Injection assembly for a wearable auto-injector, and wearable auto-injector

Abstract

An injection assembly (10) injecting medicament to a patient. The assembly (10) is configured to be carried within a wearable auto-injector (20). The injection assembly (10) includes a reservoir (100) configured as a shallow, open-topped container defining a width (X) and depth (Y), the width (X) being substantially greater than the depth (Y), and an internal volume (102) for containing the medicament. The reservoir (100) has a peripheral rim (106) defining an opening (104) into the internal volume (102). A deformable diaphragm (110) is fixed to the rim (106) to be arranged across and seal the opening (104). The injection assembly (10) also includes a pressurised gas source (120) operable to release pressurised gas, and at least one conduit (130) fluidly coupling the pressurised gas source (120) and the diaphragm (110). The injection assembly (10) further includes a hollow needle (140) fluidly coupled with the internal volume (102), the needle defining a tip (141) for injecting the medicament into the patient. The injection assembly (10) further includes a controller (150) configured to operate the pressurised gas source (120) to release a predetermined volume of pressurised gas through the at least one conduit (130) and against the diaphragm (110) to cause the diaphragm (110) to stretch into the reservoir (100) and expel a predetermined volume of the medicament through the needle (140).

Description

Injection Assembly for a Wearable Auto-Injector, and Wearable Auto-Injector Cross-Reference to Related Applications

[0001] This application claims priority to Australian patent application no.2025200064 entitled “High-Efficiency Elastomer Diaphragm Fluid Delivery System for Accurate Medication Administration”, filed on 6 January 2025, and to Australian patent application no. 2025220798 entitled “Injection Assembly for a Wearable AutoInjector, and Wearable Auto-Injector”, filed on 21 August 2025, the contents of which are incorporated herein in their entirety.Technical Field

[0002] The present disclosure relates, generally, to auto-injectors operable by a patient to inject a medicament into their own body, and, particularly, to wearable autoinjectors configured to be worn on the patient’s body to facilitate injecting medicament.Background

[0003] An autoinjector is a medical device designed to deliver a specific dose of medication automatically. It is commonly used for self-administration of drugs, especially in emergency situations. The device typically consists of a pre-filled syringe housed in a spring-loaded mechanism. When activated, the autoinjector rapidly injects the medication into the body, usually into the muscle or under the skin.

[0004] Wearable auto-injectors are medical devices that facilitate delivery of medication automatically and continuously over a period of time. Unlike traditional autoinjectors which are used for single, immediate doses, wearable autoinjectors are worn on the patient’s body, allowing for the administration of medication over an extended period. These devices are particularly useful for patients who require regular, consistent and / or high volume dosing of medication, such as during an infusion of medicament. Wearable auto-injectors also usefully allow patient mobility during theinjection process. In some cases, auto-injectors may be used for the management of chronic diseases.

[0005] A typical injection assembly for a wearable auto-injector includes a syringe or cartridge containing the medicament. The syringe is associated with a mechanism that automates the injection process, such as insertion and withdrawal of the needle to the injection site, and driving a stopper or bung through the syringe to expel the medicament.

[0006] Wearable auto-injectors, while highly beneficial for continuous medication delivery, can encounter several common problems. Some patients find the size, weight, and / or shape of the device uncomfortable and / or indiscrete, which can cause physical and / or mental distress, and can affect willingness to use the device. Known devices can also prove unreliable, where mechanical and / or electronic failures lead to improper dosing or failure to deliver the medication. This issue can be exacerbated when the patient requires a large volume of medicament and / or the medicament is highly viscous.

[0007] Wearable auto-injectors are often useful for administration of medicament in volumes greater than typically administered by syringes, such as greater than 20 mL. However, injecting large volumes of medicament, such as more than 20 mL, can cause substantial tissue resistance to the administration of the medicament. This can result in leakage of the medicament at the injection site and related tissue damage and / or patient discomfort.

[0008] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.Summary

[0009] According to some disclosed aspects, there is provided an injection assembly for delivering a medicament to a patient. The assembly is typically configured to be carried within a wearable auto-injector. The injection assembly includes a reservoir configured as a shallow, open-topped container that defines a width and a depth, where the width can be substantially greater than the depth, and that provides an internal volume for containing the medicament. The reservoir has a peripheral rim which defines an opening into the internal volume, and at least the rim portion of the reservoir is formed from a rigid material. A deformable diaphragm is fixed to the rim so as to extend across and seal the opening. A pressurised gas source is operable to release pressurised gas, and at least one conduit fluidly couples the gas source to the diaphragm. A hollow needle is fluidly coupled with the internal volume and defines a tip for injecting medicament into the patient. A controller is configured to operate the gas source to release a predetermined volume of pressurised gas through the at least one conduit and against the diaphragm so as to stretch the diaphragm into the reservoir and thereby expel a predetermined volume of medicament through the needle.

[0010] The reservoir may be shaped so that its internal volume is substantially cylindrical. The reservoir may define a shaped base portion that forms a concave dome with an outlet defined in the dome, and the needle be fluidly coupled to that outlet. Alternatively, the entire, or a substantial portion of the internal volume may define a concave dome.

[0011] The diaphragm may form a sheet having opposed sides, where at least one side defines one or more recesses or bosses arranged to influence and / or control deformation of at least a portion of the diaphragm into the reservoir. At least one side of the diaphragm may define a plurality of concentric recesses to guide or condition deformation during pressurisation.

[0012] The pressurised gas source may include a pressuriser mechanism that is operable to generate the pressurised gas in situ. The pressuriser mechanism may beconfigured to electrolyse water to produce pressurised hydrogen and oxygen gases for driving the diaphragm. The reservoir may be configured to contain at least 25 mL of medicament, and the pressuriser mechanism may be operable to generate a volume of gas sufficient to deform the diaphragm so as to expel 25 mL of medicament through the needle in a single, continuous operation.

[0013] The at least one conduit may include a pressure chamber arranged to cover the diaphragm, where the pressure chamber is aligned with and extends away from the rim of the reservoir to define a volume that spans across the diaphragm to distribute pressurised gas over the diaphragm surface. The pressure chamber may include one or more guide structures arranged to direct the pressurised gas across the diaphragm. The guide structures may define a plurality of channels configured to direct and / or diffuse the pressurised gas over the diaphragm.

[0014] The injection assembly may further include one or more sensors configured to sense at least one of the internal pressure of the reservoir and a flow rate of medicament exiting the reservoir, and the controller may be communicatively connected to such sensors to adjust control of the pressurised gas source responsive to sensor data. A pressure sensor may be provided to sense internal reservoir pressure and a flow sensor may be provided to sense medicament flow rate, and the controller may, responsive to receiving data from both sensors, calculate a tissue resistance to injection and consequently adjust control of the pressurised gas source.

[0015] The injection assembly may further include a needle displacement assembly that uses a first coil spring arranged to linearly displace the needle from a withdrawn position to an injection position, together with a first latch mechanism arranged to retain the first spring in a compressed configuration and thus retain the needle in the withdrawn position; the controller may be communicatively connected with the first latch mechanism and operate the first latch mechanism to permit the first spring to expand and displace the needle into the injection position.

