Systems and methods for detecting the state of a medication delivery device

Abstract

A sensing system for determining the state of a compression spring is provided. The system may include capacitance plates positioned on either side of the compression spring, a temperature sensor, and at least one processing circuit configured to measure a capacitance between the capacitance plates, measure a temperature based on a signal output by the temperature sensor, and determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature. In some embodiments, the sensing system may be used to detect the state of a compression spring disposed on or in a medication delivery device to determine the state of the medication delivery device. For example, the sensing system may be used to determine whether the medication delivery device has been activated or whether the device has completed delivery of a medication.

Description

[Technical Field]

[0001] The present disclosure relates to systems and methods for detecting the state of a compression spring, and more particularly, to systems and methods for detecting whether a compression spring used on or in a medication delivery device is in a compressed or extended state and inferring the state of the medication delivery device therefrom. [Background technology]

[0002] Medication delivery devices commonly use compression springs for operation. Such springs may transition from a compressed state to an extended state or from an extended state to a compressed state when components of the delivery device move to a specific position or transition to a different configuration. For example, a spring may be used to drive a syringe assembly to penetrate a user's skin or to pump medication once a needle is inserted. A spring may also be used to retract the syringe assembly after use to reduce the possibility of an accidental needlestick or to extend a needle guard surrounding the syringe needle. Summary of the Invention [Means for solving the problem]

[0003] According to an exemplary embodiment of the present disclosure, a medication delivery device is provided for determining a state of a compression spring of the medication delivery device, the sensing system comprising: a first capacitance plate and a second capacitance plate, wherein the compression spring is configured to be disposed between at least a portion of the first capacitance plate and at least a portion of the second capacitance plate; a temperature sensor; and at least one processing circuit connected to the first capacitance plate, the second capacitance plate, and the temperature sensor, wherein the at least one processing circuit is configured to measure a capacitance between the first capacitance plate and the second capacitance plate, measure a temperature based on a signal output by the temperature sensor, and determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature.

[0004] According to another embodiment of the present disclosure, there is provided an injection system comprising: a medication delivery device housing; a syringe assembly at least partially disposed within the medication delivery device housing, the syringe assembly including a reservoir configured to hold a medicament and an injection needle; a drive mechanism at least partially disposed within the medication delivery device housing, the drive mechanism configured to dispense the medicament from the syringe assembly through the injection needle upon activation by a user, the drive mechanism including a compression spring configured to transition from a compressed state to an extended state or from an extended state to a compressed state after activation; and a sensing system comprising: a first capacitance plate and a second capacitance plate, the compression spring configured to be disposed between at least a portion of the first capacitance plate and at least a portion of the second capacitance plate; a temperature sensor; and at least one processing circuit, the at least one processing circuit configured to measure a capacitance between the first capacitance plate and the second capacitance plate and to measure a temperature based on a signal output by the temperature sensor.

[0005] According to yet another embodiment of the present disclosure, there is provided a method for determining a state of a compression spring positioned between at least a portion of a first capacitive plate and at least a portion of a second capacitive plate, the method including measuring a temperature using a temperature sensor; measuring a capacitance between the first capacitive plate and the second capacitive plate; and determining whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature.

[0006] Among other advantages, the disclosed methods, devices, and systems provide a reliable and cost-effective way to determine whether a spring is in compression or extension. In some embodiments, an exemplary advantage is that the disclosed methods, devices, and systems can determine the state of a spring without having to make physical contact with the spring (or with any component in physical contact with the spring), as such physical contact can interfere with the operation of the spring. In some embodiments, another exemplary advantage is that the disclosed methods, devices, and systems can be mounted on or integrated with a thin, flexible sheet that can be adhered to the exterior surface of existing drug delivery devices, thereby providing sensing and communication capabilities to such existing or previously available devices in a low-cost manner and without the need for any modifications to the internal components of such delivery devices. In some embodiments, another exemplary advantage of the disclosed methods, devices, and systems is that by taking into account the ambient temperature (and / or the temperature of the sensing system or the sensed compression spring), the disclosed methods, devices, and systems can detect whether the compression spring is in a compressed or extended state with greater accuracy and reliability. Other advantages will be recognized by those skilled in the art. [Brief explanation of the drawings]

[0007] The above and other features and advantages of the present disclosure, and the manner in which they are achieved, will become more apparent and will be better understood by referring to the following description of embodiments of the invention taken in conjunction with the accompanying drawings. [Figure 1] 1 is a logical block diagram depicting an exemplary sensing system for determining the state of a compression spring, according to some embodiments, the compression spring depicted being in a compressed state. [Figure 2] 1 shows the sensing system when the compression spring is in an extended state. [Figure 3A] 1 depicts another embodiment of a sensing system including a capacitive shield, according to some embodiments. [Figure 3B] 1 depicts another embodiment of a sensing system including a plate with sets of fingers interleaved to form an interdigital capacitor, according to some embodiments. [Figure 4A] FIG. 2 is an electrical circuit diagram modeling the electrical circuit of the sensing system depicted in FIG. 1. [Figure 4B] FIG. 3 is an electrical circuit diagram modeling the electrical circuit of the sensing system depicted in FIG. 2. [Figure 5A] FIG. 4 is an electrical circuit diagram modeling the electrical circuit of the sensing system depicted in FIG. 3 when the compression spring is in its compressed state. [Figure 5B] FIG. 4 is an electrical circuit diagram modeling the electrical circuit of the sensing system depicted in FIG. 3 when the compression spring is in its extended state. [Figure 6] 1 depicts an exemplary process for determining the state of a compression spring, according to some embodiments. [Figure 7] 1 illustrates an exemplary medication delivery device in its initial, pre-use configuration, according to some embodiments. [Figure 8] 1 illustrates a drug delivery device after its end cap has been removed, but before the device has been activated to deliver a drug. [Figure 9] 1 illustrates a drug delivery device after the device has been activated to deliver a drug. [Figure 10]1 illustrates an exemplary label wrapped around the exterior of a medication delivery device, according to some embodiments. [Figure 11] Shows the label after it has been laid flat and unwrapped. [Figure 12] A diagram of the back of the label is shown. [Figure 13] 10 illustrates a second exemplary label wrapped around the exterior surface of a medication delivery device, according to some embodiments. [Figure 14] 1 shows a view of the back of the second label. [Figure 15] 10 shows a back view of a third exemplary label using a plate with interleaved sets of fingers, according to some embodiments.

[0008] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set forth herein illustrate exemplary embodiments of the present invention, and such exemplifications should not be construed as limiting the scope of the present invention in any way. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1 is a logical block diagram depicting an exemplary sensing system 102 for determining the state of a compression spring 104, according to some embodiments. The compression spring 104 may be any suitable spring at least partially formed of a conductive material (e.g., metal). Components of the system 102 may receive power from a power source 114, which may be a battery, a supercapacitor, a power grid, or a harvested power source that receives power inductively and wirelessly from an external source (e.g., from an external device 150 described below). The system 102 includes a first capacitance plate 108a configured to be positioned on a first side of the spring 104 and a second capacitance plate 108b configured to be positioned on a second side of the spring 104 circumferentially spaced from the first side, such that the spring 104 is disposed between the first plate 108a and the second plate 108b (plates 108a and 108b collectively referred to as plates 108). Plate 108 may take the form of any substantially flat or curved sheet at least partially formed of a conductive metal (or another conductive material). System 102 further includes a temperature sensor 112 configured to sense a temperature. The sensed temperature may be, according to different embodiments, the temperature of spring 104, the temperature of one or both of plates 108, the temperature of any other component of system 102 described herein, the temperature of a device or system to which system 102 is attached or integrated, and / or the ambient temperature. Temperature sensor 112 may take the form of any suitable sensor for sensing temperature, such as, but not limited to, a thermistor (e.g., a negative temperature coefficient (NTC) thermistor or a resistance temperature detector (RTD)), a thermocouple, or a semiconductor-based temperature sensor.

