Status sensing system for connected injection devices

Abstract

To provide medication-delivery devices, and specifically, status sensing systems used in connected medication-delivery devices.SOLUTION: A drug-delivery system may comprise a syringe assembly, one or more skin contact sensors, and one or more syringe assembly sensors configured to detect initiation and / or completion of a dispensing event. The system may further comprise one or more processing circuits configured to measure a time duration between when the skin contact sensors detect contact with a skin tissue and when the syringe assembly initiates the dispensing event, compare the measured time duration with a threshold time duration, and generate a user indication signal if the measured time duration exceeds the threshold time duration.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to medication delivery devices, and in particular to status sensing systems for use in connected medication delivery devices.

[0002] Injection devices in the form of or including syringes are widely used by medical professionals and self-medicating patients. Patients suffering from several different diseases must frequently inject themselves with medication, and various devices have been developed to facilitate such self-treatment. In one example, the use of an automatic injection device that includes mechanisms to perform some of the steps of the injection process makes self-treatment more convenient for patients, especially those with limited manual dexterity. Automatic injection devices are typically single-use devices that are disposed of after use. Summary of the Invention

[0003] In some exemplary embodiments, a drug delivery system includes a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue; and a sensor disposed within the housing that is responsive to a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly. one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of the signal levels; and one or more processing circuits configured to: determine when the one or more skin contact sensors detect contact with skin tissue; determine when a syringe assembly initiates a dispensing event based at least in part on the syringe assembly sensor signal; measure a first duration between when the one or more skin contact sensors detect contact with skin tissue and when the syringe assembly initiates a dispensing event; compare the first duration with a first preprogrammed threshold duration; and generate a first user instruction signal when the first duration is greater than the first threshold duration.

[0004] In some exemplary embodiments, a drug delivery system is provided, comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to detect at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; one or more base cap sensors configured to detect when the movable base cap is removed from the opening; and one or more processing circuits configured to: determine when the syringe assembly initiates a dispense event based on data output from the one or more syringe assembly sensors; and generate a misuse indication signal when the one or more base cap sensors detect that the movable base cap has been removed from the opening and then subsequently replaced over the opening before the syringe assembly initiates a dispense event.

[0005] In some exemplary embodiments, a drug delivery system includes a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue; and a drive mechanism disposed within the housing and configured to detect a position of at least a portion of the syringe assembly and at least a portion of the syringe assembly. and one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of: a syringe assembly sensor signal indicating a syringe movement; and one or more processing circuits configured to: determine, based at least in part on the syringe assembly sensor signal, when a syringe assembly initiates a dispensing event; count a number of proximity events in which the one or more skin contact sensors detect contact with skin tissue and then subsequently stop detecting contact with skin tissue before the syringe assembly initiates a dispensing event; compare the number of proximity events to a preprogrammed maximum threshold; and generate a user instruction signal when the number of proximity events is greater than the preprogrammed maximum threshold.

[0006] In some exemplary embodiments, a drug delivery system includes a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to output a skin detection signal when contact with skin tissue is detected; and a drive mechanism disposed within the housing and configured to drive at least a portion of the syringe assembly and the syringe assembly. and one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of: a syringe assembly sensor signal based on at least one of a syringe assembly sensor signal and a syringe assembly sensor signal; and one or more processing circuits configured to: determine, based at least in part on the syringe assembly sensor signal, when the syringe assembly initiates a dispensing event and when the syringe assembly completes the dispensing event; process one or more skin detection signals from the one or more skin contact sensors received after the dispensing event has been initiated and before the dispensing event has been completed to derive data indicative of continuity of skin contact during the dispensing event; and generate a user indication signal when the data meets one or more preprogrammed criteria.

[0007] In yet another illustrative embodiment, a drug delivery system is provided, comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to detect at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; one or more base cap sensors configured to detect when the movable base cap is removed from the opening; and one or more processing circuits configured to: determine when the movable base cap is removed from the opening based on data output from the one or more base cap sensors; determine when the syringe assembly initiates a dispense event based on data output from the one or more syringe assembly sensors; and generate a user indication signal when the syringe assembly does not initiate a dispense event within a threshold time after the base cap is moved from the opening. [Brief explanation of the drawings]

[0008] The above and other features of the present disclosure, as well as the manner in which they are achieved, will become more apparent, and the invention itself will be better understood, by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a cross-sectional view of an injection device before use. [Figure 2] FIG. 10 is a cross-sectional view of an injection device with the syringe assembly in a retracted position and ready for a dispensing event. [Figure 3] FIG. 1 is a cross-sectional view of an injection device with the syringe assembly in the injection position. [Figure 4] FIG. [Figure 5] FIG. 1 is a perspective view of a syringe carrier. [Figure 6] FIG. 10 is a perspective view of the upper shuttle member. [Figure 7] FIG. 10 is a perspective view of the lower shuttle member. [Figure 8] 1A-1C are cross-sectional views of an injection device illustrating the placement of one or more main PCBs within an end portion of the housing of the injection device according to a first set of embodiments. [Figure 9A] 1A-1C are top (i.e., distal) perspective views of a main PCB and a secondary PCB according to a first set of embodiments. [Figure 9B] 1A-1C are bottom (i.e., proximal) perspective views of a main PCB and a secondary PCB according to a first set of embodiments. [Figure 10A] FIG. 10 is a top view of a first set of main and secondary PCBs of an embodiment. [Figure 10B] FIG. 10 is a bottom view of the first set of main and secondary PCBs of the embodiment. [Figure 11] 1 is a side cross-sectional view of an injection device according to a first set of embodiments, showing the spatial relationship between a magnet and two magnetometers. [Figure 12] FIG. 1 is a system architecture diagram of electrical components within an injection device and an external device according to a first set of embodiments. [Figure 13] FIG. 10 is a flow diagram illustrating a process for "pairing" or establishing a communication session between an injection device and an external device according to any of the first set of embodiments and any of the second and third sets of embodiments. [Figure 14A] 10 illustrates a flowchart showing a process implemented by a mobile medical application running on an external device according to any of the first, second, and third sets of embodiments. [Figure 14B] 10 illustrates a flowchart showing a process implemented by a mobile medical application running on an external device according to any of the first, second, and third sets of embodiments. [Figure 15] FIG. 10 is a schematic diagram for displaying the status of the skin contact sensor on a display of an external device. [Figure 16A] 10A-10C show alternative shapes of the outwardly flared end portion of the injection device housing according to any of the first, second and third sets of embodiments. [Figure 16B] 10A-10C show alternative shapes of the outwardly flared end portion of the injection device housing according to any of the first, second and third sets of embodiments. [Figure 16C] 10A-10C show alternative shapes of the outwardly flared end portion of the injection device housing according to any of the first, second and third sets of embodiments. [Figure 17A] FIG. 10 is a top perspective view of the main PCB and syringe position detector switch according to a second set of embodiments. [Figure 17B] FIG. 10 is a bottom perspective view of the main PCB and syringe position detector switch according to a second set of embodiments. [Figure 18A] FIG. 10 is a top view of the main PCB and syringe position detector switch according to a second set of embodiments. [Figure 18B] FIG. 10 is a bottom view of the main PCB and syringe position detector switch according to a second set of embodiments. [Figure 19] FIG. 10 is a side view of an injection device according to a second set of embodiments, with the syringe assembly in a stored or retracted position. [Figure 20] FIG. 10 is a side view of an injection device according to a second set of embodiments, with the syringe assembly in the injection position. [Figure 21A] FIG. 10 is a top perspective view of a main PCB according to a third set of embodiments. [Figure 21B] FIG. 10 is a bottom perspective view of a main PCB according to a third set of embodiments. [Figure 22A] FIG. 10 is a top view of a main PCB according to a third set of embodiments. [Figure 22B] FIG. 10 is a bottom view of the main PCB according to the third set of embodiments. [Figure 23A] 10A-10C are perspective views of a base cap removal sensor according to a third set of embodiments. [Figure 23B] 10A-10C are perspective views of a base cap removal sensor according to a third set of embodiments. [Figure 24A] FIG. 10 is a perspective view showing the main PCB and base cap removal sensor associated with the removal end cap when the end cap is removed from the injection device according to a third set of embodiments. [Figure 24B] FIG. 10 is a perspective view showing the main PCB and base cap removal sensor associated with the removal end cap when the end cap is attached to the injection device according to a third set of embodiments. [Figure 25A] 10A-10C are side views showing the base cap removal sensor when the end cap is removed from the injection device according to the third set of embodiments. [Figure 25B] 10A-10C are side views showing the base cap removal sensor when the end cap is attached to the injection device according to the third set of embodiments. [Figure 26] 10 is a graph showing an exemplary signal output from an accelerometer disposed on an injection device according to a third set of embodiments. [Figure 27] FIG. 10 is a system architecture diagram of the electrical components in the injection device according to a third set of embodiments. [Figure 28] 10 is a flowchart illustrating an exemplary process implemented by a processing circuit on an injection device according to a third set of embodiments. [Figure 29] FIG. 10 is a circuit diagram showing exemplary logic for determining whether a dispense event has started and completed, according to a third set of embodiments. [Figure 30] 10 is a flowchart illustrating an exemplary process for detecting the start and completion of a dispense event according to a third set of embodiments. [Figure 31] 10 is a flowchart illustrating another exemplary process for detecting the start and completion of a dispense event according to a third set of embodiments. [Figure 32]10 is a flowchart illustrating yet another exemplary process for detecting the start and completion of a dispense event according to a third set of embodiments. [Figure 33] 10 is a flowchart illustrating an exemplary process for detecting acceleration spikes according to a third set of embodiments. [Figure 34] 1 illustrates an exemplary series of user steps for using an injection device according to any of the first, second, or third sets of embodiments. [Figure 35] 10 is a flowchart illustrating an exemplary process for generating user instructions if the user does not initiate a dispense event within a threshold time of placing the device on the patient's body. [Figure 36] 10 is a flowchart illustrating an exemplary process for generating user instructions if the user does not remove the device from the patient's body within a threshold time to complete a dispense event. [Figure 37] 10 is a flowchart illustrating an exemplary process for generating an abuse indication that a user has removed the base cap of an injection device and then replaced it without initiating and / or completing a dispense event. [Figure 38] 10 is a flowchart illustrating an exemplary process for generating user instructions when a user places a device against a patient's body one or more times without initiating a dispense event. [Figure 39] 10 is a flowchart illustrating an exemplary process for generating user instructions when a user lifts the device off the patient's body while a dispense event is in progress. [Figure 40] 10 is a flowchart illustrating an exemplary process for generating user instructions dependent on whether a user initiates a dispense event within a certain threshold time after removing the base cap.

[0009] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set forth herein illustrate embodiments of the present disclosure, however, in some aspects the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure relates to a sensing system for a medication delivery device. The sensing system may be integrated within the delivery device or incorporated into a removable module that is attached to the delivery device. Such a sensing system may be configured to determine the current operational status of the device by sensing various parameters or signals indicative of the operational status of the device.