[0016] A needle shield assembly may be provided that includes a sleeve positioned around the needle, a second coil spring arranged to linearly displace the sleeve from a retracted position to a deployed position, and a second latch mechanism arranged to retain the second spring in a compressed configuration and thus retain the sleeve in the retracted position; the controller may be communicatively connected with the second latch mechanism and operate the second latch mechanism to permit the second spring to expand and displace the sleeve to the deployed position surrounding the needle in the injection position. Each latch mechanism may include a coil-shaped shape-memory alloy wire, and the controller may apply a voltage to the wire to cause the coil-shape to compress and thereby release the associated spring from its compressed configuration.

[0017] The injection assembly may further include a port fluidly coupled with the internal volume, the port being configured to receive a supply of medicament to facilitate filling the reservoir.

[0018] A wearable auto-injector may include any of the injection assemblies described above, together with a housing that carries the injection assembly, and an adhesive layer attached to the housing, where the adhesive layer is configured to releasably secure the housing to the patient’s skin. The housing may carry an actuator button operable by a user to generate a trigger signal, and, responsive to receiving the trigger signal, the controller may operate the pressurised gas source to cause medicament to be expelled from the needle. The housing may carry a status indicator that provides one or more of a visual, auditory, and tactile output to indicate a status of the wearable auto-injector.

[0019] The wearable auto-injector may further include a battery for powering the controller, terminals wired to the controller, and a removable battery protector arranged between the battery and the terminals, where the battery protector includes a tab arranged and shaped to be manually pulled to remove the protector and couple the battery with the controller. The controller may be associated with a wireless communications module configured to communicate with an external computing device, and the controller may transmit data to the external device and / or receiveinstructions from the external device to enable patient-specific and / or medicament-specific settings for the injection assembly.

[0020] Throughout this specification, any mention of the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0021] It will be appreciated embodiments may comprise steps, features and / or integers disclosed herein or indicated in the specification of this application individually or collectively, and any and all combinations of two or more of said steps or features.Brief Description of Drawings

[0022] Embodiments will now be described by way of example only with reference to the accompany drawings in which:

[0023] Figure 1 is a perspective view of a wearable auto-injector;

[0024] Figure 2 is an exploded perspective view of an injection assembly carried by the wearable auto-injector shown in Figure 1;

[0025] Figure 3 is a side cross-sectional view of the injection assembly of Figure 2, where the assembly is shown in isolation;

[0026] Figure 4 is a perspective view of the injection assembly shown in Figure 3;

[0027] Figure 5 is a top cross-sectional view of the wearable auto-injector shown in Figure 1, where the auto-injector is carrying an alternative embodiment of the injection assembly;

[0028] Figure 6 is an exploded view of a sub-assembly of the injection assembly of Figure 5, where the sub-assembly is shown in isolation;

[0029] Figure 7 is a top cross-sectional view of the wearable auto-injector shown in Figures 1 and 2;

[0030] Figure 8 is a perspective, detail view of the wearable auto-injector of Figure 7;

[0031] Figure 9 is a side cross-sectional view of the wearable auto-injector shown in Figures 1 and 2, shown with a needle displacement assembly in a withdrawn position;

[0032] Figure 10 is a side cross-sectional view of the wearable auto-injector shown in Figures 1 and 2, shown with the needle displacement assembly in an injection position;

[0033] Figure 11 is a perspective view of the injection assembly shown in Figure 3;

[0034] Figure 12 is a side cross-sectional view of the wearable auto-injector shown in Figures 1 and 2, shown with a needle shield assembly in a deployed position.

[0035] Figures 13 and 14 are perspective and cross-sectional views, respectively, of an alternative diaphragm for use in the injection assembly of Figure 2; and

[0036] Figures 15 and 16 are perspective and cross-sectional views, respectively, of a further alternative diaphragm for use in the injection assembly of Figure 5.

[0037] Figure 17 is an exploded view of the injection assembly of Figure 5 including the diaphragm of Figure 15.Description of Embodiments

[0038] In the drawings, reference numeral 10 generally designates an injection assembly 10 injecting medicament to a patient. The assembly 10 is configured to be carried within a wearable auto-injector 20. The injection assembly 10 includes areservoir 100 configured as a shallow, open-topped container defining a width (X) and depth (Y), the width (X) being substantially greater than the depth (Y), and an internal volume 102 for containing the medicament. The reservoir 100 has a peripheral rim 106 defining an opening 104 into the internal volume 102. A deformable diaphragm 110 is fixed to the rim 106 to be arranged across and seal the opening 104. The injection assembly 10 also includes a pressurised gas source 120 operable to release pressurised gas, and at least one conduit 130 fluidly coupling the pressurised gas source 120 and the diaphragm 110. The injection assembly 10 further includes a hollow needle 140 fluidly coupled with the internal volume 102, the needle defining a tip 141 for injecting the medicament into the patient. The injection assembly 10 further includes a controller 150 configured to operate the pressurised gas source 120 to release a predetermined volume of pressurised gas through the at least one conduit 130 and against the diaphragm 110 to cause the diaphragm 110 to stretch into the reservoir 100 and expel a predetermined volume of the medicament through the needle 140.

[0039] The term “medicament” as used herein refers to a liquid substance, or substantially liquid substance such as a suspension, for example, a drug, suitable for subcutaneous injection into a patient to treat a condition or a disease. The medicament may comprise a viscous substance. The medicament may include an active pharmaceutical ingredient and an excipient or formulation buffer. The medicament may be a biologic to provide biological therapy.

[0040] It will be appreciated that “wearable auto-injector” as used herein refers to a device which is configured to be temporarily secured, typically by adhesion to skin, to a patient’s body to facilitate an automatic injection, usually over a prolonged, defined time period. Such devices may also be referred to as on-body drug delivery devices (OBDDs). While “injection” is discussed throughout the specification, it will be appreciated that this also includes infusion of medicament, being an injection process which occurs over a prolonged period of time.

[0041] The term “user” as used herein refers to a person who is capable of operating the disclosed wearable auto-injector 20 and injection assembly 10. The patient may bethe user, however, another person, such as a nurse, clinician, or other caregiver, may be the user.

[0042] In some embodiments, the disclosed injection assembly 10 may be configured to enable injection of viscous, or highly viscous, medicament, such as having a dynamic viscosity in the range of 10-20 cP, and / or enable injection of a large volume of medicament, such as equal to or greater than 2 mL, or between 10-50 mL, and for some applications equal to or greater than 20 mL. Dose volume and viscosity of medicament can pose difficulties for conventional injection assemblies. For example, biological medicaments may require high concentrations, driven by the nature of the molecules, the composition of the final medicament, and / or by efforts to decrease a frequency of treatment for the patient. The viscosity of the medicament may increase as the concentration increases. Further, while subcutaneous injection is generally preferable to intravenous injection for ease of self-administration, the volume of medicament that can be effectively administered subcutaneously is typically limited to below 1.5 mL. This is due to mechanical resistance in the body tissues, which limits the spread of medicament and thus limits the volume that can be administered and absorbed into the body. Hyaluronidase has been used as a spreading agent for subcutaneous delivery, enabling volumes in excess of the typical 1.5 mL to be administered by facilitating loosening of tissues local to the injection site. However, subcutaneous drug therapies formulated with the addition of Hyaluronidase tend to be more viscous.