[0010] Plate 108 and temperature sensor 112 are coupled to processing circuitry 106. Processing circuitry 106 may take the form of a processor (e.g., a microprocessor or microcontroller, a field-programmable gate array (FPGA) and / or a digital signal processor (DSP), or any combination of the above) configured to execute logic stored in memory (not shown) to perform the operations described herein. As used herein, the terms “logic,” “control logic,” “instructions,” or “application” may include software and / or firmware executed on any of the previously mentioned processing circuits. Memory is accessible by processing circuitry 106 and may be any suitable computer-readable medium, including both volatile and non-volatile memory. Exemplary memory includes random-access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, magnetic storage devices, optical disk storage, or any other suitable medium configured to store data and accessible by processor circuitry 106 directly or indirectly via one or more intermediary devices or wired or wireless communication links. While the foregoing description assumes the memory is separate from but communicatively coupled to processing circuitry 106, in some embodiments, memory may also be integrated with processing circuitry 106. In some embodiments, instead of a processor executing logic stored in memory, processing circuitry 106 may take the form of hardwired logic, e.g., a state machine and / or an application-specific integrated circuit (ASIC), that performs the functions described herein.In sensing system 102, processing circuit 106 is electrically coupled to plates 108 to measure the capacitance between plates 108a and 108b. Similarly, processing circuit 106 is also communicatively coupled to temperature sensor 112 to determine the temperature sensed by sensor 112 based on the signal output by sensor 112. Although processing circuit 106 and temperature sensor 112 are illustrated as separate elements in Figures 1 and 2, in some embodiments, temperature sensor 112 and processing circuit 106 may be integrated into a single integrated circuit.

[0011] The processing circuit 106 may also be communicatively coupled to the communication circuit 110. The communication circuit 110 may take the form of a circuit configured to communicate data to and from the external device 150 using any suitable wireless transmission protocol, such as, but not limited to, a cellular transmission protocol, Bluetooth Low Energy (BLE), Near Field Communication (NFC), and / or Radio Frequency Identification (RFID). The processing circuit 106 may use the communication circuit 110 to communicate at least one of the measured capacitance, the measured temperature, and data indicative of whether the compression spring is in a compressed or extended state to the external device 150. Although the processing circuit 106 and the communication circuit 110 are illustrated in FIGS. 1 and 2 as separate elements, in some embodiments the communication circuit 110 and the processing circuit 106 (potentially together with the temperature sensor 112) may be integrated into a single integrated circuit.

[0012] External device 150 may comprise any device that receives, stores, and / or processes data from communication circuit 156 via wireless signal 130 received by communication circuit 110. Exemplary external devices include a smartphone, a smartwatch, a tablet, a laptop, a desktop PC, a wireless hub, and / or a WiFi access point. Wireless signal 130 may be an active signal in which external device 150 receives a signal transmitted by communication circuit 110, or a passive signal in which external device 150 senses a modulation on a signal transmitted by communication circuit 110 (e.g., a passive NFC signal) caused by communication circuit 156. Similar to communication circuit 110, communication circuit 156 may comprise any circuitry configured to receive data from and / or transmit data to processing circuit 106 using any of the wireless transmission protocols mentioned above. External device 150 may further include processing circuitry 152, which may take the form of any of the types of processing circuitry mentioned above, and memory 154, which may also take the form of any of the types of memory mentioned above. In some embodiments, the external device may further include a user interface for displaying data and / or receiving user input. For example, the user interface may include a graphical user interface (GUI) including a touchscreen display. The touchscreen display allows a user to interact with presented information, menus, buttons, and other data to receive information from and provide user input to the system. Alternatively, or in addition, a keyboard, keypad, microphone, mouse pointer, or other suitable user input device may be provided. External device 150 may also include separate communications circuitry configured to communicate with other devices (e.g., using long-range or cellular wireless transmission protocols).

[0013] 1 shows the sensing system 102 when the compression spring 104 is in a compressed state. In this compressed state, the coils of the spring 104 are closely spaced such that the sides of the spring act as capacitance plates positioned between plates 108a and 108b. Thus, when the spring 104 is in its compressed state, the spring 104 and plates 108a and 108b can be modeled using the electrical circuit diagram 402 depicted in FIG. 4A. In the electrical circuit diagram 402, terminal 404 is considered to be connected to the processing circuit 106. C ps represents the capacitance formed by one of the plates 108 and the side of the compressed spring 104. C ps can be calculated according to Equation 1 below:

[0014]

number

[0015] Because there are two plates 108, the total capacitance (C) measured by processing circuitry 106 between terminals 404 when spring 104 is in compression is total,comp ) is calculated using the following equation 2.

[0016]

number

[0017] This is the total capacitance (C total ) can be calculated using the following equation 3:

[0018]

number

[0019]

number

[0020] 2 shows the sensing system 102 when the compression spring 104 is in an extended state. In this extended state, the coils of the spring 104 are spaced widely apart, or at least further apart, than when the spring 104 is in its compressed state. In this configuration, the sides of the spring no longer function as (or function less effectively as) capacitance plates positioned between plates 108a and 108b. Thus, when the spring 104 is in its extended state, the spring 104 and plates 108a and 108b can be modeled using the electrical circuit diagram 403 of FIG. 4B. As in FIG. 402, terminals 404 in FIG. 403 can be considered connected to the processing circuitry 106. pp represents the capacitance formed by the two plates 108, with no intervening capacitive plate between them. C pp can be calculated according to the following Equation 4:

[0021]

number

[0022] d ps and d pp is a parameter that can be set according to different embodiments. However, for the sake of explanation, pp =x d ps where x is a configurable parameter, Cpp and C ps The relationship between is expressed by the following Equation 5:

[0023]

number

[0024]

number

[0025] Thus, the capacitance measured by processing circuit 106 can be expected to change as spring 104 transitions between its compressed and extended states (assuming x is not equal to 2). For example, if x is equal to 3, then the capacitance observed by processing circuit 106 when spring 104 is in its extended state is expected to be approximately 2 / 3 of the capacitance observed by processing circuit 106 when spring 104 is in its compressed state. Thus, by measuring the capacitance of spring 108 and the system formed by spring 104, processing circuit 108 can determine whether the spring is in its extended or compressed state.

[0026] The inventors further understand that the capacitance measured by the processing circuit 106 may change depending on the temperature of the components of the system 102, such as the spring 104 and the plates 108. This may be because, as the temperature increases, the gaps between the links in the spring 104 may increase or decrease due to thermal expansion. Furthermore, as the temperature increases, the capacitance plates 108 may expand, thus increasing their surface area and, consequently, increasing the measured capacitance. Also, as the temperature increases, the distance between the capacitance plates 108 and the spring 104 may change. Additionally, as the temperature increases, thermal noise and / or other temperature dependencies that affect measurements taken by the capacitance sensors on the processing circuit 106 may increase, thus increasing the measured capacitance. In some cases, the inventors have observed that the capacitance measured by the processing circuit 106 may vary so greatly between a first (lower) temperature and a second (higher) temperature that it may be difficult to determine whether the spring 104 is in its compressed or extended state based solely on the measured capacitance. In other words, in some use cases, the measured capacitance of the spring in its compressed state while at a first temperature may be too similar to the measured capacitance of the spring in its extended state while at a second temperature. This makes it difficult to determine whether the spring 104 is in its compressed or extended state based solely on the measured capacitance without taking into account the temperature of the system 102.

[0027] This is particularly the case when system 102 is used to detect the state of a spring in a drug delivery device that needs to be cooled for storage. Many types of injectable drugs need to be stored at lower temperatures (e.g., 36-46 degrees Fahrenheit, or 2-8 degrees Celsius) to prevent degradation, but then need to be warmed to a higher temperature (e.g., room temperature, or 65-75 degrees Fahrenheit) before being injected into a patient. Drug delivery devices used to store and deliver such drugs may be provided with instructions instructing the patient to store such devices in a refrigerator but remove the device and allow it to warm to room temperature before administration. In some embodiments, the measured capacitance of the spring in its compressed state while at a lower temperature (e.g., in a refrigerator) may be too similar to the measured capacitance of the spring in its extended state while at a higher temperature (e.g., room temperature) to allow sensing system 102 mounted on such a drug delivery device to reliably determine what state the spring is in without taking temperature into account.

