Injection device with play compensation

Abstract

The invention relates to an injection device (100) having an elongate housing (200) and an integrated electronic circuitry (400). The improved design allows the combination of mechanical play compensation and optical signal transmission through the housing by using a translucent or transparent thermoplastic elastomer (TPE) to achieve a resilient coupling in the opening of the housing.

Description

Technical Field

[0001] The present invention relates to injection devices, in particular to syringes with elongated housings and integrated electronic circuit systems. By using translucent or transparent thermoplastic elastomers (TPE), the improved design allows a combination of mechanical play compensation and optical signal transmission. Background Art

[0002] There are multiple diseases that need to be conventionally treated by subcutaneous administration of medicaments, and many delivery devices have been developed to support patients in accurately and controllably delivering a certain amount of medicine during self-administration. Drug delivery devices include injection devices removed from the applied site after each medication event or drug delivery process and infusion devices with cannulas or needles that remain in the patient's skin for a long time. For example, diabetes can be treated by self-administering insulin by the patient with the help of a variable dose insulin injection pen or an infusion pump. Alternatively, a patch injector, a wearable injector or a wearable pump is attached or adhered to the patient's skin.

[0003] What all devices for subcutaneous drug delivery have in common is a reservoir for storing fluid medicaments, and a fluid path for making the drug leave the device and enter the subcutaneous tissue of the patient. In most injection devices or infusion devices, the reservoir is an elongated barrel, which leads to an even more elongated design of the delivery device, such as a handheld device with a pen-like shape. The direct result of the elongated design is that the tolerances of the mechanical parts involved are accumulated in the axial direction. In order to allow the manufacture of the housing and the reservoir to be inserted into the syringe, the housing is usually divided into two or more axially connected parts. The connection can be fixed and directly between the housing parts (such as a cap for closing the housing that is latched on the top of the tube), or indirectly between the housing parts and the internal parts (such as a plurality of outer tubes or caps that are latched to the internal structure). The more complex the mechanical function of the injection device, the more challenging the tolerance problem is, the higher the number and complexity of the mechanical parts involved, and therefore the higher the cost of such a device. The requirements of handheld operation further increase the mechanical stress of the housing in all possible directions, and increase the complexity and cost of the design again. The mechanical stresses naturally applied to all handheld or mobile devices during handling and a wide variety of uses have the effect of slightly tearing apart the components. A completely rigid design with all fixed connections tends to be bulky and expensive when it comes to manufacturing; especially for lightweight devices, it is common practice to use a housing and a basic retaining structure made of plastic, snap the various components together, and let them slide apart in a controlled manner during use. The retaining structure or a string of slidingly connected components is designed to limit the distance the components are allowed to slide apart. In some cases, for example, if a reusable add-on is removably attached to a disposable syringe for application, a certain degree of mechanical play is required for proper function. Such a design including mechanical play of the connections and strings of connected components is required to ensure proper operation in all cases, and often requires compensation for play at specific interfaces. Without play compensation, the integration of play-sensitive components such as electromechanical switches or optical components is likely to become impractical.

[0004] The most common way to deal with mechanical play is to minimize the number of engaging parts involved. Quite complex functionality is possible, as disclosed, for example, in EP3506966 A1 (Sanofi Aventis, published 2019). This document discloses an add-on for an injection device that provides complementary functionality such as wireless communication. The interface between the add-on and the injection device is based on latches; no play compensation is provided, so play-sensitive functionality is not possible.

[0005] As the complexity of mechanical functions increases, and the small form factors required for handheld operation, attempts to avoid play compensation are becoming increasingly difficult to achieve. In handheld injection devices, electromechanical switches typically have only a single millimeter of travel. Any mechanical function that interacts with the electronic circuit system by means of a switch becomes highly dependent on manipulation and other external forces, and will not work reliably due to the presence of mechanical play. To overcome this problem, elastic elements are typically introduced into the chain of connected components and pre-tensioned to hold the components in an initial state. This allows designs with higher tolerances and larger play along the mechanical connections, while keeping all components in well-defined positions even for operating the electromechanical switch.