[0043] In some embodiments, the assembly 10 may be configured so that a volumetric flow rate of medicament delivery during an injection is adjustable. High flow rates of medicament injection may impose greater injection forces on tissues at or adjacent to the injection site, and may result in higher perception of pain by some patients. Limiting the rate of injection to a low flow rate for a portion of the injection process, such as the initial portion, may reduce the pain associated with the injection. Additionally, at or near the end of an injection, tissues at or adjacent to the injection site may be saturated with medicament, which may contribute to perceived pain due to an increase in forces exerted on the tissues. As such, providing a reduced flow rate of liquid medicament into the injection site for a portion of the injection process near theend of the injection may lower the forces exerted on tissues at or adjacent to the injection site and may ameliorate the pain associated with the injection. Providing a reduced flow rate of liquid medicament into the injection site near the end of an injection may also enhance medicament absorption. The controller 150 may be preconfigured, such as by factory settings or during a calibration stage in manufacture or product setup, to adjust the flow rate throughout an injection process, or the controller 150 may be configurable to do so, such as due to receiving instructions from an external computing device and / or data from one or more sensors, as described below.

[0044] The injection assembly 10 is generally configured as a single-use mechanism such that the assembly 10 administers a single dose of medicament and is unable to be re-set to deliver any further dose. Configuring the assembly 10 in this way means that it can be supplied, such as in the auto-injector 20, as a sterile, armed mechanism prepared to deliver the dose, either after being filled with medicament by a user, or being pre-filled during manufacture. Furthermore, configuring in this way can ensure the assembly 10 administers the single dose in a continuous, smooth injection process intended to optimise tissue health and patient comfort. After use, the assembly 10 and auto-injector 20 are disposable.

[0045] Figure 1 shows the wearable auto-injector 20 configured to house the injection assembly 10. The wearable auto-injector 20 includes a housing 200 and an adhesive layer 210 fixed to a base 202 of the housing 200, the layer 210 configured to be ‘skinsafe’ to allow removably adhering to a patient’s skin within causing damage to the skin. The adhesive layer is covered with a non-adhesive, removable backing 211 which is removed to expose the adhesive layer 210 before application of the layer 210 to a patient, such as to the patient’s abdomen. The housing 200 is dimensioned to enclose the injection assembly 10 and shaped to facilitate mounting to the patient at a desired injection site, for example, on the patient’s abdomen. As shown in Figure 1, the housing 200 may define a low profile, rounded disk to enhance patient comfort while the injector 20 is secured to the skin. It will be appreciated that the housing 200 may be alternatively shaped to define different forms and may, for example, be configured to define a customised shape to suit a specific user’s body shape or preference. Forexample, the housing 200 may be formed by injection moulding to suit a wide range of users, or may be formed by an additive manufacturing process, such as 3D printing, to suit a specific user. As shown in Figure 1, the housing 200 typically defines a relatively flat and smooth base 202 for mounting of the adhesive layer 210, and a textured portion 208 about a peripheral region to assist a user gripping the housing 200, such as during application to, and removal from, the body.

[0046] The housing 200 carries an actuator, in the illustrated embodiment in the form of a depressible button 220 carried by a top surface of the housing 200, operable by the user to generate a trigger signal. The controller 150 is communicatively connected with the actuator so that, responsive to receiving the trigger signal, the controller 150 operates the pressurised gas source 120 to cause the medicament to be expelled from the needle 140, as described in greater detail below. It will be appreciated that the actuator may be alternatively configured to enable actuation of the injection assembly 10, for example, the actuator may include a capacitor button, or a membrane switch. Alternatively, the injector 20 may include a pair of spaced buttons which must be operated concurrently to operate the injector 20 which may inhibit inadvertent actuation of the assembly 10.

[0047] In the illustrated embodiment, the housing 200 carries a status indicator 230 operable to provide at least one of a visual, auditory, and tactile stimulus output to indicate a status of the wearable auto-injector 20. For example, the status indicator 230 may include one or more LEDs configured to emit a green light when the wearable auto-injector 20 is injecting medicament, and emit a red light when the wearable autoinjector 20 has finished injecting medicament. In some embodiments, the status indicator 230 includes a vibration generator and / or sound device operable to emit an acoustic signal and / or cause the injector 20 to vibrate to indicate the status. It will be appreciated that, in other embodiments, the status indicator 230 may be omitted, or may be alternatively configured to only convey auditory and / or tactile feedback.

[0048] Figures 2 to 4 illustrate the injection assembly 10 in the context of the injector 20 (Fig. 2) and in isolation (Figs. 3 and 4). Best shown in Figures 2 and 3, the reservoir100 is shaped as a shallow, open-topped container having a peripheral rim 106 defining the opening 104 into the internal volume 102. The diaphragm 110 is arranged across and fixed to the rim 106 to seal the opening 104. As shown in Figure 3, the reservoir defines a width, labelled “X”, and a depth, labelled “Y”. The width X is substantially greater than the depth Y to form the shallow container shape. For example, the width X may be in the order of five to ten times greater than the depth Y. The reservoir 100, or at least the rim 106 portion, is typically formed from a rigid material, such as an injection moulded plastic, to provide a stable structure to carry the diaphragm 110 and support the diaphragm 100 when being stretched by the pressurised gas into the internal volume 102.

[0049] The shallow configuration of the reservoir 100 limits the distance over which the diaphragm 110 must stretch to press against and cause displacement of a comparatively substantial volume of medicament from the reservoir 100. This configuration therefore may advantageously limit an elasticity requirement of the diaphragm 110 and / or enable injecting large doses of medicament which can otherwise be difficult or impossible to achieve with traditional syringe-type injection mechanisms. Furthermore, this arrangement can enhance efficiency of the injection mechanism 10, as only a small volume of pressurised gas is required to cause a small displacement distance of the diaphragm 110 across the proportionally large surface area of the internal volume 102 and, consequently, cause a substantial volume of medicament to be expelled from the reservoir 100.

[0050] In other embodiments (not illustrated), the reservoir 100 may be alternatively configured to define alternative proportions of width X and depth Y, such as according to the requirements of the medicament dose. For example a greater depth dimension, with the same width dimension as the illustrated embodiment, allows containing a larger volume of medicament. In other embodiments (not illustrated), the reservoir 100 may be configured as a close-topped container where the rim of the opening 104 is defined by an aperture in a top surface of the reservoir 100.

[0051] As shown in Figures 2 and 3, in the illustrated embodiment, the reservoir 100 is shaped so that the internal volume 102 is substantially cylindrical. The substantially cylindrical shape can assist the diaphragm 110, particularly portions of the diaphragm 110 at or adjacent to the sidewall 101 of the reservoir 100 extending away from the rim 106, to stretch at an even or predictable rate. In other embodiments, such as illustrated in Figures 5 and 6, the reservoir 100 may be alternatively shaped to define an alternatively configured internal volume, including extruded, domed, prismatic or other structures. For example, the embodiment of Figs. 5 and 6 includes a reservoir 103 shaped to define a hemi cylindrical internal volume 105.