[0028] Accordingly, system 102 may include a temperature sensor 112 communicatively coupled to processing circuit 106. Sensor 112 enables processing circuit 106 to measure the ambient temperature or the temperature of one or more components of system 102 (e.g., spring 104 and / or plate 108). By taking into account the temperature measured by sensor 112, processing circuit 106 may more accurately determine whether spring 102 is in compression or extension.

[0029] For example, processing circuit 106 may determine that spring 102 is in its compressed state when the measured capacitance of plate 108 is greater than the capacitance threshold. Conversely, processing circuit 106 may determine that spring 102 is in its extended state when the measured capacitance is less than the capacitance threshold. Processing circuit 106 may be further configured to adjust the capacitance threshold based on the temperature measured by sensor 112. For example, processing circuit 106 may increase the capacitance threshold as the temperature increases and decrease the capacitance threshold as the temperature decreases. Processing circuit 106 may do this in any of several ways, including (i) defining two or more temperature bands (e.g., high / low, high / medium / low, or any other number of temperature bands), each delineated from the other temperature bands by a temperature threshold, and implementing logic to set the capacitance threshold depending on which temperature band the current temperature falls within; and / or (ii) deriving the capacitance threshold to apply by multiplying the current temperature by a pre-programmed conversion constant. Any known mathematical or logical method may be used to vary the capacitance threshold based on the temperature measured by sensor 112. In this manner, processing circuit 106 may better determine whether spring 102 is in its compressed state or its extended state based on both the measured capacitance of plate 108 and the temperature measured by sensor 112.

[0030] In some embodiments, processing circuit 106 may be configured to measure the capacitance between plates 108 and the temperature measured by sensor 112 and communicate this measurement data to processing circuit 152 within external device 150. Processing circuit 152 then determines whether spring 104 is in compression or tension based on the measured and received capacitance and temperature data. In yet other embodiments, processing circuit 106 and processing circuit 152 may cooperate to determine whether the spring is in compression or tension.

[0031] FIG. 3A depicts an embodiment of system 102 that includes a capacitance shield 114. For simplicity, temperature sensor 112 is not shown in FIG. 3A , but it should be understood that such a temperature sensor may be connected to and / or integrated with processing circuit 106. In this embodiment, plates 108a and 108b are configured as curved plates that conform to the curvature of spring 104. Additionally, capacitance shield 114 may be configured as a metallic or conductive layer of material shaped like all or part of a cylinder and surrounding all or part of plate 108 and spring 104. Similar to plate 108, shield 114 may also be electrically connected to processing circuit 106. Shield 114 may reduce the effect of any conductive object (e.g., a user's hand) touching or positioned in proximity to plate 108 on the capacitance measured by processing circuit 106. By reducing the magnitude of any such interference on the measured capacitance, shield 114 mitigates the likelihood of such interference causing processing circuit 106 to erroneously determine that spring 104 is in its compressed state when it is actually in its extended state (or vice versa). In some embodiments, a polyester film (or a layer of some other dielectric material) (not shown) may be inserted between plate 108 and shield 114 to separate these components from one another.

[0032] FIG. 3B depicts another embodiment of system 102 that, instead of using two solid curved plates 108a and 108b, uses two “plates” 109a, 109b (collectively, plates 109), each plate comprising a set of spaced-apart, parallel fingers formed at least in part from a metal or conductive material that covers at least a portion of the surface of spring 104. The first “plate” comprising fingers 109a is electrically connected to a first conductive strip 111a, and the second “plate” comprising fingers 109b is electrically connected to a second conductive strip 111b. As depicted in FIG. 3B, the two plates are arranged such that the fingers of each plate are alternately interleaved with one another, thus forming an interdigital capacitor. Conductive strips 111a and 111b are then communicatively coupled to processing circuitry 106. Although not depicted in FIG. 3B, it should be understood that a capacitance shield 114 may also be provided that surrounds all or part of the plates 109a, 109b and conductive strips 111a, 111b.

[0033] When spring 104 is in its compressed state, spring 104, plate 108 (or 109), and shield 114 can be modeled using the electrical circuit diagram 502 depicted in FIG. 5A. In electrical circuit diagram 502, terminal 504 is considered to be connected to processing circuit 106. As previously mentioned, C ps represents the capacitance formed by one of the plates 108 (or 109) and the side of the compressed spring 104. C p,shield represents the capacitance formed by one of the plates 108 or 109 and the shield 114. C ps can be calculated according to Equation 1. p,shield can be calculated using Equation 7 below:

[0034]

number

[0035] The capacitance of two capacitors connected in series can be calculated using Equation 3. Therefore, the capacitance of the two capacitors connected in series, C p,shield The capacitance (C offset ) is calculated using the following equation 8.

[0036]

number

[0037] When compression spring 104 is in its extended state, the coils of spring 104 are widely spaced apart. As previously mentioned, in this configuration, the sides of the spring no longer function as (or function less effectively as) capacitance plates positioned between plates 108a and 108b (or 109a and 109b). Thus, when spring 104 is in its extended state, spring 104, plates 108 or 109, and shield 114 can be modeled using electrical circuit diagram 503 in FIG. 5B. Similar to diagram 502, terminal 504 can be considered connected to processing circuitry 106. As can be seen, diagram 503 illustrates the capacitance Cp,shield Two capacitors with C pp 403 except that the spring 104 is arranged in parallel with the shield 114. Therefore, the capacitance (C total,exp,shielded ) is calculated by the following equation 10. Equation 10: C total,exp,shielded =C total,exp +C offset

[0038] Therefore, the addition of the shield 114 reduces the C total,comp and C when the spring 104 is in its extended state. total,exp and capacitance C offset It can be expected that C offset By taking into account the capacitance measured by the processing circuit 106, the capacitance can continue to serve as an indicator of whether the spring 104 is in its compressed state or its extended state.

[0039] FIG. 6 depicts an exemplary process 600 for determining the state of a compression spring, according to some embodiments. Process 600 may be implemented using sensing system 102. Process 600 begins in step 602, where a first capacitance plate (e.g., plate 108a or 109a) is positioned on a first side of a compression spring (e.g., spring 104). In step 602, a second capacitance plate (e.g., plate 108b or 109b) is positioned on a second side of the compression spring opposite the first side. In some embodiments, the second capacitance plate is positioned such that the compression spring is disposed between the first capacitance plate and the second capacitance plate. In step 606, temperature is measured using a temperature sensor (e.g., temperature sensor 112). In step 608, capacitance is measured between the first capacitance plate and the second capacitance plate. This measurement may be performed using a processing circuit, such as processing circuit 106. In step 610, the processing circuit determines whether the compression spring is in a compressed or extended state based on the measured capacitance and the measured temperature. This determination may be made using any of the methods described herein. The processing circuit making this determination may be, for example, processing circuit 106. Alternatively, the processing circuit making this determination may be processing circuit 106 in external device 150 based on measured capacitance and temperature data measured and wirelessly communicated from processing circuit 152 via communication circuits 110 and 156. In some embodiments, this determination may be made by two or more processing circuits, e.g., processing circuit 106 and processing circuit 152, that are communicatively coupled to each other (e.g., via a wired or wireless data link) and configured to cooperatively process measured capacitance and / or temperature data to determine the state of spring 104.

[0040] In some embodiments, the compression spring may be part of a medication delivery device, as described in further detail herein. The medication delivery device may be configured to be activated to dispense a medication and, upon such activation, transition the compression spring from a compressed state to an extended state, or transition the compression spring from an extended state to a compressed state. The transition of the spring between states may be used to move the syringe assembly between a retracted position and an injection position, or vice versa.

[0041] In some embodiments, the method may further include reporting at least one of the measured capacitance, the measured temperature, and / or data indicative of whether the compression spring is in a compressed or extended state to an external device via wireless communication, which may be performed using communications circuitry 110 and any of the wireless communications protocols described in connection therewith.