[0011] In some embodiments, the sensing system may sense the location or movement of a device component relative to other device components. For example, such a sensing system may track the location and / or movement of a plunger used to expel a drug from a drug delivery device. By tracking the location or movement of the plunger, the drug delivery device may determine the amount of drug expelled, the rate at which the drug is being expelled, and / or when the drug in the delivery device has been fully delivered. Such a sensing system may utilize various types of sensors, such as a visual sensor that tracks the movement of the device component, an optical or radiation sensor that detects when the device component enters or leaves a detection zone targeted by the sensing system, a magnetic field sensor that detects changes in a sensed magnetic field caused by the movement of the device component, or one or more accelerometers that detect the movement of the device component.

[0012] In some embodiments, the sensing system may determine the orientation of the device. The determined orientation may be used to determine whether the medication delivery device is properly oriented to deliver medication; for example, the delivery device may warn its user or prevent medication delivery when the device is oriented upside down or in any orientation that makes safe and reliable delivery of medication difficult or impossible. Such a sensing system may utilize one or more accelerometers disposed at one or more locations on the device configured to determine the direction of gravitational attraction. The sensing system may also include processor circuitry configured to determine the orientation of the device about one, two, or three axes of orientation based on readings from the accelerometers.

[0013] In some embodiments, the sensing system may measure the temperature of a medication stored within the medication delivery device. Certain medications may need to be stored at a first (e.g., lower) temperature range to avoid degradation, but may need to be brought to a second (e.g., higher) temperature range before being delivered to the patient. The temperature sensing system may be used to monitor the temperature of the medication within the delivery device while stored to ensure the medication is not exposed to dangerous temperatures that may render it unsuitable for consumption. The temperature sensing system may also be used to alert the user when the medication's temperature is approaching a dangerous level. When the device is ready for use, the sensing system may be used to determine when the medication's temperature is within the second temperature range. The medication delivery device may then notify the user that the medication is ready to be delivered, for example, by using a visual indicator (e.g., by turning one or more LEDs on and / or off), an audible indicator (e.g., an announcement or tone output from a speaker), or a wireless signal that is sent to an external mobile device and then notifies the user. Such a temperature sensing system may utilize any of several types of sensors, such as an infrared sensor or a thermistor, to measure the medication's temperature.

[0014] In some embodiments, the sensing system may include one or more sensors configured to determine when and / or where the drug delivery device is in contact with a patient's skin. The drug delivery device may use such a sensing system to determine when the device is properly positioned to inject a drug into the patient's body. Such a sensing system may include one or more sensors configured to measure electrical resistance or capacitance and processing circuitry configured to determine when an individual sensor is in contact with human tissue, such as skin, based on the measured resistance or capacitance. If the sensing system includes multiple sensors, the system may be configured to determine which individual sensor of the multiple sensors is in contact with human tissue. Such a sensing system may also include a temperature sensor, similar to that discussed above, configured to determine when the sensor is in contact with human tissue.

[0015] The sensing system may determine the current operational status of the device. This current status may be communicated to the user via visual, audible, or tactile indicators integrated with or physically attached to the delivery device, such as, for example, one or more displays, LEDs, speakers, or vibration motors. This current status may also be communicated to the user by sending data regarding the current status to an external device via a wired or wireless communication link, which may then communicate the current status to the user. For example, in some embodiments, the medication delivery device may include a short-range wireless communication interface, such as Near Field Communication (NFC), Bluetooth, and / or Bluetooth Low Energy (BLE) communication circuitry, that transmits data regarding the current operational status of the delivery device to an external device. The external device may be an electronic computing device configured to execute software and / or firmware to receive and process data and communicate the operational status of the delivery device to the user. Exemplary external devices include mobile handheld devices (e.g., smartphones, cell phones, pagers, personal digital assistants (PDAs), tablets, etc.), wearable devices (e.g., smart watches or augmented or virtual reality devices), portable general-purpose computers (e.g., laptops), or desktop general-purpose computers. When a user is informed of the operational status of the device, the user is less likely to take actions that may impair the effective use of the device, such as removing the device from the injection site before drug delivery is complete or delivering the drug before it has been heated to the appropriate delivery temperature. By way of example, the drug delivery device is described in the form of an automatic injector device. However, the drug delivery device can be any device used to deliver a dose of drug, such as a pen injector, an infusion pump, and a syringe. The drug can be of any type that can be delivered by such a drug delivery device.

[0016] It may be advantageous to provide a single sensing system positioned along the device to capture at least one of a needle guard present state, an injection ready state, a needle insertion state, a drug delivery state, and a needle retraction state, or any combination thereof. It may be beneficial to determine whether a dose has been delivered and / or the operating state during an injection process using a module without having to change the mechanical architecture of the drive mechanism of the delivery device.

[0017] 1-3 illustrate a medication injection device 20 in various operational states. An example of such a device and its operation is described in U.S. Patent No. 8,734,394 (B2), issued May 27, 2014 to Adams et al., the entire disclosure of which is incorporated herein by reference. The device 20 includes a syringe assembly 22, a drive mechanism 24, and a retraction mechanism 26, and may include, for example, one or more main printed circuit boards (PCBs) 82 and / or one or more secondary PCBs 84, as shown in FIGS. 8, 9A, 9B, 10A, and 10B. The syringe assembly 22 includes a barrel 30 forming a reservoir 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 injection needle 34 and a needle hub 35 that attaches the needle 34 to the syringe barrel 30. Advancing a piston 32 within barrel 30 toward needle 34 causes medication to be dispensed through needle 34 .

[0018] Devices described herein, such as device 20, may further include a medication, such as, for example, in syringe barrel 30. In another embodiment, a system may include one or more devices, including device 20, and a drug. The term "medication" 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, 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 capable of being delivered by the above-described devices. Medicaments such as those used in the devices may be formulated with one or more excipients. The device is operated by a patient, caregiver, or medical professional in a manner generally as described above to deliver medication to a person.

[0019] FIG. 1 illustrates the device 20 in its initial, pre-use configuration, where an end cap 36 is fixedly attached to an injection device housing 38 and covers a proximal end opening 40 of the 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. The housing 38 may be formed from a plastic material and may be shown extending generally longitudinally along a longitudinal axis 48 between a distal end proximate the activation button 52 and a proximal end proximate the proximal end opening 40. As shown in FIGS. 2 and 8, the housing 38 may include a user-graspable portion 37 configured to be grasped by a user's hand, the user-graspable portion 37 extending outward from the longitudinal axis 48 by 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 preferred length). Also, as shown in FIGS. 2 and 8 , housing 38 may also include an outwardly flared end portion 39 at the proximal end of the housing adjacent proximal opening 40. The end portion extends outward from longitudinal axis 48 a radial distance 43 greater than radial distance 41. In some embodiments, radial distance 43 may be greater than 10 mm in length. For example, in some embodiments, radial distance 43 may be 10-20 mm in length (e.g., in some embodiments, 15-20 mm may be a preferred length). End portion 39 may smoothly slope radially outward from user-graspable portion 37, as shown in FIGS. 1-3 . In other embodiments, end portion 39 may take the form of other shapes. 16A-16C show some exemplary alternative shapes for end portion 39, but end portion 39 can take any shape that extends away from longitudinal axis 48 a radial distance 43 that is greater than the radial distance 41 of the user-graspable portion.

[0020] 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 2 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.

[0021] Syringe assembly 22 is movable relative to injection device 20 between a retracted position and an injection position. Figure 3 illustrates device 20 after syringe assembly 22 has been moved relative to device 20 from its retracted position, shown in Figure 2, to the injection position. In the retracted position (Figures 1 and 2), needle 34 is retracted to a position such that needle 34 is disposed within housing 38 of device 20. In the injection position (Figure 3), 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.

[0022] 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 exemplary 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. 1 and 2 ) to its final piston position (shown in FIG. 3 ) during a dispensing event, dispensing medicament from needle 34. Prior to any dispense 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 a single use, syringe assembly 22 holds a single dose of medication to be delivered in a single dispense event, and piston 32 advances from its initial piston position to its final piston position in that single dispense event, thereby delivering the entire contents of the single dose of syringe assembly 22. While the device is shown as a single use device, multiple use devices can also benefit from a device status indication during single use.

[0023] 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.

[0024] Plunger 44 may include a magnet 25 adjacent foot 50. As shown in Figures 1-3, magnet 25 is configured to maintain a constant axial distance from piston 32. Magnet 25 emits a magnetic field that is sensed by magnetometers 118 and 112, discussed below in connection with Figures 9A, 9B, and 11.

[0025] 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 (shown in FIG. 4 ) from shuttle assembly 60, thereby allowing spring 46 to advance plunger 44 axially. Spring 46 has a helical shape and surrounds protrusions 54. A proximal end of spring 46 biasingly engages flange 56 on plunger 44.

[0026] The shuttle assembly 60 may include an upper shuttle member 62, shown in FIG. 6, and a lower shuttle member 64, shown in FIG. 7. 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. 1 and 2. Depressing the button 52 causes a tab on the button 52 to engage with a ramp 55 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 the flange 56, advancing the plunger 44 from the position shown in FIG. 2 to the position shown in FIG. 3. 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.

[0027] Upon completion of the dispensing event, the retraction mechanism 26 optionally moves the syringe assembly 22 from the injection position shown in FIG. 3 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 proximally extends 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 68 shown in FIG. 5, and a rotating member 70 acting as a follower. In still other embodiments, device 20 may not include retraction mechanism 26 such that after the medication has been dispensed, the syringe assembly remains indefinitely in its injection position until it is manually removed or repositioned by the user.

[0028] The plunger 44 may include an outrigger 58 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 58 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. With further reference to FIG. 7 , the member 70 may include a slot that receives a tab 78 on the lower shuttle member 64. At one end of the slot, the member 70 defines an axially extending channel. As the member 70 rotates, the tab 78 may move within the slot on the member 70 until the tab 78 reaches the axially extending channel.

[0029] 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. A radial flange of 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 exert an axial force, a torsional force, or both, on the member 70 proximally to bias the member 70 proximally, thereby maintaining the member 70 in an axial position where the radial flange of the member 70 engages an internal ledge of the housing member 38. The shuttle assembly 60 may include axially extending channels or ribs that engage corresponding features on the housing member 38 to allow the shuttle assembly 60 to move axially within the housing 38 but prevent relative rotation of the shuttle assembly 60 with respect to the housing member 38.

[0030] Spring 66 is also axially preloaded and exerts a distally directed biasing force on shuttle assembly 60. When tab 78 reaches the axially extending channel, spring 66 moves shuttle assembly 60 distally within housing 38 as tab 78 slides axially through the channel. A vibration damping compound may be disposed adjacent rotating member 70 to slow the rotation of member 70 and allow the dispensing event to be completed before tab 78 reaches the axially extending channel. For example, rotating member 70 may include a skirt with multiple axially extending tabs disposed in a grease collar to provide vibration damping.