[0006] EP2729201 A1 (published by Novo Nordisk) discloses an example of such an injection device in which the attachment is latched to the main housing. A biasing spring compensates for the mechanical play and ensures proper function of the electromechanical switch. However, such a biasing spring will increase the size of the device and significantly increase the manufacturing cost of the attachment or any injection device following this design.

[0007] These examples illustrate that there is a clear need for a robust yet cost effective method to design injection devices with or without add-ons that include backlash compensation and still fit into a small form factor. This is particularly true for injection devices that include electronic components and optical interfaces.

[0008] The term "injection device" or "injection system" or "syringe" refers to a device that is removed from the injection site after each medication event or drug delivery process, while the term "infusion system" refers to a device with a cannula or needle that remains in the patient's skin for an extended period of time, such as several hours.

[0009] The term "injection device" also refers to any device that is manipulated by a user to administer an injection, expressly including configurations in which supplementary additional devices are fixedly or removably attached to the injector to support or enhance the functionality of the injector.

[0010] The terms "substance", "drug", "medicament" and "drug" will be understood to include any flowable medical formulation suitable for controlled administration through a device such as, for example, a cannula or hollow needle, and include liquids, solutions, gels or fine suspensions containing one or more medically active ingredients. A medicament may be a composition comprising a single active ingredient, or a premixed or co-formulated composition in which more than one active ingredient is present in a single container. Drugs include drugs such as peptides (e.g., insulin, insulin-containing drugs, GLP-1-containing drugs or derivative or similar preparations), proteins and hormones, active ingredients derived from or harvested from biological sources, hormone- or gene-based active ingredients, nutritional formulations, enzymes and other substances in solid (suspended) or liquid form, as well as polysaccharides, vaccines, DNA, RNA, oligonucleotides, antibodies or parts of antibodies, and appropriate basic substances, auxiliary substances and carrier substances.

[0011] The term "distal" means the direction or end of the drug delivery device carrying the injection needle or injection cannula, whereas the term "proximal" means the opposite direction or end pointing away from the needle or cannula. Summary of the invention

[0012] It is an object of the present invention to provide a robust and cost-effective backlash compensation for an injection device, in particular for an injection device having an optical interface.

[0013] This object is achieved by combining a component with a mechanical play compensation function and a component with an optical function into one single integral component. In a preferred embodiment, the window or light guide integrated in one housing component is made of a resilient but still transparent or translucent material and is configured to double as a biasing device to compensate for mechanical play relative to the other housing component and bias all mechanical components connecting the two housing components. As mentioned previously, one housing component may be part of an add-on that is removably attached to the other housing component. Injection devices with an elongated housing typically have a series or string of components arranged in an axial direction relative to a central axis, which makes them particularly susceptible to mechanical play and therefore makes them a preferred candidate to benefit from the present invention. Since the present invention includes an optical function, it may involve an optical component such as a lens, a light sensor or a light emitting diode LED, which is typically mounted on a printed circuit board PCB that is part of a string of components connected to the housing and is biased to a well-defined operating position by a resilient component that provides play compensation. The optical function involves an optical interface on the injection device, typically an opening in the housing, a transparent or translucent window or the outer surface of a light guide. Thus, a preferred embodiment is an injection device comprising an elongated housing having a first housing part and a second housing part defining a main axis, having a signal opening configured to let light pass through the housing, the elongated housing enclosing an internal assembly comprising a retaining structure and an elastic coupling, wherein the second housing part is slidably connected to the retaining structure, and wherein the internal assembly is configured to limit the axial distance between the second housing part and the retaining structure to a maximum distance; and wherein the elastic coupling is compressed to maximize the axial distance, biasing and defining the axial position of all components between the retaining structure and the second housing part. The internal assembly also includes a printed circuit board PCB with optical components connected to the retaining structure. According to the present invention, the elastic coupling is configured to mechanically close the signal opening while allowing visible light to pass from the outside of the housing to the optical components, or vice versa.