[0042] 7-9 depict a medication delivery device 20 that can be used with the sensing system 102 in various operational states. One example of such a device and its operation is described in U.S. Pat. No. 8,734,394 B2, issued May 27, 2014, to Adams et al., and U.S. Patent Application Publication No. 2021 / 0093784 A1, published April 1, 2021, to Adams et al., the entire disclosures of each of which are incorporated herein by reference. The device 20 includes a syringe assembly 22, a drive mechanism 24, and a retraction mechanism 26. The syringe assembly 22 includes a barrel 30 forming a container body for holding the medication and a piston 32 disposed within the barrel 30 for driving the medication out of the barrel. The syringe assembly 22 also includes a needle assembly 33 having a hollow syringe needle 34 and a needle hub 35 that attaches the needle 34 to the syringe barrel 30. A lower body support member 29, coupled to a device housing 38, surrounds the needle 34. Advancing a piston 32 within the barrel 30 toward the needle 34 causes medication to be dispensed through the needle 34.

[0043] The devices described herein, such as device 20, may further include a medicament, such as, for example, in syringe barrel 30. In another embodiment, a system may include one or more devices, including device 20, and a medicament. The term "medicament" or "drug" refers to one or more therapeutic agents, including, but not limited to, insulin, insulin analogs such as insulin lispro or insulin glargine, insulin derivatives, GLP-1 receptor agonists such as dulaglutide or liraglutide, glucagon, glucagon analogs, glucagon derivatives, gastric inhibitory polypeptide (GIP), GIP analogs, GIP derivatives, combined GIP / GLP-1 agonists such as tirzepatide, oxyntomodulin analogs, oxyntomodulin derivatives, therapeutic antibodies, including, but not limited to, IL-23 antibody analogs or derivatives such as mirikizumab, IL-17 antibody analogs or derivatives such as ixekizumab, therapeutic agents for pain-related treatments such as galcanezumab, lasmiditan, and any therapeutic agent that can be delivered by the devices described herein. Medicaments such as those used in the devices may be formulated with one or more excipients. The device is operated by a user, caregiver, or medical professional in a manner generally as described above to deliver medication to a patient. As used herein, the term "user" may refer to the operator of a device described herein, and the term "patient" may refer to the person receiving the medication. In some cases, the user and the patient may be the same person (e.g., the patient is operating a device described herein to give themselves an injection). In other cases, the user and the patient may be different people (e.g., the user may be the person providing care to the patient).

[0044] FIG. 7 illustrates device 20 in its initial, pre-use configuration, where end cap 36 is fixedly attached to lower body support member 29 (which is coupled to device housing 38). End cap 36 covers proximal end opening 40 of housing 38. As used herein, distal and proximal refer to axial locations relative to an injection site when the device is oriented for use at the injection site; thus, for example, the proximal end of the housing refers to the end of the housing closest to such injection site, and the distal end of the housing refers to the end of the housing farthest from such injection site. Also, as used herein, "injection site" can refer to the exact spot on a patient's body that will be injected by the needle, as well as the bodily tissue surrounding the spot where the needle injects (e.g., within 1-5 cm or 1-10 cm of the spot where the needle pierces the patient's skin). Housing 38 may be formed from a plastic material and may be shown extending generally longitudinally along longitudinal axis 48 between a distal end proximate activation button 52 and a proximal end proximate proximal end opening 40. As shown in FIG. 8 , housing 38 may include a user-graspable portion 37 configured to be grasped by a user's hand, with user-graspable portion 37 extending outward from longitudinal axis 48 a radial distance 41. In some embodiments, radial distance 41 may be 5-10 mm in length (e.g., in some embodiments, 5-8 mm may be a suitable length). Also shown in FIG. 8 , housing 38 may also include an outwardly flared end portion 39 at the proximal end of the housing adjacent proximal opening 40.

[0045] A needle guard 42 is mounted on the syringe assembly 22 and covers and surrounds the needle 34. The end cap 36 and needle guard 42 protect the user from accidental needle sticks and also protect the needle 34 from damage. When using the device 20 to dispense a medication, for example, to inject the medication into a patient, the end cap 36 and needle guard 42 are first removed. Figure 8 illustrates the device 20 after the end cap 36 and needle guard 42 have been removed from the syringe assembly 22, with the syringe assembly in a retracted position and the device 20 ready for a dispensing event.

[0046] Syringe assembly 22 is movable relative to medication delivery device 20 between a retracted position and an injection position. Figure 9 illustrates device 20 after syringe assembly 22 has been moved relative to device 20 from its retracted position shown in Figure 8 to the injection position. In the retracted position (Figures 7 and 8), needle 34 is retracted to a position such that needle 34 is disposed within housing 38 of device 20. In the injection position (Figure 9), needle 34 protrudes outward from housing 38 in a proximal direction parallel to longitudinal axis 48 and beyond proximal opening 40, thereby allowing needle 34 to be inserted into a patient.

[0047] Drive mechanism 24 includes a plunger 44 that engages piston 32. Drive mechanism 24 includes a spring 46 that drives plunger 44 in a translational motion. In the illustrated embodiment, spring 46 advances plunger 44 along a linear path defined by a longitudinal axis 48 of device 20. As plunger 44 advances, a foot 50 of plunger 44 contacts piston 32. Further advancement of plunger 44 advances syringe assembly 22 along axis 48 from its retracted position to its injection position. After syringe assembly 22 has advanced to its injection position, continued proximal advancement of plunger 44 advances piston 32 proximally within barrel 30 from its initial piston position (shown in FIGS. 7 and 8 ) to its final piston position (shown in FIG. 9 ) during a dispense event, dispensing medicament from needle 34. Prior to any dispensing of medication, and when syringe barrel 30 holds the entire original volume of medication, piston 32 will be in its initial piston position. After advancing piston 32 through its entire length of travel toward needle assembly 33, piston 32 will be in its final piston position adjacent needle assembly 33, and medication from within barrel 30 will have been expelled. In some embodiments, syringe assembly 22 will hold a single dose of medication to be delivered in a single injection event, and piston 32 will advance from its initial piston position to its final piston position during that single injection event, thereby delivering the entire single-dose contents of syringe assembly 22. Although the device is shown as a single-use device, device 20 may also be configured, with appropriate modifications, as a multiple-use device.

[0048] Advancement of plunger 44 generally will not result in the dispensing of medicament from syringe assembly 22 until syringe assembly 22 is advanced to the injection position. Factors exist that may prevent medicament from being dispensed before the syringe is advanced to the injection position. One factor may be friction between piston 32 and barrel 30. Typically, piston 32 will be formed of a rubber material and barrel 30 will be glass. The frictional resistance between these two components may be sufficient to prevent advancement of piston 32 within barrel 30 until syringe assembly 22 is advanced to its injection position and engagement with a suitable stop member prevents further advancement of syringe assembly 22. Additionally, medicament within the syringe may be somewhat viscous, thereby providing some resistance to flow from needle 34. If necessary, modification of piston 32 and syringe barrel 30 to change the frictional resistance of the dispensing motion of engagement member 32 relative to syringe barrel 30 can limit or prevent premature dispensing of medicament before container 22 reaches its injection position.

[0049] To activate drive mechanism 24, a user depresses an activation button 52 on the distal end of device 20. Depressing button 52 disengages one or two elongated protrusions 54 on plunger 44 from shuttle assembly 60, thereby allowing spring 46 to extend to advance plunger 44 axially. Spring 46 has a helical shape and surrounds protrusions 54. A proximal end of spring 46 biasingly engages a flange on plunger 44.

[0050] The shuttle assembly 60 may include an upper shuttle member 62 and a lower shuttle member 64. The shuttle members 62, 64 are secured together in the final assembly. In the final assembly, the upper shuttle member 62 captures the button 52 and spring 46, limiting axial movement of these components in the distal direction. The protrusion 54 engages a surface on the upper shuttle 62 when the device is in the state shown in FIGS. 7 and 8. Depressing the button 52 causes a tab on the button 52 to engage a ramp (not shown) on the protrusion 54, urging the protrusion 54 inward and disengaging it from the upper shuttle member 62. After the protrusion 54 is disengaged, the spring 46 exerts a biasing force on a flange on the plunger 44, advancing the plunger 44 from the position shown in FIG. 8 to the position shown in FIG. 9 as the spring 46 transitions from its compressed to its extended state. As plunger 44 advances, it moves syringe assembly 22 to an injection position, which in turn advances piston 32 to dispense the medication as discussed above.