[0031] As shuttle assembly 60 moves distally, it carries syringe assembly 22 distally, moving syringe assembly 22 back to the retracted position shown in FIG. 2. Spring 66 biases retraction mechanism 26 distally, thereby maintaining syringe assembly 22 in its retracted position after a dispensing event. Locking features, such as detents on shuttle assembly 60 and recesses on housing 38 members, additionally provide locking engagement to secure syringe assembly 22 with needle 34 disposed within housing 38 in the retracted position after a dispensing event, thereby allowing the user to then dispose of or otherwise handle device 20 in a safe manner.

[0032] Syringe carrier 68 is shown in FIG. 5. Arcuate arms 84 of the carrier may grip barrel 30 of syringe assembly 22. Syringe carrier 68 also includes a flange 86. The flange on syringe barrel 30 is captured between arm 84 and flange 86. A lower portion 88 of flange 86 engages a small flange 90 on plunger 44, thereby preventing proximal axial movement of syringe assembly 22 before plunger 44 is advanced. When shuttle assembly 60 is retracted, lower shuttle member 64 engages arm 84 to carry syringe assembly 22 distally to its retracted position.

[0033] 1-7 illustrate and describe an exemplary drive mechanism 24 and an exemplary retraction mechanism 26, other mechanisms may also be used to drive the syringe assembly 22 from the retracted position to the injection position and / or from the injection position to the retracted position. Such drive and / or retraction mechanisms may (but need not) include one or more springs or deformable parts that store energy when held in a pre-triggered state and release the stored energy when triggered to drive the syringe assembly from the retracted position to the injection position and / or from the injection position to the retracted position. Such mechanisms may (but need not) include mechanisms that generate power using a chemical reaction or process, for example, by generating a gas by mixing two or more reagents or by igniting a small amount of flammable or explosive material. Such chemically driven mechanisms may include one or more reservoirs for chemical reagents, a trigger that punctures or opens the reservoirs, allowing the reagents to mix and / or provides a spark or other ignition source to initiate a chemical reaction, and a movable piston or other component that moves in response to the increase in gas pressure generated by the resulting chemical reaction. Such mechanisms may (but need not) include mechanisms that use stored power (e.g., in a battery) to operate an electric motor or trigger other physical or chemical mechanisms that drive and / or retract the syringe assembly. Such mechanisms may (but need not) include hydraulic or pneumatic systems (e.g., tubing), gears, cables, pulleys, or other known components for transferring kinetic energy from one component to another. In some embodiments, rather than having separate mechanisms for driving the syringe assembly and then retracting it, a single mechanism may be configured to both drive the syringe assembly and then retract it.

[0034] FIG. 8 illustrates an exemplary arrangement of one or more main PCBs 82 within end portion 39 according to a first set of embodiments of device 20. The one or more main PCBs may be disposed orthogonal to longitudinal axis 48, stacked on top of each other, and / or disposed alongside each other in the same plane orthogonal to longitudinal axis 48. The main PCBs define an opening 83 configured to receive needle 34 of syringe assembly 22, for example, when end cap 36 is removed and the needle is driven proximally to inject a patient during a dispensing event. As shown, the main PCB extends away from longitudinal axis 48 a radial distance 45 that is greater than radial distance 41 of user-graspable portion 37. FIG. 8 also illustrates one or more secondary PCBs 84 extending substantially orthogonal to the main PCB and parallel to longitudinal axis 48, which may be communicatively coupled to the main PCB via one or more PCB connectors 114. A secondary PCB 84 may mount additional sensing systems, although such a secondary PCB is optional and may be omitted in certain embodiments to reduce manufacturing complexity and cost.

[0035] End portion 39 may be a convenient location and size within device 20 for locating the main PCB. The increased footprint of end portion 39 results from the radial extension of the end portion outward from longitudinal axis 48 by a radial distance 43 that is greater than the radial distance 41 of the user-graspable portion. The increased footprint provides more space to accommodate the main PCB and its various components than elsewhere in device 20. Therefore, many components may be pre-assembled onto the main PCB, with many components disposed in the convenient location of end portion 39. As a result, incorporating the main PCB into end portion 39 requires little or no modification to the shape of an existing automatic injector housing, reducing disruptions to the manufacturing process and lowering manufacturing costs. Furthermore, locating the main PCB in end portion 39 allows skin contact sensors 122, 123, and 124 to be located farther from longitudinal axis 48, improving the reliability of skin contact readings received from these sensors.

[0036] FIG. 9A shows a top perspective view of the main and secondary PCBs according to a first set of embodiments of the device 20, while FIG. 9B shows a bottom perspective view of the same PCBs. FIGS. 10A and 10B show top and bottom views, respectively, of the same PCBs. The main PCB 82 (shown in FIG. 8) may have a top surface 82a (shown in FIGS. 9A and 10A, where the top surface 82a is understood to be part of the PCB 82) that includes or supports a power source 102, which in some embodiments may include a battery, such as a coin cell battery. The power source 102 provides power to electrical components integrated with or coupled to the injection device 20. The main PCB 82 may also include a processing circuit 108. In some embodiments, the processing circuit 108 may take the form of a system-on-chip (SOC) integrated circuit that includes a processor, memory, and input / output ports. However, processing circuit 108 may also be implemented using other types of components, such as a microcontroller (MCU) or an application specific integrated circuit (ASIC). Processing circuit 108 may be configured to execute computer-executable instructions stored on a non-transitory storage medium. The main PCB may also include multiple different types of sensors, such as microswitch sensor 110, magnetometer 112, accelerometer 140, ambient light sensor 106, and / or one or more skin contact resistance sensors 122, 123, and 124. In embodiments that include a secondary PCB, the secondary PCB may include additional sensors, such as another microswitch sensor 116, magnetometer 118, and infrared temperature sensor 120.

[0037] The microswitch sensors 110 and 116 may be communicatively coupled to the processing circuit 108. Each microswitch sensor may include a physical switch coupled to an electrical circuit, which outputs an electrical signal to the processing circuit 108 depending on the physical position or orientation of the physical switch. The microswitch sensors 110 and 116 may be used to detect the position of a component of the injection device 20. For example, the microswitch sensor 110 may be used to detect whether the end cap 36 is attached to the proximal end of the device housing 38. As discussed in more detail below, depending on the output of the microswitch sensor 110, the processing circuit 108 may indicate to the user whether the end cap 36 is attached to the device 20. Similarly, the microswitch sensor 116 may be used to detect whether the syringe assembly 22 is in one of two states, such as (i) a retracted position or (ii) an injection position. Microswitch sensor 116 may also be configured to detect whether syringe assembly 22 is in one of three states, such as (i) a retracted position, (ii) an injecting position, or (iii) a retracted position. Depending on the output of microswitch sensor 116, processing circuit 108 may indicate to the user which position syringe assembly 22 is in.

[0038] The ambient light sensor 106 may be communicatively coupled to the processing circuit 108 and may detect the amount or intensity of ambient light to which the injection device 20 is exposed. Excessive exposure to ambient light may render the medication stored in the barrel 30 ineffective or unsafe for injection. In some embodiments, the processing circuit 108 may log the intensity and / or duration of the ambient light detected by the ambient light sensor 106. If the intensity and / or duration of exposure to ambient light exceeds a predetermined threshold, the user may be notified that the medication should not be used.

[0039] The accelerometer 140 may be communicatively coupled to the processing circuit 108 and may determine the orientation of the injection device 20 (e.g., facing up, facing down, or sideways). This may be important for certain types of medications that may be significantly affected by gravity due to settling of particulate matter, etc., which require the medication to be delivered in a specific orientation. The processing circuit 108 may also use the output of the accelerometer 140 to alert the user if the device 20 is improperly oriented for injection (e.g., if the device is upside down). As described in more detail below, the accelerometer 140 may also be used to detect vibrations from an external device to assist in wirelessly pairing the injection device 20 with the external device.

[0040] Many types of medications need to be stored at a first, relatively low temperature (e.g., 36-46°F, or 2-8°C) to prevent degradation, but then need to be heated to a second, higher temperature (e.g., room temperature, or 65-75°F, or 18-24°C) before being injected into a patient. To ensure that the medication in the barrel 30 is stored at the appropriate storage temperature and / or to ensure that the medication is heated to the appropriate injection temperature, the injection device 20 may include a mechanism for estimating the medication's temperature. By ensuring that the medication has been heated to the appropriate temperature, this information may be transmitted to a phone call, or the device itself may signal to the patient that the device is ready for use. In some embodiments, this temperature measurement function may be performed by an infrared (IR) temperature sensor 120 on the secondary PCB 84. The IR sensor 120 may be communicatively coupled to the processing circuit 108. 8, IR sensor 120 may be disposed adjacent to and facing toward barrel 30. IR sensor 120 may detect and measure electromagnetic radiation in the IR spectrum from barrel 30 and output an electrical signal based on the detected IR radiation. By sampling the electrical signal output by IR sensor 120, processing circuit 108 may estimate the temperature of the medication within barrel 30.

[0041] The main PCB may also include one or more antennas for transmitting and receiving wireless communications. For example, Figures 9A and 9B illustrate a Bluetooth Low Energy (BLE) antenna 104 disposed on the top surface 82a of the main PCB and a near field communication (NFC) antenna 126 (shown as a thick black line element) disposed on the bottom surface 82b of the main PCB. Other embodiments are possible in which the main PCB includes only one antenna or only one type of antenna. As discussed in more detail below, these antennas may enable the injection device 20 to establish a wireless communication link with an external device.

[0042] The main PCB may also be communicatively coupled to or integrated with multiple sensors that detect contact with skin tissue. The skin contact sensors may be used to verify proper contact with a user's skin before the user activates the injection device 20. The injection device 20 may also indicate to the user which sensors detect skin contact and which sensors do not, allowing the user to know in which direction to tilt or move the injection device 20 before injecting. This feature reduces the likelihood of an unsuccessful injection, where the needle 34 fails to penetrate the user's skin or penetrates at an inappropriately shallow angle.

[0043] 9B and 10B illustrate an exemplary embodiment including three skin contact sensors 122, 123, and 124 disposed on the bottom surface 82b of the main PCB and arranged in a symmetrical trilobal configuration. In this exemplary embodiment, each skin contact sensor 122, 123, and 124 includes two separate electrical terminals: sensor 122 includes terminals 122a and 122b, sensor 123 includes terminals 123a and 123b, and sensor 124 includes terminals 124a and 124b. While only two electrical terminals are illustrated for each sensor, other embodiments are possible in which each sensor has three or more electrical terminals. Each skin contact sensor may measure the electrical resistance between its electrical terminals and output an electrical signal to processing circuit 108 based on the measured resistance. The electrical resistance of skin tissue is generally lower than that of air; therefore, processing circuit 108 may determine that a particular skin contact sensor is in contact with skin tissue when the measured resistance is below a predetermined threshold.