[0014] The effect of this improved design of backlash compensation of the injection device is that no bulky springs, additional spring support structures and other additional components are required to provide backlash compensation, thereby resulting in a smaller and more cost-effective injection device with significantly reduced manufacturing costs while still being able to achieve backlash sensitive functions.

[0015] Preferred embodiments of the invention may also comprise an electromechanical switch mounted on a printed circuit board PCB.Since the position of the PCB is well defined, the invention makes possible a robust design of a switch with very small travel despite all mechanical play. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The subject matter of the invention will be explained in more detail below with reference to preferred exemplary embodiments illustrated in the accompanying drawings, in which:

[0017] FIG1 depicts an injection device according to the invention;

[0018] Figure 1a An integrated injection device without additional components is depicted;

[0019] Figure 1b An injection device comprising a disposable syringe and additional parts is depicted.

[0020] Figure 2 depicts the Figure 1a A cutaway of the proximal end of the injection device to show a preferred embodiment of the internal components:

[0021] Figure 2a is the injection device in a state before the housing parts are connected;

[0022] Figure 2b The invention relates to an injection device in a state where the housing parts are connected.

[0023] Figure 3a A perspective view depicting the transparent elastic coupling inside the second housing component:

[0024] Figure 3a depicts the second housing component of FIG. 2 having a transparent elastic coupling;

[0025] Figure 3b An alternative embodiment is depicted having a second housing component and an alternative transparent elastic coupling.

[0026] Figure 4 Depicted is the distal end of an injection device with an electromechanical switch.

[0027] The reference numerals used in the drawings and their main meanings are listed in summary form in the list of drawings. In principle, identical parts are provided with identical reference numerals in the drawings. DETAILED DESCRIPTION

[0028] Figure 1aA first preferred embodiment of an injection device (100) according to the invention is depicted. It has an elongated housing (200) enclosing internal components configured to implement an injection function. The housing (200) will protect the internal components while allowing reliable operation of the injection device. In FIG1 , the housing (200) comprises a first substantially cylindrical housing part (210) closed on a proximal end by a second housing part (220) and on a distal end by a removable cap (230). Other housing designs with any number of housing parts or geometries are suitable for application of the invention; a common feature being that there is an axis, which can be determined following the elongation of the housing, along which the internal components of the mechanical components are operatively arranged. The connection between the housing parts may be fixed or releasable, direct between the housing parts or indirect via the internal components. Since the connecting parts are arranged substantially along an axis, the play between the parts will increase and may need to be compensated for proper and reliable function. The housing may be provided with openings or other features to allow manipulation and application of the injection device. wherein the internal components include an optical component (700, Figure 2a ) in a preferred embodiment, the signal opening (222) is arranged in one of the housing parts to allow light to pass through the housing in two directions. Figure 1b A second preferred embodiment is shown in , in which an additional device (120) is attached to an autoinjector (110) to form an injection device (100). Such an additional device (120) may provide improved functionality or ease of use to the autoinjector (110) when used without the additional device (120). The additional device (120) may be reusable, while the autoinjector (110) may be designed for low cost and single use, thereby forming one injection device (100) when connected together for use. Therefore, the connection between the two devices is typically releasable, and some play will be required to disconnect the additional device (120), making this configuration particularly attractive for play compensation according to the present invention. The housing of the autoinjector (110) will then be the first housing part (210) according to the present invention, and the housing of the additional device (120) will be the second housing part (220).

[0029] The internal components inside the housing are configured to provide the functions of the injection device, in particular to inject the fluid medicament into the patient's body. To this end, the internal components typically include a reservoir, a fluid path, a needle and an actuator to bring the fluid into the patient's body. The medicament can be moved out of the reservoir by means of external energy, such as by a user applying mechanical force to a button, or by an internal energy source driving the actuator, such as a preloaded spring or a battery that provides power to an electric motor. The internal components may also include components for manipulating the device, such as a mechanical interface with a latch, an electromechanical button, an optical signal or wireless communication. The internal components may include an electrical power source or a battery, and electronic components typically mounted on a printed circuit board PCB, such as a programmable microcontroller, a memory, a sensor and a control circuit system.