[0051] After the dispensing event is completed, the retraction mechanism 26 optionally moves the syringe assembly 22 from the injection position shown in FIG. 9 back to the retracted position. More specifically, the retraction mechanism is adapted to move the medication container from the injection position to the retracted position with a retraction motion. The retracted position may be similar to the retracted position in that the syringe assembly is retracted into the housing 38, such that the needle 34 no longer protrudes proximally from the proximal opening 40 but is disposed completely within the housing 38. In some embodiments, the retracted position may be the same as the retracted position. However, in other embodiments, the syringe assembly 22 in the retracted position may be located slightly proximal or distal relative to the syringe assembly in the retracted position. In the illustrated embodiment, the retraction mechanism includes a spring 66, a syringe carrier, and a rotating member 70 acting as a follower. In still other embodiments, the device 20 may not include a retraction mechanism 26 such that the syringe assembly remains indefinitely in its injection position until it is manually removed or repositioned by the user after the medication has been dispensed.

[0052] The plunger 44 may include an outrigger (not shown) that unlocks the rotating member 70 when the plunger 44 nears the end of its proximal travel. The rotating member 70 is rotatably secured to the lower shuttle member 64 by engagement between a latch and a latch recess in the lower shuttle member 64. The outrigger unlocks the member 70 by depressing the latch. The spring 66 is torsionally preloaded and has one end engaged with the member 70 and an opposite end engaged with the shuttle assembly 60. Upon depression of the latch, the spring 66 rotates the member 70.

[0053] The member 70 is rotatable within the housing 38 but is not axially movable relative to the housing 38. Other embodiments may also include an axially movable member 70. Rotation of the member 70 acts as a delay mechanism that prevents the retraction mechanism 26 from retracting the syringe assembly 22 until the syringe assembly has delivered its dose of medication. The rotational speed of the member 70 may be adjusted by adjusting the viscosity of the grease disposed on or around the surface of the member 70 that is in contact with the housing 38; more viscous grease results in slower rotation and less viscous grease results in faster rotation. A radial flange on the rotating member 70 may engage a ledge in the housing member 38 to limit proximal movement of the member 70. The spring 66 may also be compressively preloaded so that it is initially in a compressed state. In this compressed state, spring 66 may exert an axial force, a torsional force, or both, on member 70 proximally biasing member 70, thereby maintaining member 70 in an axial position in which the radial flange of member 70 engages the internal ledge of housing member 38.

[0054] The shuttle assembly 60 may include axially extending channels or ribs that engage corresponding features on the housing member 38, allowing the shuttle assembly 60 to move axially within the housing 38 but preventing relative rotation of the shuttle assembly 60 with respect to the housing member 38. The shuttle assembly 60 is biased distally by a spring 66 but is prevented from moving distally by engagement of a latch (not shown) prior to activation of the drive mechanism 24. When the rotating member 70 completes its rotation, it disengages the previously-referenced latch, thus allowing the shuttle assembly 60 to move distally under the biasing force of the spring 66.

[0055] As the shuttle assembly 60 moves distally, it carries the syringe assembly 22 distally, moving it back to the retracted position. Also, as the shuttle assembly 60 moves, the spring 66 transitions from its compressed state to its extended state. The spring 66 biases the retraction mechanism 26 distally, thereby maintaining the syringe assembly 22 in its retracted position after an injection event. In some embodiments, the spring 46 of the drive mechanism 24 may also transition from an extended state to a compressed state as the shuttle assembly 60 moves distally. Locking features, such as detents on the shuttle assembly 60 and recesses on members of the housing 38, additionally provide a locking engagement to secure the syringe assembly 22 with the needle 34 disposed within the housing 38 in the retracted position after an injection event, allowing the user to then dispose of or otherwise handle the device 20 in a safe manner.

[0056] According to some embodiments, FIG. 10 illustrates a label 1000 wrapped around the exterior surface of the user-gripable portion 37 of the medication delivery device 20, while FIG. 11 illustrates the label 1000 lying flat without being wrapped. The label 1000 may comprise a flexible paper and / or plastic material that can be attached to the exterior surface of the device 20. The label 1000 may be attached using any of a variety of methods, including (but not limited to) using adhesives, adhesive films (e.g., polyurethane films), magnetic attachments, clip-on attachments, ultrasonic bonding / welding, injection molding / in-mold labeling, laser bonding / welding, etc. The label 20 may be printed with information about the device 20 and / or the medication stored therein, such as the name of the medication, the manufacturer's name, the manufacturing batch / lot number, the expiration date, instructions for use and / or storage, the amount of medication stored therein, etc.

[0057] The sensing system 102 may be mounted on and / or integrated with the label 1000 to provide the label 1000 with the ability to sense whether a compression spring within the medication delivery device 20 (e.g., spring 46 of the drive mechanism 24 and / or spring 66 of the retraction mechanism 26) is in a compressed or extended state. This determination of the state of the compression spring within the device 20 may indicate whether the device 20 has been activated to deliver medication and / or whether the device 20 has completed delivery of medication. For example, when the medication delivery device 20 is activated to dispense medication, the spring 46 transitions from a compressed state to an extended state, and therefore the sensing system 102 mounted on and / or integrated with the label 1000 may be used to detect the state of the spring 46 and infer therefrom whether the medication delivery device 20 has been activated. As another example, since the spring 66 transitions from a compressed state to an extended state when the medication delivery device 20 retracts the syringe assembly 22 at the end of an injection, the sensing system 102 mounted on and / or integrated with the label 1000 can be used to detect the state of the spring 66 and infer therefrom whether the medication delivery device 20 has completed its retraction of the syringe assembly 22 and / or has completed its injection. As yet another example, since in some embodiments the spring 46 can transition from an extended state to a compressed state when the medication delivery device 20 retracts the syringe assembly 22 at the end of an injection, the sensing system 102 mounted on and / or integrated with the label 1000 can be used to detect the state of the spring 46 and infer therefrom whether the medication delivery device 20 has completed its retraction of the syringe assembly 22 and / or has completed its injection. The sensing system 102 mounted on and / or integrated with the label 1000 may also use the communication circuitry 110 to communicate its determination regarding the state of the sensed compression spring to an external device, such as the external device 150.The external device may infer from this information whether the user has given and / or completed an injection, record such information and / or inferences, and / or transmit such information and / or inferences to other devices for storage, analysis, and / or further action.

[0058] 12 shows a view of the back side (e.g., the surface configured to be wrapped around and / or adhered to the outer surface of the medication delivery device 20) of an exemplary label 1000 attached to and / or integrated with the sensing system 102 according to the first embodiment. The label 1000 includes a processing circuit 1206 configured similarly to and performing the same functions as the processing circuit 106. Although not separately shown, the processing circuit 1206 may also include a temperature sensor similar to the sensor 112, as described above. In some embodiments, the processing circuit 1206 may be a package-less "bumped die" integrated circuit formed with an on-board temperature sensor and capacitive sensing interface; such circuitry has an exemplary thickness of 0.15 mm or less and may be mounted on a flexible substrate, thus allowing the circuitry to be easily adhered to the barrel-shaped user-graspable portion 37 of the medication delivery device 20.

[0059] The label 1000 further comprises capacitive plates 1208a and 1208b (collectively referred to herein as plates 1208), which are configured similarly to plates 108a and 108b and perform the same functions. The label 1000 further comprises a conductive shield 1214 that covers the capacitive plates 1208 and shields them from contact with (or capacitive interference from) a user's hand when the label 1000 is wrapped around the outer surface of the user-gripable portion 37 of the medication delivery device 20. The shield 1214 is separated from the capacitive plates by a thin layer of dielectric material, such as a thin film of polyester, as previously described. The shield 1214 may also be electrically connected to the processing circuit 1206 via wires or conductive traces that pass through this thin layer of dielectric material via through-holes 1216. The label 1000 further comprises near field communication (NFC) loop antennas 1210 communicatively coupled to the processing circuit 1206, which NFC antennas correspond to the communication circuit 110 as described above. In addition to communicating data to an external device, the NFC antennas 1210 can also be used to inductively and wirelessly collect power from the external device.