[0052] Best shown in Figure 3, the reservoir 100 may define a base portion forming a concave dome 108 and an outlet 109 (Fig. 2) defined by the dome 108. The outlet is generally arranged at, or close to, the apex of the dome 108. In such embodiments, the needle 140 is fluidly coupled to the outlet 109. The structure of the concave dome 108 may advantageously enhance the diaphragm 110 conforming to the base portion as it is stretched into the reservoir 100 by the gas, thereby displacing medicament from the concave dome 108 and through the outlet 109. In some embodiments, the entire internal volume 102, or substantial portion thereof, may define the concave dome 108 structure to enhance the diaphragm 110 conforming to the surfaces of the internal volume 102 to displace medicament from the reservoir 100. In some embodiments, the concave dome 108 may be sized and shaped to substantially match a curvature of the diaphragm 110 when the diaphragm 110 is stretched into the reservoir 100. In other embodiments, such as illustrated in Figures 5 and 6, the reservoir 100 may define an alternatively shaped base portion, for example, the reservoir 103 defines a planar base portion. This configuration may be useful for simplifying manufacturing of the reservoir 103.

[0053] The reservoir 100 is configurable to contain a range of medicament volumes, such as according to patient or dosing requirements. Typically, the reservoir is dimensioned to contain 20-50 mL of medicament. In some embodiments, the reservoir 100 may be configured to contain equal to or greater than 60 mL of medicament. Inother embodiments, the reservoir is configured to contain between 5-20 mL of medicament.

[0054] The reservoir 100 is formed from one or more materials suitable for holding the medicament. The reservoir 100 material is typically specified to be corrosion resistant, biocompatible, and / or inhibit absorbing the medicament. The surfaces of the reservoir 100 that define the internal volume 102 may include coatings or treatments to modify one or more properties of the material forming the reservoir 100. For example, the surfaces may be modified to inhibit the adhesion of medicament to the surfaces, inhibit absorption of the medicament by the reservoir 100 material, and / or improve the chemical compatibility of the reservoir 100 with specific medicaments. The modified surfaces may improve the safety of the wearable auto-injector 20 and / or improve the accuracy of the wearable auto-injector 20.

[0055] Best shown in Figures 2 and 3, in the illustrated embodiment, the diaphragm 110 forms a generally planar sheet having opposed sides 111, 113. The diaphragm 110 is mounted to the reservoir 100 so that one of the sides 111 receives the pressurised gas causing the other side 113 to stretch and press into the reservoir 100 to expel the medicament from the internal volume 102. It will be appreciated that the diaphragm may be alternatively configured, such as defining a non-planar, including wave-like, structure, to affect deformation into the reservoir 100 and consequently affect displacing the medicament.

[0056] The diaphragm 110 may be sized and shaped to control deformation of the diaphragm 110 into the reservoir 100. In the illustrated embodiment, the diaphragm 110 defines the opposed sides 111, 113 arranged to stretch into the reservoir 100, and a thickness between the sides 111, 113, and has one or more regions which define a non-uniform thickness to control deformation into the reservoir 100. The one or more regions may include thinned or thickened regions. At least one side 111, 113 may define one or more recesses or bosses arranged to control deformation of the diaphragm 110 into the reservoir 100. For example, recesses (defining a thickness less than the general thickness of the planar sheet) may accelerate deformation of specific portions,and bosses (defining a thickness greater than the general thickness of the planar sheet) may decelerate deformation of specific portions. Configuring the diaphragm 110 in this way may therefore control deformation of the diaphragm 110 responsive to force applied by the pressurised gas, for example, to assist the diaphragm 110 deforming evenly across the cross-section area of the internal volume 102 of the reservoir 100 and / or enhance displacing all / a specific dose of medicament from the reservoir 100. Also, deformation of the diaphragm 110 may be controlled to inhibit blockage of the reservoir outlet 109 by the diaphragm 110 when medicament is contained in the reservoir 100.

[0057] As shown in Fig. 2, at least one side 111 of the diaphragm 110 may define a plurality of concentric recesses 116 to reduce thickness of the diaphragm 110 in specific portions. The concentric recesses 116 may define a stepped configuration so that the diaphragm 110 is progressively thinned across the portions. The concentric recesses 116 may be useful to enhance deformation of the diaphragm 100 into comers or edges defined by the reservoir, such as at the junction of the sidewall 101 and the base portion 108. In other embodiments, such as shown in Figure 6, the diaphragm 110 may be alternatively sized and shaped to affect deformation of the diaphragm 110 into the reservoir 100. For example, the diaphragm 110 shown in Fig. 6, has substantially planar sides 111, 113 without any recesses, bosses, or other structures. Control of diaphragm 110 deformation may be advantageous in calculating the volume of pressurised gas required to expel a predetermined volume of medicament, or induce medicament flow to be directed towards and through the outlet 109 of the reservoir 100.

[0058] Figures 13 and 14 show an alternative diaphragm 190 in isolation, the diaphragm 190 configured to be arranged across and fixed to the rim 106 of the reservoir 100 of the injection mechanism 10, in place of the diaphragm 110 illustrated in the previous figures. The alternative diaphragm 190 is shaped to optimise the volume of medicament contained in the reservoir 100 and / or enhance conforming against the base portion of the reservoir 100 when urged by the pressurised gas, such as to effectively expel the medicament from the base portion and through the outlet 109.The diaphragm 190 has opposed sides 192, 196 where at least one side 192 is shaped to define a dome. In the illustrated embodiment, the diaphragm 190 has a first side 192 configured to face towards the pressurised gas contained in the reservoir 100 and defining a convex domed portion 194. The diaphragm 190 has a second side 196, opposite to the first side, 192, configured to face towards the medicament contained in the reservoir and defining a concave domed portion 198.

[0059] The convex domed portion 194 defines a greater curvature than the concave domed portion 198 so that the diaphragm 190 is thickened at a central region. This configuration of the diaphragm 190 can mean that a peripheral region of the diaphragm 190 surrounding the thickened domed portion 194 more readily deforms than the domed portion 194 to assist the diaphragm 190 stretching into and pressing against the concave dome-shaped base 108 of the reservoir 100 to expel the medicament from the reservoir 100.

[0060] In other embodiments (not illustrated), the diaphragm may be alternatively configured so that the entire sides 192, 196 define a domed structure, and / or so that the curvature of the second side 196 is greater than, or equal to, the curvature of the first side 192, such as to effect deformation of the diaphragm during use. For some applications, the diaphragm 190 may be arranged in an inverse orientation so that the first side 192 is arranged to face the medicament and the second side 196 is arranged to face the pressurised gas.

[0061] When the diaphragm 190 is arranged and sealed across the rim 106, the domed portions 194, 198 are arranged to bulge away from the base portion of the reservoir 100, which can expand the capacity of the reservoir 100 compared to the diaphragm 110 illustrated in Figs. 2 and 3. Configuring the curve geometry of the domed portions 194, 198 may also affect deformation of the domed diaphragm 190 by the pressurised gas.