[0030] An example of an injection device having an elongated housing (200) and internal components is given in EP-3280472-B1, which is incorporated in its entirety into the present application. An example of an add-on (120) including electronic components and an optical output signal is described in WO2018 / 085952-Al.

[0031] Due to the miniature form factor of electronic components, the interface between electronic components and mechanical components is often difficult to achieve. Optical signals need to be aligned with light guides, or electromechanical switches need to be positioned with a precision that matches the travel of the switch in all situations and device states. On the other hand, the components of the housing and the operatively connected components of the internal assembly will allow a certain degree of play, and they often even require a certain degree of play for proper and reliable operation. Due to the elongated shape of the injection device, the number of connected components and therefore the amount of accumulated play in the axial direction is most significant. Mechanical play is the freedom of movement of the connected components in the axial direction between a minimum value (where a string of slidingly connected components is compressed) and a maximum value (where the string of components is stretched to its maximum length). All housing components and components of the internal assembly are designed to ensure controlled sliding movement over a defined axial distance and to provide defined stops at both ends of the movement. Although this play can occur in any direction, the description of the present invention focuses on embodiments with axial play because they are most relevant to injection devices with an elongated shape.

[0032] A typical way to compensate for play in mechanical design is to include at least one resilient member in a critical series of slidingly connected components. The resilient member is pre-compressed during manufacture of the device and ensures that the axial distance over the series of components is maintained at a maximum when the device is used as intended.

[0033] Figure 2a and Figure 2bA cut through a preferred embodiment of the invention is shown having first and second housing components (210, 220) and internal components including various components, particularly a retaining structure (300), a PCB (400) with optical components (700), and a battery (800). Figure 2a , the components are shown in a state prior to final assembly to illustrate the connection of components with mechanical play and components in a series. In this embodiment, the second housing component (220) has a fixture (221) that is paired with the fixture (321) of the retaining structure (300). The retaining structure (300) also has a fixture (311) that is paired with the fixture (211) of the first housing component (210). Each pair of fixtures is configured to provide a limited minimum and a limited maximum axial distance between two components connected at one point. In the preferred embodiment of FIG. 2, the fixture is a latch designed into the plastic component. However, there may be embodiments with a variety of alternative types of fixtures such as glue, welding, heat riveting or even releasable fixtures (such as threads or bayonet connections). In a series of connected components, many components may not have fixtures at all: in an elongated housing, they will be stacked together in the axial direction and held in place at a minimum distance by the force of the compressed elastic component.

[0034] exist Figure 2a and Figure 2b In the embodiment of the invention, three series of slidingly connected components can be identified. The first series of components starts from a retaining structure (300) and ends with a second housing part (220). Both components have fixings (221, 321) and are slidingly connected together, allowing for mechanical play (632). Between the retaining structure (300) and the second housing part (220) are arranged two components without fixings: a printed circuit board PCB (400) and an elastic coupling (500). The elastic coupling (500) compensates for the play visible as a gap (632), keeps the axial distance along the first series of components (300, 400, 500, 220) at a maximum and ensures a well-defined axial position of all the components involved.

[0035] The second string of components starts from the first housing component (210) and ends with the retaining structure (300). Both components are shown with fixtures (211, 311), and no other components are involved in the second string of slidingly connected components. In this embodiment, the axial play between the first housing component (210) and the retaining structure can be maintained at a level that is not critical to operation, so the play at the gap (613) remains uncompensated. In scenarios with other requirements, such as scenarios including a watertight design, a seal can be used to close the gap (613), which will also provide play compensation for this string of components.

[0036] A third string of components can be seen between the first housing component (210) and the second housing component (220). It will include a combination of the first and second strings and will be visible through the gap (612) between the two housing components (210, 220). In this embodiment, no further compensation for play is included, but other embodiments exist where separate compensation for play in more than one string of components is used, depending on the requirements and the components involved. As seen in the example of the preferred embodiment, some play in a particular string of components may be intentionally left uncompensated.