[0044] 9B and 10B illustrate each skin contact sensor 122, 123, and 124 as having two electrical terminals, other embodiments are possible in which each skin contact sensor has only one electrical terminal. In such cases, the electrical terminal on one skin contact sensor (e.g., sensor 122) may function as a reference electrode that outputs a predetermined voltage. The electrical terminal on each of the other two skin contact sensors (e.g., sensors 123 and 124) may function as a sensor electrode that measures the electrical resistance of the conductive path between itself and the reference electrode. When the measured resistance between the reference electrode and a particular sensor electrode is below a predetermined threshold, processing circuit 108 may determine that both the reference electrode and the particular sensor electrode are in contact with human tissue, such as skin. When both sensor electrodes (e.g., on sensors 123 and 124) report measured resistances below a predetermined threshold, processing circuit 108 may determine that the reference electrode and both sensor electrodes are in contact with human tissue. Exemplary embodiments of device 20 incorporating capacitive sensors are discussed below in connection with FIGS. 17A, 17B, 18A and 18B and a second set of device 20 embodiments.

[0045] As best shown in FIG. 10B , each skin contact sensor 122, 123, and 124 may be located at radial distances 128, 130, and 132, respectively, outward from longitudinal axis 48 (which, in the view shown in FIG. 10B , extends into the page). Sensors 122, 123, and 124 may optionally be positioned symmetrically around opening 83 such that radial distances 128, 130, and 132 are equal to one another and the angular separation between each sensor is also equal (e.g., 120° in this case). Radial distances 128, 130, and 132 may be greater than radial distance 41 of user-graspable portion 37 (as shown in FIGS. 2 and 9 ) and may be greater than 10 mm in length. For example, in some embodiments, radial distances 128, 130, and 132 may each be 10 mm to 20 mm in length, with distances of 15 mm to 20 mm being appropriate in some cases. While three skin sensors are shown, other embodiments having only one or two skin sensors are possible. Conversely, embodiments having four or more skin contact sensors are also possible, and in such embodiments, the skin sensors may (but need not) be positioned symmetrically around opening 83. Other embodiments are also contemplated, including, for example, between four and twenty skin sensors.

[0046] While skin contact sensors 122, 123, and 124 are described above as measuring electrical resistance, these skin contact sensors may alternatively be configured to detect skin contact by measuring electrical capacitance. Capacitive sensors may be configured to detect the proximity of human tissue by detecting the effect of such tissue on the electric field created by the sensor (e.g., by detecting the effect of such tissue on the capacitance of a circuit being monitored or measured by the sensor). Because capacitive sensors do not require metallic electrical terminals that directly contact skin tissue, they may be partially or completely sealed behind a protective non-conductive cover (e.g., plastic, etc.). This may improve the durability of capacitive sensors by reducing the penetration of moisture or foreign matter into sensitive electrical components. Capacitive sensors may also reduce the risk of electrostatic discharge damaging sensitive electrical components within the device because they do not require exposed metal contacts. Exemplary embodiments of device 20 incorporating capacitive sensors are discussed below in connection with FIGS. 21A, 21B, 22A, and 22B and a third set of device 20 embodiments.

[0047] The injection device 20 may also include means for estimating the axial position or movement of the piston 32 within the barrel 30. This estimated axial position and / or movement may be used by the processing circuit 108 to estimate the amount of medication remaining in the barrel 30 and / or the amount of medication, if any, that has been dispensed. In some embodiments, this may be accomplished by providing a magnet on or near the piston 32 as it slides along the longitudinal axis 48 and one or more magnetometers that sense the magnetic field emitted by the magnet as it slides along the longitudinal axis. FIGS. 1-3 and 11 show an exemplary magnet 25 disposed on the plunger 44 such that the plunger 44 maintains a constant axial distance from the piston 32 as the piston slides along the longitudinal axis 48 within the barrel 30. FIGS. 9A, 9B, 10A, and 10B also show an exemplary arrangement of two magnetometers: magnetometer 112 on the main PCB 82 and magnetometer 118 on the secondary PCB 84. As shown, magnetometer 112 may be disposed radially farther from longitudinal axis 48 than magnetometer 118. Furthermore, magnetometer 118 may be disposed at a midpoint along the length of barrel 30 instead of being positioned proximate one end of barrel 30.

[0048] FIG. 11 provides a side view of injection device 20 according to a first set of embodiments of device 20, illustrating the spatial relationship between magnet 25 and magnetometers 112 and 118. In FIG. 11, injection device 20 is illustrated with syringe assembly 22 in the retracted position and end cap 36 secured to device housing 38 to cover proximal opening 40. Magnet 25 outputs a magnetic field that can be sensed by magnetometers 112 and 118 when magnet 25 is sufficiently close to the magnetometer. Each magnetometer can output a signal to processing circuit 108 based on the strength of the sensed magnetic field. The strength of the magnetic field sensed by magnetometers 112 and 118 changes based on the position of magnet 25 as magnet 25 slides in the direction of arrow 1102 along longitudinal axis 48. For example, when syringe assembly 22 is in the retracted position and piston 32 is in its initial piston position at the distal end of barrel 30 (as illustrated in FIG. 11 and FIGS. 1 and 2), magnetometers 118 and 112 may detect only a very weak magnetic field or no magnetic field. When syringe assembly 22 advances to the injection position but piston 32 is still in the initial piston position, magnetometer 112 may detect only a weak magnetic field or no magnetic field at all, but magnetometer 118 may detect a stronger magnetic field than when syringe assembly 22 is in the retracted position. By sampling the strength of the magnetic fields measured by magnetometers 112 and 118, processing circuit 108, in some embodiments, may determine whether syringe assembly 22 is in the retracted position or the injection position.

[0049] When syringe assembly 22 is in the injection position, as piston 32 advances from its initial position in the direction of arrow 1102 toward its final piston position (shown in FIG. 3 ), magnetometer 118 detects the magnetic field that increases and then decreases as magnet 25 moves toward, past, and then away from magnetometer 118. Simultaneously, advancing piston 32 in the direction of arrow 1102 causes magnetometer 112 to detect the magnetic field that increases as magnet 25 moves toward and toward magnetometer 112. By sampling the strength of the magnetic fields detected by both magnetometers 118 and 112, processing circuit 108 can estimate the position of magnet 25 along longitudinal axis 48. Based on this position estimate, processing circuit 108 can estimate the position of piston 32 as well as the amount of medication still remaining in barrel 30.

[0050] 12 provides a system architecture diagram of electrical components within device 20 and communication links with an exemplary external device 1250 according to a first set of embodiments of device 20. As discussed above, processing circuit 108 may be powered by battery 102 and may include a processing core 1208 and memory 1210 (e.g., internal flash memory, on-board electrically erasable and programmable read-only memory (EPROM), etc.). Memory 1210 may store instructions that, when executed by processing core 1208, cause processing circuit 1208 to perform the operations described herein. Processing circuit 108 may also be communicatively coupled to multiple sensors, such as ambient light sensor 106, end cap microswitch 110, magnetometer 112, accelerometer 140, and skin contact sensors 122, 123, and 124. The processing circuit 108 may also, optionally, be communicatively coupled to one or more secondary PCBs via a flex connector 114. The secondary PCBs may further incorporate a microswitch 116, a magnetometer 118, and an IR temperature sensor 120. The processing circuit 108 may also be connected to a means for user feedback 1208 integrated with the device 20. The means for user feedback may include one or more indicator lights (e.g., implemented using light emitting diodes (LEDs)), a display, a tactile indicator such as a vibration motor, and / or an audio indicator such as a speaker. The processing circuitry 108 may be communicatively coupled to each of the above-described components via one or more physical or electrical channels, such as, but not limited to, General-Purpose Input / Output (GPIO) pins, an Inter-Integrated Circuit (I2C) bus, a Serial Peripheral Interface (SPI) connection, a Universal Asynchronous Receiver / Transmitter (UART) connection, a Controller Area Network (CAN) bus, or the like.In some cases, the signals received by the processing circuitry 108 from some or all of the sensors may also be converted from analog to digital signals using an analog-to-digital converter (ADC).

[0051] The processing circuit 108 may also be configured to enable the injection device 20 to communicate wirelessly with an external device (e.g., a mobile phone, a wearable device, a laptop, and / or a server database, etc.). To facilitate wireless communication, the processing circuit 108 may include a near-field communication (NFC) circuit 1204 communicatively coupled to an NFC antenna 1205, such as the NFC antenna 126 illustrated in FIGS. 9B and 10B. The NFC circuit 1204 and the NFC antenna 1205 enable the processing circuit 108 to establish a wireless NFC communication link 1232 with the external device 1250. Alternatively or additionally, the processing circuit 108 may include a Bluetooth Low Energy (BLE) circuit 1206 communicatively coupled to a BLE antenna 1207, such as the BLE antenna 104 illustrated in FIGS. 9A and 10A. The BLE circuit 1206 and the BLE antenna 1207 enable the processing circuit 108 to establish a wireless BLE communication link 1234 with the external device 1250.

[0052] FIG. 12 also illustrates an exemplary external device 1250 that is physically separate from the injection device 20. In this embodiment, the exemplary external device 1250 may take the form of a mobile smartphone having a processor 1252 (e.g., a microprocessor or CPU) and a memory 1258. The memory 1258 may include a non-transitory computer-readable medium that stores computer-executable instructions that, when executed by the processor 1252, cause the device 1250 to perform the operations described herein. These computer-executable instructions may include a mobile application, such as a medical mobile application. The device 1250 may further include a display 1260 and a user input device 1262. The user input device 1262 may include physical buttons or switches integrated with the smartphone. Although illustrated separately in FIG. 12 , all or a portion of the user input device 1262 may be integrated with the display 1260, for example, in a touch-sensitive screen. The device 1250 may also include a vibration source 1264, such as a vibration motor.

[0053] The device 1250 may be configured to establish a wireless communication link with the injection device 20. For example, the external device 1250 may include an NFC circuit 1254 coupled to an NFC antenna 1255 that communicates with the processing circuit 108 via communication link 1232. The device 1250 may also include a BLE circuit 1256 coupled to a BLE antenna 1207 that communicates with the processing circuit 108 via communication link 1234.

[0054] FIG. 13 is a flow diagram illustrating an exemplary process 1300 for “pairing” or establishing a communication session between the injection device 20 and the external device 1250. The process 1300 may be used by any of the first set of device 20 embodiments, as well as any of the second and third sets of device 20 embodiments described below. To conserve power, the injection device 20 may first be stored in a low-power sleep mode 1326. While in this sleep mode 1326, some or all of the components coupled to or integrated with the processing circuit 108 may be shut down or placed in a low-power state to conserve power. For example, some or all of the sensors coupled to the processing circuit 108 may be powered down, the BLE circuitry 1206 and BLE antenna 1207 may be powered down, and some or all of the processing core 1208 may be powered down or operate at a slower clock speed. When the device 20 is in the low-power sleep mode 1326, the device may need to be “woke up” before it can be paired with the external device 1250.