[0060] The back side of the label 1000 may be mounted on and / or attached to the outer surface of the medication delivery device 20 (or some other surface of the device 20). For example, the label 1000 may be wrapped around and adhesively secured to the outer surface of the user-gripable portion 37 of the medication delivery device 20. When the label 1000 is so attached, the plates 1208 may be positioned on either side of the spring 46, the spring 66, or some other spring in the medication delivery device 20 and may be used to detect whether the sensed spring is in a compressed or extended state using any of the techniques described herein. Data regarding the state of the sensed spring may be used by the processing circuit 1206 to determine whether the device 20 has been activated to dispense medication and / or has finished dispensing medication, as described above. Alternatively, or additionally, label 1000 may be configured to wirelessly communicate data regarding the capacitance between plates 1208 measured by processing circuit 152 and / or the temperature sensed by its on-board temperature sensor to a processing circuit on an external device (e.g., processing circuit 1206 in external device 150), thus enabling the external device to determine whether the sensed spring is in compression or extension.

[0061] In some embodiments, the label 1200 may be modified to remove the shield 1214. As previously mentioned, the shield 1214 may function to reduce capacitive interference from a user's hand when the user is gripping the user-gripable portion 37 of the medication delivery device 20. However, in some embodiments, the shield 1214 may be intentionally removed so that the capacitance plate 1208 may be used to sense whether the user is gripping the medication delivery device 20. When the shield 1214 is not installed, the capacitance of the plate 1208 measured by the processing circuit 1206 may be expected to change depending on whether the user is gripping the user-gripable portion 37 of the medication delivery device 20. That change in capacitance may be used to enable the processing circuit 1206 to determine whether the user is gripping the device 20.

[0062] 13 shows another exemplary label 1300 wrapped around the outer surface of the user-gripable portion 37 of the medication delivery device 20, according to some embodiments. FIG. 14 shows a view of the back side of the label 1300. The label 1300 is configured similarly to the label 1000, except that the label 1300 includes an additional flag 1302 extending from one side of the otherwise rectangular label 1300. When the label 1300 is wrapped around the medication delivery device 20, the flag 1302 is configured to overlap a portion of the label 1300, as shown in FIG. 13.

[0063] Like label 1000, label 1300 also includes a processing circuit 1406 that is configured similarly to processing circuit 106 and performs the same functions. Unlike processing circuit 1306, processing circuit 1406 does not need to be directly adhered to the surface of medication delivery device 20 and therefore does not need to be as thin and / or flexible as processing circuit 1306. For example, processing circuit 1406 may be formed from a packaged NFC chip having a thickness of approximately 1 mm or more. The packaged NFC chip may be equipped with an on-board temperature sensor and a capacitive sensing interface and does not need to be mounted on a flexible substrate that allows the chip to bend. Such a packaged chip may be easier to purchase and / or manufacture than the thinner and more flexible processing circuit 1306, thus reducing manufacturing costs.

[0064] In other respects, label 1300 is substantially similar to label 1000. Label 1300 also includes capacitive plates 1408a and 1408b, which are configured similarly to and perform similar functions as capacitive plates 1208 and 108. Label 1300 further includes a conductive shield 1414 separated from capacitive plate 1408 by a thin insulating film (e.g., polyester film). Shield 1414 is configured similarly to shields 1214 and 114 and performs similar functions, and is electrically connected to processing circuit 1406 via wires or conductive traces that pass through polyester film via through-holes 1416. Label 1300 also includes NFC loop antennas 1410 communicatively coupled to processing circuit 1306; these NFC antennas correspond to communication circuit 110, as described above. In addition to communicating data to an external device, NFC antenna 1410 can also be used to inductively and wirelessly harvest power from the external device.

[0065] FIG. 15 shows a back view of yet another exemplary label 1500. Label 1500 is configured similarly to label 1300, except that instead of using capacitance plates 1408a and 1408b, label 1500 uses a first plate 1509a with a set of fingers interleaved with a second set of fingers from a second plate 1509b to form an interdigital capacitor. In other respects, label 1500 is substantially similar to label 1300. Label 1500 also includes a processing circuit 1506 configured similarly to processing circuit 106, as well as an NFC loop antenna 1510 communicatively coupled to processing circuit 1506, which NFC antenna corresponds to communication circuit 110 as described above. Although not depicted in FIG. 15, it should be understood that label 1500 may also be provided with capacitance shielding similar to shields 1414, 1214, and / or 114.

[0066] While the previous embodiments have been described as systems for detecting whether a spring is in compression or tension, in some embodiments, a processing circuit (e.g., processing circuit 106, 152, 1206, 1406, and / or 1506) may be configured to detect whether a user's body part is positioned near a capacitive plate. The processing circuit may perform this function either in addition to, or as an alternative to, the previously mentioned methods for detecting the compression / tension state of the spring.

[0067] For example, in embodiments in which the system 102 is used with a medication delivery device (e.g., device 20 described above in FIGS. 7-9), the processing circuit may use the measured capacitance of the capacitance plates (e.g., plates 108, 1208, 1408, and / or 1508) to determine whether a user's hand is gripping the medication delivery device (e.g., gripping the user-gripable portion 37 shown in FIG. 8). In such embodiments, the capacitance shields (e.g., shields 114, 1214, 1414) may be omitted. When a user grips the medication delivery device, the processing circuit may detect a measurable increase in the measured capacitance of the capacitance plates. Based on this detected increase in capacitance, the processing circuit 106 and / or processing circuit 152 may determine whether the medication delivery device is being gripped by the user's hand or is not being gripped by the user's hand.

[0068] In some embodiments, a single set of capacitance plates 108 (e.g., capacitance plates 108a and 108b) may be used to detect both whether a user is holding the medication delivery device and whether the spring is in a compressed or extended state. For example, when the processing circuit measures a capacitance greater than a first maximum capacitance threshold, the processing circuit may determine that the spring is in a compressed state and the user's hand is holding the medication delivery device. When the processing circuit measures a capacitance less than a second minimum capacitance threshold, the processing circuit may determine that the spring is in an extended state and the user's hand is not holding the medication delivery device. When the processing circuit measures a capacitance between the first maximum capacitance threshold and the second minimum capacitance threshold, the processing circuit may determine that either (1) the spring is in an extended state and the user's hand is holding the medication delivery device, or (2) the spring is in a compressed state and the user's hand is not holding the medication delivery device.

[0069] In some embodiments, the medication delivery device (or a label for the medication delivery device) may be provided with multiple sets of capacitance plates. A first set of plates may be positioned and configured to detect whether the spring 104 is in compression or tension. This first set of plates may be provided with a capacitance shield similar to the shields 114, 1214, and 1414 described above. A second set of capacitance plates (or an additional single capacitance plate) may be positioned and configured to determine whether a user's hand is gripping the medication delivery device. This second set of plates may be unshielded. In this manner, the processing circuit 106 may determine both (1) whether the spring is in compression or tension based on the capacitance measured by the first set of plates, and (2) whether a user is gripping the medication delivery device based on the capacitance measured by the second set of plates.

[0070] In yet another embodiment, the medication delivery device (or a label for the medication delivery device) may be provided with three sets of capacitance plates. The first set of plates may be positioned and configured to determine whether the spring 46 is in a compressed or extended state. When an injection is initiated, the spring 46 extends, and this determination may help the processing circuit 106 determine whether the medication delivery device has started the injection. The second set of plates may be positioned and configured to determine whether the spring 66 is in a compressed or extended state. When the injection is completed and the syringe assembly is retracted, the spring 66 extends, and this determination may help the processing circuit 106 determine whether the medication delivery device has completed the injection. The third set of plates (or an additional single plate) may be positioned along the user-gripable portion 37 of the medication delivery device 20 and configured to determine whether the user is gripping the medication delivery device. The first and second sets of plates may be provided with capacitance shielding, while the third set of plates may be unshielded.

[0071] The capacitance plates and processing circuitry in the previously mentioned embodiments may also be modified to enable the processing circuitry to determine whether the device is being held by only one hand or by both hands of the user. For example, the previously mentioned capacitance plates may be enlarged (or multiple sets of capacitance plates may be provided) to cover a relatively large area of ​​the user-gripable portion 37 of the medication delivery device 20. When the device is being held by both hands, the capacitance of the capacitance plates measured by the processing circuitry may be higher than when the device is being held by only one hand. In this way, the processing circuitry may determine whether the device is being held by one hand, both hands, or no hand at all. If the previously mentioned capacitance plates are also positioned near the end of the medication delivery device that contacts the user's injection site during injection, the previously mentioned capacitance plates may also be used to detect whether the medication delivery device is in contact with an injection site on the user's body. This additional detection function for detecting contact with the injection site may be in addition to, or as an alternative to, the detection functions mentioned earlier, i.e., detecting the compressed and / or extended state of the spring and detecting whether the delivery device is being grasped by one or more hands of the user.