[0037] As will be apparent from the description of the series of connected mechanical parts, variations of the preferred embodiment include injection devices in which the retaining structure (300) itself is composed of several parts, in fact a series of connected parts itself. Also apparent are embodiments in which the retaining structure (300) is formed together with the first housing part (210) to form one integral part.

[0038] With mechanical play compensated, more critical interfaces can be achieved, in particular interfaces with electronic components such as light emitting diodes LEDs for signalling, visible light sensors for detecting optical properties of the environment, or electromechanical switches for controlling the operation of the injection device.

[0039] The core of the present invention involves combining the mechanical design for backlash compensation in an injection device with the design of an optical interface. These two functions are achieved together by providing a transparent or translucent elastic coupling to allow visible light to pass through. Although this novel approach can be applied to many different situations, a preferred embodiment is an injection device (100) having a substantially opaque housing (200), a signal opening (222), and internal components, as discussed previously using FIG. 2. In such an embodiment, the elastic coupling (500) mechanically closes the signal opening (222) and provides backlash compensation in the first series of slidingly connected components while allowing visible light to pass from the outside of the housing (200) to the optical component (7)00, or vice versa. The elastic coupling (500) can also be used as a seal to protect the internal components from water ingress or contamination.

[0040] Figure 3aA series of components of the injection device (100) are shown to illustrate the shape of the elastic coupling (500): The second housing component (220) with the elastic coupling (500) in place is cut away and shown in a perspective view. With the elastic coupling (500) made of a transparent or translucent material, visible light freely enters and leaves the housing (200). All kinds of materials can be used for the elastic coupling (500) as long as it is elastic and transparent or translucent under the conditions of use of the injection device. Transparent plastic (more specifically thermoplastic elastomer TPE) is a preferred material because of its low cost and ease of manufacture. Transparent TPE can also be manufactured together with the second housing component (220) using 2K molding technology, thereby further reducing costs and facilitating manufacturing.

[0041] With the transparent elastic coupling (500) in place, both play compensation and optical design can be achieved with one integral component. Additional functions can be added to the transparent elastic coupling (500), such as sealing any of the gaps (613, 612, 632) to prevent the ingress of water, dust or contaminated air, or flexibly positioning other components of the internal assembly. Figure 3b An embodiment is shown in which a transparent elastic member (500) is expanded laterally to define the radial position of a PCB (400) and combined with axial play compensation to provide an improved retention structure for electronic components.

[0042] Go to Figure 4 , further showing an embodiment of FIG. 1 , in which an electromechanical switch (900) is mounted on a PCB (400). PCB mounted switches typically have very small travel, but with a transparent elastic coupling (500) compensating for most of the play (612) between the housing components (210, 220), such a switch (900) can be safely operated as part of an internal component of an injection device. Standard methods of mechanical design can be applied to define the precise size, shape and elasticity of the coupling element to ensure the switch function specified for the delivery device. Using a typical electromechanical switch (900) with a switch force of 0.4N and a switch travel of 1mm would, for example, mean that the elastic coupling (500) would not be compressed by more than 1mm when a force of 0.4N is applied to the switch. In a syringe according to the present invention designed using appropriate techniques in the art, manufacturing tolerances or external forces (such as those occurring during manipulation or application of the device) will no longer affect the function or accuracy of the device.

[0043] In addition to all possible mechanical functions, the transparent elastic connector (500) can also be configured to provide any other optical function suitable for the selected material. Although shown as a window in Figure 2, it can shape light in terms of color or focus, acting as a lens, scattering device, filter or polarizer. Special categories of embodiments include transparent elastic connectors (500) configured to guide visible light from optical components (700) or vice versa. Solutions with several elastic and non-elastic transparent or translucent components combined with each other or with other components are also within the scope of the present invention, as long as they follow the concept of allowing visible light to pass through the housing (200) while providing mechanical compensation for play.

[0044] By integrating the mechanical function of the elastic coupling with the optical function, all the benefits of clearance compensation can be achieved without additional components, resulting in an improved injection device that can be implemented in a smaller form factor, with lower manufacturing effort and at lower cost without compromising the accuracy or reliability of drug delivery.