[0055] One means of activating the injection device 20 is to configure the external device 1250 to emit an NFC field (e.g., an electromagnetic field) using its NFC circuitry 1254 and NFC antenna 1255 (step 1328). When the external device 1250 is placed in close proximity (e.g., within a few centimeters) to the injection device 20, the emitted NFC field induces a current flowing in the NFC antenna 1205, which is coupled to the processing circuit 108. The processing circuit 108 may then be configured to wake the injection device 20 from its low-power sleep mode when the processing circuit 108 detects this induced current. The processing circuit 108 may also be configured to wake the device 20 only upon detecting an induced current that matches an expected code or pattern, thereby preventing spurious background electromagnetic emissions from activating the injection device 20.

[0056] Another way to wake up the injection device 20 is to configure the device 20 to wake up when it detects a particular vibration pattern (also step 1328). For example, to wake up the device 20, a user can position the device 20 so that it is in contact with the external device 1250, e.g., the device 20 can be placed on top of the external device 1250. The external device 1250 can then be instructed by the user to vibrate according to a particular predetermined pattern using the vibration source 1264. The vibrations from the external device 1250 can be detected by the accelerometer 120 within the injection device 20. When the detected vibrations match the expected pattern, the processing circuit 108 can be configured to wake up the injection device 20 from its low-power sleep mode.

[0057] When the injection device 20 first wakes up from its low-power sleep mode, the processing circuit 108 may engage in a BLE pairing process 1330 with the external device 1250. The BLE pairing process 1330 is similar to or the same as the BLE pairing process defined in Bluetooth Core Specification v5.0, published by the Bluetooth SIG on December 6, 2016, and is incorporated herein by reference in its entirety. The BLE pairing process 1330 may begin with the injection device 20 broadcasting one or more BLE advertisement packets using its BLE circuitry 1206 and BLE antenna 1207. When the external device 1250 receives the broadcasted BLE advertisement packets via the BLE circuitry 1206 and BLE antenna 1257, the external device 1250 may respond with a wireless BLE transmission that initiates a communication flow between the injection device 20 and the external device 1250. The end result of this communication flow is an established BLE communication session between the injection device 20 and the external device 1250, over which the two devices may exchange data.

[0058] 14A and 14B are flowcharts illustrating an exemplary process 1400 implemented by a mobile medical application running on the external device 1250. Process 1400 may be used in conjunction with any of the first set of device 20 embodiments, as well as any of the second and third sets of device 20 embodiments described below. Process 1400 begins when a BLE connection is established between the injection device 20 and the external device 1250 (step 1402). In step 1404, the external device 1250 receives data from the injection device 20 through the established BLE connection. The data received from the injection device 20 may include data or measurements from some or all of the sensors described above within the injection device 20, or information derived from or based on such data or measurements. The data received from the injection device 20 may also include data stored in the device 20's memory or information derived from such data; such data may include the type of medication stored within the injection device 20, the medication's expiration date, the prescribing physician's identification, the medication's manufacturer's location or date, the injection device model, etc.

[0059] In step 1406, process 1400 determines whether the medication is expired. This may be done by comparing the expiration date of the medication received in step 1404 with the current date. If the medication is expired, process 1400 branches to step 1414, where external device 1250 notifies the user that the medication is expired, such as through a message on a display or an audio message on device 1250. If the medication is not expired, process 1400 branches to step 1408.

[0060] In step 1408, process 1400 determines whether the medication has been exposed to unsafe conditions. This step may include checking data stored in or derived from an ambient light exposure log stored by processing circuit 108. If the intensity and / or duration of exposure to ambient light exceeds a predetermined threshold, process 1400 may branch to step 1414 and notify the user that the medication should not be used. The logic for comparing the data from the ambient light exposure log with predetermined limits on exposure intensity and / or duration may be implemented either by the processing circuit 108 of the injection device 20, by the processor 1252 of the external device 1250, or a combination of both. Alternatively or additionally, step 1408 may include determining whether the medication has been exposed to unsafe temperatures during storage or transport. This may be accomplished by checking data stored in or derived from a medication temperature log stored by processing circuit 108. If the medication is exposed to a temperature outside the ideal storage range (e.g., 36-46 degrees Fahrenheit), or if the medication is exposed to a temperature outside the ideal storage range for an unacceptable period of time, the process 1400 may also branch to step 1414 and notify the user that the medication should not be used. The logic for comparing the temperature log data to predetermined temperature limits may also be performed by the processing circuit 108 of the injection device 20, by the processor 1252 of the external device 1250, or by a combination of both.

[0061] In step 1410, process 1400 determines whether the medication is at a safe temperature for injection. The medication in injection device 20 may need to be stored at a low temperature (e.g., 36-46 degrees Fahrenheit) to prevent degradation, and the medication may need to be warmed to a higher temperature (e.g., about room temperature, or 65-75 degrees Fahrenheit) before it is injected. In step 1410, process 1400 determines whether the medication has been warmed to the target injection temperature. If the medication has not been warmed to the target injection temperature, process 1400 branches to step 1416, where process 1400 notifies the user that the medication is still warmed, and then branches back to step 1410. If the medication has been warmed to the target injection temperature, process 1400 branches to step 1422 (shown in FIG. 14B). If, in step 1410, process 1400 determines that the user initiated the injection before the medication was warmed to the target injection temperature, process 1400 may branch to step 1414, notifying the user of the error and advising the user to allow the medication to warm to the target injection temperature before dispensing. Alternatively or additionally, process 1400 may log the user error in memory and / or send a notification of the user error to a caregiver and / or device manufacturer, payer, or designer.

[0062] 14B, in step 1422, process 1400 may prompt the user to remove end cap 36. In step 1424, process 1400 determines whether end cap 36 has been removed. As discussed above, processing circuit 108 may use end cap microswitch sensor 110 to determine whether end cap 36 has been removed and may notify external device 1205 via BLE communication link 1234. If the end cap has not been removed, process 1400 branches back to step 1422. If the end cap has been removed, process 1400 branches to step 1426.

[0063] In step 1426, process 1400 may instruct the user to position the injection device 20 for injection. This may include instructing the user to place the proximal opening 40 of the device 20 flush against a portion of the user's body, such as the user's abdomen or the user's thigh. In step 1428, process 1400 determines whether all skin contact sensors (e.g., sensors 122, 123, and 124) have detected contact with skin tissue. If fewer than all of the skin contact sensors have detected contact with skin tissue, process 1400 branches to step 1430. If all of the skin contact sensors have detected contact with skin tissue, process 1400 branches to step 1432.

[0064] In step 1430, process 1400 may indicate to the user which individual sensors of the multiple skin contact sensors (e.g., sensors 122, 123, and 124) have detected contact with skin tissue and which individual sensors have not detected contact with skin tissue. As illustrated in FIG. 15 , this may be done by displaying a schematic 1502 on the display 1260 of external device 1250. Schematic 1502 may include three separate indicators 1522, 1523, and 1524, corresponding to skin contact sensors 122, 123, and 124, respectively. As shown, indicators 1522, 1523, and 1524 may be positioned to mimic the physical placement of skin contact sensors 122, 123, and 124; for example, the indicators may be symmetrically positioned around a central opening. In embodiments with fewer or more than three skin contact sensors, schematic 1502 may also include a corresponding number of indicators. If a skin contact sensor does not detect contact with skin tissue, schematic 1502 may change the appearance of that skin sensor's corresponding indicator. In the example shown in FIG. 15 , skin contact sensors 122 and 123 detect skin contact, but skin contact sensor 124 does not detect contact with skin tissue. Thus, indicator 1524 corresponding to skin contact sensor 124 is filled with a color, pattern, or visual pattern that is different from the color, pattern, or visual pattern of indicators 1522 and 1523 corresponding to skin contact sensors 122 and 123 (as indicated by the cross-hatching for indicator 1524). Other means of indicating the presence or absence of skin contact are possible; for example, the shape of the indicator may change, or an icon or graphic may be displayed or hidden, depending on whether a particular skin contact sensor detects any contact with skin tissue.

[0065] Alternatively or additionally, device 20 may include visual indicators (e.g., light-emitting diodes (LEDs)) that indicate to the user which skin contact sensors have detected skin contact and which have not. For example, device 20 may include multiple LEDs on the top surface of main PCB 82a, each LED corresponding to one of the skin contact sensors. The physical placement of the LEDs may correspond to the placement of the skin contact sensors so as to make it clear to the user which LED corresponds to which skin contact sensor, and each LED may be disposed on the top surface of its corresponding skin contact sensor. One such exemplary LED is illustrated in FIG. 11 as LED 142. Depending on whether the sensor has detected contact with skin tissue, the corresponding LED may be illuminated, extinguished, and / or change color. This provides another intuitive means for the user to quickly determine which skin contact sensors have not detected contact with skin tissue and how the user should tilt or move device 20 to achieve better skin contact.

[0066] FIG. 17A shows a top perspective view of a main PCB 1782 according to a second set of embodiments of device 20, while FIG. 17B shows a bottom perspective view of the same PCB 1782. FIGS. 18A and 18B show top and bottom views, respectively, of the same PCB. Like the above-described main PCB 82 of the first set of embodiments, main PCB 1782 may also be positioned in end portion 39 of housing 38 of device 20, as illustrated in FIG. 8. Also like the above-described main PCB 82, main PCB 1782 defines opening 1703 (similar to opening 83 of PCB 82) configured to receive injection needle 34 of syringe assembly 22 therethrough. Main PCB 1782 includes a top surface 1782 a and a bottom surface 1782 b (top surface 1782 a and bottom surface 1782 b are understood to be parts of PCB 1782). The top surface 1782a includes or supports a power source 1702, which in some embodiments may include a battery, such as a coin cell battery. The power source 1702 provides power to electrical components integrated with or coupled to the injection device 20. The main PCB 1782 may also include a processing circuit 1708, which may be configured similarly to the processing circuit 108 described above.

