleeve 1200, where the plunger rod resetting30 part 1026 travels along the resetting thread 1206 in the resetting sleeve 1200.In figures 17B-C, the distal injector housing 2200 is shown together with the plunger rod 1020and the resetting sleeve 1200 in a view from the proximal direction. After end resetting in figure17C, the plunger rod resetting part 1026 abuts the rotational stop surface 2210 on the distal35 injector housing plate 2212 of the distal injector housing 2200. This prevents further rotationalmovement of the resetting sleeve relative 1200 relative to the plunger rod 1020 since theresetting sleeve 1200 is rotationally locked to the distal injector housing 2200. The plunger rodWO 2025 / 109058 PCT / EP2024 / 08308943resetting part 1026 comes in contact with the rotational stop surface 2210 after the plungerrod resetting part 1026 has moved along the resetting thread 1206.Figures 18A-E show the resetting of the auto injector 1000 by rotation of the resetting sleeve5 1200. The resetting sleeve 1200 is shown in a view partly showing the inside the auto injector1000 during resetting. The movement of the plunger rod resetting part 1026 when rotating thedistal injector housing 2200, and also the resetting sleeve 1200 rotationally locked thereto,forces the plunger rod 1020 to move distally due to the interaction of the plunger rod resettingpart 1026 with the resetting thread 1206. In figure 18D, the plunger rod resetting part 102610 abuts the rotational stop surface 2210 inside the distal injector housing 2200 therebypreventing further rotational movement of the resetting sleeve 1200 and the distal injectorhousing 2200 relative to the plunger rod 1020.Figures 19A-G show cut-throughs of the auto injector 1000 during a process of receiving a15 cassette, unlocking of the cassette, whereby the plunger rod can be unlocked, duringmedicament delivery and during resetting of the auto injector after medicament delivery. Thecassette has been omitted in figures 19A-G for a clearer view of the injector parts.Figure 19A shows auto injector 1000 in the configuration prior to receiving the cassette. In20 figure 19B, a cassette has been received in the auto injector 1000 and the cassette interactingtab 1601 has been pressed radially inwardly and in the proximal direction, whereby the injectorrelease members 1508 have been moved proximally. This locks the cassette in the autoinjector 1000. Along with the injector release member 1508, the injector skin sensor detectorpin 1703 also moves proximally. The injector skin sensor detector pin 1703 thereby comes25 into contact with a skin sensor 400 in the cassette 100. In the locked position shown in figure19B, a cap 700 on the cassette (see figures 30A-D) can be removed. This unlocks the skinsensor 400 allowing it to move proximally (see figures 26A-I, figures 27A-I and figures 29AG).30 The removal of the cap 700 and the proximal movement of the skin sensor 400 in the cassette100 allows the injector skin sensor detector pin 1703 to move further proximally into thecassette 100 as shown in figure 19C. The auto injector and cassette system is now ready formedicament delivery.35 In figure 19D, the user has pressed the cassette against the injection site, which pushes theskin sensor 400 to a distal position also pushing the injector skin sensor detector pin 1703 intothe auto injector 1000. Pushing the injector skin sensor detector 1700 into the auto injectorWO 2025 / 109058 PCT / EP2024 / 083089441000 unlocks the plunger rod 1020 (see details in figures 20A-B). The plunger rod spring 1040therefore pushes the plunger rod 1020 in the proximal direction medicament delivery as shownin figure 19E.5 In figure 19F, the user has removed the cassette from the injection site after end medicamentdelivery, which allows injector skin sensor detector 1700 to push the skin sensor 400 to alocked proximal position (see figures 25A-B, figures 26A-l, figures 27A-I and figures 29A-G).The cassette can now be removed from the auto injector 1000.10 In figure 19G, the user has reloaded the auto injector 1000, which has retracted the cassetteactivation part 1500, the pullback part 1600 and the plunger rod 1020 and reloaded the plungerrod spring 1040.Figures 19H-I show the auto injector of figures 19A-G in a situation, where the user has15 interrupted the medicament delivery and removed the cassette and auto injector system fromthe injection site prior to completing the medicament delivery. The two views are cut-throughof the auto injector 1000 at two different angles. If the user has interrupted the medicamentdelivery mid-delivery, the skin sensor 400 in the cassette 100 is pushed forward to a lockedposition by the injector skin sensor detector 1700 of the auto injector 1000 due to the injector20 skin sensor spring 1710 pushing the injector skin sensor detector 1700 in the proximaldirection as shown in figure 19H. The proximal movement of the injector skin sensor detector1700, secures the plunger rod 1020 in an intermediate position. When the injector skin sensordetector 1700 moves proximally, the distal release end surface 1709 no longer keeps theplunger rod release tab 1310 flexes radially outwardly. This allows the plunger rod release tab25 1310 to stop the movement of the plunger rod 1020, by coming into contact with one of theplunger rod tabs 1027b. This ensures that if stopping mid-delivery, the plunger rod 1020 doesnot continue its proximal movement to the most proximal position for full medicament delivery.The remaining medicament is thereby kept in the now locked cassette. The cassette can beremoved from the auto injector 1000 during resetting of the auto injector 1000.30Alternatively, the cassette interacting tab may be moved from the proximal cassette lockingposition PD to the distal cassette release position PP prior to resetting the auto injector. Thismay seem more natural for the user wanting to remove and discharge of the cassette beforeresetting the auto injector. The movement of the cassette interacting tab from the proximal35 cassette locking position PD to the distal cassette release position PP may be user controlledby movement of e.g. the cassette interacting tab.WO 2025 / 109058 PCT / EP2024 / 08308945Figure 20A-B show the unlocking of the plunger rod 1020 by the user pushing the injector skinsensor detector 1700 into the auto injector 1000 after cap removal. Figure 20A-B are close-upviews of the area M marked with the dotted square in figure 19D. When the injector skin sensordetector 1700 is pushed distally, the distal release end surface 1709 on the injector skin sensor5 detector 1700 abuts the plunger rod release tab 1310 and causes the flexible side arm 1309to flex radially outwardly. When the flexible side arm 1309 flexes radially outwardly, the plungerrod release tab 1310 no longer abuts the plunger rod tabs 1027a on the plunger rod 1020.This allows the compressed drive spring 1040 to relax thereby forcing the plunger rod 1020 inthe proximal direction for medicament delivery. The movements are indicated with the arrows.10 Figure 19E shows the movement the plunger rod 1020 in the proximal direction medicamentdelivery after release of the plunger rod 1020.Figures 21A-D show the interaction of the longitudinally extending bar 1033 on the plunger rod1020, the distal end protrusion 1510 on the cassette activation part 1500, and the cassette15 activation part stop protrusion 1307 on the plunger rod support part 1300. This interactionensures that the cassette activation part 1500 cannot move distally during medicamentdelivery. In figure 21A is shown the auto injector 1000 prior to a cassette 100 being insertedin the auto injector 1000. The cassette activation part 1500 is still in the distal cassette releaseposition PD. The distal end protrusion 1510 is positioned between the plunger rod support bar20 1306 and the cassette activation part stop protrusion 1307 in the initial position prior topositioning a cassette 100 in the auto injector 1000. In figure 21B, the cassette activation part1500 has been moved to the proximal cassette locking position PP locking the cassette 100in the auto injector 1000. The injector release members 1508 now extend into the cassette100 (not shown in the figures). In this position, the distal end protrusion 1510 on the cassette25 activation part 1500 is allowed to flex radially inwardly and move to a position proximally of thecassette activation part stop protrusion 1307 on the first proximally extending arm 1305. Infigure 21C, the plunger rod 1020 has been releases and now moves proximately formedicament delivery. This moves the longitudinally extending bar 1033 on the plunger rod1020 to a proximal position in contact with the distal end protrusion 1510 preventing the distal30 end protrusion 1510 from flexing inwardly. The distal end protrusion 1510 is thereby preventedfrom moving distally by the longitudinally extending bar 1033 and the cassette activation partstop protrusion 1307. In figure 21D, medicament delivery has finalized and the plunger rod1020 is in the most proximal position. The distal end protrusion 1510 is still prevented frommoving distally until auto injector 1000 has been reloaded and the plunger rod 1020 retracted35 distally.WO 2025 / 109058 PCT / EP2024 / 08308946Figures 22A-C show the cassette detector 1800 and cassette 100 interaction for locking thecassette 100 in the auto injector 1000. When the cassette 100 is inserted in the auto injector1000, the release surface 1806 on the cassette detector 1800 is in contact with the proximalprotruding part 1311 on the plunger rod support part 1300. The cassette detector pin 18035 extends proximately through the end plate 1110 in the cassette receiver 1100 as shown infigure 22A.The cassette detector 1800 detects that a cassette 100 is positioned in the auto injector 1000when the cassette detector pin 1803 comes in contact with a proximal end 422 of a skin sensor10 400 in the cassette 100. This contact result in the cassette detector 1800 being pushed distallyas shown in figure 22C. Thereby, the release surface 1806 is pushed against the proximalprotruding part 1311 on the plunger rod support part 1300. The proximal flexible part 1312flexes radially inwardly as a consequence thereof, thereby releasing the cassette activationpart 1500 from the plunger rod support part 1300. This allows for locking of the cassette 10015 in the auto injector 1000 by further proximal movement of the cassette activation part 1500.If a used cassette is inserted into the auto injector 1000, the cassette detector pin 1803 is notpushed distally by the proximal end 422 of the skin sensor 400 (see figure 23), since the skinsensor is locked in a position being so proximal compared to the skin sensor position in a new20 cassette that pushing the cassette detector pin 1803 distally is impossible as shown in figure22B. The cassette activation part 1500 is therefore not released from the plunger rod supportpart 1300, and the used cassette is not locked in the auto injector 1000.Figure 23 shows an exploded view of a cassette 100 extending along a longitudinal direction25 L, and a syringe 200 for being mounted in the cassette 100. The cassette comprises a syringeholder 300, a skin sensor 400, an index ring 500, a cassette housing 600, a cap 700, andpossibly a cassette housing cover 800. The cassette housing cover 800 may be formed as anintegral part of the cassette housing 700.30 The syringe 200 extends from a proximal end 202 to a distal end 204. At the distal end 202 ofthe syringe 200 is a flange 220, which assists in securing the syringe 200 inside the cassette100. The medicament is contained inside a syringe compartment 206, which is in fluidconnection with a syringe outlet 208 (see figures 30A-D). Inside the syringe compartment 206is a stopper 210 (see figure 28B), which pushes medicament out of the syringe outlet 20835 when moving in the proximal direction. Normally, the stopper 210 is pushed in the proximaldirection by means of a plunger rod 1020 included in the auto injector 1000 into which thecassette 100 with the syringe 200 is mounted.WO 2025 / 109058 PCT / EP2024 / 08308947The syringe outlet 208 may be a hollow needle attached to the syringe compartment 206 asshown in figures 30A-D. The needle 208 may be detachable to the syringe compartment bymeans or e.g. threaded connection or a Luer lock, or be an integral part of the syringe. The5 syringe compartment 206 has a shoulder 218 at its proximal connecting to the syringe outlet208. Positioned around the syringe shoulder 218 is a needle shield 212, e.g. a rigid needleshield. The needle shield 212 may be constructed from two parts; an inner part and an outerpart. The needle shield 212 protects the needle prior to use.10 The syringe holder 300 is extending from a proximal end 302 to a distal end 304 and is hasopenings 306, 315 at both of these ends 302, 304. The syringe 200 is mounted in the syringeholder 300 through the opening 315 at the distal end 304 of the syringe holder 300. Whenmounted in the syringe holder 300, the syringe compartment 206 is contained in a syringeholder tubular part 310 having a syringe holder tubular part inspection opening 312 through15 which the syringe 200 can be inspected. At the distal end 304 of the syringe holder 300 is adistal tubular ring part 314 having a larger outer diameter than that of the syringe holder tubularpart 310. At the most distal end, there is a hinged syringe holder lid 330 with a lid opening 332having a diameter, which allows passage of the plunger rod 1020 included in the auto injector1000 there through. The syringe holder lid 330 is closed during assembly when a syringe 20020 has been inserted into the cassette 100. The shown syringe lid 330 is just one example of away to close the syringe holder 300 and secure the syringe 200 inside the syringe holder 300.A number of different ways to secure the syringe 200 inside the syringe holder 300 may alsobe imagined. For example, the syringe holder lid 330 may be substituted with flexible arms,which flex inwardly to secure the syringe 200 after mounting of the same in the syringe holder25 300. The proximal opening 306 in the syringe holder 300 has a diameter, which allows theneedle shield 212 to pass there through, but which prevents the syringe compartment 206 topass there through.The cassette housing 600 extends from a proximal end 602 to a distal end 604 and has an30 opening 606 at the distal end 602 through which the index ring 500, the skin sensor 400, andthe syringe holder 300 is mounted. When the cassette 100 is assembled, the cassette housing600 at least partly if not fully encloses the syringe holder 300, the syringe 200 when positionedin the syringe holder 300, the skin sensor 400, and the index ring 500. The syringe holder 300will normally be longitudinally and rotationally locked to the cassette housing 600. The cassette35 housing 600 has an inspection opening 610 on at least one surface side allowing the user toinspect the syringe compartment 206 containing the medicament when the syringe 200 ismounted inside the cassette 100. The cassette 100 may be symmetrically constructed suchWO 2025 / 109058 PCT / EP2024 / 08308948that it may be mounted in an auto injector in different orientations. At the distal end of thecassette housing, cassette securing tabs 612 are positioned. The locking mechanism forlocking the cassette 100 in the auto injector 1000 is shown and described in figures 24A-E.5 The cassette cap 700 is removably attached to the cassette housing 600 at the proximal end602 of the cassette housing 600. The cassette cap 700 comprises an inner cassette cap part714 with second distally extending part 710 in the form of a tubular cap part, which isconfigured for griping the needle shield 212 by means of e.g. a gripping portion 712. Whenremoving the cassette cap 700, the needle shield 212 is also removed allowing for medicament10 delivery. Enclosing the inner cassette cap part 714 is an outer cassette cap part 716, whichthe user can hold when removing the cassette cap 700. The inner and the outer cassette capparts 714, 716 may also be formed as one integral item. On the inner cassette cap part 714 isalso found a cap locking part 706 with a cassette cap locking protrusion 708. The cap lockingpart 706 with the cassette cap locking protrusion 708 ensures that the cassette cap 700 is15 firmly secured to the cassette housing 600 before enabling the cassette 100 for cassette capremoval.Positioned around the syringe holder 300 is a skin sensor 400, which extends from a proximalend 402 to a distal end 404. At the proximal end 402 of the skin sensor 400 is a proximal skin20 contact surface 405, which rest against the skin of the patient during medicament delivery. Atthe proximal end 402 is also a proximal recess 406 in which the cassette cap locking protrusion708 of the cassette cap 700 is secured prior to assembling the cassette 100 in the auto injector1000 and initiation release of the cassette cap 700. The proximal recess 406 is adjacent to aprotruding tab 408 connected by a proximal protruding ramp 410 as more clearly seen in25 figures 30A-D.The skin sensor 400 has a tubular skin sensor part 420 from where cassette skin sensor pins422 extends in the distal direction. The tubular skin sensor part 420 has an inspection opening426 for inspection of the syringe 200. The skin sensor 400 is normally symmetrically with a30 cassette skin sensor pin 422 on both sides of the skin sensor 400 and inspection openings426 on both sides as well.The skin sensor 400 is rotationally locked relative to the syringe holder 300. The skin sensor400 is movable relative to the syringe holder 300 in the longitudinal direction L. The skin sensor35 400 may move relative to the syringe holder 300 between a plurality of longitudinal positionsincluding at least a proximal longitudinal position LP and a distal longitudinal position LD. Asseen in figure 25A, three proximal positions LP are present apart from the distal position LD.WO 2025 / 109058 PCT / EP2024 / 08308949The three proximal positions LP include an initial locked position LP1, an intermediate positionLP2, and a final locked position LP3. The proximal positions LP are all positions, where theskin sensor 400 covers the syringe outlet 206 when a syringe 200 is mounted in the cassette100, whereas the syringe outlet 206 is exposed when the skin sensor 400 is in the distal5 longitudinal position LD. The proximal positions LP1, LP2, LP3 may be positions in which theskin sensor 400 is locked relative to the syringe holder 300 in at least one longitudinal direction.Thus, in a locked position, proximal and / or distal movement of the skin sensor 400 relative tothe syringe holder 300 is prevented. Whether the position is a locked position or not isdetermined by the rotational position of the index ring 500, as the skin sensor 400 and the10 index ring 500 are coupled such the rotation of the index ring 500 locks and / or releases theskin sensor 400 for longitudinal movement in either the proximal and / or the distal direction.The skin sensor 400 also has a first locking recess 412 and a second locking recess 414 forinteracting and coupling with the index ring 500. Between the two locking recesses 412, 41415 is a first locking tab 413 and distally of the second locking recess 414 is a second locking tab415. The second locking tab 415 is longer than the first locking tab 413. The distally directedsurface of the second locking tab 415 is referred to as the first distal surface 416. The skinsensor 400 also comprises a proximally directed surface referred to as the first proximalsurface 418. The first proximal surface 418 is proximally of the first locking recess 412.20The index ring 500 extends from a proximal end 502 to a distal end 504. The index ring 500 ispositioned around the syringe holder 300 and is longitudinally locked to the syringe holder 300.The index ring 500 is rotationally movable relative to the skin sensor 400 / the syringe holder300 between a plurality of rotational positions including at least a first rotational position R1 in25 which the skin sensor 400 is prevented from moving distally, and a second rotational positionR2 in which the skin sensor 400 is moveable between the distal longitudinal position LD andthe proximal longitudinal position LP. The rotational positions are illustrated in figure 25B, andas seen in the figure, the two rotational positions; the cap-release rotational position and thedelivery rotational position both fall under the definition of a second rotational position R2 in30 which the skin sensor 400 is moveable between the distal longitudinal position LD and theproximal longitudinal position LP (see also the positions in figures 26B-E)The index ring 500 has two first longitudinally extending part 506 positioned opposite eachother on the index ring 500. A tubular index ring part 520 on the index ring 500 is extending35 around the syringe holder 300. The index ring 500 comprises a first radially extending part522, which may be part of the first radially extending part 522 as shown most clearly in figures26A-I. The first radially extending part 522 has a first surface area 528 extending between aWO 2025 / 109058 PCT / EP2024 / 08308950first proximal surface 524 and a first distal surface 526 (see e.g. figure 26H). The first surfacearea 528 comprises a track 530 extending from a first corner 532 of the surface area 528 toasecond corner 534 of the surface area 528 as shown in figure 26A. The surface area 528 onthe first racially extending part 522 need not cover the entire surface of the first radially5 extending part 522, but can instead be a smaller area, which is defined by the by the twocorners 532, 534 between which the track 530 extends.The track 530 extends from the first corner 532 in an angled direction towards the secondcorner 534, wherein the angled directions is between 20 and 70 degrees, such as between 3010 and 60 degrees, such as between 35 and 55 degrees, such as between 40 and 50 degrees,such as approximately 45 degrees relative to the longitudinal direction of the cassette. In thetrack 530m shown most clearly in figures 26A-I, the track 530 comprises a first track section536, a second track section 538 and a third track section 540. The first track section 536extends from the first corner 532 in a first angled direction towards a first middle point 542, the15 second track section 538 extends from the first middle point 542 to a second middle point 544along the longitudinal direction of the cassette in a second angle direction, and the third tracksection 540 extends from the second middle point 544 in a third angled direction towards thesecond corner 534, as shown most clearly in figure 26l.20 The first and / or third angled directions are normally sloping directions, with an angle between20 and 70 degrees, such as between 30 and 60 degrees, such as between 35 and 55 degrees,such as between 40 and 50 degrees, such as approximately 45 degrees relative to thelongitudinal direction of the cassette. The second track section 538 is normally a plateau tracksection with a second angled directions between -20 and 20 degrees, such as between -1025 and 10 degrees, such as approximately 0 degrees relative to the longitudinal direction of thecassette.On the first longitudinally extending part 506 of the index ring 500 is a second radiallyextending part 512. The second radially extending part 512 forms a locking tab 507, which is30 configured for fitting into the two locking recesses 412, 414 on the skin sensor 400. The lockingtab 507 has a second proximal surface 514 and a second distal surface 516 of the secondradially extending part 512.The position of the locking tab 507 and thereby the rotational position of the index ring 50035 relative to the skin sensor 400 is controlled by one or more injector release members 1508 inthe auto injector 1000 when the cassette 100 is secured in the auto injector 1000. Morespecifically, the index ring 500 is configured for rotating from the first rotational position R1 toWO 2025 / 109058 PCT / EP2024 / 08308951a second rotational position R2 when the cassette 100 is inserted in the auto injector 1000 anda track-guide protrusion 1509 comprised in the auto injector travels proximally inside the track530. When the track-guide protrusion 1509 travels distally again, the index ring 500 rotatesback form the second rotational position R2 to the first rotational position R1. Thus, by5 retrieving the injector release member 1508 with the track-guide protrusion 1509 into the autoinjector again, the index ring is rotated back to its initial position.As seen in figure 25B and figures 26B-E, the two rotational positions; the cap-release rotationalposition and the delivery rotational position both fall under the definition of a second rotational10 position R2 in which the skin sensor 400 is moveable between the distal longitudinal positionLD and the proximal longitudinal position LP. Thus, the second rotational position R2 need notbe a position from where the index ring 500 cannot rotate further. The second rotationalposition may also be an intermediate position in which the skin sensor 400 is unlocked, but inwhich the skin sensor 400 is still prevented from moving to the most proximal position and / or15 the most distal position possible.When assembling the cassette 100 and the auto injector 1000, the cassette 100 is first loadedinto the auto injector 1000. Upon loading of the cassette 100 in the auto injector 1000, cassettesecuring tabs 612 at the distal end 604 of the cassette housing 600 snap behind corresponding20 cassette locking parts 1109. By forward movement of the injector release member 1508, thecassette securing tabs 612 are prevented from deflecting and moving past the cassette lockingparts 1109 thereby locking the cassette 100 to the auto injector 1000. As the cassette 100 isnow firmly locked inside the auto injector 1000. When the injector release member 1508 movesdistally again, the cassette 100 is unlocked. The locking process is shown in figures 24A-E,25 where figures 24A-C show the cassette being inserted into the injector 1000 and engaging intoa snap fit connection. Figures 24D-E show the movement of the injector release member 1508into the cassette 100 thereby locking