[0062] Figures 15 and 16 show a further alternative diaphragm 195 in isolation, the diaphragm 195 configured to be arranged across and fixed to the rim 106 of thereservoir 103 of the injection mechanism 10, in place of the diaphragm 110 illustrated in Fig. 6. The alternative diaphragm 195 is shaped to optimise the volume of medicament contained in the reservoir 103 and / or enhance conforming against the reservoir 103 when urged by the pressurised gas, such as to effectively expel the medicament out of the reservoir 103. The diaphragm 195 has opposed sides 196, 197 where at least one side 197 is shaped to define a dome. In the illustrated embodiment, the diaphragm 195 has a first side 196 configured to face towards the pressurised gas contained in the reservoir 103 and defining a protrusion 199 forming a thickened portion. The diaphragm 195 has a second side 197, opposite to the first side 196, configured to face towards the medicament contained in the reservoir 103 and defining a concave domed portion 201.

[0063] The concave domed portion 201 is arranged to bulge away from the internal volume of the reservoir 103, which can expand the capacity of the reservoir 103 compared to the diaphragm 110 illustrated in Fig. 6. This configuration of the diaphragm 195 with the central protrusion 199 can mean that a peripheral region of the diaphragm 195 surrounding the protrusion 199 more readily deforms than the thickened central portion 199 to assist the diaphragm 195 stretching into the reservoir 103 and pressing against the medicament to expel the medicament from the reservoir 103.

[0064] In some embodiments, such as illustrated in Figure 17, the further alternative diaphragm 195 can be arranged in the inverse orientation so that the first side 196 of the diaphragm 195 faces towards the medicament contained in the reservoir 103 and the second side 197 of the diaphragm 195 faces towards the pressurised gas contained in the pressure chamber 132.

[0065] Typically, at least a portion of the diaphragm 110, 190, 195 is formed from an elastomer material capable of significant, typically elastic, deformation, generally configured to stretch up to 1,000% its original size, or in some embodiments configured to stretch up to 1,200% its original size. In some embodiments, the diaphragm 110, 190, 195 may be composed of more than one material. For example, the diaphragm 110, 190, 195 may include materials of different elasticities, or comprise plastically andelastically deformable materials. In some embodiments, the diaphragm 110, 190, 195 may be formed from a composite material that that includes fibres or mesh structures arranged in one or more portions of the diaphragm 110, 190, 195 to affect the properties of the one or more portions, such as to affect stiffness, durability, and / or gas permeability of the portion(s). In some embodiments, the material(s) and / or geometry of the diaphragm 110, 190, 195 may be configured to cause stretching more readily in one or more directions. The diaphragm 110, 190, 195 may thereby be configured to enhance control of the deformation of the diaphragm 110, 190, 195.

[0066] In some embodiments, the diaphragm 110, 190, 195 may be configured to inhibit gas permeation through the diaphragm 110, 190, 195. For example, the diaphragm 110, 190, 195 may include a coating that inhibits the permeation of gas. Alternatively, a separate membrane (not illustrated) configured to inhibit permeation of gas may be arranged adjacent to the diaphragm 110, 190, 195. Alternatively or additionally, the injection assembly 10 may include vents (not illustrated) fluidly coupled with the pressurised gas source 120 and the diaphragm 110, 190, 195 to enable evacuation of gas after an injection is complete. Any or all of these features may prevent gas from permeating through the diaphragm 110, 190, 195 and gathering in the reservoir 103 and / or interacting with the medicament, thereby improving safety, stability, and / or reliability of the injection assembly 10.

[0067] It will be appreciated that the diaphragm 110, 190, 195 may be fixed to the reservoir 10 using a variety of methods. For example, the diaphragm 110, 190, 195 may be overmoulded onto the rim 106 of the reservoir 100. Alternatively, the diaphragm 110, 190, 195 may be fixed to the rim 106 using adhesive, ultrasonic welding, or mechanical fasteners. It will be understood that the chosen method may be dependent on the materials of the diaphragm 110, 190, 195 and the reservoir 100, the manufacturing requirements, and / or functional requirements of the wearable autoinjector 20.

[0068] The pressurised gas source 120 is typically configured to be housed within the wearable auto-injector 20 to maintain portability of the injector 20. In someembodiments, the gas source 120 may comprise a container of pressurised gas, such as a canister or cartridge. In other embodiments, such as illustrated, the gas source 120 includes a pressuriser mechanism 122 operable to generate the pressurised gas. The pressuriser mechanism 120 may include a mechanical generator, such as a pump (including a diaphragm air pump) or an electrical generator.

[0069] Best shown in Figure 4, the pressuriser mechanism 122 may be configured as a miniaturised hydrogen electrolyzer (also referred to as an electrolyzer gas generator) operable to electrolyse water contained in the mechanism 122 to produce pressurised hydrogen and oxygen gases. This configuration of the pressuriser mechanism 122 does not require moving parts and can therefore advantageously minimise noise and vibration while generating the pressurised gas, which can limit or avoid auditory and / or tactile discomfort of the patient during the injection process. Furthermore, the electrolyzer pressuriser mechanism 122 can minimise the size of the injection assembly 10, and consequently minimise the dimensions of the wearable auto-injector 20.Regardless of configuration of the pressurised gas source 120, it is typically operable to generate a volume of pressurised gas sufficient to deform the diaphragm 110 to expel a defined dose (volume) of medicament, e.g. 25 mL, through the needle 140 in a single, continuous operation which can, for example, enhance patient comfort and health of tissue at the injection site. That is, the gas source 120 is operable to release the pressurised gas in one continuous stream rather than requiring cyclical operation which can cause fluctuation in medicament flow rate and cause patient discomfort and / or harm.

[0070] In other embodiments, the pressuriser mechanism 122 may be configured to produce pressurised gases other than oxygen and hydrogen. In yet other embodiments, the pressurised gas source 120 may be couplable to an external gas supply, arranged outside of the injector 20, and receive and compress the gas from the external source to be stored before an injection.

[0071] The at least one conduit 130 includes one or more hollow components arranged to convey the pressurised gas to the diaphragm 110. In the illustratedembodiment, this may include pipes 131, as shown in Fig. 4. As shown in Figs 2, and 3, the at least one conduit 130 may include a pressure chamber 132 arranged to cover the diaphragm 110. The pressure chamber 132 may be shaped to distribute the pressurised gas across the diaphragm 110 to enhance consistency of deformation of the diaphragm 110. In the illustrated embodiment, the pressure chamber 132 is aligned with and extends away from the rim 106 of the reservoir 100 to define a volume extending across the diaphragm 110 to distribute the pressurised gas over the diaphragm 110.

[0072] The pressure chamber 132 defines at least one inlet 134 for receiving pressurised gas. In some embodiments, the chamber 132 also defines one or more guide structures or, in this embodiment, guide members 136 arranged to direct the pressurised gas across the diaphragm 110. Best shown in Figure 6, the one or more guide members 136 may define a plurality of channels 137 for directing the gas. The guide members 136 in this embodiment extend from a base of the pressure chamber 132 to define generally concentric channels 137, the members 136 arranged to contact the diaphragm 110 when the pressure chamber 132 is not pressurised by the gas. It will be appreciated that the one or more guide structures are alternatively configurable to affect fluid flow through the chamber 130. For example, in some embodiments (not illustrated), the guide structures include a plate extending at least partially across the pressure chamber 132 and defining a plurality of apertures arranged to direct gas flow through the apertures and at the diaphragm 110. In other embodiments, as illustrated in Figure 17, the pressure chamber 132 does not define or house any guide structure and instead provides a clear cavity for receiving the pressurised gas.