[0067] The main PCB 1782 of the second set of embodiments may differ in several respects from the main PCB 82 of the first set of embodiments. As best seen in comparing FIGS. 9A and 17A , instead of the secondary PCB 84, the main PCB 1782 mounts a syringe position detector switch 1710 that enables the processing circuit 1708 to determine whether the syringe assembly 22 is in the stored position, the injecting position, or the retracted position. The syringe position detector switch 1710 includes two proximally extending arms 1710 a, 1710 b. In one example, the arm 1710 a is an angled arm 1710 a, and the arm 1710 b is disposed adjacent to the arm 1710 a. In one example, arms 1710a and 1710b each include a distal end coupled to PCB 1782 (in the illustrative example, the distal end includes a foot configuration for attachment to the PCB), and the arms may extend proximally in a parallel relationship. Angled arm 1710a includes an angled radial portion that projects inward toward longitudinal axis 48 to contact the movable syringe barrel and cause deflection of arm 1710a, and a laterally extending portion that overlaps a contact portion of arm 1710b for selective electrical contact with arm 1710b. Both arms may be made of metal or any other relatively flexible, conductive material and may be electrically connected to processing circuit 1708. When the contact portion of arm 1710a contacts arm 1710b, the contact completes an electrical circuit between angled arms 1710a and 1710b. When angled arm 1710a is not in contact with straight arm 1710b, the electrical circuit between the two arms is broken. By continuously or periodically monitoring whether the two arms 1710a and 1710b are in contact, processing circuit 1708 can determine whether the syringe assembly is in the stored, injecting, or retracted position.

[0068] FIG. 19 shows a side view of the device 20 when the syringe assembly 22 is in the retracted or retracted position. As shown, when the syringe assembly 22 is in one or both of these positions, the angled arm 1710a and the straight arm 1710b are positioned slightly apart and do not contact one another. FIG. 20 shows a side view of the device 20 when the syringe assembly 22 is in the injection position. As the syringe assembly 22 moves to the injection position, the barrel 30 of the syringe assembly 22 translates downward in the distal direction, as represented by arrow 1902. Because the barrel 30 has a wider diameter than the needle 34 or needle hub 35, the downward translation of the barrel 30 causes the barrel 30 to contact the angled portion of the angled arm 1710a, pushing the angled arm 1710a radially away from the longitudinal axis 48, causing the angled arm 1710a to contact the straight arm 1710b. This completes an electrical circuit between angled arm 1710a and straight arm 1710b. Thus, when processing circuit 1708 detects an open circuit between arms 1710a and 1710b, it can determine that syringe assembly 22 is in either the stored or retracted position. When processing circuit 1708 detects a closed circuit between arms 1710a and 1710b, it can determine that syringe assembly 22 is in the injection position.

[0069] Main PCB 1782 may also differ from main PCB 82 in its configuration of skin contact sensors. As best seen in comparing FIGS. 9B and 17B , instead of using three skin contact sensors each including two electrodes (e.g., in the first set of embodiments, sensor 122 includes electrodes 122a and 122b, sensor 123 includes electrodes 123a and 123b, and sensor 124 includes electrodes 124a and 124b), bottom surface 1782b of main PCB 1782 in the second set of embodiments includes only three single electrodes 1722, 1723, and 1724 facing distally from the distal surface of the PCB. These electrodes may be equally spaced radially from longitudinal axis 48 or positioned equally spaced circumferentially from one another. One of these three electrodes, for example, electrode 1722, may be connected to a voltage source providing a reference voltage V. The other two electrodes may each be connected to a separate voltage sensor. The outputs of both voltage sensors may be connected to processing circuit 1708. If the voltage sensor connected to electrode 1723 senses a positive voltage above a reference threshold, processing circuit 1708 may determine that both electrodes 1722 and 1723 are in contact with skin tissue. If the voltage sensor connected to electrode 1724 senses a positive voltage above a threshold, processing circuit 1708 may determine that both electrodes 1722 and 1724 are in contact with skin tissue. If the voltage sensors connected to both electrodes 1722 and 1723 detect voltages above a threshold, processing circuit 1708 may determine that all three electrodes 1722, 1723, and 1724 are in contact with skin tissue. For main PCB 82 of the first set of embodiments, this arrangement of electrodes 1722, 1723, and 1724 reduces the number of electrodes required, thus reducing manufacturing and assembly complexity and cost.

[0070] While the above description of the second set of embodiments of device 20 describes differences between this second set of embodiments and the first set of embodiments described above, it should be understood that the second set of embodiments may also include features present in the first set of embodiments, as well as other features. For example, certain embodiments of this second set of embodiments may include the secondary PCB 84 of the first set of embodiments, either instead of or in addition to the proximally extending arms 1710a, 1710b. This secondary PCB 84 of the second set of embodiments may include one, some, or all of the sensors described above as mounted on the secondary PCB 84 of the first set of embodiments. The second set of embodiments of device 20 may also use different configurations of skin contact sensors, including configurations that are the same or similar to those described with respect to the first set of embodiments. As an example, the main PCB 1782 of the second set of embodiments may, in some embodiments, include electrode pairs similar to those described in the first set of embodiments (e.g., electrodes 122a and 122b, 123a and 123b, etc., as shown in FIG. 9B ). The main PCB 1782 may include one, two, three, or more sets of such electrode pairs.

[0071] FIG. 21A shows a top perspective view of a main PCB 2082 according to a third set of embodiments, while FIG. 21B shows a bottom perspective view of the same PCB 2082. FIGS. 22A and 22B show top and bottom views, respectively, of the same PCB. Like the above-described main PCB 82 of the first set of embodiments, the main PCB 2082 may also be positioned in the end portion 39, as illustrated in FIG. 8. Also like the above-described main PCB 82 of the first set of embodiments, the main PCB 2082 defines an opening 2003 (similar to opening 83 of PCB 82) configured to receive the injection needle 34 of the syringe assembly 22 therethrough. The main PCB 2082 includes a top surface 2082 a and a bottom surface 2082 b (the top surface 2082 a and the bottom surface 2082 b are understood to be parts of the PCB 2082). The top surface 2082 includes or supports a power source 2002, which in some embodiments may include a battery, such as a coin cell battery. The power source 2002 provides power to electrical components integrated with or coupled to the injection device 20. A battery door (not shown) in the housing 38 may hinge or swing open to allow access to the power source 2002. The main PCB 2082 may also include a processing circuit 2008, which may be configured similarly to the processing circuit 108 described above.

[0072] Main PCB 2082 may optionally differ in some respects from main PCB 82 (first set of embodiments) and main PCB 1782 (second set of embodiments).

[0073] First, the main PCB 2082 may not include either the secondary PCB 84 or the syringe position detector switch 1710. The position of the syringe assembly 22 may be detected using other methods (e.g., using an accelerometer), eliminating the need for the secondary PCB 84 and / or the syringe position detector switch 1710. Eliminating the secondary PCB 84 and / or the syringe position detector switch 1710 may reduce manufacturing and assembly complexity and / or cost.

[0074] Second, the main PCB 2082 may mount or support a temperature check button 2001. This temperature check button 2001 may protrude from a port or notch (not shown) on the housing 38 of the device 20. As discussed in more detail below, this button 2001 may be a physical button that, when activated by a user, sends an electrical and / or digital signal that causes the processing circuit 2008 to power up, check the temperature of the device 20, and indicate to the user whether the device 20 is at the correct temperature for administering medication.

[0075] Third, instead of using an NFC or BLE trace antenna disposed on the top and / or bottom surface of the PCB, the NFC or BLE connection may be provided by one or more chip antennas 2004 mounted on the PCB 2082. Such chip antennas 2004 may receive signals from the processing circuit 2008 that cause the antenna to send wireless communications to an external device. While FIG. 21A illustrates only one chip antenna 2004, some embodiments of the third set of embodiments may include two or more chip antennas, e.g., one BLE chip antenna and a separate NFC chip antenna. In some embodiments, the processing circuit 2008 may itself include an integrated BLE antenna, while the chip antenna 2004 may include an NFC antenna. Some embodiments of the third set of embodiments may also use a PCB trace antenna (similar to that discussed above for the first set of embodiments) instead of a chip antenna.

[0076] Fourth, the main PCB 2082 may include a base cap removal sensor 2010 that enables the processing circuit 2008 to detect whether the base cap 36 is attached to the housing 38 or removed by a user. The base cap removal sensor 2010 may be communicatively or electrically coupled to the processing circuit 2008. FIGS. 23A and 23B provide more detailed perspective views of the base cap removal sensor 2010. The sensor 2010 comprises a base 2302 that supports a first arm 2304 and a second arm 2306. The base 2302 may be coupled to the PCB and may be circumferentially disposed along a proximal surface of the PCB. The arms extend proximally away from the base 2302 and may be in a parallel relationship to one another. The first arm 2304 is connected to a horizontal lever 2310. In one example, the arm 2304 and the lever 2310 form an L-shape and may be unitary. The lever 2310, in turn, supports an angled tab 2308 and a first contact surface 2309. The surface 2309 may be angled and extend distally and / or radially inward from the lever 2307. The tab 2308 is shown depending from the lever 2310 and disposed between the arms 2304 and 2306. The tab 2308 may include an angled portion that extends radially inward toward the longitudinal axis 48. The lever 2310 is shown as having a multi-planar structure, with a first portion contiguous with the arm 2304 lying along a first radial plane and a second portion contiguous with the contact surface 2309 lying along a second radial plane that is further from the longitudinal axis 48 than the first radial plane. The second arm 2306 is connected to the second contact surface 2307. The contact surface 2307 may be angled from the body of the arm 2306 and may extend proximally and / or radially outward at some angles. The contact surfaces 2307, 2309 are shaped and configured to be in contacting relationship in one configuration, such as when the base cap is removed, and in a separated configuration in another configuration, such as when the base cap is attached, or vice versa. The first arm 2304, the second arm 2306, and the tabs and contact surfaces attached on both arms may be formed from metal or any other suitable flexible and conductive material.

[0077] FIG. 24A shows the PCB 2082 and base cap removal sensor 2010 in relation to the end cap 36 when the end cap 36 has been removed from the rest of the device 20. For clarity, the housing 38 that surrounds and supports the PCB 2082 has been removed. When the sensor 2010 is mounted on the PCB 2082, the angled tab 2308 faces inward toward the longitudinal axis 48. The end cap 36 includes an internal tab 2402. The end cap 36 can be attached to the housing 38 by moving the end cap 36 in the direction of arrow 2404. FIG. 24B shows the PCB 2082 and end cap 36 when the end cap 36 is attached. When the end cap 36 is attached, the internal tab 2402 extends upward through the opening 2003 in the PCB 2082 and presses against the angled tab 2308. This forces the angled tab 2308 and the horizontal lever 2310 to which it is attached radially outward in the direction of arrow 2406 .

[0078] 25A and 25B show the base cap removal sensor 2010 as viewed along axis 2312 in FIGS. 23A and 23B. FIG. 25A shows the base cap removal sensor 2010 when it is in its neutral state, e.g., when the end cap 36 has been removed and therefore the internal tab 2402 is not in contact with any portion of the sensor 2010. When the sensor 2010 is in this neutral state, the first contact surface 2309 is biased into contact with the second contact surface 2307 by the horizontal lever 2310. Contact between the first contact surface 2309 and the second contact surface 2307 completes an electrical circuit between the first arm 2304 and the second arm 2306. When the processing circuit 2008 detects that this electrical circuit has been formed, the processing circuit 2008 can determine that the end cap 36 has been removed.