the cassette 100 to the injector 1000. Thus, the injectorcomprises one or more cassette locking parts 1109 configured for engaging in a snap-fitconnection with corresponding one or more cassette securing tabs 612 on the cassette 10030 when the cassette is inserted into the injector, and wherein proximal movement of the injectorrelease member 1508 prevents a disengagement of the snap-fit connection thereby securingthe cassette 100 inside the auto injector 1000. The locking mechanism shown in figures 24AE could alternatively be substituted with the similar locking turned 90 degrees.35 As described in connection with figures 10A-C, the auto injector 1000 comprises injectorrelease members 1508 each comprising a track-guide protrusion 1509. The injector releaseWO 2025 / 109058 PCT / EP2024 / 08308952member 1508 travels inside the index ring track 530 thereby rotating the index ring 500, whenthe auto injector is activated after a cassette 100 is mounted in the auto injector 1000.As described in connection with figure 11 and figure 12, the auto injector 1000 further5 comprises an injector skin sensor detector pin 1703 and an injector skin sensor detector spring1710, which pushes the injector skin sensor detector pin 1703 proximally. When the cassette100 is mounted in the auto injector 1000, the injector skin sensor detector pin 1703 will pushthe skin sensor 400 proximally when the skin sensor 400 is free to move proximally, and theuser is not pressing the skin sensor in the distal direction simultaneously. Normally, the injector10 skin sensor detector pin 1703 will be abutting one of the cassette skin sensor pins 422 in theskin sensor 400.As described in connection with figure 13 and figure 14, inside the auto injector 1000 is acassette detector 1800 and a cassette detector spring 1810, which detects when a cassette15 100 has been mounted in the auto injector 1000 by making contact with the other cassetteskin sensor pin 422 in the skin sensor 400.Figures 26A-I| show the syringe holder 300, the skin sensor 400, the index ring 500, and theinjector release member 1508 in the injector in the different skin sensor longitudinal positions20 and index ring rotational positions as the injector release member 1508 moves longitudinallyin the index ring track 530.Figure 26A shows the initial locked position in which the cassette 100 is in prior to use. Thelocking tab 507 on the index ring 500 is secured in the first locking recess 412 on the skin25 sensor 400, which prevents longitudinal movement of the skin sensor 400 relative to thesyringe holder 300. The skin sensor 400 is in the initial locked position LP1 and the index ring500 is in the first rotational position R1. The first rotational position may also be seen as alocking rotational position, since this rotational position always locks the skin sensor 400longitudinal in one of the proximal longitudinal positions.30Figure 26B shows the cap-release position in which the cassette cap 700 can be removedfrom the cassette 100 (see description of figures 30A-D for further details). Between figure26A and figure 26B, the auto injector track-guide protrusion 1509 on the injector releasemember 1508 has moved into the index ring track 530 through the injector release member35 opening 322 and into and along the first track section 536 and is in the second plateau tracksection 538 in figure 26B. This has rotated the index ring 500 into the cap-release rotationalposition Rer in which the locking tab 507 is released from the first locking recess 412 in theWO 2025 / 109058 PCT / EP2024 / 08308953distal direction allowing the skin sensor to move proximally until the locking tab 507 abuts thesecond locking tab 415, which is longer than the first locking tab 413 securing the locking tab507 inside the first locking recess 412 in figure 26A. figure 26B shows the position of the skinsensor 400 after release, but before the skin sensor 400 is moved from the initial locked5 position LP1 to the ready-to-remove-cap position LP2.In figure 26C, the skin sensor 400 has moved proximately to the intermediate position LP2,where the cassette cap 700 can be removed. The index ring 500 is still in the cap-releaserotational position Rer, and the locking tab 507 abuts the second locking tab 415, which10 ensures that the skin sensor 400 is prevented from moving further in the proximal directionduring cassette cap removal. The skin sensor 400 can however be moved in the distal directionby a user. This is shown in figure 26D, where the skin sensor is pushed into the distallongitudinal position LD where the needle 208 is no longer covered by the skin sensor 400 butinstead inserted into an injector site. A second proximal surface 514 on the second radially15 extending part 512 / locking tab 507 abuts a second distal surface 424 on the skin sensor 400therefore preventing further distal movement of the skin sensor 400.When the skin sensor 400 is pushed into the distal longitudinal position LD as shown in figure26D, the auto injector track-guide protrusion 1509 is ready to moved further proximally in the20 index ring track 530. When moving along the third track section 540, the index ring 500 isrotated to the delivery rotational position Rd as shown in figure 26E. When the auto injectortrack-guide protrusion 1509 reaches this position inside the index ring track 530, the injectorrelease member 1508 is decoupled from the plunger rod 1020. The plunger rod 1020 is therebyenabled for further proximal movement for medicament delivery while the injector release25 member 1508 remains in the position as shown in figure 26A.After medicament delivery, the user removed the skin sensor 400 from the skin and the injectorskin sensor detector pin 1703 and injector skin sensor detector spring 1710 ensures that theskin sensor 400 is pushed first into the intermediate position LP2 as shown in figure 26F and30 finally into the final position LP3 as shown in figure 26G. When the skin sensor 400 is the finalposition LP3 as shown in figure 26G, the plunger rod 1020 can be moved distally by resettingof the auto injector 1000. The plunger rod 1020 and the injector release member 1508 movestogether distally, which forces the index ring 500 to rotate from the delivery rotational positionRd into the first rotational position R1 again. When the index ring 500 is in the first rotational35 position R1 once more, the skin sensor 400 is locked longitudinally, this time in the finalposition LP3 as shown in figure 26H. The locking tab 507 now abuts a first distal surface 416on the second locking tab 415.WO 2025 / 109058 PCT / EP2024 / 08308954Figure 261 shows the locked position, which the auto injector forces the cassette into if a userhaving removed the cassette cap when the cassette was in a configuration as shown in figure26C, but for some reason have been prevented from continuing the medicament delivery5 process by inserting the needle into the injections site by pushing the skin sensor 400 distally.If this happens, the auto injector may be programmed to after a pre-determined time periodmove the injector release member 1508 distally, whereby the index ring 500 rotates into thefirst rotational position R1 thereby locking the skin sensor in the intermediate position LP2,where the locking tab 507 is secured in the second locking recess 414 on the skin sensor 400.10 The cassette 100 will be seen as being a used cassette if the user tries to mount it again theauto injector 1000, since the injection needle 208 may have been contaminated after removalof the needle shield 212 when removing the cassette cap 700.Figures 27A-| show a second example of the syringe holder 300, the skin sensor 400, the15 index ring 500, and the injector release member 1508 in the different skin sensor longitudinalpositions and index ring rotational positions as the injector release member 1508 moveslongitudinally in the index ring track 530. The positions which are shown are the same in thea-i figures for the examples shown in figure 26 and figure 27, i.e. figure 27A shows the initiallocked position in which the cassette 100 is in prior to use; figure 27B shows the cap-release20 position; figure 27C shows the skin sensor in the intermediate position LP2, where the cassettecap 700 can be removed; figure 27D shows the position, where the skin sensor is pushed intothe distal longitudinal position LD, but the index ring not completely rotated for delivery; figure27E shows the delivery position; figure 27F shows an intermediate position after delivery;figure 27G shows the final position LP3 before locking; and figure 27H shows the locked final25 position. figure 271 shows the locked position, which the auto injector forces the cassette intoif a user having removed the cassette cap when the cassette was in a configuration as shownin figure 27C, but for some reason have been prevented from continuing the medicamentdelivery process by inserting the needle into the injections site by pushing the skin sensor 400distally.30The differences between figures 26A-I and figures 27A-I are the design and form of the skinsensor 400 and the index ring 500. In figures 27A-I, the index ring 500 has a secondlongitudinally extending part 518 such that the longitudinal extending parts 516, 518 and theradially extending parts 512, 522 form a rectangle. Inside the rectangle on the first35 longitudinally extending part 506 is a first recess 508 and a second recess 510. Theserecesses are configured for containing a protruding tab 408 on the skin sensor 400. In theinitial locked position LP1 as shown in figure 27A, the protruding tab 408 is contained insideWO 2025 / 109058 PCT / EP2024 / 08308955the first recess 508. When the skin sensor 400 is in the intermediate position LP2, theprotruding tab 408 is either in the second recess 510 if the index ring is rotated to the firstrotational position as shown in figure 271, or above the second recess 510, but supported inthe proximal direction by the second distal surface 516 of the second radially extending part5 512 thereby preventing further proximal movement during cap removal as shown in figure 27C.When the delivery of medicament occurs, the index ring 500 is rotated such that the protrudingtab 408 is aligned with an opening 513 in the second radially extending part 512 such thatwhen the skin sensor 400 is removed from the injection site, the protruding tab 408 is allowedto pass through the opening 513 in the second radially extending part 512 to the most proximal10 position, i.e. the final position LP3. This alignment is shown in figures 27E-G. When the indexring 500 is rotated back to the first rotational position R1, the protruding tab 408 is abutting thesecond proximal surface 514 of the second radially extending part 512 preventing theexposure of the needle 208 after medicament delivery as shown in figure 27H.15 Figures 28A-C and figures 29A-I show a third example of the cassette, where figures 28A-Bshow the syringe holder 300, the skin sensor 400, the index ring 500, figure 28C shows thecassette housing 600, figures 29A-G show the syringe holder 300, the skin sensor 400, theindex ring 500, and the injector release member 1508 in the different skin sensor longitudinalpositions and index ring rotational positions as the injector release member 1508 moves20 longitudinally in the index ring track 530, and figures 29H-I show a cut-through of the cassettehousing 600 and the skin sensor 400 showing the skin sensor 400 in non-locked position(figure 29H) and the final position LP3 (figure 29l).The differences between figures 26A-l, figures 27A-l, figures 28A-C, and figures 29A-l, are the25 design and form of the skin sensor 400 and the index ring 500, the shape of the injector releasemember 1508 in the injector 1000, and the locking of the skin sensor 400 in the final lockedposition LP3. In the third example, the track 530 is positioned on the first longitudinallyextending part 506, which is attached to the tubular index part 520 on its outside. The track530 is an open track. On an inner surface of the longitudinally extending part 506 are a first30 recess 508’, a second recess 510’ and an index ring ramp 509 extending distally from the firstrecess 508’. The skin sensor 400 has a protruding tab 408, which is confined in the first recess508’ prior to us as shown in figure 29A. After the index ring 500 is rotated to the cap-releaserotational position Rer position as shown in figure 29B, the skin sensor 400 moves to the capremoval position shown in figure 29C. The cassette cap 700 and the needle shield 212 can be35 removed as shown in figure 29C. In the position shown in figure 29C, the protruding tab 408rest against the second distal surface 516 of the second radially extending part 512. Duringdistal movement of the skin sensor 400 by the user for insertion of the needle at the injectionWO 2025 / 109058 PCT / EP2024 / 08308956site, the index ring 500 is rotated to the delivery rotational position Rd as shown in figure 29D.Thus, in the third example shown in figures 28A-B and figures 29A-G, the injector releasemember 1508 is not the item rotating the index ring from the cap-release rotational positionRer to the delivery rotational position Rd, but instead the protruding tab 408 coming in contact5 with the index ring ramp 509 thereby forcing the index ring 500 to rotate. During medicamentdelivery as shown in figure 29E, the injector release member 1508 moves further into thecassette 100. After end medicament delivery, the skin sensor 400 moves to the final positionLP3 due to the spring force from the injector skin sensor spring system 1700, 1710 in theinjector 1000. This is shown in figure 29F. In the position shown in figure 29G, the skin sensor10 400 is in final locked position. In the final locked position LP3, the skin-sensor 400 is pushedproximally by a spring system as described in the previous examples of the cassette and autoinjector and locked into a locking position in the cassette housing 600. The locking is obtainedby a cassette housing locking protrusion 428 on the skin sensor 400 fitting into a skin sensorlocking opening 614 in the cassette housing 600 as shown in figure 291. In the position shown15 in figure 29H, the skin sensor 400 is in non-locked position. The skin sensor locking opening614 in the cassette housing 600 is visible most clearly in figure 28C.In figure 28A, an alternative securing of the syringe 200 inside the syringe holder 300 is alsoshown, where two flexible syringe securing tabs 320 moves from an open to a closed position20 securing the syringe 200 inside the syringe holder 300.Figures 30A-D show the removal of the cassette cap 700 from the cassette 100. The cassettecap 700 has locking cap parts 706 extending distally from a proximal end 702 of the cassettecap 700. Prior to use, a cassette cap locking protrusion 708 on each of the one or more locking25 cap parts 706 is secured inside the cassette housing 600 by a cap holding part 608, which isextending radially inwardly at the proximal end 602 of the cassette housing 600. At theproximal end 402 of the skin sensor 400, the skin sensor 400 has a ramp 410 and a recess406 positioned distally of the ramp 410. The ramp 410 normally forms a protruding tab 408.An inwardly extending part 709 of the cassette cap locking protrusion on each of the locking30 parts 706 are secured between the recess 406 of the skin sensor 400 and a cap holding part608, and is further abutting the proximal protruding ramp part 410 preventing proximalmovement of the cassette cap 600 prior to use as shown in figure 30A. This locks the cassettecap 700 to the cassette 100 and prevents that the cassette cap 700 is removed from thecassette 100 before the cassette 100 is assembled inside the auto injector 1000.35The cap locking parts 706 and / or the cassette cap locking protrusion 708 on each of the oneor more cap locking part 706 are flexible. Upon proximal movement of the skin sensor 400WO 2025 / 109058 PCT / EP2024 / 08308957from the initial locked position LP1 to the intermediate position LP2, the cap locking parts 706and / or the cassette cap locking protrusion 708 on the locking part 706 first flex slightly radiallyinwards in the recess 406 of the skin sensor 400 thereby enabling the cassette cap lockingprotrusion locking protrusions 708 to move proximally pass the cap holding part 608. When5 the skin sensor 400 is moved from the initial locked position LP1 to the intermediate positionLP2, the distal locking ends 708 thereby move outside the cassette housing 600 as shown infigure 30B. Since the locking parts 706 and / or the cassette cap locking protrusion 708 on thelocking part 706 are configured to flex, they now flex radially outwardly and slide up the ramp410 as the user removes the cassette cap 700 from the cassette 100. This is shown in figure10 30. The cassette cap 700 with the needle shield 212 inside may be positioned on the skinsensor 400 after use to provide an additional security preventing access to the used needle.This is shown in figure 30D. The cassette cap 700 is not non-removably connected to thecassette 100 again, but it will stay in position unless pulled off again by a user.15 Figures 31A-G show perspective views of parts of a cassette 100 and the auto injector 1000during a process of unlocking of the cassette cap 700, removal of the cap 700, medicamentdelivery and during resetting of the auto injector 1000 after medicament delivery. In figure 31A,the cassette and auto injector are shown just after assembly but prior to locking of the cassettein the auto injector. In figure 31B, the injector release members 1508 have moved into the20 cassette 100 by user movement of the cassette interacting tab 1601. This locks the cassette100 in the auto injector 1000 as described in figures 24A-E. The injector release members1508 movement also rotates the index ring 500 whereby the cap 700 can be removed asshown in figure 31C. Removal of the cap 700 allows the injector skin sensor detector spring1710 to push the injector skin sensor detector 1700 proximally whereby the skin sensor 40025 is also pushed forward in a proximal position as shown in figure 31C. In figure 31D, the userhas pressed the proximal end 402 of the skin sensor 400 against the injection site. The needle208 can be seen in figure 31D. Full medicament delivery is shown in figure 31E, and in figure31F, the cassette has been removed from the injection site whereby the injector skin sensordetector 1700 pushes the skin sensor 400 to the final locked proximal position. In figure 31G,30 the auto injector 1000 has been reset and the injector release members 1508, the cassetteinteracting tab 1601, and the injector skin sensor detector 1700 are once again in a distalposition whereby the auto injector 1000 is ready for use again with a new cassette.Figures 32A-D show a rotational damper 1900, which may be included in the auto injector35 1000. The rotational damper 1900 comprises a damper sleeve 1902 positioned between thechassis sleeve 1400 and the resetting sleeve 1200. In figures 32A-D, only the chassis sleeve1400 can be seen through a damper channel 1904 in the damper sleeve 1902. The damperWO 2025 / 109058 PCT / EP2024 / 08308958channel 1904 extends helically around the damper sleeve 1902. The damper sleeve 1902 isrotatable relative to the chassis sleeve 1400.The plunger rod resetting part 1026 extends through the damper channel 1904 and into the5 resetting thread 1206 (not shown here) in the resetting sleeve 1200.The rotational damper 1900 further comprises a damper end surface 1906. In the shownexample, the damper end surface 1906 is a damper plate. Other configurations could also beused.10Movement of the plunger rod 1020 in the proximal direction rotates the damper sleeve 1902due to the plunger rod resetting part 1026 extending through the damper channel 1904. Thiscan be seen by comparing figures 32A-C showing the rotational damper prior to injection(figure 32A), during injection (figure 32B), and after injection (figure 32C). The damper end15 surface 1906 is not moving during injection and the damper sleeve 1902 and the damper endsurface 1906 thereby rotates relatively during injection. This reduces, i.e. dampens, a speedof the plunger rod 1020 during injection when moving in the proximal direction.During reloading, the damper end surface 1906 rotates with the damper sleeve 1902 as shown20 in figure 32D. The damper sleeve 1902 is non-rotatable relative to the resetting sleeve 1200during distal movement of the plunger rod 1020, i.e. during reloading. The rotational damper1900 have two damper channels 1904. Each of these damper channels 1904 may have a pitchin the first rotation direction being identical to a pitch of the resetting thread 1206 in theresetting sleeve 1200 in the first rotation direction R1. This ensures that rotation of the damper25 sleeve 1902 relative to the resetting sleeve 1200 is prevented. Normally a gearwheel (notshown) will connect with the damper sleeve 1904 to control the movement of the dampersleeve 1904.The example shown in figures 32A-D has a second cassette interacting tab 1611 in addition30 to the first mentioned cassette interacting tab 1601 for activation of the auto injector 1000. Theadditional second cassette interacting tab 1611 may provide an improved structural stability.Figure 33A show an exploded view of an example of another auto injector 1000a extendingalong the longitudinal direction L. The auto injector 1000a is very similar to the first shown auto35 injector 1000 and like parts are marked with the same reference numbers. The auto injector1000a is extending from a proximal end 1002 to a distal end 1004 and comprises differentparts, some of which are shown in close-up views in figures 34-40. Parts not shown separatelyWO 2025 / 109058 PCT / EP2024 / 08308959are similar both in function and design as the parts shown and described in connection withthe auto injector 1000 shown in figures 1-32.Both the auto injector 1000 of figures 1A-B and the auto injector 1000a of figures 33A-B may5 comprise a distal housing cap 2216 attached to a distal end 2204 of the distal injector housing2200 as shown in figure 33A. The additional distal housing cap 2216 is included to provide aneasier assembly of the auto injector.Figure 33B shows the assembled auto injector 1000a of figure 33A. During loading and10 preparation of a cassette 100 (an example of a cassette 100 is shown in figure 23) formedicament delivery, and during medicament delivery, there is no rotational movementbetween the different parts in the auto injector 1000a. Instead, the different parts in the autoinjector 1000a move relative to each along the longitudinal direction L and some parts flexand / or tilt relative to other parts as described in the following. After medicament delivery and15 removal of the auto injector and cassette system from the injection site, the auto injector 1000amay be reloaded by rotation of the resetting sleeve 1200 and the distal injector housing 2200relative to the other parts of the auto injector 1000a in a similar manner as described previouslyfor the auto injector 1000 of figures 1A-B. This retracts the plunger rod 1020a to its initial distalposition and reloads the drive spring 1040 as described in the following.20Figure 34 shows the plunger rod 1020a of the auto injector 1000a of figures 33A-B. Theplunger rod 1020a extends from a proximal end 1022 to a distal end 1024. At the distal end1024 is found the two plunger rod resetting parts 1026, which each travels along one of thetwo resetting threads 1206 inside the resetting sleeve 1200 when the two parts rotate relatively25 as described for the auto injector 1000 of figures 1A-B.The plunger rod 1020a comprises a distal tubular part 1034 and a proximal tubular part 1035.The two tubular parts 1034, 1035 have different diameters. The average circumference of thedistal tubular part 1034 is larger than the average circumference of the proximal tubular part30 1035. The plunger rod cavity 1030a inside the plunger rod 1020a still contains the drive spring1040 as is best seen in figures 42A-H and 45A-B. Compared to the plunger rod cavity 1030as described for the auto injector 1000 of figures 1A-B, the plunger rod cavity 1030a in thesecond example of the auto injector does not extend to the proximal end 1022 of the plungerrod 1020a. The plunger rod cavity 1030a mainly extends through the distal tubular part 1034.35 The plunger rod 1020a of figure 34 may also be used in the auto injector 1000 of figures 1AB.WO 2025 / 109058 PCT / EP2024 / 08308960The plunger rod 1020a as shown in figure 34 comprises a plurality of plunger rod openings1036. The plunger rod openings 1036 are found on an outer surface of the proximal tubularpart 1035. The number of plunger rod openings 1036 includes a first plunger rod opening1036A. Before insertion of a cassette 100 in the auto injector 1000a, a plunger rod release5 hook 1356 on a plunger rod release element 1350 (see figures 37A-B) is secured in the firstplunger rod opening 1036A (see figures 42A-C). This prevents proximal movement of theplunger rod 1020a. Thus, it is ensured that the plunger rod 1020a and the plunger rod spring1040 (see figures 33A-B) are not allowed to move proximally for medicament delivery beforethe user initiates medicament delivery. The initiation of medicament delivery — and thereby10 release of the plunger rod 1020a and the drive spring 1040 allowing the drive spring 1040 toexpands / decompress thereby pushing the plunger rod 1020a in the proximal direction — isdone by the user pressing the cassette 100 (see figures 26-27) against the injection site. Thispushes the plunger rod release hook 1356 out of the first plunger rod opening 1036A as shownin figures 43A-D allowing the plunger rod 1020a to move proximally for medicament delivery.15If the user stops mid medicament delivery, e.g. performing an early lift of the auto injectorsystem from the patient’s skin, the plunger rod 1020a does not continue its movement to themost proximal position for full medicament delivery. Instead, the plunger rod 1020a is stoppedby the plunger rod release hook 1356 entering into one of the other plunger rod openings20 1036B, as shown figure 43.The drive spring guide 1050a is shown in a closeup view in figures 35A-B. The drive springguide 