[0073] Returning to Figure 2, the controller 150 is typically configured as a microprocessor carried by a PCB 151. The controller 150 is associated with a battery (not shown) to provide electrical power. The battery may be initially coupled with a battery protector 159, in the illustrated embodiment comprising a removable layer between the battery contacts and terminals on the PCB 151, to prevent discharging the battery 158 during storage of the injector 20. As shown in Fig. 1, the battery protector159 may include a tab arranged to be manually gripped by the user to allow removal of the protector 159 and resulting electrical activation of the injector 20.

[0074] In some embodiments, the injection assembly 10 includes one or more sensors arranged and configured to sense at least one of an internal pressure of the reservoir 100 and a flow rate (typically determined as a volumetric flow rate) of medicament flowing out of the reservoir 100. In embodiments including both pressure and flow sensors, the controller 150 is communicatively connected to both sensors to receive data and configured to calculate a tissue resistance to injection based on the data. The controller 150 may be further configured to adjust control of the pressurised gas source 120 responsive to determining the tissue resistance to injection, which can result in a dynamic flow rate during injection which may reduce the risk of medicament leakage at the injection site, enhancing medicament flow rate consistency, and / or minimising patient discomfort. Additionally, it will be understood that when the reservoir 100 is emptied of medicament and the pressurised gas source 120 is still producing gas, the internal pressure may rise at a greater rate than when medicament is being expelled. The controller 150 may therefore be configured to, responsive to data from the pressure and / or flow sensors, operate the pressurised gas source 120 to cease gas generation, operate the needle shield assembly 170, and / or operate the status indicator 230 to indicate that the reservoir 100 is empty.

[0075] In some embodiments, the injection assembly 10 may include a sensor configured to measure the volume of medicament in the internal volume 102 of the reservoir 100. The controller 150 may, responsive to medicament volume sensor data, operate the status indicator 230 to indicate when the reservoir 100 has been filled with a desired volume of medicament or prevent operation of the assembly 10 if medicament is not present.

[0076] In some embodiments, the pressurised gas source 120 may be operable before the reservoir 100 is filled with medicament. For example, the controller 150 may, responsive to user input or data from a sensor configured to measure the volume of air in the internal volume of the reservoir 102, operate the pressurised gas source 120 tourge the diaphragm 110 into the internal volume 102 and thereby expel the air. The expulsion of air before the reservoir 100 is filled with medicament may improve the ease of filling, or may protect the medicament from contact with air and potential degradation.

[0077] In other embodiments, the injection assembly 10 may also include other sensors configured to sense other properties of the wearable auto-injector 20 or the medicament, and the controller 150 may be communicatively connected to the other sensors. For example, the assembly 10 may include a pressure sensor 156 for measuring a pressure of the pressure chamber. In such embodiments, the controller 150 may adjust control of the pressurised gas source 120 responsive to data received from the pressure sensor.

[0078] In some embodiments the controller 150 may include, or be associated with, a wireless communications module configured to transmit sensed and / or calculated data to an external computing device, such as a smartphone. The transmission of data may be advantageous for monitoring injection performance and adapting injection settings to personalise future injections. The controller 150 may also be configured to receive injection parameters, typically in the form of instructions configured to enable specific settings for the assembly 10, or other data, from the external computing device, such as to adjust the injection process. This may allow enhancing patient comfort or efficacy of injection, depending on personal or drug requirements / parameters. For example, the injection of a high viscosity drug may require the drug to be injected at a low pressure and / or over a long duration when compared to a low viscosity drug, and therefore the data received by the controller 150 configured setting for the assembly 10 to enable injection of the high viscosity drug.

[0079] Figures 7 to 10 illustrate a needle displacement assembly 160 operable to displace the needle 140 to puncture a patient’s skin to facilitate an injection of medicament. The needle displacement assembly 160 includes a drive member, in the illustrated embodiment in the form of a coil spring 162, and an actuator, in the illustrated embodiment in the form of a latch mechanism 164. It will be appreciatedthat, in other embodiments, the spring 162 may be substituted with an alternative drive mechanism, such as a torsion spring, leaf spring, shape memory allow (SMA) actuator, solenoid or electromagnetic actuator, electric motor-driven mechanism, such as a cam or rack. Similarly, it will be appreciated that the latch mechanism 164 may be substituted with a ratchet and pawl, or magnetic release mechanism.

[0080] The spring 162 is arranged to linearly displace the needle 140 from a withdrawn position (Fig. 9) to an injection position (Fig. 10). The latch mechanism 164 (Figs. 7 and 8) is arranged to obstruct and retain the spring 162 in a compressed configuration and, consequently, retain the needle 140 in the withdrawn position. The latch mechanism 164 is configured for electronic operation, and the controller 150 is communicatively connected with the mechanism 164 and configured to operate the mechanism 164 to release the spring 162 from the compressed state, allowing it to expand and displace the needle 140 to the injection position.

[0081] Figures 11 and 12 illustrate a needle shield assembly 170 operable to displace a needle shield 172 to enclose the needle 140 after it has been displaced to the injection position, the displaced needle shield 172 arranged to inhibit causing harm to the patient or other persons after the injection process is complete. The needle shield assembly 170 includes the sleeve 172, a coil spring 174 (second spring 174, in addition to the spring 162 described above), a latch mechanism 176 (second mechanism 176, in addition to the mechanism 164 described above), and a sleeve lock 177. The sleeve 170 is arranged to surround the needle 140 and define an opening 173 in a base portion to allow the needle 140 to extend through the sleeve 170 during an injection, as shown in Fig. 10. The spring 174 is arranged to linearly displace the sleeve 172 from a retracted position (Fig. 11) to a deployed position (Fig. 12). The latch mechanism 176 (Figs. 7 and 8) is arranged to retain the spring 174 in a compressed configuration and, consequently, retain the sleeve 172 in the retracted position. The latch mechanism 174 is configured for electronic operation, and the controller 150 is communicatively connected with the latch mechanism 176 and configured to operate the mechanism 176 to release the spring 174 from the compressed state, allowing it to expand and displace the sleeve 172 to the deployed position to surround the needle 140 in the injectionposition. The sleeve lock 177 is arranged to inhibit the sleeve 172 being displaced back to the retracted position after it has been displaced to a deployed position. The lock 177 typically includes a deformable tab arranged to interact with the sleeve 172 when in the deployed position to inhibit linear displacement. It will be appreciate that, in other embodiment (not illustrated), the needle shield assembly 170 is absent, for example, to simplify the device 20 for particular applications.