[0079] 25B shows the base cap removal sensor 2010 when the end cap 36 is installed. When the end cap 36 is installed, the internal tab 2402 contacts and presses against the angled tab 2308 of the sensor 2010. This pressing force displaces the angled tab 2308, as well as the horizontal lever 2310 to which the angled tab 2308 is attached, outward in the direction of arrow 2406. This causes the first contact surface 2309 to move relative to the stationary second contact surface 2307, removing it from contact with the second contact surface 2307, thereby breaking the electrical circuit between the first arm 2304 and the second arm 2306. When the processing circuit 2008 detects that this electrical circuit has been broken, the processing circuit 2008 can determine that the end cap 36 is installed.

[0080] Fifth, instead of using electrodes to detect skin contact by measuring electrical resistance (as in the first and second sets of embodiments), the main PCB 2082 instead uses two capacitive pads 2022 and 2023 to detect skin contact. The pads 2022 and 2023 are shown as separate planar structures disposed along the distal surface of the PCB. The capacitive pads 2022 and 2023 may be configured to detect the proximity of human tissue by measuring the effect of such tissue on the electric field generated by the sensor, e.g., by measuring the effect of such human tissue on the capacitance of an electrical circuit being monitored or measured by the sensor. Because capacitive sensors do not require metallic electrical terminals that directly contact skin tissue, they may be partially or completely encapsulated behind a protective non-conductive cover (e.g., plastic, etc.). This may improve the durability of the capacitive sensor by reducing the penetration of moisture or foreign matter into sensitive electrical components. Because capacitive sensors do not require exposed metal contacts, they may also reduce the risk of electrostatic discharge damaging sensitive electrical components within the device. Capacitive pads 2022 and 2023 may each independently detect contact with skin tissue, allowing processing circuit 2008 to determine when one pad has detected contact but the other has not. While Figures 21B and 22B illustrate only two capacitive pads 2022 and 2023, other embodiments in the third set of embodiments may have fewer or more capacitive pads. For example, main PCB 2082 may include only a single capacitive pad, or may have three, four, five, six, or more capacitive pads.

[0081] Sixth, the third set of main PCB 2082 in this embodiment includes an accelerometer 2012 that detects the impact or acceleration caused by the initiation of a dispense event in which syringe assembly 22 is driven by drive mechanism 24 from the retracted position to the injection position. Accelerometer 2012 may also detect the impact or acceleration caused by the retraction motion upon completion of a dispense event in which syringe assembly 22 is driven by retraction mechanism 26 from the injection position to the retracted position. Accelerometer 2012 may send an output signal to processing circuit 2008 via one or more electrical connections to enable the processing circuit to analyze the output signal.

[0082] FIG. 26 illustrates a graph showing an exemplary signal output from the accelerometer 2012 according to a third set of embodiments. The vertical y-axis of the graph 2600 illustrates the magnitude of the signal in volts. The x-axis of the graph 2600 illustrates the passage of time, e.g., in units of seconds. In this example, the signal from the accelerometer 2012 is centered around a voltage of approximately 1.75 V. This 1.75 signal may represent a constant downward gravitational acceleration. Deviations around this constant value indicate accelerations or shocks (other than gravity) applied to or received by the device 20 and detected by the accelerometer 2012 mounted on the main PCB 2082. For example, accelerations, vibrations, or shocks caused by the removal of the base cap 36 (indicated by reference numeral 2062) or the unlocking of the activation button 52 (indicated by reference numeral 2064) may be detected by the accelerometer 2012.

[0083] In some embodiments, processing circuit 2008 may analyze signals output from accelerometer 2012 to determine a particular condition or state of device 20 or to detect the occurrence of a particular event or action. For example, processing circuit 2008 may analyze the output signals to discern when base cap 36 has been removed (e.g., as indicated by a signal at 2062) or when activation button 52 has been unlocked (e.g., as indicated by symbol 2064). Processing circuit 2008 may also be configured to determine when a dispense event has begun or completed based on signals from accelerometer 2012, either alone or in conjunction with signals from one or more skin contact sensors.

[0084] When a dispense event is initiated, drive mechanism 24 is actuated to drive syringe assembly 22 from the retracted position to the injection position. This drive motion imparts one or more accelerations that can be detected in a signal output from accelerometer 2012. For example, the pushing force exerted by drive mechanism 24 as it drives syringe assembly 22 proximally from the retracted position may cause accelerometer 2012 to detect a distal acceleration along longitudinal axis 48. When syringe assembly 22 hits its stop position at its injection position at the end of this drive motion, the sudden stop of syringe assembly 22 may cause accelerometer 2012 to detect a proximal acceleration along longitudinal axis 48. Either this proximal or distal acceleration (or both) may cause accelerometer 2012 to output a first acceleration spike (indicated by numeral 2606) that can be detected by processing circuit 2008. This first acceleration spike may indicate the start of a dispense event.

[0085] Similarly, when the dispense event is completed, retraction mechanism 26 is actuated to drive syringe assembly 22 from the injection position to the retracted position. This driving motion imparts one or more accelerations that may also be detected in the signal output from accelerometer 2012. For example, the pushing force exerted by retraction mechanism 26 as it drives syringe assembly 22 distally from the injection position may cause accelerometer 2012 to detect an acceleration in the proximal direction along longitudinal axis 48. Once the syringe assembly reaches the retracted position, a sudden stop of syringe assembly 22 may cause accelerometer 2012 to detect an acceleration in the distal direction along longitudinal axis 48. Either this proximal or distal acceleration (or both) may cause accelerometer 2012 to output a second acceleration spike (indicated by numeral 2068) that may be detected by processing circuit 2008. This second acceleration spike may indicate the completion of the dispense event. As used herein, an "acceleration spike" is defined as any artifact in the acceleration or vibration signal output by an accelerometer or vibration sensor (e.g., a piezoelectric sensor) that indicates the start and / or completion of a dispense event.

[0086] Seventh, instead of measuring the temperature of the medicament within the barrel 30 using an IR sensor 120 mounted on the secondary PCB 84 (as shown and described in FIGS. 8 and 9A ), the third set of main PCBs 2082 of this embodiment utilizes a temperature sensor 2025 mounted directly on the main PCB 2082 to estimate the temperature of the medicament. This temperature sensor may be communicatively or electrically coupled to the processing circuit 2008 and output a temperature output signal that is received and analyzed by the processing circuit. In one example, the temperature sensor 2025 is mounted on a distal surface of the PCB and, in some examples, is circumferentially spaced from the pads 2022, 2023. By using a temperature sensor 2025 mounted directly on the main PCB 2082 and eliminating the secondary PCB 84 entirely, the third set of main PCBs 2082 of this embodiment reduces manufacturing and assembly cost and complexity.

[0087] The temperature sensor 2025 may include any of several types of temperature sensors that may be mounted on a PCB, 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. The temperature sensor 2025 may be configured and positioned to measure the temperature of the thermal ballast. The thermal ballast may include all or a portion of the silicon substrate of the main PCB 2082 itself. Alternatively, the thermal ballast may include a suitable heat sink constructed from another material (e.g., a polymer) that is mounted on the main PCB 2082. The thermal ballast may be in contact with or surround all or a portion of the temperature sensor 2025.

[0088] The material, size, shape, and location of the thermal ballast are determined so that the thermal ballast is able to adjust the thermal time constant (τ drug ) thermal time constant (τ ballast ) As used herein and in the claims, the "thermal time constant (τ)" of a body (such as of a thermal ballast or of an agent within barrel 30) should be understood to be a constant that satisfies Equation 1 below:

[0089]

number

[0090] In other words, the thermal time constant τ of a body characterizes how quickly the body's temperature adjusts to match the ambient temperature of its environment, with a high thermal constant meaning that the body's temperature adjusts quickly and a low thermal constant meaning that the body's temperature adjusts slowly. Hence, the thermal time constant (τ) of a thermal ballastballast ) is the thermal time constant (τ drug ), the temperature of the thermal ballast may be assumed to rise and fall to match the ambient temperature at approximately the same rate as the temperature of the medication. Because the thermal ballast may be attached to the main PCB 2082, the thermal ballast will generally be exposed to the same ambient temperature as the medication in the barrel 30. Therefore, the processing circuit 2008 may estimate the temperature of the medication in the barrel 30 by measuring the temperature of the thermal ballast and assuming that the temperature of the medication in the barrel 30 is equal to the measured temperature. Thus, the third set of main PCBs 2082 in this embodiment may estimate the temperature of the medication in the barrel 30 without requiring an infrared (IR) sensor or other type of temperature sensor to be located immediately adjacent to (or in physical contact with) the barrel 30. This reduces the cost and complexity of manufacturing and assembly, and also reduces the space and form factor requirements of the device 20.

[0091] In some embodiments, the material, size, shape, and / or location of the thermal ballast may be adjusted to reduce τ ballast is τ drug In other embodiments, the material, size, shape, and / or location of the thermal ballast may be selected to be within 10% of τ ballast is τ drug In some embodiments requiring that the temperature of the drug be determined with high accuracy, the material, size, shape, and / or location of the thermal ballast may be selected to be within 5% of τ ballast is τ drug In yet other embodiments, the material, size, shape, and / or location of the thermal ballast may be selected so that the temperature of the ballast is always within a certain degree (e.g., + / - 2°C, or + / - 5°C) of the drug in barrel 30 when both the ballast and drug are brought from a first, relatively low storage temperature (e.g., 36-46°F, or 2-8°C) to a second, relatively high temperature (e.g., room temperature, or 65-75°F, or 18-24°C).

[0092] FIG. 27 provides a system architecture diagram of electrical components within device 20 according to a third set of device 20 embodiments. Some or all of these components may be mounted on main PCB 2082, previously illustrated in FIGS. 21A, 21B, 22A, and 22B. As previously discussed and illustrated in the above figures, these electrical components may include processing circuitry 2008. In some embodiments, processing circuitry 2008 may take the form of a Bluetooth Low Energy (BLE) system-on-chip (SOC). Such a BLE SOC may include a chip that includes computational circuitry (e.g., a miniprocessor or arithmetic logic unit (ALU)), on-board memory (e.g., a non-transitory computer-readable medium such as volatile or non-volatile memory) used to store programming instructions executed by the computational circuitry, and a BLE antenna 2714. Processing circuitry 2008 is configured to control and coordinate the functions of the electrical components illustrated in FIG. 27.