[0072] The terms "first," "second," "third," and the like, whether used herein or in the claims, are provided to distinguish between similar elements and do not necessarily describe a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances (unless otherwise expressly disclosed), and that the disclosed embodiments described herein are capable of operation in other orders and / or configurations than those described or illustrated herein.

[0073] While this invention has been described as having exemplary designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.

[0074] Various aspects are described in this disclosure, including but not limited to the following aspects. 1. A drug delivery device having a sensing system for determining a state of a compression spring of the drug delivery device, the sensing system comprising: a first capacitance plate and a second capacitance plate, wherein the compression spring is configured to be disposed between at least a portion of the first capacitance plate and at least a portion of the second capacitance plate; a temperature sensor; and at least one processing circuit connected to the first capacitance plate, the second capacitance plate, and the temperature sensor, wherein the at least one processing circuit is configured to measure a capacitance between the first capacitance plate and the second capacitance plate, measure a temperature based on a signal output by the temperature sensor, and determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature. 2. The medication delivery device of claim 1, wherein the at least one processing circuit comprises a first processing circuit and a second processing circuit, the first processing circuit configured to measure capacitance, measure temperature, and communicate the measured capacitance and the measured temperature to the second processing circuit, and the second processing circuit configured to determine whether the compression spring is in a compressed state or an extended state based on the communicated capacitance and the communicated temperature. 3. The medication delivery device of claim 1, wherein the at least one processing circuit consists of a single processing circuit. 4. A drug delivery device according to any one of claims 1 to 3, wherein the temperature sensor and at least one processing circuit are integrated into a single integrated circuit. 5. The drug delivery device of any one of claims 1 to 4, wherein the sensing system is configured to receive the harvested power wirelessly from an external power source. 6. The drug delivery device of any one of claims 1 to 5, wherein at least one processing circuit is configured to determine that the compression spring is in a compressed state when the measured capacitance is greater than a capacitance threshold, and to determine that the compression spring is in an extended state when the measured capacitance is less than the capacitance threshold. 7. The medication delivery device of claim 6, wherein the at least one processing circuit is configured to adjust the capacitance threshold based on the measured temperature. 8. A drug delivery device as described in any one of claims 1 to 7, wherein the sensing system further comprises a wireless communication interface, and at least one processing circuit is connected to the wireless communication interface and configured to communicate at least one of the measured capacitance, the measured temperature, and data indicating whether the compression spring is in a compressed state or an extended state to an external device via the wireless communication interface. 9. A drug delivery device as described in any one of claims 1 to 8, wherein the first capacitance plate has a first plurality of fingers, the second capacitance plate has a second plurality of fingers, and the first capacitance plate and the second capacitance plate are arranged such that the first plurality of fingers are interleaved with the second plurality of fingers. 10. A medication delivery device as described in any one of claims 1 to 9, wherein at least one processing circuit is configured to determine whether a user's hand is gripping the medication delivery device based on the measured capacitance. 11. A medication delivery device as described in any one of claims 1 to 9, further comprising at least a third capacitance plate arranged on a user-gripable portion of the medication delivery device, and wherein the at least one processing circuit is configured to determine whether a user's hand is gripping the medication delivery device based on the capacitance measured by the third capacitance plate. 12. The drug delivery device of any one of claims 1 to 11, further comprising a drug. 13. An injection system comprising: a medication delivery device housing; a syringe assembly at least partially disposed within the medication delivery device housing, the syringe assembly including a reservoir configured to hold a medicament and an injection needle; a drive mechanism at least partially disposed within the medication delivery device housing, the drive mechanism configured to dispense the medicament from the syringe assembly through the injection needle upon activation by a user, the drive mechanism including a compression spring configured to transition from a compressed state to an extended state or from the extended state to a compressed state after activation; and a sensing system comprising first and second capacitance plates, wherein the compression spring is configured to be disposed between at least a portion of the first capacitance plate and at least a portion of the second capacitance plate; a temperature sensor; and at least one processing circuit, wherein the at least one processing circuit is configured to measure a capacitance between the first capacitance plate and the second capacitance plate; and to measure a temperature based on a signal output by the temperature sensor. 14. The injection system of claim 13, wherein the temperature sensor and the at least one processing circuit are integrated into a single integrated circuit. 15. The injection system of claim 13 or 14, further comprising a wireless communication interface, wherein the at least one processing circuit is configured to communicate the measured capacitance and the measured temperature to an external device via the wireless communication interface, thereby enabling the external device to determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature. 16. The injection system of claim 13 or 14, wherein the at least one processing circuit is further configured to determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature. 17. The injection system of claim 16, further comprising a wireless communication interface, wherein the at least one processing circuit is configured to communicate data indicating whether the compression spring is in a compressed state or an extended state to an external device via the wireless communication interface. 18. An injection system according to claim 15 or 17, wherein the wireless communication interface comprises a near field communication (NFC) circuit. 19. An injection system as described in any one of claims 13 to 18, wherein the first capacitance plate, the second capacitance plate, the temperature sensor, and the at least one processing circuit are attached to a label fixed to the outer surface of the medication delivery device housing. 20. The injection system of any one of claims 13 to 19, wherein the medication delivery device housing defines an injection hole, the syringe assembly is movable between a retracted position in which the injection needle does not extend through the injection hole and an injection position in which the injection needle extends through the injection hole, and the compression spring is configured to transition from a compressed state to an extended state after activation of the medication delivery device to move the syringe assembly from the injection position to the retracted position after the medication has been dispensed. 21. The injection system of any one of claims 13-19, wherein the compression spring is configured to transition from a compressed state to an extended state to dispense the medication from the reservoir through the injection needle. 22. The injection system of any one of claims 13 to 21, further comprising a metal shield covering the first capacitance plate and the second capacitance plate. 23. The injection system of any one of claims 13 to 16, wherein the first capacitive plate comprises a first plurality of fingers and the second capacitive plate comprises a second plurality of fingers, the first and second capacitive plates being arranged such that the first plurality of fingers are interleaved with the second plurality of fingers. 24. An injection system according to any one of claims 13 to 23, wherein at least one processing circuit is configured to determine whether a user's hand is gripping the medication delivery device based on the measured capacitance. 25. An injection system as described in any one of claims 13 to 23, further comprising at least a third capacitance plate disposed on a user-gripable portion of the medication delivery device, and wherein the at least one processing circuit is configured to determine whether a user's hand is gripping the medication delivery device based on the capacitance measured by the third capacitance plate. 26. The injection system of any one of claims 13 to 25, further comprising a medicinal agent. 27. A method for determining a state of a compression spring positioned between at least a portion of a first capacitive plate and at least a portion of a second capacitive plate, the method including: measuring, by a processing circuit, a temperature using a temperature sensor; measuring, by the processing circuit, a capacitance between the first capacitive plate and the second capacitive plate; and determining, by the processing circuit, whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature. 28. The method of claim 27, wherein the compression spring is part of the medication delivery device and is configured to transition from a compressed state to an extended state or from an extended state to a compressed state after the medication delivery device is activated to dispense medication. 29. The method of claim 28, wherein the medication delivery device includes a syringe assembly movable between a retracted position and an injection position, and the compression spring is configured to transition from a compressed state to an extended state to move the syringe assembly from the injection position to the retracted position. 30. The method of claim 28 or 29, further comprising reporting at least one of the measured capacitance, the measured temperature, and data indicative of whether the compression spring is in a compressed or extended state to an external device via wireless communication. 31. The method of any one of claims 27 to 30, wherein determining whether the compression spring is in a compressed state or an extended state includes determining an applicable capacitance threshold based on the measured temperature, determining that the compression spring is in a compressed state when the measured capacitance is greater than the determined capacitance threshold, and determining that the compression spring is in an extended state when the measured capacitance is less than the determined capacitance threshold. 32. The method of claim 31, wherein determining the capacitance threshold to apply includes determining to apply a first capacitance threshold when the measured temperature is a first temperature, and to apply a second capacitance threshold lower than the first capacitance threshold when the measured temperature is below the first temperature.