1050a extends from a proximal end 1052 to the distal end 1054. The drive spring guide1050a comprises a spring guide rod 1058 extending from the proximal end 1052 of the drive25 spring guide 1050a to the spring distal end surface 1056. The drive spring 1040 is positionedaround the spring guide rod 1058 (see figure 33B). The spring guide rod 1058 comprisesspring guide tracks 1060 for supporting the drive spring 1040.Depending on the medicament to be delivered and its viscosity, different requirements to the30 spring force may be required. Some types of medicaments may be uncomfortable to receiveif delivered too fast. Also, if there is a distance between proximal end 1022 of the plunger rod1020a and the stopper 210 inside the syringe compartment 206 after mounting of the cassette100 in the auto injector 1000a, the user may experience the impact when the plunger rod1020a comes in contact with the stopper 210 during medicament delivery as an uncomfortable35 event. Some users may wrongly assume that something is wrong and remove the injectorsystem from the skin too early, i.e. prior to medicament delivery has been finalized. Thisscenario may equally well occur for the auto injector 1000 of figures 1A-B. Dampening of theWO 2025 / 109058 PCT / EP2024 / 08308961drive spring 1040 is therefore sometimes needed, e.g. to improve user experience. Toovercome such problem, a rotational damper 1900 as shown and described in connection withfigures 32A-D can be implemented. As an alternative, or in combination, a linear damper maybe implemented.5The plunger rod 1020a comprises a cassette activation lock element 1038. The cassetteactivation lock element 1038 is found at a proximal end 1046 of the distal tubular plunger rodpart 1035. Prior to a cassette 100 being received in the auto injector 1000a, the cassetteactivation lock element 1038 is secured by the one or more plunger rod lock elements 151810 onthe cassette activation part 1500a as shown in figures 41A-B.Figure 36 shows the plunger rod support part 1300a from two different directions. The plungerrod support part 1300a does not have the flexible side arm 1309 as shown for the plunger rodsupport part 1300a of the auto injector 1000 shown in figures 1A-B since the direct lock and15 release of the plunger rod 1020a has been relocated to plunger rod release element 1350 asshown in figures 37A-B.Figures 37A-B show the plunger rod release element 1350 from two different directions. Theplunger rod release element 1350 extends from a proximal end 1352 to a distal end 1354. The20 plunger rod release element 1350 comprises a plunger rod release hook 1356, which is seenmost clearly in figure 37A. Prior to insertion of a cassette 100 in the auto injector 1000a, theplunger rod release hook 1356 is secured in the first plunger rod opening 1036A (see figures42A-C). This prevents proximal movement of the plunger rod 1020a.25 The plunger rod release element 1350 shown in figures 37A-B comprises chassis sleeveinteracting rods 1360 as seen most clearly in figure 37B. The chassis sleeve interacting rods1360 are positioned at the distal end 1354 of the plunger rod release element 1350. Theplunger rod release element 1350 is tiltable, i.e. able to rotate slightly, around the chassissleeve interacting rods 1360. The tilting moves the plunger rod release hook 1356 radially30 outwardly as the proximal end 1352 of the plunger rod release element 1350 moves radiallyoutwardly.A push back spring 1370 acting on a push back surface 1362 of the plunger rod releaseelement 1350 exert a force on plunger rod release element 1350 radially inwardly securing the35 plunger rod release hook 1356 in the first plunger rod opening 1036A (see figure 34) prior touse. The push back spring 1370 is positioned between the plunger rod release element 1350and the injector skin sensor detector 1700a (see figure 40).WO 2025 / 109058 PCT / EP2024 / 08308962The plunger rod release element 1350 of figures 37A-B comprises two push protrusions 1358positioned on opposite sides of the plunger rod release element 1350. The push protrusions1358 each abuts a sloping surface 1720 on the injector skin sensor detector 1700a (see figure5 43B and figure 43D). When the injector skin sensor detector 1700 moves distally relative tothe plunger rod release element 1350, the sloping surface 1720 on the injector skin sensordetector 1700a forces the push protrusions 1358 radially outwardly. This pushes the plungerrod release hook 1356 out of the first plunger rod opening 1036A. The plunger rod 1020a isnow released. After release of the plunger rod 1020a, the plunger rod 1020a moves proximally10 for medicament delivery (see figures 42A-H).As shown in figure 42I, if the user removes the auto injector and cassette system from theinjection site mid medicament delivery, the injector skin sensor detector 1700a is pushedproximally by the injector skin sensor detector spring 1710 (similar as described for the injector15 skin sensor detector 1700 shown in the auto injector 1000 of figures 1A-B). The sloping surface1720 thereby no longer abuts the push protrusions 1358. Since the plunger rod 1020a has notmoved all the way to its most proximal position at the end of medicament delivery, the proximaltubular part 1035 of the plunger rod 1020a is close to the plunger rod release hook 1356. Thepush back spring 1370 acting on a push back surface 1362 of the plunger rod release element20 1350 exerts a force on plunger rod release element 1350 radially inwardly. This pushes theplunger rod release element 1350 radially inwardly.The additional plunger rod openings 1036B found on the plunger rod 1020a distally of the firstplunger rod opening 1036A facilitates that the plunger rod release hook 1358 may be secured25 in these openings when the user removes the auto injector and cassette system from the skinbefore medicament delivery has been finalized. This ensures that the medicament deliverydoes not continue after the user has removed the injector during an early lift. The early lift andthe subsequent securing of the plunger rod release hook 1356 in the additional plunger rodopenings 1036B is shown in figure 43.30When the user removes the auto injector and cassette system from the skin after endmedicament delivery, the injector skin sensor detector 1700a is still pushed proximally by theinjector skin sensor detector spring 1710. The push back spring 1370 still acts on a push backsurface 1362 of the plunger rod release element 1350 exerting a force on plunger rod release35 element 1350 radially inwardly. However, the plunger rod release element 1350 is not pushed(much) radially inwardly, since the plunger rod release hook 1356 now abuts the thicker distaltubular part 1034 of the plunger rod 1020a and not the thinner proximal tubular part 1035.WO 2025 / 109058 PCT / EP2024 / 08308963Further proximal movement of the plunger rod 1020a is prevented by the proximal end 1046of the distal tubular part 1034 abutting the end plate in the cassette receiver 1110.5 The cassette activation part 1500a is shown in figures 38A-B. In the auto injector 1000a offigures 33A-B, the cassette interacting tab 1601 is coupled to the cassette activation part1500a instead of the pullback part 1600 as the latter is not included in the auto injector 1000aof figures 33A-B. The cassette interacting tab 1601 may be positioned in a cassette interactingtab interface 1522 as shown in figure 38B and figures 41C-D. Alternatively, the cassette10 interacting tab 1601 is a part of the cassette activation part 1500a as shown in figure 38A.The cassette activation part 1500a shown in figures 38A-B comprises two plunger rod lockarms 1516 extending distally. At the distal end 1504 of the cassette activation part 1500a (andthereby also the distal end of the plunger rod lock arms 1516), plunger rod lock elements 151815 are positioned. The cassette activation lock element 1038 on the plunger rod 1020a is securedin the plunger rod lock elements 1518 prior to the auto injector 1000a receiving a cassette 100as most clearly seen in figure 41A. This prevents relative longitudinal movement of thecassette activation part 1500a and the plunger rod 1020a prior to the auto injector 1000areceiving a cassette 100.20The cassette activation part 1500a further comprises a plunger rod interaction arm 1524extending from distally. When the plunger rod 1020a moves proximally for medicamentdelivery, the distal tubular part 1035 of the plunger rod 1020a secures the plunger rodinteraction arm 1524 between the distal tubular part 1035 and the chassis sleeve 1400.25The release of the cassette activation lock element 1038 on the plunger rod 1020a from theplunger rod lock elements 1518 is controlled by a unlock sledge element 1750 as shown infigures 39A-B.30 ~The unlock sledge element 1750 as shown in figures 39A-B extends from a proximal end 1752to a distal end 1754. The unlock sledge element 1750 is further configured for moving betweena proximal position USP and a distal position USD as shown in figures 41A-D. In the proximalposition, longitudinal movement of the cassette activation part 1500a is normally prevented.In the distal position, longitudinal movement of the cassette activation part 1500a into the35 cassette 100 is normally permitted.WO 2025 / 109058 PCT / EP2024 / 08308964The unlock sledge element 1750 comprises an unlock sledge release tab 1758. When theunlock sledge element 1750 moves distally relative to the cassette activation part 1500a, theunlock sledge release tab 1758 pushes the two plunger rod lock elements 1518 away fromeach other. The cassette activation lock element 1038 on the plunger rod 1020a is thereby5 released from the plunger rod lock elements 1518 as shown in figure 41B and figure 41D. Thisallows relative longitudinal movement of the cassette activation part 1500a and the plungerrod 1020a. The one or more plunger rod lock elements 1518 flex outwardly when the unlocksledge release tab 1558 moves distally, whereby the grab on the plunger rod 1020a isreleased. However, other solutions for releasing the plunger rod 1020a from the cassette10 activation part 1500a could also be imagined.The unlock sledge element 1750 and the injector skin sensor detector 1700a as shown infigures 41A-D are longitudinal locked. The unlock sledge element 1750 comprises an injectorskin sensor detector lock tab 1756 fixing the unlock sledge element 1750 in a sledge receiving15 channel 1716 in the injector skin sensor detector 1700a. Alternatively, the unlock sledgeelement 1750 may be part of the injector skin sensor detector 1700a. Splitting the unlocksledge element 1750 and the injector skin sensor detector 1700a into two parts may be doneto facilitate easy assembly of the auto injector parts.20 When an unused cassette 100 is received in the auto injector 1000a, the injector skin sensordetector pin 1703 on the injector skin sensor detector 1700a is pushed distally. This movesthe unlock sledge element 1750 distally thereby releasing the two plunger rod lock elements1518 hold on the cassette activation lock element 1038 on the plunger rod 1020a.25 When the cassette activation part 1500a is no longer locked to the plunger rod 1020a, thecassette activation part 1500a is allowed to move proximally such that the one or more injectorrelease members 1508 into the cassette 100. The cassette activation part 1500a can therebybe moved proximally by the user for locking the cassette 100 in the auto injector 1000a.Movement of the one or more injector release members 1508 into the cassette 100 locks the30 cassette 100 in the auto injector 1000a as shown in figures 24A-E. The skin sensor 400 is alsoallowed to move proximally by the index ring 500 interaction with the injector release members1508 as described previously.In the example shown in the figures, the cassette activation part 1500a is moved proximally35 by the user. The user moves the cassette activation part 1500a proximally by pushing thecassette interacting tab 1601 proximally.WO 2025 / 109058 PCT / EP2024 / 08308965The unlock sledge element 1750 is configured for moving distally when an unused cassette100 is received in the auto injector 1000a thereby moving the injector skin sensor detector1700a distally. However, if an already used cassette is received in the auto injector 1000a, theinjector skin sensor detector 1700 is not moved distally as the injector skin sensor detector pin5 1703 is not pushed distally by the skin sensor 400 in the cassette 100 being in a too proximalposition when the cassette is a used cassette. The unlock sledge is thereby also not moveddistally, and the cassette activation part 1500 is thus not unlocked. This ensures that the autoinjector 1000a cannot be activated if a used cassette is inserted into the auto injector 1000ainstead of an unused cassette. This is illustrated in figures 44A-B.10Figures 41A-B show the interaction of the unlock sledge element 1750, the cassette activationpart 1500a, the plunger rod 1020a, and the injector skin sensor detector 1700a before (figure41A) and after (figure 41B) distal movement of the unlock sledge element 1750 and the injectorskin sensor detector 1700a relative to the cassette activation part 1500a and the plunger rod15 1020a. The distal movement of the unlock sledge element 1750 and the injector skin sensordetector 1700a unlocks the cassette activation part 1500a from the plunger rod 1020a. Figure41C and figure 41D show the cassette activation part 1500a and the unlock sledge element1750 at the same parts positions as in figure 41C and figure 41D, respectively. The dottedcircles (1) highlight the unlock sledge release tab 1758 movement, and the dotted circles (2)20 highlight the plunger rod lock element 1518 movement to release the cassette activation lockelement 1038 on the plunger rod 1020a.Figures 42A-H show cut-throughs of the auto injector 1000a of figures 33A-B during a processof receiving a cassette, unlocking of the cassette, whereby the plunger rod can be unlocked,25 during medicament delivery and after resetting of the auto injector after medicament delivery.The cassette has been omitted in figures 42A-H for a clearer view of the injector parts.Figure 42A shows auto injector 1000a in the configuration prior to receiving the cassette. Theinjector skin sensor detector pin 1703 are in a proximal position extending proximally from the30 end plate in the cassette receiver 1110.In figure 42B, a cassette has been received in the auto injector 1000a. When the cassette isreceived in the auto injector 1000a, the injector skin sensor detector pin 1703 comes intocontact with a skin sensor 400 in the cassette 100 and are pushed distally by the skin sensor35 400. This moves the unlock sledge element 1750 distally thereby unlocking the cassetteactivation part 1500a as shown in figures 41A-B.WO 2025 / 109058 PCT / EP2024 / 08308966In figure 42C, the user has subsequently moved the cassette activation part 1500a proximallyby pushing the cassette interacting tab 1601 proximally. Moving the cassette activation part1500a proximally as shown in figure 42C, locks the cassette in the auto injector 1000a. Thecap 700 on the cassette (see figures 30A-D) can now be removed. At this point, the skin sensor5 400 is unlocked allowing it to move proximally (see figures 26A-l, figures 27A-I and figures29A-G).Due to the injector skin sensor detector spring 1710 acting on the injector skin sensor detector1700a, the injector skin sensor detector 1700a, and the unlock sledge element 1750 moves10 proximally when the skin sensor 400 is moved proximally as shown in figure 42D. The autoinjector 1000a, and cassette system is now ready for medicament delivery.In figure 42E, the user has pressed the cassette against the injection site, which pushes theskin sensor 400 to a distal position also pushing the injector skin sensor detector pin 1703 and15 thereby the injector skin sensor detector 1700a, into the auto injector 1000a. Pushing theinjector skin sensor detector 1700a into the auto injector 1000a unlocks the plunger rod 1020(see figures 43A-D).In figure 42F, the plunger rod spring 1040 has pushed the plunger rod 1020a in the proximal20 direction medicament delivery. Figure 42F shows the auto injector 1000a after full medicamentdelivery.In figure 42G, the user has removed the cassette and auto injector system from the injectionsite after end medicament delivery, which allows injector skin sensor detector spring 1720 to25 push the injector skin sensor detector 1700a proximally, which in turn pushes the skin sensor400 in the cassette to a locked proximal position (see figures 25A-B, figures 26A-l, figures27A-| and figures 29A-G). The auto injector 1000a is now ready for resetting by rotation of thedistal injector housing 2200 coupled to the resetting sleeve 1200 relative to the proximalinjector housing 2100 as shown in figures 18A-E. The cassette can subsequently be removed30 __ from the auto injector 1000a.Alternatively, the injector release member 1508 and the cassette interacting tab 1601 may bemoved from the proximal cassette locking position PD to the distal cassette release positionPP prior to resetting the auto injector. This may seem more natural for the user wanting to35 remove and discharge of the cassette before resetting the auto injector. The movement of thecassette interacting tab from the proximal cassette locking position PD to the distal cassetterelease position PP may be user controlled by movement of e.g. the cassette interacting tab.WO 2025 / 109058 PCT / EP2024 / 08308967The reset auto injector 1000a as shown figure 42H, brings the auto injector 1000a back to theconfiguration identical to the one shown in figure 42A, i.e. where the auto injector 1000a isready for receiving a new unused cassette. During resetting of the auto injector 1000a by5 rotation of the resetting sleeve 1200 in the first rotational direction DR1, the plunger rod 1020ais moved in the distal direction as described previously in connection with e.g. figures 18A-D.As the plunger rod 1020a moves distally, the cassette activation lock element 1038 on theplunger rod 1020a comes into contact with the one or more plunger rod lock elements 1518on the cassette activation part 1500a and is positioned inside a lock element enclosure 152010 formed by the plunger rod lock elements 1518 as shown in figure 41A. Further distal movementof the plunger rod 1020a pulls the cassette activation part 1500a, the injector skin sensordetector 1700a, and the unlock sledge element 1750 along distally. This resets the cassetteactivation part 1500a, the injector skin sensor detector 1700a, and the unlock sledge element1750 to the original positions.15Figure 42I shows the auto injector 1000a in a situation, where the user has interrupted themedicament delivery and removed the cassette and auto injector system from the injectionsite prior to completing the medicament delivery. If the user has interrupted the medicamentdelivery mid-delivery, the skin sensor 400 in the cassette 100 is pushed forward to a locked20 position by the injector skin sensor detector 1700a of the auto injector 1000a due to the injectorskin sensor spring 1710 pushing the injector skin sensor detector 1700a. The proximalmovement of the injector skin sensor detector 1700a, secures the plunger rod 1020a in anintermediate position by the plunger rod release hook 1356 movement into one of the otherplunger rod openings 1036B.25In figures 43A-D, release of the plunger rod 1020a for medicament delivery is shown in aclose-up. Figures 43A-B are two different close-up views of figure 42D, where the cassette islocked in the auto injector 1000a but the user is yet to push the skin sensor 400 against theinjection site. As seen in figure 43B, the sloping surface 1720 of the injector skin sensor30 detector 1700a is not in contact with the push protrusion 1358 on the plunger rod releaseelement 1350. The plunger rod release hook 1356 secured in the first plunger rod opening1036A prevents proximal plunger rod 1020a movement as shown in figure 43A.Figures 43C-D are two different close-up views of figure 42E, where the user has pushed the35 skin sensor 400 against the injection site. As seen in figure 43D, the sloping surface 1720 ofthe injector skin sensor detector 1700a has pushed the push protrusion 1358 radially outwardlyas the injector skin sensor detector 1700a is pushed distally. The plunger rod release hookWO 2025 / 109058 PCT / EP2024 / 083089681356 is no longer secured in the first plunger rod opening 1036A as shown in figure 43C andthe plunger rod 1020a is therefore ready for proximal medicament delivery movement.Figure 44A and figure 44B show the difference between the auto injector 1000a when an5 unused cassette and a used cassette is received in the auto injector 1000a, respectively.As shown in figures 45A-B, the reusable auto injector 1000a may comprise a linear damper.The linear damper comprises an O-ring 1010 extending around a first part 1062 of the drivespring guide 1050a extending inside the plunger rod cavity 1030a. The O-ring 1010 is in10 contact with an inner surface 1037 of the plunger rod cavity 1030a. Frictional force betweenthe O-ring 1010 and the plunger rod cavity 1030a upon proximal movement of the plunger rod1030a introduces a linear dampening effect.The plunger rod 1020a may also comprise an inner plunger rod tube extending into the plunger15 rod cavity 1030a. At least a part of the drive spring 1040 may be positioned around the innerplunger rod tube, and at least a part of the spring guide 1050a may be extending through theinner plunger rod tube. The O-ring 1010 may exert an additional linear damper effect by beingmovable into the inner plunger rod tube when the drive spring 1040 pushes the plunger rod1020a proximally.20Figure 46A show an exploded view of an example of another auto injector 1000b, also referredto as a third example of the auto injector 1000b, extending along the longitudinal direction L.The auto injector 1000b is very similar to the first shown auto injector 1000 and the secondshown auto injector 1000a. Like parts are therefore marked with the same reference numbers.25 The auto injector 1000b is extending from a proximal end 1002 to a distal end 1004 andcomprises different parts, some of which are shown in close-up views in figures 47-55. Partsnot shown separately are similar both in function and design as the parts shown and describedin connection with the auto injector 1000 shown in figures 1-32, and / or the auto injector 1000ashown in figures 33-46.30Compared to the auto injectors 1000, 1000a of figures 1A-B and figures 33A-B, the autoinjector 1000b of figures 46A-B comprises a user button 2020 and a converter 2000. Rotationof the user button 2020 and a converter 2000 locks a cassette 100 (an example of a cassette100 is shown in figure 23) in the auto injector 1000b as described in connection with figures35 56A-C. Apart from the user button 2020 and the converter 2000 rotation, during loading andpreparation of the cassette 100 for medicament delivery, and during medicament delivery,there is no rotational movement between the other parts in the auto injector 1000b. Instead,WO 2025 / 109058 PCT / EP2024 / 08308969the other parts in the auto injector 1000b move relative to each along the longitudinal directionL and some parts flex and / or tilt relative to other parts as described also for the auto injectorshown in figures 33A-B. After medicament delivery and removal of the auto injector andcassette system from the injection site, the auto injector 1000b may be reloaded by rotation of5 the resetting sleeve 1200b and the distal injector housing 2200b relative to the other parts ofthe auto injector 1000b in a similar manner as described previously for the auto injector 1000of figures 1A-B, and the auto injector 1000a of figures 33A-B. This retracts the plunger rod1020b to its initial distal position and reloads the drive spring 1040 as described previously forthe auto injector 1000a of figures 33A-B.10Figure 47 shows the plunger rod 1020b of the auto injector 1000b of figures 46A-B. Comparedto the plunger rod 1020a shown in figure 34, the plunger rod 1020b in figure 47, the cassetteactivation lock element 1038 on the distal tubular part 1034 is not present. The remaining partshave similar functions as described previously for the plunger rod 1020a shown in figure 34.15Prior to a cassette 100 being received in the auto injector 1000b, the plunger rod 1020b issecured by the plunger rod release element 1350 as shown for the previously describedsecond example of the auto injector 1000a.20 Figures 48A-B show the injector skin sensor detector 1700b from two different directions.Compared to the previously shown and described injector skin sensor detectors 1700, 1700a,the injector skin sensor detector 1700b in figures 48A-B has a converter blocking surface 1718.The converted blocking surface 1718 prevents rotation of the converter 2000 until an unusedcassette 100 is positioned in the auto injector 1000b. This is shown and described in more25 detail in figures 56A-C.Figures 49A-B show the chassis sleeve 1400b from two different directions. Compared to thechassis sleeve 1400 of figures 9A-B, the chassis sleeve 1400b of figures 49A-B has anactivation part plate channel 1416. The activation part plate channel 1416 is a channel in which30 an activation part plate 1530 on the cassette activation part 1500b may extend. The twointerfaces 1416, 1530 do normally not prevent movement of one compared to the other.Instead, the activation part plate 1530 can move inside the activation part plate channel 1416in the longitudinal direction.35 The activation part plate 1530 is clearly seen in figures 50A-B showing the cassette activationpart 1500b from two different directions. The activation part plate 1530 has an activation partplate thread 1532. A resetting sleeve pin 1214 on the resetting sleeve 1200b can come inWO 2025 / 109058 PCT / EP2024 / 08308970contact with and travel inside the activation part plate thread 1532 when the resetting sleeve1200b is rotated. Thus, when the resetting sleeve 1200b is rotated for resetting of the autoinjector 1000b, the cassette activation part 1500b is pulled from a proximal (forward) positionand distally (backward) to the initial position due to the resetting sleeve pin 