[0082] Figures 7 and 8 illustrate the latch mechanisms 164, 176 in detail. In the illustrated embodiment, each mechanism 164, 176 includes coil-shaped shape memory alloy wire 166, 178 arranged to provide an actuator to withdraw a latch 167, 179 coupled to the wire 166, 178. Each latch 167, 179 is biased by the associated wire 166, 178 to obstruct the associated spring 164, 174 until the mechanism 164, 176 is actuated. The controller 150 is configured to actuate the mechanisms 164, 176 by applying a voltage to either wire 166, 178 to cause the coil-shape to compress and, consequently, withdraw the associated latch 167, 179 to release the associated spring 162, 174 from the compressed configuration. In some embodiments (not illustrated), the shape memory alloy wire 166, 178 is alternatively configured to define a different shape to enable actuating the mechanism 164, 174. The inclusion of coil-shaped shape memory alloy wires 166,178 in the latch mechanisms 164,176 may advantageously limit the physical dimensions, weight, and / or power requirements of the latch mechanisms 164,176. In other embodiments (not illustrated), the wires 166, 178 may be substituted with other suitable actuation mechanisms, such as solenoids.Furthermore, the needle displacement assembly 160 and needle shield assembly 170 may include other means of displacing the needle 140 or sleeve 172. For example, pressurised gas may be used to displace the needle 140 and / or sleeve 172.

[0083] The illustrated embodiment of the injection assembly 10 is configured for filling with a medicament, by the user, pharmacist, clinician, or other person. This arrangement allows the assembly 10 to be provided to the user empty of medicament and then filled, and in some embodiments, operational parameters configured, for injecting one of a range of suitable medicaments. As shown in Figure 4, the injection assembly 10 includes a port 180 fluidly coupled with the internal volume 102 of thereservoir 100 and configured to receive a supply of the medicament to allow filling the volume 102 with the medicament. In the illustrated embodiment, the port 180 is configured to engage with the supply of the medicament to form a secure connection. The port 180 includes a female Luer taper connector configured to engage with a complementary male Luer taper connector defined by the medicament supply. It will be appreciated that, in other embodiments (not illustrated), the port 180 includes the male connector to couple with the female connector of the supply. It will also be appreciated that other suitable fluid connectors may be employed and that the Luer connectors are exemplary. The port 180 is typically associated with a one-way valve, which may be an integrated component of the Luer connector, arranged to inhibit medicament flowing out of the port 180. In other embodiments, the port 180 is omitted and instead the reservoir 100 is pre-filled with medicament duringmanufacture / assembly.

[0084] To prepare the wearable auto-injector 20 for injecting medicament, the user first removes the battery protector 159 to enable supplying electrical power to the controller 150. Where the controller 150 is configured for wireless communication and remote configuration, the user may pair the auto-injector 20 with a computing device and configure settings of the auto-injector 20, through manual interaction with the computing device and / or via data / instructions downloaded from the computing device. The user then couples a supply of the medicament to the port 180 and fills the internal volume 102 of the reservoir 100 with a volume of the medicament sufficient to provide the prescribed dose.

[0085] To attach the wearable auto-injector 20, the user peels off the non-adhesive film 210 by pulling on the tab 211, and applies the adhesive layer 210 to the patient’s skin at the injection site, such as on the abdomen, to secure the wearable auto-injector 20 to the patient.

[0086] To inject the medicament, the user presses the actuator button 220 to generate the trigger signal causing the controller 150 to execute the injection process, as described below. The controller 150 may also operate the status indicator 230 duringthe process, and / or after completion, to indicate the status of the auto-injector 20. The controller 150 may also communicate with the external computing device during the injection process.

[0087] To begin the injection process, the controller 150 applies a voltage to the first coil-shaped shape memory alloy wire 166, causing the wire 166 to deform and compress its coil shape, consequently withdrawing the latch 167 from engagement with the spring 162. The spring 162 is released from its compressed configuration and expands to linearly displace the needle 140 from the withdrawn position to the injection position to pierce the patient’s skin at the injection site.

[0088] The controller 150 then operates the pressuriser mechanism 122 to electrolyse water to produce pressurised hydrogen and oxygen gases. The pressurised gas is conveyed through the at least one conduit 130 to the pressure chamber 132. Pressure within the chamber 132 increased, causing the diaphragm 110 to stretch into the reservoir 100. The stretching of the diaphragm 110 causes displacement of medicament from within the volume 102 of the reservoir 100 and through the needle 140 to be expelled from the tip 141 of the needle into the patient.

[0089] By controlling the operation of the pressurised gas source 120, by the controller 150, a defined volume, typically being a specific dose, of medicament is expelled from the reservoir 100 and through the needle 140. Also, a medicament flow rate out of the reservoir 100, and / or medicament pressure, may be controlled until the medicament dose is delivered.

[0090] After injecting the dose, the controller 150 applies a voltage to the second coilshaped shape memory alloy wire 178 causing the wire 178 to deform and compress its coil shape, consequently withdrawing the latch 179 from engagement with the spring 174. The spring 174 is released from its compressed configuration and expands to linearly displace the needle shield 172 from the retracted position to the deployed position to surround and protect the protruding needle 140. If the auto-injector 20 is attached to the patient’s skin at this stage, the shield 172 will collide with the skin andcontinue to be urged outwards, to cover the needle 140, when the auto-injector 20 is removed from the skin.

[0091] To remove the wearable auto-injector 20 from the patient, the user grasps the housing 200 and peels the adhesive layer 210 from the skin of the patient. As the autoinjector 20 is being removed, the second spring 174 expands and linearly displaces the sleeve 172 until reaching the deployed position. When the sleeve 172 has reached the deployed position the sleeve lock 177 engages to prevent the sleeve 172 from returning towards the retracted position.

[0092] The injection mechanism 10 includes the shallow, wide open-topped reservoir 100, 103 having the stretchable diaphragm 110 fixed across the open top. The diaphragm 110 is stretched by pressurised gas released from the gas source 120, controlled by the controller 150. Configuring the mechanism 10 in this way allows for efficient and / or accurate displacement of large doses of medicament from the reservoir 110, 103 and into the patient. The configuration of the reservoir 100 and diaphragm 110 means that a relatively small travel distance by the diaphragm 110 causes expulsion of a substantial volume of medicament from the reservoir 100, which can efficiently enable subcutaneous injection of high-volume doses, e.g., 20-50 mL, while minimising elasticity burden of the diaphragm 110. Furthermore, the relatively large surface area covered by the diaphragm 110, and urged against by stretching of the diaphragm 100, can provide a mechanical advantage which can assist reliably and / or accurately injecting high viscosity medicament, such as having a dynamic viscosity equal to or greater than 20 cP. The configuration of the assembly 10 therefore enables injection and / or infusion of large vole, high viscosity medicament from an auto-injector 20. When carried by the injector 20 and secured to the patient, this allows selfadministration of medicament in a non-clinical setting, e.g. at home. The injection assembly 10 and auto-injector 20 may therefore significantly improve a patient physical and mental wellbeing comparted to conventional hospital-based procedures, such as intravenous infusion of a drug.

[0093] The combination of the wide, shallow reservoir 100 and diaphragm 110 arranged across the rim 106 can provide predictable displacement of medicament from the reservoir 100 by the diaphragm 110, while minimising strain of the diaphragm 110. This approach can enhance reliability of operation of the mechanism 10 and, consequently, increase the likelihood of successful delivery of the dose of medicament to the patient.

[0094] The injection mechanism 10 is configurable for uniform diaphragm 110 actuation for consistent dosing. Embodiments including the pressure chamber 132 that overlays the diaphragm 110 can assist distributing gas evenly so the diaphragm 110 deforms predictably, aiding dose precision and consistent flow. For example, the pressure chamber 132 may include guide structures, such as the members 136, to direct gas flow to assist with uniform pressure distribution and, as a result, enhance consistent diaphragm 110 deformation. Moreover, the diaphragm 110 may be shaped, such as by defining recesses, bosses, or other structures, to enhance consistent deformation into the reservoir 100.