Claims

1. 1. A medication delivery device, the medication delivery device comprising: a sensing system for determining a state of a compression spring of the medication delivery device, the sensing system comprising: a first capacitance plate and a second capacitance plate, wherein the compression spring is configured to be disposed between at least a portion of the first capacitance plate and at least a portion of the second capacitance plate; A temperature sensor; at least one processing circuit coupled to the first capacitive plate, the second capacitive plate, and the temperature sensor, the at least one processing circuit comprising: measuring a capacitance between the first capacitive plate and the second capacitive plate; measuring a temperature based on a signal output by the temperature sensor; The medication delivery device is configured to determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature.

2. the at least one processing circuit comprises a first processing circuit and a second processing circuit; the first processing circuit is configured to measure the capacitance, measure the temperature, and communicate the measured capacitance and the measured temperature to the second processing circuit; 2. The medication delivery device of claim 1, wherein the second processing circuit is configured to determine whether the compression spring is in the compressed state or the extended state based on the communicated capacitance and the communicated temperature.

3. The medication delivery device of claim 1 , wherein the at least one processing circuit consists of a single processing circuit.

4. The medication delivery device according to any one of claims 1 to 3, wherein the temperature sensor and the at least one processing circuit are integrated into a single integrated circuit.

5. The medication delivery device of any one of claims 1 to 4, wherein the sensing system is configured to receive harvested power wirelessly from an external power source.

6. 6. The drug delivery device of claim 1, wherein the at least one processing circuit is configured to determine that the compression spring is in the compressed state when the measured capacitance is greater than a capacitance threshold, and to determine that the compression spring is in the extended state when the measured capacitance is less than the capacitance threshold.

7. The medication delivery device of claim 6 , wherein the at least one processing circuit is configured to adjust the capacitance threshold based on the measured temperature.

8. the sensing system further comprises a wireless communication interface; 8. The medication delivery device of claim 1, wherein the at least one processing circuit is connected to the wireless communication interface and configured to communicate at least one of the measured capacitance, the measured temperature, and data indicating whether the compression spring is in the compressed state or the extended state to an external device via the wireless communication interface.

9. 9. The drug delivery device of claim 1, wherein the first capacitance plate has a first plurality of fingers, the second capacitance plate has a second plurality of fingers, and the first capacitance plate and the second capacitance plate are arranged such that the first plurality of fingers are interleaved with the second plurality of fingers.

10. The medication delivery device of any one of claims 1 to 9, wherein the at least one processing circuit is configured to determine whether a user's hand is holding the medication delivery device based on the measured capacitance.

11. A medication delivery device as described in any one of claims 1 to 9, further comprising at least a third capacitance plate arranged on a user-holdable portion of the medication delivery device, and the at least one processing circuit is configured to determine whether a user's hand is holding the medication delivery device based on the capacitance measured by the third capacitance plate.

12. The drug delivery device of any one of claims 1 to 11, further comprising a drug.

13. 1. An injection system comprising: a medication delivery device housing; a syringe assembly at least partially disposed within the medication delivery device housing, the syringe assembly including a reservoir configured to hold a medication and an injection needle; and a drive mechanism disposed at least partially within the medication delivery device housing, the drive mechanism configured to dispense a medication from the syringe assembly through the injection needle upon activation by a user, the drive mechanism including a compression spring configured to transition from a compressed state to an extended state or from an extended state to a compressed state after the activation; a sensing system, the sensing system comprising: a first capacitance plate and a second capacitance plate, wherein the compression spring is configured to be disposed between at least a portion of the first capacitance plate and at least a portion of the second capacitance plate; A temperature sensor; at least one processing circuit, wherein the at least one processing circuit measuring a capacitance between the first capacitive plate and the second capacitive plate; An injection system configured to measure a temperature based on a signal output by the temperature sensor.

14. 14. The injection system of claim 13, wherein the temperature sensor and the at least one processing circuit are integrated into a single integrated circuit.

15. 15. The injection system of claim 13 or 14, further comprising a wireless communication interface, wherein the at least one processing circuit is configured to communicate the measured capacitance and the measured temperature to an external device via the wireless communication interface, thereby enabling the external device to determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature.

16. 15. The injection system of claim 13 or 14, wherein the at least one processing circuit is further configured to determine whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature.

17. 17. The injection system of claim 16, further comprising a wireless communication interface, wherein the at least one processing circuit is configured to communicate data indicating whether the compression spring is in the compressed state or the extended state to an external device via the wireless communication interface.

18. 18. The injection system of claim 15 or 17, wherein the wireless communication interface comprises a near field communication (NFC) circuit.

19. An injection system according to any one of claims 13 to 18, wherein the first capacitance plate, the second capacitance plate, the temperature sensor, and the at least one processing circuit are attached to a label fixed to the outer surface of the medication delivery device housing.

20. the medication delivery device housing defines an injection hole; the syringe assembly is movable between a retracted position in which the needle does not extend through the injection hole and an injection position in which the needle extends through the injection hole; 20. The injection system of any one of claims 13 to 19, wherein the compression spring is configured to transition from the compressed state to the extended state after activation of the medication delivery device to move the syringe assembly from the injection position to the retracted position after the medication has been dispensed.

21. 20. The injection system of any one of claims 13 to 19, wherein the compression spring is configured to transition from the compressed state to the extended state to dispense medicament from the reservoir through the injection needle.

22. 22. The injection system of any one of claims 13 to 21, further comprising a metal shield covering the first capacitive plate and the second capacitive plate.

23. 23. The injection system of any one of claims 13 to 22, wherein the first capacitance plate comprises a first plurality of fingers and the second capacitance plate comprises a second plurality of fingers, and the first capacitance plate and the second capacitance plate are arranged such that the first plurality of fingers are interleaved with the second plurality of fingers.

24. An injection system according to any one of claims 13 to 23, wherein the at least one processing circuit is configured to determine whether a user's hand is holding the medication delivery device based on the measured capacitance.

25. An injection system according to any one of claims 13 to 23, further comprising at least a third capacitance plate arranged on a user-holdable portion of the medication delivery device, wherein the at least one processing circuit is configured to determine whether a user's hand is holding the medication delivery device based on the capacitance measured by the third capacitance plate.

26. The injection system of any one of claims 13 to 25, further comprising the drug.

27. 1. A method for determining a state of a compression spring positioned between at least a portion of a first capacitive plate and at least a portion of a second capacitive plate, the method comprising: measuring, by a processing circuit, a temperature using the temperature sensor; measuring, with the processing circuitry, a capacitance between the first capacitive plate and the second capacitive plate; determining, by the processing circuitry, whether the compression spring is in a compressed state or an extended state based on the measured capacitance and the measured temperature.

28. 28. The method of claim 27, wherein the compression spring is part of a medication delivery device and is configured to transition from a compressed state to an extended state, or from the extended state to the compressed state, after the medication delivery device is activated to dispense medication.

29. 29. The method of claim 28, wherein the medication delivery device includes a syringe assembly movable between a retracted position and an injection position, and the compression spring is configured to transition from the compressed state to the extended state to move the syringe assembly from the injection position to the retracted position.

30. 30. The method of claim 28 or 29, further comprising reporting at least one of the measured capacitance, the measured temperature, and data indicative of whether the compression spring is in the compressed state or the extended state to an external device via wireless communication.

31. Determining whether the compressed state is in the compressed state or the expanded state includes: determining an applicable capacitance threshold based on the measured temperature; determining that the compression spring is in the compressed state when the measured capacitance is greater than the determined capacitance threshold; and determining that the compression spring is in the extended state when the measured capacitance is less than the determined capacitance threshold.

32. 32. The method of claim 31 , wherein determining the capacitance threshold to apply comprises determining to apply a first capacitance threshold when the measured temperature is a first temperature, and to apply a second capacitance threshold lower than the first capacitance threshold when the measured temperature is below the first temperature.

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