1214 traveling5 inside the activation part plate thread 1532 forcing the activation part 1500b to move distally.Thus, the reloading of the auto injector 1000b by rotation of the resetting sleeve 1200b alsoretracts the cassette activation part 1500b. This unlocks the cassette 100, since the injectorrelease members 1508 no longer lock the cassette 100 in the auto injector 1000b. The cassetteactivation part 1500b comprises a quaternary converter pin receiving channel 1534 for10 containing a quaternary converter pin 2004 of the converter 2000 (see figures 56A-C).Figures 51A-B show the resetting sleeve 1200b with the resetting sleeve pin 1214 from twodifferent directions. The resetting sleeve pin 1214 is not positioned inside the activation partplate thread 1532 in the initial and the final position. Instead, the resetting sleeve pin 121415 enters into the activation part plate thread 1532 during rotation of the resetting sleeve 1200band exits the activation part plate thread 1532 before a full resetting rotation of the resettingsleeve 1200b is completed. The remaining parts of the resetting sleeve 1200b have alreadybeen described in connection with the first shown resetting sleeve 1200.20 Figures 52A-B show the cassette receiver 1100b from two different directions. Compared tothe first shown cassette receiver 1100, the cassette receiver 1100b shown in figures 52A-Bcomprises a cassette receiver channel 1124 through which the cassette activation part 1500bcan travel. The cassette receiver 1100b also comprises an interface 1126 to the plunger rodrelease element 1350. On an outer surface of the cassette receiver 1100b is interfaces to25 interact with the converter 2000. Inside a tertiary converter pin receiving opening 1133, atertiary converter pin 2003 on the converter 2000 can be positioned. The tertiary converter pinreceiving opening 1133 constitutes the axis around which the converter 2000 rotates. Aconverter pin channel 1134 provides a channel for movement of a quaternary converter pin2004 of the converter 2000. When the converted is rotated around the axis defined by the30 tertiary converter pin 2003 and the tertiary converter pin receiving opening 1133, thequaternary converter pin 2004 travels inside the converter pin channel 1134. This is shownand described in more details in connection with figures 56A-C. The remaining parts of thecassette receiver 1100b have already been described in connection with the first showncassette receiver 1100.35Figures 53A-B show the converter 2000 from two different directions. The converter 2000comprises a number of converter pins 2001, 2002, 2003, 2004. The converter pins 2001, 2002,WO 2025 / 109058 PCT / EP2024 / 083089712003, 2004 extends from either a primary converter plate surface 2010 or a secondaryconverter plate surface 2012 of a converter plate 2008. The primary converter plate surface2010 is opposite the secondary converter plate surface 2012. The converter pins 2001, 2002,2003, 2004 include a primary converter pin 2001, a secondary converter pin 2002, a tertiary5 converter pin 2003, and a quaternary converter pin 2004. The primary converter pin 2001 andthe secondary converter pin 2002 extends from the primary converter plate surface 2010. Thetertiary converter pin 2003 and the quaternary converter pin 2004 extend from the secondaryconverter plate surface 2012. The primary converter pin 2001 and the tertiary converter pin2003 may also be seen as a throughgoing pin extending through the converter plate 2008.10 The converter 2000 also comprises a skin sensor detector pin interaction surface 2018. Theskin sensor detector pin interaction surface 2018 abuts against the converted blocking surface1718 on the injector skin sensor detector 1700b until an unused cassette 100 is positioned inthe auto injector 1000b. By positioning an unused cassette 100 in the auto injector 1000b, theinjector skin sensor detector 1700b is pushed distally as previously described. The skin sensor15 detector pin interaction surface 2018 no longer abuts the converted blocking surface 1718,and rotation of the converter 2000 is possible. This is shown and described in more detail infigures 56A-C.Figures 54A-B show the user button 2020 from two different directions. The user button 202020 comprises a user button plate 2022 with a primary user button plate surface 2024 and asecondary user button plate surface 2026. The primary user button plate surface 2024 isopposite the secondary user button plate surface 2026. The user button 2020 comprises auser button tab 2028. The user uses the user button tab 2028 a knob for rotating the userbutton 2020. The user button tab 2028 extend from the primary user button plate surface 2024.25 The user button 2020 comprises a primary converter pin receiving opening 2031 and asecondary converter pin receiving opening 2032. The converter pin receiving openings 2031,2032 are on the secondary user button plate surface 2026. The primary converter pin 2001 ofthe converter 2000 is positioned inside the primary converter pin receiving opening 2031 ofthe user button 2020. Similarly, the secondary converter pin 2002 of the converter 2000 is30 positioned inside the secondary converter pin receiving opening 2032 of the user button 2020.The user button 2020 and the converter 2000 are thereby coupled such that they do not moverelative to each other. Instead of the user button 2020 and the converter 2000 being twoseparate parts, one combined part could also be imagined.35 The proximal injector housing 2100b as shown in figure 55 comprises a user button receivingopening 2021 in which the user button 2020 is positioned. The user button 2020 is allowed torotate inside the user button receiving opening 2021.WO 2025 / 109058 PCT / EP2024 / 08308972Figures 56A-C show the resetting sleeve 1200b, the cassette activation part 1500b, theinjector skin sensor detector 1700b, and the converter 2000 during activation of the autoinjector 1000b of figures 46A-B. In figure 56A, an unused cassette 100 has not yet been5 positioned in the auto injector 1000b and the skin sensor detector pin interaction surface 2018therefore abuts the converted blocking surface 1718 on the injector skin sensor detector1700b. This prevents rotation of the converter 2000.In figure 56B, an unused cassette 100 (not shown in the figures) has been positioned in the10 auto injector 1000b, and the injector skin sensor detector pin 1703 has been pushed distally.The skin sensor detector pin interaction surface 2018 therefore no longer abut the convertedblocking surface 1718 on the injector skin sensor detector 1700b. This allows for rotation ofthe converter 2000 by the user rotating the user button 2020.15 In figure 56C, the converter 2000 has been rotated around the axis defined by the tertiaryconverter pin 2003 inside the tertiary converter pin receiving opening 1133. This is illustratedwith the arrow in the figure. The rotation of the converter 2000 moves the injector skin sensordetector 1700b proximally due to the position of the quaternary converter pin 2004 inside thequaternary converter pin receiving channel 1534. Thus, when the converter 2000 rotates, the20 injector skin sensor detector 1700b moves proximally along the longitudinal direction. Thislocks the cassette 100 inside the auto injector 1000b in a similar manner as described infigures 24A-E. Since the resetting sleeve pin 1214 is not positioned inside the activation partplate thread 1532 until the resetting sleeve 1200b is rotated, the resetting sleeve 1200b is notaffected by the rotation of the converter 2000, which locks the cassette 100 in the auto injector25 1000b. When the resetting sleeve 1200b is rotated for reloading of the auto injector 1000b,the cassette activation part 1500b is moved distally. The converter 2000 is thereby rotatedback to its original position due to the quaternary converter pin 2004 being positioned insidethe quaternary converter pin receiving channel 1534 of the cassette activation part 1500b.30 Figure 57A show an exploded view of an example of another auto injector 1000c, also referredto as a fourth example of the auto injector 1000c, extending along the longitudinal direction L.The auto injector 1000c is very similar to the previously shown auto injectors 1000, 1000a,1000b. Like parts are therefore marked with the same reference numbers. The auto injector1000c is extending from a proximal end 1002 to a distal end 1004 and comprises different35 parts, some of which are shown in close-up views in figures 58A-61. Parts not shownseparately are similar both in function and design as the parts shown and described inconnection with the previously shown auto injectors 1000, 1000a, 1000b of figures 1-56.WO 2025 / 109058 PCT / EP2024 / 08308973Compared to the auto injector 1000b of figures 46A-B, the auto injector 1000c of figures 57AB comprises an alternative user button 2020c, an alternative cassette receiver 1100c, analternative proximal injector housing 2100c, and a cover part 2050. Compared to the auto5 injector shown in figures 46A-B, sideways movement of the user button 2020c translates to arotation of the converter 2000, which in turn locks a cassette 100 (an example of a cassette100 is shown in figure 23) in the auto injector 1000c as described previously. Apart from therotation of the converter 2000 during loading and preparation of the cassette 100 formedicament delivery, and during medicament delivery, there is no rotational movement10 between the other parts in the auto injector 1000c. Instead, the other parts in the auto injector1000b move relative to each along the longitudinal direction L or an axis perpendicular thereto,and some parts flex and / or tilt relative to other parts as described also for the auto injectors1000a, 1000b shown in figures 33A-B and 46A-B. After medicament delivery and removal ofthe auto injector and cassette system from the injection site, the auto injector 1000c may be15 reloaded by rotation of the resetting sleeve 1200b and the distal injector housing 2200b relativeto the other parts of the auto injector 1000c in a similar manner as described previously for theauto injector 1000 of figures 1A-B, and the auto injector 1000a of figures 33A-B. This retractsthe plunger rod 1020b to its initial distal position and reloads the drive spring 1040 as describedpreviously.20Figures 58A-B show the cassette receiver 1100c from two different directions. Compared tothe cassette receiver 1100b shown in figures 52A-B, the cassette receiver 1100c shown infigures 58A-B comprises a cover part plate tab receiving opening 1128 for receiving a coverpart plate tab 2058 on the cover part 2050.25Figure 59A-B show the cover part 2050 from two different directions. The cover plate 2050comprises primary cover part plate surface 2054 and a secondary cover part plate surface2056 opposite the primary cover part plate surface 2054. The cover plate 2050 furthercomprises a cover part plate tab 2058 which is positioned inside a cover part plate tab30 receiving opening 1128 on the cassette receiver 1100c. The cover plate 2050 is able to rotatearound an axis defined by the cover part plate tab 2058. The rotation is defined by the sidewaymovement of the user button 2020c. The cover plate 2050 is positioned such that it is visibleat least partly inside the user button receiving opening 2110 of the proximal injector housing2100c. The cover plate 2050 comprises a curving cover part surface 2060 in which the user35 button 2020c is able to come in contact with the converter 2000.WO 2025 / 109058 PCT / EP2024 / 08308974Figure 60A-B show the user button 2020c from two different directions. The user button 2020chas a squared shape instead of the round shape of the user button 2020 shown and describedin figures 54A-B. The user button 2020c comprises two primary user button protrusion 2040together forming a user button channel 2042 in which the secondary converter pin 20025 travels. Sideways movement of the user button 2020c thereby rotates the converter 2000 asdescribed previously. In addition to the two primary user button protrusion 2040, twosecondary user button protrusions 2044 are present on the secondary user button platesurface 2026. The secondary user button plate surface 2026 follows the curving cover partsurface 2060 on the cover part 2050. The movement of the user button 2020c from one side10 to the other in a direction perpendicular to the longitudinal direction, causes the cover part2050 to rotate around the cover part plate tab 2058. Movement of the user button 2020c backto its original position, rotates the cover part 2050 to its original position. The cover part 2050is visible inside the user button receiving opening 2110 of the proximal injector housing 2100c.15 Figure 61 shows the proximal injector housing 2100c with the user button receiving opening2110 under which the cover part 2050 is visible.Figure 62 show an exploded view of an example of another auto injector 1000d, also referredto as a fifth example of the auto injector 1000d extending along the longitudinal direction L.20 The auto injector 1000d is very similar to the previously shown auto injectors 1000, 1000a,1000b, 1000c. Like parts are therefore marked with the same reference numbers. The autoinjector 1000d is extending from a proximal end 1002 to a distal end 1004 and comprises analternative proximal injector housing 2100d with no opening for a user button, and analternative resetting sleeve 1200d shown in more details in figure 63. Parts not shown25 separately are similar both in function and design as the parts shown and described inconnection with one or more of the previously shown auto injectors 1000, 1000a, 1000b, 1000cof figures 1-61.Compared to the auto injector 1000b of figures 46A-B and the auto injector 1000c of figures30 57A-B, the auto injector 1000d of figure 62 comprises no user button. Instead, the converter2000 is rotated by a rotation of the resetting sleeve 1200d. The rotation of the converter 2000is a consequence of the interface between the quaternary converter pin receiving channel1534 of the cassette activation part 1500b and the quaternary converter pin 2004 of theconverter 2000 as described previously. Thus, the converter 2000 rotates when the cassette35 activation part 1500b moves proximally to lock the cassette 100 in the auto injector 1000d.The converter rotation locking the cassette 100 in the auto injector 1000d is normally in anWO 2025 / 109058 PCT / EP2024 / 08308975opposite rotational direction, such as a second rotational direction compared to the rotationaldirection for resetting of the auto injector 1000d, such as a first rotational direction.As shown in figure 63, the resetting sleeve 1200d comprises a number of sleeve pins 1214,5 1215, 1216. The resetting sleeve 1200d comprises one resetting sleeve pin 1214, which cantravel inside activation part plate thread 1532 of the cassette activation part 1500. When theresetting sleeve 1200d is rotated in a rotational direction opposite the resetting direction, theresetting sleeve pin 1214 enters into the activation part plate thread 1532 of the cassetteactivation part 1500 thereby moving the cassette activation part 1500 proximally for locking an10 unused cassette 100 in the auto injector 1000d. Further rotational movement of the resettingsleeve 1200d is prevented by a first blocking pin 1215 abutting the activation part plate 1530.When the resetting sleeve 1200d is rotated in the resetting rotational direction, furtherrotational movement than that required for the resetting is prevented by a second blocking pin1216 abutting the activation part plate 1530. Thus, the resetting sleeve 1200d is configured15 for rotating forth and back depending on whether one is locking cassette in the auto injector1000d or resetting the auto injector and unlocking the cassette after medicament delivery. Therotational movement is normally a 180 degrees movement is a first or a second rotationaldirection depending on whether one is locking or resetting the device.20 ~The remaining functionality of the auto injector 1000d is as described for the previous autoinjectors 1000, 1000a, 1000b, 1000c.25 The invention is further described in the following items.1. A reusable auto injector (1000, 1000a, 1000b, 1000c, 1000d) for administration ofmedicament, the auto injector being configured for receiving a cassette (100)comprising a syringe (200) containing the medicament;30wherein the auto injector is extending from a proximal end (1002) to a distal end (1004)along a longitudinal axis (L);wherein the cassette (100) is configured for being removable received in the auto35 injector in a longitudinal direction along the longitudinal axis (L);wherein the auto injector comprises:WO 2025 / 109058 PCT / EP2024 / 08308976e acassette receiver (1100, 1100b, 1100c) configured for receiving the cassette(100);e a plunger rod (1020, 1020a, 1020b) configured for proximal movement of astopper (210) inside the syringe (200) for medicament delivery;5 e aplunger rod resetting part (1026) connected to and protruding radially from theplunger rod (1020, 1020a, 1020b);e adrive spring (1040) adapted for moving the plunger rod (1020, 1020a, 1020b)in a proximal direction; ande a resetting sleeve (1200, 1200b, 1200d) rotatable relative to the cassette10 receiver (1100, 1100b, 1100c) in a first rotational direction (DR1), the resettingsleeve (1200, 1200b, 1200d) comprising a resetting thread (1206) located onan inner surface (1205) of the resetting sleeve (1200, 1200b, 1200d), whereinthe plunger rod resetting part (1026) engages with the resetting thread (1206)such that a rotation of the resetting sleeve (1200, 1200b, 1200d) in a first15 rotational direction (DR1) moves the plunger rod (1020, 1020a, 1020b) in adistal direction for resetting the plunger rod (1020, 1020a, 1020b).2. The reusable auto injector according to item 1, wherein the cassette receiver (1100,1100b, 1100c) is configured for receiving the cassette (100) releasably in the cassette20 receiver (1100, 1100b, 1100c).3. The reusable auto injector according to any preceding item, wherein rotation of theresetting sleeve (1200, 1200b, 1200qd) in the first rotational direction (DR1) moves theplunger rod (1020, 1020a, 1020b) in a distal direction for resetting the plunger rod25 (1020, 1020a, 1020b) relative to the cassette receiver (1100, 1100b, 1100c).4. The reusable auto injector according to any preceding item, wherein the plunger rod(1020, 1020a, 1020b) is configured for proximal movement between a retractedplunger rod position and an extended plunger rod position, wherein the resetting30 sleeve (1200, 1200b, 1200d) is configured for moving the plunger rod from theextended plunger rod position to the retracted plunger rod position by rotation of theresetting sleeve (1200, 1200b, 1200c) in the first rotational direction (DR1) apredefined amount of degrees relative to the cassette receiver (1100, 1100b, 1100c).35 5. The reusable auto injector according to item 4, wherein the predefined amount ofdegrees is between 150 degrees and 210 degrees, such as between 160 degrees and200 degrees, such as between 170 degrees and 190 degrees, such as 180 degrees.WO 2025 / 109058 PCT / EP2024 / 083089776. The reusable auto injector according to item 4 or 5, wherein the predefined amount ofdegrees is between 150 degrees and 360 degrees, such as between 160 degrees and340 degrees, such as between 170 degrees and 320 degrees, such as between 1755 degrees and 300 degrees, such as between 175 degrees and 280 degrees, such asbetween 175 degrees and 260 degrees, such as between 175 degrees and 240degrees, such as between 175 degrees and 220 degrees, such as between 175degrees and 200 degrees, such as between 175 degrees and 190 degrees, such asbetween 175 degrees and 185 degrees.107. The reusable auto injector according to any preceding claim, wherein the plunger rod(1020, 1020a, 1020b) is non-rotatable relative to the cassette receiver (1100, 1100b,1100c).15 8. The reusable auto injector according to any preceding item, wherein the plunger rodresetting part (1026) extends from a distal end (1024) of the plunger rod (1020, 1020a,1020b).9. The reusable auto injector according to any preceding item, wherein the plunger rod20 resetting part (1026) comprises two pin parts positioned opposite another.10. The reusable auto injector according to item 9, wherein the resetting thread (1206)comprises two helical threads positioned opposite each other inside the resetting sleeve(1200, 1200b, 1200d), each of the two helical threads interfacing with each of the two25 oppositely positioned pin parts extending from a distal end (1024) of the plunger rod(1020, 1020a, 1020b).11. The reusable auto injector according to any preceding item, wherein the reusable autoinjector further comprises a distal injector housing (2200, 2200b) surrounding the30 resetting sleeve (1200, 1200b, 1200d), the distal injector housing (2200, 2200b) beingrotatable relative to the cassette receiver (1100, 1100b, 1100c).12. The reusable auto injector according to item 11, wherein the distal injector housing(2200, 2200b) is rotationally locked to the resetting sleeve (1200, 1200b, 1200d).3513. The reusable auto injector according to any of the items 11-12, wherein the distalinjector housing (2200, 2200b) comprises at least one rotational stop surface (2210)WO 2025 / 109058 PCT / EP2024 / 08308978protruding from a distal injector housing plate (2212) of the distal injector housing (2200,2200b), wherein the at least one rotational stop surface (2210):e prevents further rotation of the resetting sleeve (1200, 1200b, 1200d) than apredefined amount of degrees relative to the cassette receiver (1100, 1100b,5 1100c), and / ore abuts the plunger rod resetting part (1026) when the resetting sleeve has beenrotated the predefined amount of degrees relative to the cassette receiver,whereby further rotation of the resetting sleeve (1200, 1200b, 1200d) relativeto the cassette receiver (1100, 1100b, 1100c) is prevented.1014. The reusable auto injector according to any of the items 11-13, wherein the reusableauto injector further comprises a distal housing cap (2216) attached to a distal end(2204) of the distal injector housing (2200, 2200b).15 15. The reusable auto injector according to any preceding item, wherein the rotation of theresetting sleeve (1200, 1200b, 1200d) in the first rotational direction (DR1) compressesthe drive spring (1040).16. The reusable auto injector according to any preceding item, wherein the plunger rod20 (1020, 1020a, 1020b) comprises a plunger rod cavity (1030, 1030a) extending into theplunger rod (1020, 1020a, 1020b) and wherein the drive spring (1040) is positioned atleast partly inside the plunger rod cavity (1030, 1030a).17. The reusable auto injector according to item 16, wherein the reusable auto injector25 comprises a spring guide (1050, 1050a) around which at least a distal end (1044) of thedrive spring (1040) extends, wherein the drive spring (1040) is biased between aproximal end surface (1032) inside the plunger rod cavity (1030, 1030a) and a distalend surface (1056) of the spring guide (1050, 1050a).30 18. The reusable auto injector according to item 17, wherein the spring guide (1050, 1050a)extends into the plunger rod (1020, 1020a, 1020b) opening.19. The reusable auto injector according to any preceding item, wherein the reusable autoinjector further comprises a first damper assembly configured for dampening at least35 part of the proximal movement of the drive spring (1040) during medicament delivery.WO 2025 / 109058 PCT / EP2024 / 0830897920. The reusable auto injector according to item 19, wherein during medicament delivery,the plunger rod (1020, 1020a, 1020b) is configured for moving a total plunger rodmovement length, the total plunger rod movement length being from an initial distalplunger rod position to a proximal delivery plunger rod position, wherein the first damper5 assembly is configured for dampening a first part of the total plunger rod movementlength or the entire total plunger rod movement length.21. The reusable auto injector according to item 20, wherein the first damper assembly isconfigured for dampening only a first part of the total plunger rod movement length,10 wherein the first part of total plunger rod movement length is less than 25%, such asless than 20%, such as less than 15% of the total plunger rod movement length.22. The reusable auto injector according to any of the items 19-21, wherein the plunger rod(1020, 1020a, 1020b) is configured for moving between:15 © aninitial distal plunger rod position where the plunger rod (1020, 1020a, 1020b)is not in contact with the stopper (210) inside the cassette (100);o astopper contact position, wherein the plunger rod is in contact with the stopper(210) inside the cassette (100); and© a proximal delivery plunger rod position, where the stopper (210) inside the20 syringe (200) has been moved proximally for medicament delivery,wherein the first damper assembly dampers the movement of the plunger rod (1020,1020a, 1020b) only from the initial distal plunger rod position to the stopper contactposition.25 23. The reusable auto injector according to any of items 19-22 depending on any of theitems 16-18, wherein the first damper assembly comprises an O-ring (1010) extendingaround a first part (1062) of the spring guide (1050a) extending inside the plunger rodcavity (1030a), wherein the O-ring (1010) is in contact with an inner surface of theplunger rod cavity (1030a), and wherein movement between the O-ring (1010) and the30 plunger rod cavity (1030a) upon proximal movement of the plunger rod (1030a)introduces a dampening effect.24. The reusable auto injector according to item 23, wherein movement between the O-ring(1010) and the plunger rod cavity (1030a) is a frictional force introducing a linear35 dampening effect.WO 2025 / 109058 PCT / EP2024 / 0830898025. The reusable auto injector according to any of the items 23-24, wherein the plunger rod(1020a) comprises an inner plunger rod tube (1039) extending into the plunger rodcavity (1030a), wherein at least part of the drive spring (1040) is positioned around theinner plunger rod tube (1039), and at least a part of the spring guide (1050a) is extending5 through the inner plunger rod tube (1039), wherein the