[0045] Although the invention has been described in detail in the drawings and the foregoing description, such description is to be considered illustrative or exemplary rather than restrictive. By studying the drawings, the disclosure and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The fact that certain elements or steps are described in different claims does not indicate that a combination of these elements or steps cannot be used to advantage. Specifically, any further meaningful claim combination, except for actual claim dependencies, should be considered disclosed.

[0046] Reference numerals list

[0047] 100 Injection equipment

[0048] 110 Disposable Syringe

[0049] 120 Accessories

[0050] 200 Shell

[0051] 210 first housing component

[0052] 211 Fixing device (to connecting structure)

[0053] 220 second housing component

[0054] 221 Fixing device (to connecting structure)

[0055] 222 signal opening

[0056] 230 Removable Cap

[0057] 300 Connection structure

[0058] 311 Fixing device (to housing)

[0059] 321 Fixing device (to the second housing part)

[0060] 400 Printed Circuit Board PCB

[0061] 500 elastic connector

[0062] 612 Gap or distance between the first housing part and the second housing part

[0063] 613 Gap or distance between the first housing component and the connecting structure

[0064] 632 Gap or distance between the second housing component and the connecting structure

[0065] 700 Optical components, LEDs or sensors

[0066] 800 Batteries

[0067] 900 Electromechanical Switches

Claims

1. An injection device (100), comprising: An elongated housing (200) having a first housing member (210) and a second housing member (220) defining a major axis, having a signal opening (222) configured to allow light to pass through the housing (200); as well as an internal assembly comprising a retaining structure (300) and an elastic coupling (500); wherein the second housing component (220) is slidably connected to the retaining structure (300) in a direction substantially parallel to the main axis, and wherein, The internal assembly and / or the second housing component is configured to limit an axial distance (632) between the second housing component (220) and the retaining structure (300) to a maximum distance; and wherein, The resilient coupling (500) is compressed to maximize the axial distance (632) to define the axial position of all components between the retaining structure (300) and the second housing component (220); and wherein, The internal assembly further comprises a printed circuit board PCB (400) having an optical component (700) arranged between the retaining structure (300) and the second housing component (220); It is characterized in that the elastic coupling (500) is configured to mechanically close the signal opening (222) while allowing visible light to pass from the outside of the housing (200) to the optical component (700), or vice versa.

2. The injection device according to claim 1, wherein: The retaining structure (300) comprises a series of connected components.

3. An injection device according to claim 1 or 2, wherein: At least a portion of the retaining structure (300) is formed together with the first housing component (210) to form an integral component.

4. An injection device according to any one of the preceding claims, wherein: The elastic connector (500) is made of transparent or translucent plastic, preferably transparent or translucent thermoplastic elastomer TPE.

5. An injection device according to any one of the preceding claims, wherein: The optical component (700) is a light emitting diode (LED).

6. An injection device according to any one of the preceding claims, wherein: The optical component (700) is an optical sensor.

7. The injection device according to claim 5, wherein: The PCB (400) also carries an axially operated electromechanical switch (900).

8. An injection device according to any one of the preceding claims, wherein: The elastic coupling is manufactured as an integral component together with the second housing component (220) by 2K molding.

9. An injection device according to any one of the preceding claims, wherein: The second housing component (220) is part of an attachment (120) operatively connected to the first housing component (210).

10. An injection device according to any one of the preceding claims, wherein The elastic coupling (500) also acts as a translucent or transparent window.

11. An injection device according to any one of the preceding claims, wherein: The elastic coupling (500) also acts as a light guide.

12. An injection device according to any one of the preceding claims, wherein The elastic coupling (500) also acts as a seal to prevent water, dust or contaminated air from entering the volume enclosed by the housing (200).

13. An injection device according to claim 12, wherein: The resilient coupling (500) is also configured to close a gap (612) between the first housing component (210) and the second housing component (220) and provide a seal at the interface between the two housing components.

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