[0095] The injection mechanism 10 is configurable to provide the pressurised gas without using any, or minimal, moving parts, thereby minimising noise and vibration during dose delivery, which can enhance patient comfort and discretion during use. Where the gas source 120 includes the electrolyser gas generator 122, this can avoid operating any moving parts to generate the pressurised gas. Furthermore, the injection mechanism 10 and related auto-injector 20 is configurable to define a low-profile, compact device further enhancing patient comfort and discretion.

[0096] The pressurised gas source 120 is digitally controlled by the controller 150 to precisely deliver the pressurised gas to the diaphragm 110 to actuate the mechanism 10. Embodiments including sensors to provide feedback to the controller 150 can enhance the precision of controlling the gas source 120 and can allow adaptive control, such as to dynamically affect medicament flow rate out of the reservoir 100, to enhance reliability of injection and / or patient comfort.

[0097] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS1. An injection assembly for injecting medicament to a patient, the injection assembly configured to be carried within a wearable auto-injector, the injection assembly including:a reservoir configured as a shallow, open-topped container defining a width and depth, the width being substantially greater than the depth, and an internal volume for containing the medicament, the reservoir having a peripheral rim defining an opening into the internal volume, at least the rim portion of the reservoir being formed from a rigid material;a deformable diaphragm fixed to the rim to be arranged across and seal the opening;a pressurised gas source operable to release pressurised gas;at least one conduit fluidly coupling the pressurised gas source and the diaphragm;a hollow needle fluidly coupled with the internal volume, the needle defining a tip for injecting the medicament into a patient; anda controller configured to operate the pressurised gas source to release a predetermined volume of pressurised gas through the at least one conduit and against the diaphragm to cause the diaphragm to stretch into the reservoir and expel a predetermined volume of the medicament through the needle.

2. The injection assembly of claim 1, wherein the reservoir is shaped so that the internal volume is substantially cylindrical.

3. The injection assembly of claim 1 or 2, wherein the reservoir defines a base portion forming a concave dome and an outlet defined in the dome, and wherein the needle is fluidly coupled to the outlet.

4. The injection assembly of any one of the preceding claims, wherein the diaphragm forms a sheet having opposed sides, and at least one side defines one ormore recesses or bosses arranged to control deformation of at least a portion of the diaphragm into the reservoir.

5. The injection assembly of claim 4, wherein at least one side of the diaphragm defines a plurality of concentric recesses.

6. The injection assembly of claim 1, wherein the diaphragm defines opposed sides arranged to face the pressurised gas and the medicament, respectively, and wherein at least the side arranged to face the medicament defines a domed structure.

7. The injection assembly of claim 6, wherein one of the sides defines a convex domed portion, and the other side defined a concave domed portion, and wherein the convex domed portion defines curvature which is greater than the concave domed portion to form a thickened central region.

8. The injection assembly of any one of the preceding claims, wherein the pressurised gas source includes a pressuriser mechanism operable to generate the pressurised gas in situ.

9. The injection assembly of claim 8, wherein the pressuriser mechanism is configured to electrolyse water to produce pressurised hydrogen and oxygen gases.

10. The injection assembly of claim 8 or 9, wherein the reservoir is configured to contain at least 25 mL of medicament, and the pressuriser mechanism is operable to generate a volume of gas sufficient to deform the diaphragm to expel 25 mL of medicament through the needle in a single, continuous operation.

11. The injection assembly of any one of the preceding claims, wherein the at least one conduit includes a pressure chamber arranged to cover the diaphragm, the pressure chamber aligned with and extending away from the rim of the reservoir to define a volume extending across the diaphragm to distribute the pressurised gas over the diaphragm.

12. The injection assembly of claim 11, wherein the pressure chamber defines one or more guide structures arranged to direct the pressurised gas across the diaphragm.

13. The injection assembly of claim 12, wherein the guide structures define a plurality of channels for directing the pressurised gas.

14. The injection assembly of any one of the preceding claims further including one or more sensors configured to sense at least one of internal pressure of the reservoir, and a flow rate of medicament out of the reservoir, and the controller is communicatively connected to the one or more sensors and configured to adjust control of the pressurised gas source responsive to data received from the one or more sensors.

15. The injection assembly of claim 14, including a pressure sensor for sensing internal pressure of the reservoir and a flow sensor for sensing flow rate of medicament out of the reservoir, and wherein responsive to receiving data from both sensors, the controller is configured to calculate a tissue resistance to injection and consequently adjust control of the pressurised gas source.

16. The injection assembly of any one of the preceding claims further including a needle displacement assembly including a first coil spring arranged to linearly displace the needle from a withdrawn position to an injection position, and a first latch mechanism arranged to retain the first spring in a compressed configuration and, consequently, retain the needle in the withdrawn position, and the controller is communicatively connected with the first latch mechanism and configured to operate the first latch mechanism to cause the first spring to expand and displace the needle to the injection position.

17. The injection assembly of claim 16 further including a needle shield assembly including a sleeve positioned around the needle, a second coil spring arranged to linearly displace the sleeve from a retracted position to a deployed position, and a second latch mechanism arranged to retain the second spring in a compressed configuration and, consequently, retain the sleeve in the retracted position, and thecontroller is communicatively connected with the second latch mechanism and configured to operate the second latch mechanism to cause the second spring to expand and displace the sleeve to the deployed position to surround the needle in the injection position.

18. The injection assembly of claim 17, wherein each latch mechanism includes a coil-shaped shape memory alloy wire, and wherein the controller is configured to apply a voltage to the wire to cause the coil -shape to compress and, consequently, release the associated spring from the compressed configuration.

19. The injection assembly of any one of the preceding claims further including a port fluidly coupled with the internal volume, the port configured receive a supply of the medicament to allow filling the reservoir with medicament.

20. A wearable auto-injector including:the injection assembly according to any one of the preceding claims;a housing carrying the injection assembly; andan adhesive layer attached to the housing, the adhesive layer configured to releasably secure the housing to the patient’s skin.

21. The wearable auto-injector of claim 20, wherein the housing carries an actuator button operable by a user to generate a trigger signal, and the controller is communicatively connected with the button and, responsive to receiving the trigger signal, operate the pressurised gas source to cause the medicament to be expelled from the needle.

22. The wearable auto-injector of claim 20 or 21, wherein the housing carries a status indicator operable to provide at least one of a visual, auditory, and tactile output to indicate status of the wearable auto-injector.

23. The wearable auto-injector of any one of claims 20 to 22 further including a battery for powering the controller and arranged adjacent terminals wired to thecontroller, and a removable battery protector arranged between the battery and the terminals, the battery protector including a tab arranged and shaped to be manually pulled to remove the battery protector and couple the battery with the controller.

24. The wearable auto-injector of any one of claims 20 to 23, wherein the controller is associated with a wireless communications module configured to communicate with an external computing device, and wherein the controller is configured to at least one of transmit data to the external computing device, and receive instructions from the external computing device to enable patient and / or medicament specific settings for the injection assembly.

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