O-ring (1010) is movable intothe inner plunger rod tube (1039) when the drive spring (1040) pushes the plunger rod(1020a) proximally.26. The reusable auto injector according to any of items 16-25, wherein the spring guide10 (1050a) comprises a spring guide rod (1058) comprising spring guide tracks (1060) forsupporting the drive spring (1040).27. The reusable auto injector according to any preceding item, wherein the reusable autoinjector further comprises a chassis sleeve (1400, 1400b) positioned between the15 plunger rod (1020, 1020a, 1020b) and the resetting sleeve (1200, 1200b, 1200d), thechassis sleeve (1400, 1400b) comprising a longitudinally extending channel (1403)through which the plunger rod resetting part (1026) extends, the chassis sleeve (1400,1400b) being non-rotatable relative to the cassette receiver (1100, 1100b, 1100c),wherein the channel (1403) is configured for preventing the plunger rod (1020, 1020a,20 1020b) from rotating when the resetting sleeve (1200, 1200b, 1200d) is rotated in thefirst rotational direction (DR1).28. The reusable auto injector according to any preceding item, wherein the reusable autoinjector further comprises a cassette interacting tab (1601).2529. The reusable auto injector according to item 28, wherein the cassette interacting tab(1601) is movable in the longitudinal direction (L) between a proximal cassette lockingposition (PP) and a distal cassette release position (PD), wherein prior to receiving acassette (100) in the reusable auto injector, the cassette interacting tab (1601) is in the30 distal cassette release position (PD).30. The reusable auto injector according to item 29, wherein when the cassette (100) isreceived in the reusable auto injector, user induced movement of the cassetteinteracting tab (1601) from the distal cassette release position (PD) to the proximal35 cassette locking position (PP) locks the cassette (100) in the reusable auto injector .WO 2025 / 109058 PCT / EP2024 / 0830898131. The reusable auto injector according to any of the items 29-30, wherein the reusableauto injector is configured for moving the cassette interacting tab (1601) from theproximal cassette locking position (PP) to the distal cassette release position (PD) whenresetting the reusable auto injector by rotation of the distal injector housing (2200,5 2200b) or the resetting sleeve (1200, 1200b, 1200d) in the first rotational direction(DR1), whereby the cassette (100) is unlocked and removeable from the reusable autoinjector .32. The reusable auto injector according to any of the items 29-31, wherein the cassette10 interacting tab (1601) is accessible for a user through a channel (1107) in the cassettereceiver (1100, 1100b, 1100c) in which the cassette interacting tab (1601) is movablealong the longitudinal direction (L).33. The reusable auto injector according to any preceding item, wherein the reusable auto15 injector further comprises a pullback part (1600).34. The reusable auto injector according to item 33, wherein the pullback part (1600)comprises the cassette interacting tab (1601).20 35. The reusable auto injector according to any preceding item, wherein the reusable autoinjector further comprises a cassette activation part (1500, 1500a, 1500b) configuredfor moving in the longitudinal direction (L) relative to the cassette receiver (1100, 1100b,1100c).25 36. The reusable auto injector according to item 35 depending on item 33, wherein thecassette activation part (1500a) comprises the cassette interacting tab (1601).37. The reusable auto injector according to any of the items 35-36, wherein the cassetteactivation part (1500, 1500a, 1500b) comprises one or more injector release members30 (1508).38. The reusable auto injector according to item 37, wherein the one or more injectorrelease members (1508) are configured for locking the cassette (100) in the auto injectorby proximal movement of the one or more injector release members (1508) into the35 cassette (100).WO 2025 / 109058 PCT / EP2024 / 0830898239. The reusable auto injector according to any of the items 37-38, wherein the one or moreinjector release members (1508) are configured for releasing a skin sensor (400) in thecassette (100) after securing the cassette (100) in the auto injector, wherein the skinsensor (400) is released by proximal movement of the one or more injector release5 members (1508) into the cassette (100).40. The reusable auto injector according to any of the items 35-39 depending on items 33or 34, wherein the pullback part (1600) comprises at least one cassette activation parttab surface (1606), wherein the cassette activation part (1500) comprises at least one10 pullback interacting tab (1506), and wherein the at least one cassette activation part tabsurface (1606) on the pullback part (1600) engages the at least one pullback interactingtab (1506) on the cassette activation part (1500) such that the cassette activation part(1500) can be moved in relation to the pullback part (1600).15 41. The reusable auto injector according to item 40, wherein the cassette activation part(1500) and the pullback part (1600) are configured for moving together in thelongitudinal direction.42. The reusable auto injector according to item 40 or 41, wherein the cassette activation20 part (1500) can be tilted in relation to the pullback part (1600).43. The reusable auto injector according to any of the items 35-42, wherein the cassetteactivation part (1500) can be tilted in relation to the pullback part (1600) around aninteraction point constituting the at least one cassette activation part tab surface (1606)25 on the pullback part (1600) and the at least one pullback interacting tab (1506) on thecassette activation part (1506).44. The reusable auto injector according to any preceding item further comprising aconverter (2000).3045. The reusable auto injector according to item 44, wherein the converter (2000) comprisesone or more converter pins selected from the group of:e aprimary converter pin (2001);e asecondary converter pin (2002);35 e atertiary converter pin (2003); ande aquaternary converter pin (2004).WO 2025 / 109058 PCT / EP2024 / 0830898346. Thereusable auto injector according to any of the item 45, wherein the converter (2000)comprises a tertiary converter pin (2003) and the cassette receiver (1100c, 1100d)comprises a tertiary converter pin receiving opening (1133) in which the tertiaryconverter pin (2003) is positioned.547. The reusable auto injector according to item 46, wherein the converter (2000) isrotatable in a first rotational direction around the tertiary converter pin (2003).48. The reusable auto injector according to any of the items 45-47 depending on any of the10 items 36-43 depending on item 35, wherein the converter (2000) comprises aquaternary converter pin (2004) and the cassette activation part (1500b) comprises aquaternary converter pin receiving channel (1534) in which the quaternary converter pin(2004) is movable.15 49. Thereusable auto injector according to item 48, wherein rotation of the converter (2000)around the tertiary converter pin (2003) in the first rotational direction moves thequaternary converter pin (2004) proximally, whereby the cassette activation part(1500b) is moved proximally along the longitudinal direction.20 50. The reusable auto injector according to any preceding item further comprising a userbutton (2020, 2020c).51. The reusable auto injector according to item 50 depending on any of the items 45-49,wherein the converter (2000) comprises a primary converter pin (2001) and the user25 button (2020) comprises a primary converter pin receiving opening (2031) in which theprimary converter pin (2001) is positioned.52. The reusable auto injector according to any of the items 50-51 depending on any of theitems 45-49, wherein the converter (2000) comprises a secondary converter pin (2002)30 and the user button (2020) comprises a secondary converter pin receiving opening(2032) in which the secondary converter pin (2002) is positioned.53. |The reusable auto injector according to any of the items 50-52 depending on any of theitems 45-49, wherein the converter (2000) and the user button (2020, 2020c) are35 rotationally locked to each other.WO 2025 / 109058 PCT / EP2024 / 0830898454. The reusable auto injector according to any of the items 50-53 depending on any of theitems 45-49, wherein the user button (2020) is configured for rotating in the firstrotational direction whereby the converter (2000) rotates in the first rotational direction.5 55. The reusable auto injector according to item 50 depending on any of the items 45-49,wherein the converter (2000) comprises a secondary converter pin (2002) and the userbutton (2020c) comprises a user button channel (2042) in which the secondaryconverter pin (2002) is configured to travel.10 56. The reusable auto injector according to item 55, wherein the user button (2020c) isconfigured for moving sideways whereby the converter (2000) rotates in the firstrotational direction.57. The reusable auto injector according to any preceding item further comprising a15 proximal injector housing (2100, 2100b, 2100c, 2100d).58. The reusable auto injector according to item 57 depending on any of the items 50-56,wherein the proximal injector housing (2100c, 2100d) comprises a user button receivingopening (2110) configured for receiving the user button (2020, 2020c).2059. The reusable auto injector according to any of the items 44-58, wherein the converter(2000) comprises a converter plate (2008) with a primary converter plate surface (2010)and a secondary converter plate surface (2012).25 60. The reusable auto injector according to item 35 or any of the items 36-59 depending onitem 35, wherein the cassette activation part (1500b) comprises an activation part plate(1530) with an activation part plate thread (1532), and wherein the resetting sleeve(1200b, 1200d) comprises at least one resetting sleeve pin (1214) configured fortraveling inside the activation part plate thread (1532).3061. The reusable auto injector according to item 60, wherein during rotation of the resettingsleeve (1200q) in the first rotational direction (DR1) for resetting the auto injector, the atleast one resetting sleeve pin (1214) travels inside the activation part plate thread (1532)thereby moving the cassette activation part (1500b) from an extended to a retracted35 position.WO 2025 / 109058 PCT / EP2024 / 0830898562. The reusable auto injector according to any preceding item, wherein the resetting sleeve(1200d) is configured for rotating relative to the cassette receiver (1100b) in a secondrotational direction (DR2) opposite the first rotational direction (DR1).5 63. The reusable auto injector according to any of the items 60-62, wherein the at least oneresetting sleeve pin (1214) is configured for traveling inside the activation part platethread (1532) when rotating the resetting sleeve (1200d) in the second rotationaldirection (DR2), whereby the cassette activation part (1500b) is moved proximally to theextended position.1064. The reusable auto injector according to item 63, wherein the resetting sleeve (1200d)comprises a first blocking pin (1215) configured for stopping the rotation of the resettingsleeve (1200d) in the second rotational direction (DR2) when abutting the activation partplate (1530) thereby limiting the rotation of the resetting sleeve (1200d) in the second15 rotational direction (DR2) to a predefined angle.65. The reusable auto injector according to any of the item 63 or 64, wherein the resettingsleeve (1200d) comprises a second blocking pin (1216) configured for stopping therotation of the resetting sleeve (1200d) in the first rotational direction (DR1) when20 abutting the activation part plate (1530) thereby limiting the rotation of the resettingsleeve (1200d) in the first rotational direction (DR1) to a predefined angle.66. The reusable auto injector according to any preceding item, wherein the auto injectorcomprises a plunger rod support part (1300, 1300a).2567. The reusable auto injector according to item 66, wherein the plunger rod support part(1300, 1300a) comprises a spring guide connecting opening (1301) for supporting adistal end (1054) of the spring guide (1050, 1050a).30 68. The reusable auto injector according to item 66 or 67, wherein the plunger rod (1020,1020a, 1020b) comprises at least one plunger rod tab (1027) located on an outsidesurface (1031) of the plunger rod (1020, 1020a, 1020b), and wherein the plunger rodsupport part (1300, 1300a) comprising a plunger rod release tab (1310), wherein theplunger rod release tab (1310) abuts the at least one plunger rod tab (1027) when the35 auto injector is in an initial position ready for receiving the cassette (100).WO 2025 / 109058 PCT / EP2024 / 0830898669. The reusable auto injector according to any preceding item, wherein the auto injectorcomprises an injector skin sensor detector (1700, 1700a, 1700b) configured for movingproximally into the cassette (100) and for moving distally again by a user pressing thecassette (100) against an injection site.570. The reusable auto injector according to item 69 depending on item 44 or on any of theitems 45-68 depending on item 44, wherein the injector skin sensor detector (1700b)comprises a converter blocking surface (1718), and wherein the converter (2000)comprises a skin sensor detector pin interaction surface (2018), wherein the injector10 skin sensor detector (1700b) is configured for being moved from an initial extendedposition to a distal position, wherein when in the initial extended position, the converterblocking surface (1718) abuts the skin sensor detector pin interaction surface (2018)thereby preventing rotation of the converter (2000), and wherein when in the distalposition, the converter blocking surface (1718) no longer abuts the skin sensor detector15 pin interaction surface (2018) thereby allowing rotation of the converter (2000).71. The reusable auto injector according to any of the items 35-69, wherein the reusableauto injector comprises an unlock sledge element (1750) configured for movingbetween:20 e a proximal position (USP), wherein longitudinal movement of the cassetteactivation part (1500a) is prevented; ande a distal position (USD), wherein longitudinal movement of the cassetteactivation part (1500a) into the cassette (100) is permitted.25 72. The reusable auto injector according to any of the items 35-69 and 71, wherein thecassette activation part (1500, 1500a) comprises one or more plunger rod lock elements(1518), and the plunger rod (1020a) comprises a cassette activation lock element(1038), and wherein prior to a cassette (100) being received in the auto injector, thecassette activation lock element (1038) is secured by the one or more plunger rod lock30 elements (1518) preventing relative longitudinal movement of the cassette activationpart (1500a) and the plunger rod (1020a).73. The reusable auto injector according to item 72 depending on item 71, wherein theunlock sledge element (1750) comprises an unlock sledge release tab (1758), wherein35 distal movement of the unlock sledge element (1750) relative to the cassette activationpart (1500a) moves the unlock sledge release tab (1758) towards the one or moreplunger rod lock elements (1518) whereby the cassette activation lock element (1038)WO 2025 / 109058 PCT / EP2024 / 08308987is released from the one or more plunger rod lock elements (1518) thereby allowingrelative longitudinal movement of the cassette activation part (1500a) and the plungerrod (1020a).5 74. The reusable auto injector according to item 73, wherein the cassette activation part(1500a) is configured for being moved proximally thereby moving the one or moreinjector release members (1508) into the cassette (100).75. The reusable auto injector according to any of the items 71-74 depending on item 69,10 wherein the unlock sledge element (1750) and the injector skin sensor detector (1700a)are longitudinal locked.76. The reusable auto injector according to item 69 or any of the items 71-75 depending onitem 69, wherein the plunger rod (1020a) and the drive spring (1040), being in a15 compressed state, are configured for being unlocked when the injector skin sensordetector (1700, 1700a, 1700b) is moved in the distal direction, thereby allowing thecompressed drive spring (1040) to push the plunger rod (1020a) in the proximaldirection for medicament delivery as the drive spring (1040) expands.20 77. The reusable auto injector according to item 69 depending on any of the items 67-68 orany of the items 71-76 depending on item 69 depending on any of the items 67-68,wherein the injector skin sensor detector (1700, 1700a) comprises a distal release endsurface (1709) configured for pushing the plunger rod release tab (1310) radiallyoutwardly when the user is pressing the cassette (100) against an injection site,25 whereby the plunger rod release tab (1310) no longer abuts the at least one plunger rodtab (1027) thereby allowing the drive spring (1040) to move the plunger rod (1020a)proximally for medicament delivery.78. The reusable auto injector according to any of the items 69-77, wherein the reusable30 auto injector further comprises an injector skin sensor detector spring (1710) configuredfor pushing the injector skin sensor detector (1700, 1700a) proximally after removal ofthe cassette (100) received in the auto injector from the injection site.79. The reusable auto injector according to any preceding item, wherein the plunger rod35 (1020a, 1020b) comprises at least a first plunger rod opening (1036A).WO 2025 / 109058 PCT / EP2024 / 0830898880. The reusable auto injector according to any preceding item, wherein the auto injectorcomprises a plunger rod release element (1350) with a plunger rod release hook (1358).81. The reusable auto injector according to item 80 depending on item 79, wherein the5 plunger rod release hook (1356) is secured in the first plunger rod opening (1036A)thereby preventing proximal movement of the plunger rod (1020a) when the autoinjector is in an initial position reacy for receiving the cassette (100).82. The reusable auto injector according to item 81, wherein the plunger rod release10 element (1350) comprises:e achassis sleeve interacting rod (1360) around which the plunger rod releaseelement (1350) is tiltable moving the plunger rod release hook (1356) radiallyoutwardly; ande apush protrusion (1358) abutting a sloping surface (1720) on the injector skin15 sensor detector (1700a, 1700b);wherein distal movement of the injector skin sensor detector (1700a, 1700b) relative tothe plunger rod release element (1350) pushes the plunger rod release hook (1356)radially outwardly by relative movement of the sloping surface (1720) against the pushprotrusion (1358) whereby the plunger rod release hook (1356) is released from the first20 plunger rod opening (1036A) releasing the plunger rod (1020a) for proximal movement.83. The reusable auto injector according to any of the items 80-82, wherein the auto injectorcomprises a push back spring (1370), wherein the push back spring (1370) is positionedbetween the plunger rod release element (1350) and the injector skin sensor detector25 (1700a, 1700b) exerting a pressure on the plunger rod release hook (1356) radiallyinwardly.84. The reusable auto injector according to any preceding item, wherein the auto injectorcomprises a cassette detector (1800).3085. The reusable auto injector according to item 84 depending on any of the items 67-83,wherein the cassette detector (1800) comprises a release surface (1806), wherein theplunger rod support part (1300, 1300a) comprises a proximal flexible part (1312) with aproximal protruding part (1311), and wherein the cassette activation part (1500, 1500a,35 1500b) comprises a support part lock tab (1511) abutting the proximal protruding part(1311) prior to inserting a cassette (100) in the auto injector,WO 2025 / 109058 PCT / EP2024 / 08308989wherein when the release surface (1806) is pushed against the proximal protruding part(1311), the proximal flexible part (1312) flexes radially, thereby releasing the cassetteactivation part (1500, 1500a, 1500b), thereby enabling locking of the cassette (100) inthe auto injector by proximal movement of the cassette activation part (1500, 1500a,5 1500b).86. The reusable auto injector according to any of the items 67-85, wherein the cassetteactivation part (1500, 1500a, 1500b) further comprises a distal end protrusion (1510),wherein the plunger rod support part (1300, 1300a) comprises a cassette activation part10 stop protrusion (1307), wherein the plunger rod (1020, 1020a, 1020b) comprises alongitudinally extending bar (1033),wherein the cassette activation part stop protrusion (1307) prevents distal movement ofthe cassette activation part (1500, 1500a, 1500b) after positioning a cassette (100) inthe auto injector by the distal end protrusion (1510) being positioned between the15 cassette activation part stop protrusion (1307) and the longitudinally extending bar(1033).87. The reusable auto injector according to any of the items 33-86, wherein the pullbackpart (1600) further comprises a second cassette interacting tab (1611) moving with the20 cassette interacting tab (1601) in the longitudinal direction, the second cassetteinteracting tab (1611) being radially non-movable.88. The reusable auto injector according to any preceding item, wherein the reusable autoinjector further comprises a rotational damper (1900) comprising:25 e adamper sleeve (1902) positioned between the chassis sleeve (1400, 1400b)and the resetting sleeve (1200, 1200b, 1200d), the damper sleeve (1902)comprising one or more damper channels (1904); ande adamper end surface (1908);wherein the plunger rod resetting part (1026) extends through the one or more damper30 channels (1904) and into the resetting thread (1206) in the resetting sleeve (1200,1200b, 1200d);wherein the damper sleeve (1902) is rotatable relative to the chassis sleeve (1400,1400b); andwherein movement of the plunger rod (1020, 1020a, 1020b) in the proximal direction35 rotates the damper sleeve (1902) due to the plunger rod resetting part (1026) extendingthrough the one or more damper channels (1904) in the damper sleeve (1902); andWO 2025 / 109058 PCT / EP2024 / 08308990wherein the damper sleeve (1902) and the damper end surface (1906) rotates relativelyduring injection, such that a speed of the plunger rod (1020, 1020a, 1020b) duringinjection in the proximal direction is reduced.5 89. The reusable auto injector according to item 88, wherein the damper sleeve (1902) isrotatable relative to the resetting sleeve (1200, 1200b, 1200d) during proximalmovement of the plunger rod (1020, 1020a, 1020b).90. The reusable auto injector according to any of the items 88-89, wherein the damper10 sleeve (1902) is non-rotatable relative to the resetting sleeve (1200, 1200b, 1200d)during distal movement of the plunger rod (1020, 1020a, 1020b).91. The reusable auto injector according to any of the items 88-90, wherein the one or moredamper channels (1904) in the damper sleeve (1902) each has a pitch in the first15 rotation direction being identical to a pitch of the resetting thread (1206) in the resettingsleeve (1200, 1200b, 1200d) in the first rotation direction (R1), whereby rotation of thedamper sleeve (1902) relative to the resetting sleeve (1200, 1200b, 1200d) isprevented.20 92. The reusable auto injector according to any of the items 88-91 depending on any of theitems 11-87, wherein the damper end surface (1908) is positioned inside distal injectorhousing (2200, 2200b) and connected to the distal injector housing (2200, 2200b).93. The reusable auto injector according to any of the items 88-92 depending on any of the25 items 11-87, wherein the damper end surface (1908) and the distal injector housing(2200, 2200b) are rotationally locked.94. The reusable auto injector according to any of the items 37-93, wherein the reusableauto injector is configured for receiving a cassette (100) comprising:30 e a syringe holder (300) for receiving the syringe (200) containing themedicament;e askin sensor (400) movable in the longitudinally direction relative to the syringeholder (300) between two or more longitudinal positions including at least a firstlocked position prior to securing the cassette (100) in the auto injector and an35 unlocked position after securing the cassette (100) in the auto injector ;wherein the cassette activation part (1500, 1500a, 1500b) comprises the one or moreinjector release members (1508) configured for releasing the skin sensor (400) in theWO 2025 / 109058 PCT / EP2024 / 08308991cassette (100) after securing the cassette (100) in the auto injector, wherein the skinsensor (400) is released by proximal movement of the one or more injector releasemembers (1508) into the cassette (100).5 95. The reusable auto injector according to any preceding item, wherein the reusable autoinjector is configured for receiving a cassette (100) comprising a cap (700) positionedat the proximal end of the cassette (100), and wherein the injector skin sensor detector(1700, 1700a, 1700b) is configured for moving proximally into the cassette (100) afterremoval of the cap (700).1096. The reusable auto injector according to item 95 depending on item 94, wherein afterremoval of the cap (700), the skin sensor (400) is configured for moving in the distaldirection by a user pressing the skin sensor (400) towards the injector site, wherein theinjector skin sensor detector (1700, 1700a, 1700b) is configured for moving in the distal15 direction when the skin sensor (400) is pressed towards the injector site.97. The reusable auto injector according to item 96 depending on any of the items 78-95,wherein when the injector skin sensor detector spring (1710) pushes the injector skinsensor detector (1700, 1700a, 1700b) proximally after removal of the cassette (100)20 received in the auto injector from the injection site, the skin sensor (400) of the cassette(100) is configured for being moved into a final locked position (LP3).98. The reusable auto injector according to any of the items 33-97, wherein the pullbackpart (1600) further comprises a plunger rod engagement surface (1608) configured for25 coming into contact with and abutting a distal end (1024) of the plunger rod (1020,1020a, 1020b) during medicament delivery whereby the pullback part (1600) movesproximally with the plunger rod (1020, 1020a, 1020b) during at least a last part of themedicament delivery.30 99. A reusable auto injector (1000, 1000a, 1000b, 1000c, 1000d) for administration ofmedicament, the auto injector comprising:e acassette receiver (1100, 1100b, 1100c) configured for receiving a removablecassette (100) containing the medicament;e aplunger rod (1020, 1020a, 1020b) configured for movement of a stopper (210)35 inside the cassette (100) in a first longitudinal direction for medicament delivery;e aplunger rod resetting part (1026) connected to and protruding radially from theplunger rod (1020, 1020a, 1020b);WO 2025 / 109058 PCT / EP2024 / 08308992e —adrive spring (1040) adapted for moving the plunger rod (1020, 1020a, 1020b)in the first longitudinal direction; anda resetting sleeve (1200, 1200b, 1200d) rotatable relative to the cassette receiver (1100,1100b, 1100c) in a first rotational direction (DR1), the resetting sleeve (1200, 1200b,5 1200d) comprising a resetting thread (1206), wherein the plunger rod resetting part(1026) engages with the resetting thread (1206) such that a rotation of the resettingsleeve (1200, 1200b, 1200d) in a first rotational direction (DR1) moves the plunger rod(1020, 1020a, 1020b) in a second longitudinal direction opposite the first longitudinaldirection for resetting the plunger rod (1020, 1020a, 1020b).10100. A reusable auto injector (1000, 1000a, 1000b, 1000c, 1000d) for administration ofmedicament, the auto injector being configured for receiving a cassette (100)comprising a syringe (200) containing the medicament, wherein the auto injector isextending from a proximal end (1002) to a distal end (1004) along a longitudinal axis15 (L), the auto injector comprising:e aplunger rod (1020, 1020a, 1020b) configured for proximal movement of astopper (210) inside the syringe (200) for medicament delivery, the plungerrod (1020, 1020a, 1020b) being configured for moving a total plunger rodmovement length, the total plunger rod movement length being from an initial20 distal plunger rod position to a proximal delivery plunger rod position;e adrive spring (1040) adapted for moving the plunger rod (1020, 1020a,1020b) in a proximal direction; ande afirst damper assembly configured for dampening at least part of the proximalmovement of the drive spring (1040) during medicament delivery, wherein the25 first damper assembly is configured for dampening a first part of the totalplunger rod movement length or the entire total plunger rod movement length.101. The reusable auto injector according to item 100, wherein the first damper assembly isconfigured for dampening only a first part of the total plunger rod movement length,30 wherein the first part of total plunger rod movement length is less than 25%, such asless than 20%, such as less than 15% of the total plunger rod movement length.102. The reusable auto injector according to any of the items 100-101, wherein the plungerrod (1020, 1020a, 1020b) is configured for moving between:35 © aninitial distal plunger rod position where the plunger rod (1020, 1020a, 1020b)is not in contact with the stopper (210) inside the cassette (100);WO 2025 / 109058 PCT / EP2024 / 08308993o astopper contact position, wherein the plunger rod is in contact with the stopper(210) inside the cassette (100); and© a proximal delivery plunger rod position, where the stopper (210) inside thesyringe (200) has been moved proximally for medicament delivery,5 wherein the first damper assembly dampers the movement of the plunger rod (1020,1020a, 1020b) only from the initial distal plunger rod position to the stopper contactposition.103. The reusable auto injector according to any of items 100-102, wherein the reusable auto10 injector comprises a spring guide (1050, 1050a) around which at least a distal end(1044) of the drive spring (1040) extends, wherein the drive spring (1040) is biasedbetween a proximal end surface (1032) inside the plunger rod cavity (1030, 1030a) anda distal end surface (1056) of the spring guide (1050, 1050a), and wherein the firstdamper assembly comprises an O-ring (1010) extending around a first part (1062) of15 the spring guide (1050a) extending inside the plunger rod cavity (1030a), wherein theO-ring (1010) is in contact with an inner surface of the plunger rod cavity (1030a), andwherein movement between the O-ring (1010) and the plunger rod cavity (1030a) uponproximal movement of the plunger rod (1030a) introduces a dampening effect.20 104. The reusable auto injector according to item 103, wherein movement between the Oring (1010) and the plunger rod cavity (1030a) is a frictional force introducing a lineardampening effect.105. The reusable auto injector according to any of the items 103-104, wherein the plunger25 rod (1020a) comprises an inner plunger rod tube (1039) extending into the plunger rodcavity (1030a), wherein at least part of the drive spring (1040) is positioned around theinner plunger rod tube (1039), and at least a part of the spring guide (1050a) is extendingthrough the inner plunger rod tube (1039), wherein the O-ring (1010) is movable intothe inner plunger rod tube (1039) when the drive spring (1040) pushes the plunger rod30 (1020a) proximally.106. A system comprising a reusable auto injector according to any of the preceding itemsand a cassette (100), the cassette (100) comprising:e asyringe holder (300) for receiving the syringe (200) containing the medicament;35 e askin sensor (400) longitudinally movable relative to the syringe holder (300)between two or more longitudinal positions including at least a first locked positionprior to securing the cassette (100) in the auto injector and an unlocked position;WO 2025 / 109058 PCT / EP2024 / 08308994wherein one or more injector release members (1508) in the reusable auto injector isconfigured for releasing the skin sensor (400) in the cassette (100) after securing thecassette (100) in the auto injector, wherein the skin sensor (400) is released by proximalmovement of the one or more injector release members (1508) into the cassette (100).5107. The system according to item 106, wherein the skin sensor (400) is movable in thelongitudinally direction relative to the syringe holder (300) between two or morelongitudinal positions selected from:o adistal position (LD);10 o a final locked position (LP3);o an initial locked position (LP1) between the final locked position (LP3) and thedistal position (LD); and© anintermediate position (LP2) between the initial locked position (LP1) and thefinal locked position (LP3).15108. The system according to item 107, wherein when the skin sensor (400) is in the distallongitudinal position (LD), the syringe outlet (204) is exposed, and wherein the skinsensor (400) covers the syringe outlet (208) when the skin sensor (400) is in either of:e the initial locked position (LP1); or20 e the intermediate position (LP2); ore the final locked position (LP3).109. The system according to item 107 or 108, wherein the skin sensor (400) is in the initiallocked position (LP1) prior to securing the cassette (100) in the reusable auto injector25 and movable to the intermediate position (LP2) after release of the skin sensor (400) bythe one or more injector release members (1508).110. The system according to any of the items 106-109, wherein the cassette (100) furthercomprises an index ring (500) rotatable relative to the skin sensor (400) between two or30 more rotational positions selected from:o a first rotational position (R1);o a delivery rotational position (Rd) in which the skin sensor (400) is moveablebetween the distal position (LD) and the final locked position (LP3);© acap-release rotational position (Rcr) positioned between the first rotational35 position (R1) and the delivery rotational position (Rd),wherein the one or more injector release members (1508) are configured for rotatingthe index ring (500) between the two or more rotational positions when the one or moreWO 2025 / 109058 PCT / EP2024 / 08308995injector release members (1508) moves proximally and comes into contact with theindex ring (500).111. The system according to any of the items 106-110, wherein the cassette (100) further5 comprises a syringe (200) received in the syringe holder (300), the syringe (200)comprising:o asyringe medicament compartment (208);o an outlet (204) at the proximal end (202) of a syringe medicament compartment;and10 o astopper (210) positioned inside the syringe compartment, wherein the stopperis movable from a distal end (204) of the syringe compartment towards theproximal end of the syringe compartment for emptying the medicament in thesyringe compartment through the outlet.15 112. The system according to any of the items 106-111, wherein the index ring is configuredfor moving from the cap-release rotational position (Rer) to the delivery rotationalposition (Rd) preparing the reusable auto injector for medicament delivery when the skinsensor (400) is in the distal longitudinal position (LD).20 113. The system according to any of the items 106-112, wherein the index ring (500)comprises a track (530) extending in a sloping direction, and wherein the one or moreinjector release members (1508) is configured for traveling inside the track (530), andwherein the index ring (500) is rotated when the injector release member (1508) travelsproximally inside the track (530).25114. The system according to item 113, wherein each of the one or more injector releasemembers (1508) comprises a track-guide protrusion (1509), and wherein the trackguide protrusion (1509) is configured for traveling inside the track (530).30 115. The system according to any of the items 106-114, wherein the auto injector comprisesone or more cassette locking parts (1109) configured for engaging in a snap-fitconnection with corresponding one or more cassette securing tabs (612) on the cassette(100) when the cassette (100) is inserted into the auto injector, and wherein proximalmovement of the injector release member (1508) prevents a disengagement of the35 snap-fit connection thereby securing the cassette (100) inside the auto injector .WO 2025 / 109058 PCT / EP2024 / 08308996116. The system according to item 115, wherein the one or more injector release members(1508) are adapted for moving to the initial position after delivery of medicament,whereby the cassette (100) is unlocked from the auto injector for removal of the cassette(100) after medicament delivery.5117. The system according to any of the items 115-116, wherein the auto injector comprisesan injector skin sensor detector (1700, 1700a, 1700b) and a skin sensor spring (1710)adapted for pushing the injector skin sensor detector (1700, 1700a, 1700b) against acassette skin sensor pin (422) upon proximal movement of the injector release member10 (1508) after release of the skin sensor (400) from the initial locked position.118. The system according to item 117, wherein the skin sensor spring (1710) is adapted forpushing the cassette skin sensor (400) in a proximal direction to the proximallongitudinal position (LP2) when the index ring (500) is in the cap-release rotational15 position (Rer).119. The system according to any of the items 117-118, wherein the skin sensor spring(1710) is adapted for pushing the cassette skin sensor (400) in a proximal direction tothe proximal longitudinal position (LP3) when the index ring (500) is in the delivery20 rotational position (Rd).120. The system according to any of the items 117-119, wherein after medicament deliveryand removal of the reusable auto injector from the delivery site, the skin sensor spring(1710) is configured for keeping the skin sensor (400) in the final longitudinal position25 (LP3) during distal movement of the injector release member (1508) whereby the indexring (500) is rotated from the delivery rotational position (Rd) to the first rotationalposition (R1).121. The system according to any of the items 117-120, wherein the index ring (500) is in30 the first rotational position (R1) prior to use and wherein when the index ring (500) ismoved from the first rotational position (R1) to the cap-release rotational position (Rcr)by proximal movement of the one or more injector release members (1508), the skinsensor spring reusable auto injector (1026) is adapted for pushing the skin sensor (400)to the intermediate position (LP2).35122. The system according to any of the items 106-121, wherein the cassette furthercomprises a cassette housing (600) comprising a cap holding part (608) at a proximalWO 2025 / 109058 PCT / EP2024 / 08308997end (602) of the cassette housing (600), and a removable cassette cap (700) comprisingone or more locking cap parts (706) extending distally from a proximal end (702) of thecassette cap,wherein prior to use, a cassette cap locking protrusion (708) on each of the one or more5 locking cap parts (706) is secured inside the cassette housing (600),wherein upon proximal movement of the skin sensor from the initial locked position(LP1) to the intermediate position (LP2), the distal locking ends (708) moves outside thecassette housing (600).10WO 2025 / 109058 PCT / EP2024 / 08308998References100 cassette102 proximal end of the cassette104 distal end of the cassette5 200 syringe202 proximal end of the syringe / proximal end of the syringe compartment204 distal end of the syringe / distal end of the syringe compartment206 syringe compartment208 hollow needle / syringe outlet10 210 stopper212 needle shield / RNS214 inner part of the needle shield216 outer part of the needle shield218 syringe flange15 220 syringe shoulder250 syringe sleeve252 proximal end of the syringe sleeve254 distal end of the syringe sleeve256 syringe sleeve inward protruding support surface20 258 C-shaped longitudinal mounting opening260 distal syringe sleeve support surface300 syringe holder302 proximal end of the syringe holder304 distal end of the syringe holder25 306 proximal opening in the syringe holder308 syringe support surface310 syringe holder tubular part312 syringe holder tubular part inspection opening314 distal tubular ring part30 89315 opening in the distal end of the syringe holder316 proximal index ring support surface318 syringe holder lid locking opening320 syringe securing flexible tab at the distal end of the syringe holder322 injection injector release member opening35 330 syringe holder lid332 syringe holder lid opening334 lid locking tabWO 2025 / 109058 PCT / EP2024 / 08308999336 C-shaped lid part337 opening in the C-shaped lid part338 support lid part340 inner surface on the C-shaped lid part5 342 C-shaped lid part channel344 bridge portion400 skin sensor402 proximal end of the skin sensor404 distal end of the skin sensor10 405 proximal skin contact surface of the skin sensor406 proximal recess408 protruding tab410 proximal protruding ramp412 first locking recess on the skin sensor15 9413 first locking tab414 second locking recess on the skin sensor415 second locking tab416 first distal surface418 first proximal surface20 420 tubular skin sensor part422 cassette skin sensor pin424 second distal surface426 inspection opening in the skin sensor428 cassette housing locking protrusion25 500 index ring502 proximal end of the index ring504 distal end of the index ring506 first longitudinally extending part507 locking tab30 508, 508’ first recess on the index ring509 index ring ramp510, 510’ second recess on the index ring512 second radially extending part513 opening in the second radially extending part35 514 second proximal surface of the second radially extending part516, 516’ second distal surface of the second radially extending part518 second longitudinally extending partWO 2025 / 109058 PCT / EP2024 / 083089100520 tubular index ring part522 first radially extending part524 first proximal surface of the first radially extending part526 first distal surface of the first radially extending part5 528 first surface area of the first radially extending part530 track in the first radially extending part532 first corner of the first radially extending part534 second corner of the first radially extending part536 first section of the track10 538 second section of the track540 third section of the track542 first middle point of the track544 second middle point of the track600 cassette housing15 602 proximal end of the cassette housing604 distal end of the cassette housing606 opening at the distal end of the cassette housing608 cap holding part610 inspection opening20 612 cassette securing tabs614 skin sensor locking opening700 cassette cap702 proximal end of the cassette cap704 distal end of the cassette cap25 706 cap locking part708 cassette cap track-guide protrusion / cassette cap locking protrusion709 inwardly extending part of the cassette cap locking protrusion710 second distally extending part / tubular cap part712 gripping portion30 3 3=714 inner cassette cap part716 outer cassette cap part800 cassette housing cover1000 auto injector1000a auto injector35 — 1000b auto injector1000c auto injector1000d auto injectorWO 2025 / 109058 PCT / EP2024 / 0830891011002 proximal end of the auto injector1004 distal end of the auto injector1010 O-ring1020 plunger rod5 1020a plunger rod1020b plunger rod1021 pullback part stop part1022 proximal end of the plunger rod1023 distally directed surface on the pullback part stop part10 1024 distal end of the plunger rod1025 proximally directed surface on the pullback part stop part1026 plunger rod resetting part1027 outer plunger rod tabs1028 sloping distal surface on outer plunger rod tabs15 1029 steep proximal surface on outer plunger rod tabs1030 plunger rod cavity1030a plunger rod cavity1031 outer surface of the plunger rod1032 spring proximal end surface inside the plunger rod cavity20 1033 longitudinally extending bar1034 distal tubular part1035 proximal tubular part1036 plunger rod opening1036A first plunger rod opening25 1036B second plunger rod opening1037 inner surface of the plunger rod cavity1038 cassette activation lock element1040 drive spring1042 proximal end of the drive spring30 §=1044 distal end of the drive spring1046 proximal end of the distal tubular plunger rod part1050 drive spring guide1050a drive spring guide1052 proximal end of the spring guide35 1054 distal end of the spring guide1056 spring distal end surface of the spring guide1058 spring guide rodWO 2025 / 109058 PCT / EP2024 / 0830891021060 spring guide track1062 first part of the drive spring guide1100 cassette receiver1100b cassette receiver5 1100c cassette receiver1101 tubular part of the cassette receiver1102 proximal end of the cassette receiver1103 chassis sleeve channel1104 distal end of the cassette receiver10 1105 first spring support surface for the injector skin sensor detector spring1106 second spring support surface for the cassette detector spring1107 activation part channel for the cassette activation part1108 outer coupling surface1109 cassette locking part15 1110 end plate in the cassette receiver1115 injector skin sensor detector opening1116 cassette detector opening1118 injector release member opening1120 plunger rod opening20 1122 cassette receiver tab1124 cassette receiver channel1126 interface to plunger rod release element1128 cover part plate tab receiving opening1133 tertiary converter pin receiving opening25 1134 converter pin channel1200 resetting sleeve1200b resetting sleeve1200d resetting sleeve1202 proximal end of the resetting sleeve30 1204 distal end of the resetting sleeve1205 inner surface of the resetting sleeve1206 resetting thread1208 outer surface of the resetting sleeve1209 outer housing channel35 1210 chassis sleeve interacting hook1211 sloping surface on the chassis sleeve interacting hook1212 steep surface on the chassis sleeve interacting hookWO 2025 / 109058 PCT / EP2024 / 0830891031214 resetting sleeve pin1215 first blocking pin1216 second blocking pin1300 plunger rod support part5 1300a plunger rod support part1301 spring guide connecting opening1302 proximal end of the plunger rod support part1303 support part end plate of the plunger rod support part1304 distal end of the plunger rod support part10 1305 first proximally extending arm1306 plunger rod support bar on the first proximally extending arm1307 cassette activation part stop protrusion on the first proximally extending arm1308 second proximally extending arm1309 flexible side arm15 1310 plunger rod release tab1311 proximal protruding part1312 proximal flexible part of the first proximally extending arm1350 plunger rod release element1352 proximal end of the plunger rod release element20 1354 distal end of the plunger rod release element1356 plunger rod release hook1358 push protrusion1360 chassis sleeve interacting rod1362 push back surface25 1370 push back spring1400 chassis sleeve1400b chassis sleeve1401 tubular chassis part1402 proximal end of the chassis sleeve30 1403 longitudinally extending channel in the tubular chassis part1404 distal end of the chassis sleeve1405 distal skin sensor spring support rod1406 distal cassette detector spring support rod1407 chassis sleeve plate35 1408 plunger rod support part coupling surface1409 coupling surface1410 resetting sleeve interacting tabWO 2025 / 109058 PCT / EP2024 / 0830891041411 sloping surface on the resetting sleeve interacting tab1412 steep surface on the resetting sleeve interacting tab1413 outside of the coupling surface1414 inside of the coupling surface5 1416 activation part plate channel1500 cassette activation part1500a cassette activation part1500b cassette activation part1502 proximal end of the cassette activation part10 1504 distal end of the cassette activation part1506 pullback interacting tab1507 flexible pullback arm1508 injector release member1509 track-guide protrusion15 1510 distal end protrusion1511 support part lock tab1512 guiding tab1516 plunger rod lock arm1518 plunger rod lock element20 1520 lock element enclosure1522 cassette interacting tab interface1524 plunger rod interaction arm1530 activation part plate1532 activation part plate thread25 1534 quaternary converter pin receiving channel1600 pullback part1601 cassette interacting tab1602 proximal end of the pullback part1604 distal end of the pullback part30 1605 step type bend on the pullback part1606 cassette activation part tab surface1608 plunger rod engagement surface1611 second cassette interacting tab1700 injector skin sensor detector35 1700a injector skin sensor detector1700b injector skin sensor detector1702 proximal end of the injector skin sensor detectorWO 2025 / 109058 PCT / EP2024 / 0830891051703 injector skin sensor detector pin1704 distal end of the injector skin sensor detector1705 proximal skin sensor spring support rod1706 plate part on the injector skin sensor detector5 1707 plate part channel for the plunger rod1709 distal release end surface1710 injector skin sensor detector spring1712 proximal end of the injector skin sensor detector spring1714 distal end of the injector skin sensor detector spring10 1716 sledge receiving channel1718 converter blocking surface1720 sloping surface of the injector skin sensor detector1750 unlock sledge element1752 proximal end of the unlock sledge element15 1754 distal end of the unlock sledge element1756 injector skin sensor detector lock tab1758 unlock sledge release tab1800 cassette detector1802 proximal end of the cassette detector20 1803 cassette detector pin1804 distal end of the cassette detector1805 proximal cassette detector spring support rod1806 release surface1810 cassette detector spring25 1812 proximal end of the cassette detector spring1814 distal end of the cassette detector spring1900 rotational damper1902 damper sleeve1904 damper channel30 1906 damper end surface2000 converter2001 primary converter pin2002 secondary converter pin2003 tertiary converter pin35 2004 quaternary converter pin2008 converter plate2010 primary converter plate surfaceWO 2025 / 109058 PCT / EP2024 / 0830891062012 secondary converter plate surface2018 skin sensor detector pin interaction surface2020 user button2020c user button5 2022 user button plate2024 primary user button plate surface2026 secondary user button plate surface2028 user button tab2031 primary converter pin receiving opening10 2032 secondary converter pin receiving opening2040 primary user button protrusion2042 user button channel2044 secondary user button protrusion2050 cover part15 2052 cover part plate2054 primary cover part plate surface2056 secondary cover part plate surface2058 cover part plate tab2060 curving cover part surface20 2100 proximal injector housing2100b proximal injector housing2100c proximal injector housing2100d proximal injector housing2101 first tubular part of the proximal injector housing25 2102 proximal end of the proximal injector housing2104 distal end of the proximal injector housing2106 cassette view opening2107 second activation part channel for the cassette activation part2108 chassis sleeve channel for the coupling surface on the chassis sleeve30 2109 second tubular part of the proximal injector housing2110 user button receiving opening2200 distal injector housing2200b distal injector housing2202 proximal end of the distal injector housing35 2204 distal end of the distal injector housing2205 inner surface of the distal injector housing2206 user gripping linesWO 2025 / 109058 PCT / EP2024 / 0830891072208 outer surface of the distal injector housing2209 inner resetting sleeve locking part2210 rotational stop surface2212 distal injector housing plate5 2214 plunger rod support part alignment tabs2216 distal injector housing capPP proximal cassette locking positionPD distal cassette release position10 LD distal position of the syringe holderLP1 initial locked proximal position of the syringe holderLP2 intermediate proximal position of the syringe holderLP3 final locked proximal position of the syringe holderR1 first rotational position of the index ring15 R2 second rotational position of the index ringR3 third rotational position of the index ringRd delivery rotational position of the index ringRer cap-release rotational position of the index ringDR1 first rotational direction20 USP proximal unlock sledge element positionUSD distal unlock sledge element positionWO 2025 / 109058 PCT / EP2024 / 083089

Claims

Claims1. A reusable auto injector (1000, 1000a, 1000b, 1000c, 1000d) for administration ofmedicament, the auto injector being configured for receiving a cassette (100)5 comprising a syringe (200) containing the medicament;wherein the auto injector is extending from a proximal end (1002) to a distal end (1004)along a longitudinal axis (L);10 wherein the cassette (100) is configured for being removable received in the autoinjector in a longitudinal direction along the longitudinal axis (L);wherein the auto injector comprises:e acassette receiver (1100, 1100b, 1100c) configured for receiving the cassette15 (100);e a plunger rod (1020, 1020a, 1020b) configured for proximal movement of astopper (210) inside the syringe (200) for medicament delivery;e aplunger rod resetting part (1026) connected to and protruding radially from theplunger rod (1020, 1020a, 1020b);20 e —adrive spring (1040) adapted for moving the plunger rod (1020, 1020a, 1020b)in a proximal direction; ande a resetting sleeve (1200, 1200b, 1200d) rotatable relative to the cassettereceiver (1100, 1100b, 1100c) in a first rotational direction (DR1), the resettingsleeve (1200, 1200b, 1200d) comprising a resetting thread (1206) located on25 an inner surface (1205) of the resetting sleeve (1200, 1200b, 1200d), whereinthe plunger rod resetting part (1026) engages with the resetting thread (1206)such that a rotation of the resetting sleeve (1200, 1200b, 1200d) in a firstrotational direction (DR1) moves the plunger rod (1020, 1020a, 1020b) in adistal direction for resetting the plunger rod (1020, 1020a, 1020b).

302. The reusable auto injector according to claim 1, wherein the cassette receiver (1100,1100b, 1100c) is configured for receiving the cassette (100) releasably in the cassettereceiver (1100, 1100b, 1100c).35 3. The reusable auto injector according to any preceding claim, wherein rotation of theresetting sleeve (1200, 1200b, 1200d) in the first rotational direction (DR1) moves theWO 2025 / 109058 PCT / EP2024 / 083089109plunger rod (1020, 1020a, 1020b) in a distal direction for resetting the plunger rod (1020,1020a, 1020b) relative to the cassette receiver (1100, 1100b, 1100c).

4. The reusable auto injector according to any preceding claim, wherein the plunger rod5 (1020, 1020a, 1020b) is configured for proximal movement between a retracted plungerrod position and an extended plunger rod position, wherein the resetting sleeve (1200,1200b, 1200d) is configured for moving the plunger rod from the extended plunger rodposition to the retracted plunger rod position by rotation of the resetting sleeve (1200,1200b, 1200c) in the first rotational direction (DR1) a predefined amount of degrees10 relative to the cassette receiver (1100, 1100b, 1100c).

5. The reusable auto injector according to claim 4, wherein the predefined amount ofdegrees relative to the cassette receiver is between 150 degrees and 210 degrees, suchas between 160 degrees and 200 degrees, such as between 170 degrees and 19015 degrees, such as 180 degrees.

6. The reusable auto injector according to any preceding claim, wherein the plunger rodresetting part (1026) comprises two pin parts positioned opposite another, wherein theresetting thread (1206) comprises two helical threads positioned opposite each other20 inside the resetting sleeve (1200, 1200b, 1200d), each of the two helical threadsinterfacing with each of the two oppositely positioned pin parts extending from a distalend (1024) of the plunger rod (1020, 1020a, 1020b).

7. The reusable auto injector according to any preceding claim, wherein the reusable auto25 injector further comprises a distal injector housing (2200, 2200b) surrounding theresetting sleeve (1200, 1200b, 1200d), the distal injector housing (2200, 2200b) beingrotatable relative to the cassette receiver (1100, 1100b, 1100c), wherein the distalinjector housing (2200, 2200b) is rotationally locked to the resetting sleeve (1200,1200b, 1200d).

308. The reusable auto injector according to claim 7, wherein the distal injector housing(2200, 2200b) comprises at least one rotational stop surface (2210) protruding from adistal injector housing plate (2212) of the distal injector housing (2200, 2200b), the atleast one rotational stop surface (2210) preventing further rotation of the resetting35 sleeve (1200, 1200b, 1200d) than the predefined amount of degrees relative to thecassette receiver (1100, 1100b, 1100c), wherein the rotational stop surface (2210)preferably abuts the plunger rod resetting part (1026) when the resetting sleeve hasWO 2025 / 109058 PCT / EP2024 / 083089110been rotated the predefined amount of degrees relative to the cassette receiver,whereby further rotation of the resetting sleeve (1200, 1200b, 1200d) relative to thecassette receiver (1100, 1100b, 1100c) is prevented.5 9. The reusable auto injector according to any preceding claim, wherein the rotation of theresetting sleeve (1200, 1200b, 1200qd) in the first rotational direction (DR1) compressesthe drive spring (1040), wherein the plunger rod (1020, 1020a, 1020b) comprises aplunger rod cavity (1030, 1030a) extending into the plunger rod (1020, 1020a, 1020b)and wherein the drive spring (1040) is positioned at least partly inside the plunger rod10 cavity (1030, 1030a).

10. The reusable auto injector according to any preceding claim, wherein the reusable autoinjector further comprises a first damper assembly configured for dampening at leastpart of the proximal movement of the drive spring (1040) during medicament delivery.1511. The reusable auto injector according to claim 10, wherein during medicament delivery,the plunger rod (1020, 1020a, 1020b) is configured for moving a total plunger rodmovement length, the total plunger rod movement length being from an initial distalplunger rod position to a proximal delivery plunger rod position, wherein the first damper20 assembly is configured for dampening a first part of the total plunger rod movementlength or the entire total plunger rod movement length.

12. The reusable auto injector according to claim 11, wherein the first damper assembly isconfigured for dampening only the first part of the total plunger rod movement length,25 wherein the first part of total plunger rod movement length is less than 25%, such asless than 20%, such as less than 15% of the total plunger rod movement length.

13. The reusable auto injector according to any of the claims 9-12, wherein the reusableauto injector comprises a spring guide (1050, 1050a) around which at least a distal end30 (1044) of the drive spring (1040) extends, and wherein the first damper assemblycomprises an O-ring (1010) extending around a first part of the spring guide (1050,1050a) extending inside the plunger rod cavity (1030, 1030a), wherein the O-ring (1010)is in contact with an inner surface of the plunger rod cavity (1030, 1030a), and whereincontact between the O-ring (1010) and the plunger rod cavity (1030, 1030a) upon35 proximal movement of the plunger rod (1030, 1030a) introduces a dampening effect.WO 2025 / 109058 PCT / EP2024 / 08308911114. The reusable auto injector according to any preceding claim, wherein the reusable autoinjector further comprises a chassis sleeve (1400, 1400b) positioned between theplunger rod (1020, 1020a, 1020b) and the resetting sleeve (1200, 1200b, 1200d), thechassis sleeve (1400, 1400b) comprising a longitudinally extending channel (1403)5 through which the plunger rod resetting part (1026) extends, the chassis sleeve (1400,1400b) being non-rotatable relative to the cassette receiver (1100, 1100b, 1100c),wherein the channel (1403) is configured for preventing the plunger rod (1020, 1020a,1020b) from rotating when the resetting sleeve (1200, 1200b, 1200d) is rotated in thefirst rotational direction (DR1).1015. The reusable auto injector according to any preceding claim, wherein the reusable autoinjector further comprises a cassette interacting tab (1601) movable in the longitudinaldirection (L) between a proximal cassette locking position (PP) and a distal cassetterelease position (PD), wherein prior to receiving a cassette (100) in the reusable auto15 injector, the cassette interacting tab (1601) is in the distal cassette release position (PD),wherein when the cassette (100) is received in the reusable auto injector, user inducedmovement of the cassette interacting tab (1601) from the distal cassette release position(PD) to the proximal cassette locking position (PP) locks the cassette (100) in thereusable auto injector .2016. The reusable auto injector according to any preceding claim, wherein the reusable autoinjector further comprises a cassette activation part (1500, 1500a, 1500b) configuredfor moving in the longitudinal direction (L) relative to the cassette receiver (1100, 1100b,1100c), wherein the cassette activation part (1500, 1500a, 1500b) comprises one or25 more injector release members (1508) configured for:e releasing a skin sensor (400) in the cassette (100) after securing the cassette(100) in the auto injector, wherein the skin sensor (400) is released by proximalmovement of the one or more injector release members (1508) into the cassette(100), and / or30 e locking the cassette (100) in the auto injector by proximal movement of the oneor more injector release members (1508) into the cassette (100).

17. The reusable auto injector according to claim 16, wherein the reusable auto injectorfurther comprises a pullback part (1600) comprising at least one cassette activation part35 tab surface (1606), and wherein the cassette activation part (1500, 1500a, 1500b)comprises at least one pullback interacting tab (1506), and wherein the at least onecassette activation part tab surface (1606) on the pullback part (1600) engages the atWO 2025 / 109058 PCT / EP2024 / 083089112least one pullback interacting tab (1506) on the cassette activation part (1500, 1500a,1500b) such that the cassette activation part (1500, 1500a, 1500b) can be moved inrelation to the pullback part (1600).5 18. The reusable auto injector according to claim 17, wherein the cassette activation part(1500, 1500a, 1500b) and the pullback part (1600) are configured for moving togetherin the longitudinal direction, and wherein the cassette activation part (1500, 1500a,1500b) can be tilted in relation to the pullback part (1600), wherein the cassetteactivation part (1500, 1500a, 1500b) can be tilted in relation to the pullback part (1600)10 around an interaction point constituting the at least one cassette activation part tabsurface (1606) on the pullback part (1600) and the at least one pullback interacting tab(1506) on the cassette activation part (15068).

19. The reusable auto injector according to any preceding claim further comprising a15 converter (2000). wherein the converter (2000) comprises one or more converter pinsselected from the group of:e aprimary converter pin (2001);e asecondary converter pin (2002);e atertiary converter pin (2003); and20 e a quaternary converter pin (2004).

20. The reusable auto injector according to claim 19, wherein the converter (2000)comprises the tertiary converter pin (2003) and the cassette receiver (1100c, 1100d)comprises a tertiary converter pin receiving opening (1133) in which the tertiary25 converter pin (2003) is positioned, and wherein the converter (2000) is rotatable in afirst rotational direction around the tertiary converter pin (2003).

21. The reusable auto injector according to claim 20, wherein the converter (2000)comprises the quaternary converter pin (2004) and the cassette activation part (1500b)30 comprises a quaternary converter pin receiving channel (1534) in which the quaternaryconverter pin (2004) is movable, wherein rotation of the converter (2000) around thetertiary converter pin (2003) in the first rotational direction moves the quaternaryconverter pin (2004) proximally, whereby the cassette activation part (1500b) is movedproximally along the longitudinal direction.3522. The reusable auto injector according to any preceding claim further comprising a userbutton (2020, 2020c).WO 2025 / 109058 PCT / EP2024 / 08308911323. The reusable auto injector according to claim 22 depending on any of the claims 19-21,wherein the converter (2000) comprises the primary converter pin (2001) and thesecondary converter pin (2002), and wherein the user button (2020) comprises a5 primary converter pin receiving opening (2031) in which the primary converter pin (2001)is positioned, and a secondary converter pin receiving opening (2032) in which thesecondary converter pin (2002) is positioned.

24. The reusable auto injector according to claim 23, wherein the user button (2020) is10 configured for rotating in the first rotational direction whereby the converter (2000)rotates in the first rotational direction.

25. The reusable auto injector according to claim 22 depending on any of the claims 19-21,wherein the converter (2000) comprises the secondary converter pin (2002) and the15 user button (2020c) comprises a user button channel (2042) in which the secondaryconverter pin (2002) is configured to travel, wherein the user button (2020c) isconfigured for moving sideways whereby the converter (2000) rotates in the firstrotational direction.20 26. The reusable auto injector according to claim 16 or any of the claims 17-25 dependingon claim 16, wherein the cassette activation part (1500b) comprises an activation partplate (1530) with an activation part plate thread (1532), and wherein the resetting sleeve(1200b, 1200d) comprises at least one resetting sleeve pin (1214) configured fortraveling inside the activation part plate thread (1532), wherein during rotation of the25 resetting sleeve (1200d) in the first rotational direction (DR1) for resetting the autoinjector, the at least one resetting sleeve pin (1214) travels inside the activation partplate thread (1532) thereby moving the cassette activation part (1500b) from anextended to a retracted position.30 27. The reusable auto injector according to claim 26, wherein the resetting sleeve (1200d)is configured for rotating relative to the cassette receiver (1100b) in a second rotationaldirection (DR2) opposite the first rotational direction (DR1), wherein the at least oneresetting sleeve pin (1214) is configured for traveling inside the activation part platethread (1532) when rotating the resetting sleeve (1200d) in the second rotational35 direction (DR2), whereby the cassette activation part (1500b) is moved proximally to theextended position.WO 2025 / 109058 PCT / EP2024 / 08308911428. The reusable auto injector according to claim 27, wherein the resetting sleeve (1200d)comprises a first blocking pin (1215) and / or a second blocking pin (1216), wherein firstblocking pin (1215) is configured for stopping the rotation of the resetting sleeve (1200d)in the second rotational direction (DR2) when abutting the activation part plate (1530)5 thereby limiting the rotation of the resetting sleeve (1200d) in the second rotationaldirection (DR2) to a predefined angle, and wherein the second blocking pin (1216)configured for stopping the rotation of the resetting sleeve (1200d) in the first rotationaldirection (DR1) when abutting the activation part plate (1530) thereby limiting therotation of the resetting sleeve (1200d) in the first rotational direction (DR1) to a10 predefined angle.

29. The reusable auto injector according to any preceding claim, wherein the auto injectorcomprises an injector skin sensor detector (1700, 1700a, 1700b) configured for movingproximally into the cassette (100) and for moving distally again by a user pressing the15 cassette (100) against an injection site.

30. The reusable auto injector according to claim 29 depending on claim 19 or any of theclaims 20-28 depending on claim 19, wherein the injector skin sensor detector (1700b)comprises a converter blocking surface (1718), and wherein the converter (2000)20 comprises a skin sensor detector pin interaction surface (2018), wherein the injectorskin sensor detector (1700b) is configured for being moved from an initial extendedposition to a distal position, wherein when in the initial extended position, the converterblocking surface (1718) abuts the skin sensor detector pin interaction surface (2018)thereby preventing rotation of the converter (2000), and wherein when in the distal25 position, the converter blocking surface (1718) no longer abuts the skin sensor detectorpin interaction surface (2018) thereby allowing rotation of the converter (2000).

31. The reusable auto injector according to claim 29, wherein the plunger rod (1020, 1020a,1020b) and the drive spring (1040), being in a compressed state, are configured for30 being unlocked when the injector skin sensor detector (1700, 1700a, 1700b) is movedin the distal direction, thereby allowing the compressed drive spring (1040) to push theplunger rod (1020, 1020a, 1020b) in the proximal direction for medicament delivery asthe drive spring (1040) expands.35 32. The reusable auto injector (1000) according to claim 29 or 31, wherein the plunger rod(1020) comprises at least one plunger rod tab (1027) located on an outside surface(1031) of the plunger rod (1020), and wherein the auto injector (1000) comprises aWO 2025 / 109058 PCT / EP2024 / 083089115plunger rod support part (1300) comprising a plunger rod release tab (1310), whereinthe plunger rod release tab (1310) abuts the at least one plunger rod tab (1027) whenthe auto injector (1000) is in an initial position ready for receiving the cassette (100),and wherein the injector skin sensor detector (1700) comprises a distal release end5 surface (1709) configured for pushing the plunger rod release tab (1310) radiallyoutwardly when the user is pressing the cassette (100) against an injection site,whereby the plunger rod release tab (1310) no longer abuts the at least one plunger rodtab (1027) thereby allowing the drive spring (1040) to move the plunger rod (1020)proximally for medicament delivery.1033. |The reusable auto injector (1000) according to any of the claims 18-32, wherein the autoinjector (1000) comprises a cassette detector (1800) with a release surface (1806),wherein the auto injector (1000) comprises a plunger rod support part (1300) comprisinga proximal flexible part (1312) with a proximal protruding part (1311), and wherein the15 cassette activation part (1500) comprises a support part lock tab (1511) abutting theproximal protruding part (1311) prior to inserting a cassette (100) in the auto injector(1000),wherein when the release surface (1806) is pushed against the proximal protruding part(1311), the proximal flexible part (1312) flexes radially, thereby releasing the cassette20 activation part (1500), thereby enabling locking of the cassette (100) in the auto injector(1000) by proximal movement of the cassette activation part (1500).

34. The reusable auto injector (1000) according to any of the claims 18-33, wherein thecassette activation part (1500) further comprises a distal end protrusion (1510), wherein25 the plunger rod support part (1300) comprises a cassette activation part stop protrusion(1307), wherein the plunger rod (1020) comprises a longitudinally extending bar (1033),wherein the cassette activation part stop protrusion (1307) prevents distal movement ofthe cassette activation part (1500) after positioning a cassette (100) in the auto injector(1000) by the distal end protrusion (1510) being positioned between the cassette30 activation part stop protrusion (1307) and the longitudinally extending bar (1033).

35. The reusable auto injector (1000a) according to any of the claims 16-31, wherein thecassette activation part (1500a) comprises one or more plunger rod lock elements(1518), and the plunger rod (1020a) comprises a cassette activation lock element35 (1038), and wherein prior to a cassette (100) being received in the auto injector, thecassette activation lock element (1038) is secured by the one or more plunger rod lockWO 2025 / 109058 PCT / EP2024 / 083089116elements (1518) preventing relative longitudinal movement of the cassette activationpart (1500a) and the plunger rod (1020a).

36. The reusable auto injector (1000a) according to any of the claims 16-31 and 35, wherein5 the reusable auto injector (1000a) comprises an unlock sledge element (1750)configured for moving between:e a proximal position (USP), wherein longitudinal movement of the cassetteactivation part (1500a) is prevented; ande a distal position (USD), wherein longitudinal movement of the cassette10 activation part (1500a) into the cassette (100) is permitted.

37. The reusable auto injector (1000a) according to claim 36 depending on claim 35,wherein the unlock sledge element (1750) comprises an unlock sledge release tab(1758), wherein distal movement of the unlock sledge element (1750) relative to the15 cassette activation part (1500a) moves the unlock sledge release tab (1758) towardsthe one or more plunger rod lock elements (1518) whereby the cassette activation lockelement (1038) is released from the one or more plunger rod lock elements (1518)thereby allowing relative longitudinal movement of the cassette activation part (1500a)and the plunger rod (1020a).2038. The reusable auto injector according to any preceding claim, wherein the plunger rod(1020, 1020a, 1020b) comprises at least a first plunger rod opening (1036A), andwherein the auto injector comprises a plunger rod release element (1350) with a plungerrod release hook (1356) secured in the first plunger rod opening (1036A) thereby25 preventing proximal movement of the plunger rod (1020a) when the auto injector is inan initial position ready for receiving the cassette (100).

39. The reusable auto injector according to claim 38, wherein the plunger rod releaseelement (1350) comprises:30 e achassis sleeve interacting rod (1360) around which the plunger rod releaseelement (1350) is tiltable moving the plunger rod release hook (1356) radiallyoutwardly; ande apush protrusion (1358) abutting a sloping surface (1720) on the injector skinsensor detector (1700, 1700a, 1700b);35 wherein distal movement of the injector skin sensor detector (1700, 1700a, 1700b)relative to the plunger rod release element (1350) pushes the plunger rod release hook(1356) radially outwardly by relative movement of the sloping surface (1720) against theWO 2025 / 109058 PCT / EP2024 / 083089117push protrusion (1358) whereby the plunger rod release hook (1358) is released fromthe first plunger rod opening (1036A) releasing the plunger rod (1020a) for proximalmovement.5 40. The reusable auto injector according to any preceding claim, wherein the reusable autoinjector further comprises a rotational damper (1900) comprising:e adamper sleeve (1902) positioned between the chassis sleeve (1400, 1400b)and the resetting sleeve (1200, 1200b, 1200d), the damper sleeve (1902)comprising one or more damper channels (1904); and10 e adamper end surface (1906);wherein the plunger rod resetting part (1026) extends through the one or more damperchannels (1904) and into the resetting thread (1206) in the resetting sleeve (1200,1200b, 1200d);wherein the damper sleeve (1902) is rotatable relative to the chassis sleeve (1400,15 1400b); andwherein movement of the plunger rod (1020, 1020a, 1020b) in the proximal directionrotates the damper sleeve (1902) due to the plunger rod resetting part (1026) extendingthrough the one or more damper channels (1904) in the damper sleeve (1902); andwherein the damper sleeve (1902) and the damper end surface (19086) rotates relatively20 during injection, such that a speed of the plunger rod (1020, 1020a, 1020b) duringinjection in the proximal direction is reduced.

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