[0093] According to a third set of embodiments, the processing circuit 2008 may be powered in one of two ways: it may receive power from the battery 2002 via a battery enable circuit 2718, or it may receive power from the battery 2002 via a power latch circuit 2716. The battery enable circuit 2718 may be one or more physical circuits that route power from the battery 2002 to the processing circuit 2008 when certain conditions are met, and that cut off power to the processing circuit 2008 when those conditions are not met. In other words, the battery enable circuit 2718 may both power up and power down the processing circuit 2008 depending on the sensed conditions. For example, in some embodiments, the battery enable circuit 2718 may route power to the processing circuit 2008 when either of two conditions is met: (i) the base cap removal sensor 2010 detects that the base cap 36 has been removed, and / or (ii) the temperature check button 2001 mounted on the main PCB 2082 is pressed and held down by a user, or the temperature check button 2001 has been pressed within a specific period of time in the past, e.g., within the past 45 minutes. The battery enable circuit 2718 may also route power to the processing circuit 2008 when both conditions are met. In some embodiments, the battery enable circuit 2718 may only consider condition (i) or (ii) and not the other of condition (ii) or (i). The battery enable circuit 2718 may also be configured to consider other conditions, such as device orientation, sensed shock or acceleration, or temperature, in addition to or instead of the conditions discussed above. If none of the conditions are met, the battery enable circuit 2718 may be configured to cut off power to the processing circuit 2008.

[0094] The power latch circuit 2716 may be one or more physical circuits that receive an output signal from the processing circuit 2008 via a general purpose input / output (GPIO) pin. The power latch circuit 2716 may be configured to route power from the battery 2002 to the processing circuit 2008 upon receiving a “power latch” signal from the processing circuit 2008 via the GPIO pin. This power latch signal may be a simple voltage high or voltage low, or may be a more complex coded signal that includes multiple voltage highs and / or voltage lows. Once the power latch circuit 2716 receives the power latch signal, the power latch circuit 2716 will “latch,” meaning that it will continue to route power from the battery 2002 to the processing circuit 2008 regardless of whether the power latch circuit 2716 continues to receive the power latch signal. In other words, once the power latch circuit 2716 is latched, power will continue to be supplied to the processing circuit 2008 until the battery 2002 runs out (or a timer indicating the expected battery life of the battery 2002 expires, thereby indicating that the battery 2002 is about to run out). The processing circuit 2008 can be configured to send a power latch signal to the power latch circuit 2716 under different circumstances, depending on the embodiment.

[0095] While the battery enable circuit 2718 and the power latch circuit 2716 may take the form of one or more physical circuits that perform the functions described above, they may also take the form of software or hardware instructions stored on a non-transitory computer-readable medium (e.g., non-volatile memory) that, when executed by a processing circuit, perform the functions described above. For example, the main PCB 2082 may be fitted with a secondary low-power processor that is separate and apart from the processing circuit 2008 and that determines when to power the processing circuit 2008 from the battery 2002.

[0096] The processing circuit 2008 may also be connected to an internal integrated circuit (I2C) bus 2724. The I2C bus may in turn be communicatively coupled to multiple electrical components, including the NFC circuit 2004, one or more touch sensors 2706, an accelerometer 2012, and a battery gauge 2710.

[0097] The NFC circuitry 2004 may include an NFC antenna and on-board non-volatile memory and may support both passive and active NFC communication. Passive NFC communication occurs when the NFC circuitry 2004 communicates with an external device while the NFC circuitry 2004 is not powered, and the NFC circuitry 2004 relies solely on power provided wirelessly by the external device. Active NFC communication occurs when the NFC circuitry 2004 communicates with an external device while powered by an internal power source, e.g., battery 2002. In embodiments in which the NFC circuitry 2004 supports active NFC communication, the NFC circuitry 2004 may be coupled to the battery 2002. The NFC circuitry 2004 may also be configured to store data and / or programming instructions received via its NFC antenna on its on-board non-volatile memory in a passive manner, i.e., without being powered by the battery 2002.

[0098] Touch sensor 2706 may take the form of capacitive pads 2022 and 2023, as previously shown and described in Figures 21B and 22B. However, touch sensor 2706 may also take the form of any other type of sensor configured to detect contact with skin tissue, including electrical resistance sensors 122, 123, and 124 previously shown and described in Figure 9B and / or electrical resistance sensors 1722, 1723, and 1724 previously shown and described in Figure 17B. In other words, touch sensor 2706 is not limited to the touch sensors described in connection with the third set of embodiments, but may include some or all of the skin contact sensor features described in connection with the first and second sets of embodiments.

[0099] Accelerometer 2012 may take the form of any circuit configured to detect shock, vibration, and / or acceleration associated with the initiation and / or completion of a dispense event, as described above. For example, accelerometer 2012 may take the form of an accelerometer configured to detect acceleration along one, two, or three axes, or may take the form of a piezoelectric vibration sensor.

[0100] The battery gauge 2710 may be a physical circuit, software, and / or firmware that monitors the remaining power stored in the battery 2002 and reports this remaining power level to the processing circuit 2008.

[0101] The processing circuit 2008 may also be coupled to other electrical components via channels other than the I2C bus 2724. For example, the processing circuit 2008 may be coupled to the above-mentioned temperature sensor 2025 via an analog input pin. The processing circuit may also be coupled to a watchdog integrated circuit (IC) 2722 via a GPIO pin. The watchdog IC 2722 may be an integrated circuit including a continuously running counter. The integrated circuit may be configured to reset or restart the processing circuit 2008 if the counter expires (e.g., by sending a "reset" signal or by interrupting power to the processing circuit 2008). The counter may be reset by a check-in signal from the processing circuit 2008. The processing circuit 2008 may then be configured to periodically send a check-in signal to the watchdog IC 2722. A watchdog IC 2722 configured in this manner helps ensure that the processing circuit 2008 does not accidentally become stuck in a programming loop. By periodically sending a check-in signal to watchdog IC 2722, processing circuit 2008 verifies that it is not stuck in an erroneous programming loop or some other fault condition. If watchdog IC 2722 has not received a check-in signal from processing circuit 2008 by the time a counter expires, watchdog IC 2722 will send a "reset" signal to processing circuit 2008 (and / or power down), causing processing circuit 2008 to restart itself.

[0102] 28 is a flowchart illustrating an exemplary process 2800 implemented by processing circuit 2008 when processing circuit 2008 receives power, according to a third set of embodiments of device 20. In this exemplary embodiment, if processing circuit 2008 stops receiving power at any time, all progress through process 2800 is lost. Therefore, when processing circuit 2008 receives power again, processing circuit 2008 restarts at the beginning of process 2008, i.e., step 2802.

[0103] Process 2800 begins at step 2802 when battery enable circuit 2718 supplies power to processing circuit 2008. As discussed above, this occurs either (i) when base cap removal sensor 2010 detects that base cap 36 has been removed, and / or (ii) when temperature check button 2001 mounted on main PCB 2082 has been pressed within a specified period of time (e.g., within the past 45 minutes) or is pressed down and held by a user. After processing circuit 2008 begins receiving power, it proceeds to step 2804.

[0104] In step 2804, processing circuit 2008 reads the universal unique identifier (UUID) and / or medication type from memory, e.g., a non-volatile, non-transitory computer-readable medium. This memory may be non-volatile memory coupled to or integrated with processing circuit 2008 and programmed during manufacture or assembly of device 20. In some embodiments, this memory may be coupled to or integrated with NFC circuit 2004.

[0105] The UUID may include a serial number or a sequence of alphanumeric symbols. Depending on the embodiment, the UUID may be unique to a particular device 20, a particular manufacturing lot of device 20 (e.g., a batch of devices manufactured on a particular assembly line on a particular day), and / or a particular device configuration. The UUID may also specify the type of medication contained within device 20. Alternatively, the memory may store a data field separate from the UUID that specifies the type of medication contained within device 20. In some embodiments, the processing circuit 2008 may also read other data and / or programming instructions from the memory.

[0106] Some or all of this data (e.g., UUID, drug type, programming instructions, and / or other data) may be stored in memory coupled to or integrated with NFC circuitry 2004 instead of processing circuitry 2008 to simplify the manufacturing and assembly process. In some embodiments, depending on the configuration of device 20, programming memory coupled to or integrated with processing circuitry 2008 may require processing circuitry 2008 to be powered on. This programming operation may consume valuable power stored in battery 2002, thus shortening the effective battery life of the completed device. On the other hand, memory coupled to or integrated with NFC circuitry 2004 may be programmed with some or all of this data via passive NFC communications without the need to draw any power from battery 2002. Thus, to conserve power, instructions to be executed by processing circuitry 2008 may be programmed into NFC circuitry 2004 via passive NFC communications during manufacturing. Then, upon power-up, processing circuit 2008 may be configured to read the stored data / instructions from the memory of NFC circuit 2004. After processing circuit 2008 reads the UUID, medication type, and / or any other data or programming instructions from memory, processing circuit 2008 proceeds to step 2805.

[0107] In step 2805, the processing circuit 2008 begins periodically broadcasting wireless signals via the BLE antenna 2714 that communicate the status of the injection device 20. These wireless signals, in some embodiments, can take the form of BLE advertisement packets, although other types of wireless signals and wireless protocols can also be used. The wireless signals can be broadcast at specific periodic intervals, such as once per second or once per five seconds, and can include: (i) the device's UUID; (ii) an indication of the drug type; (iii) an indication of whether the base cap is still attached to the device, whether the base cap has been removed from the device, and / or whether the base cap has been removed and reattached to the device; (iv) the amount of time (e.g., in seconds) that has elapsed since the base cap was initially removed; (v) skin contact duration (e.g., the amount of time the device was in contact with the skin); (vi) an indication of whether administration has been initiated and / or whether administration has been initiated and completed; (vii) the detected administration start time and / or the amount of time that has elapsed since an initiated administration was completed; and (viii) in some embodiments, the administration start time. (ix) the temperature sensed by the temperature sensor 2025; (x) the device orientation as measured by the accelerometer; (xi) the temperature check count, e.g., the number of times the user presses the temperature check button; (xii) the device orientation at the time of administration; (xiii) a detected fault or error condition with any or all of the temperature sensor, accelerometer, skin contact sensor, and / or base cap removal sensor; (xiv) any data derived or calculated from one or more of fields (i)-(xiii); and / or (xv) any other device or ambient conditions observed or measured by the device.

[0108] These wireless signals may be broadcast periodically by processing circuit 2008 throughout process 2800. At this point in step 2805, some or all of the fields included in the wireless signals may be null or blank until processing circuit 2008 begins receiving and processing data from device 20's on-board sensors. As processing circuit 2008 receives and processes signals from device 20's on-board sensors (e.g., base cap removal sensor 2010, touch sensor 2706, accelerometer 2012, temperature sensor 2025, etc.), it will continually update the transmitted wireless signals to reflect the device's most recent state. Processing circuit 2008 then transitions to step 2806.

[0109] In step 2806, processing circuit 2008 determines whether a medication stored in device 20 requires a temperature check based on the UUID, medication type, and / or other data and programming instructions. Certain types of medications that may be administered through device 20 may require a temperature check, while other types of medications may not require a temperature check. If the stored medication does not require a temperature check, processing circuit 2008 branches to step 2810. If the medication does require a temperature check, processing circuit 2008 branches to step 2808.

[0110] In step 2808, processing circuit 2008 checks the temperature measured by temperature sensor 2025. As noted above, this temperature may be indicative of the temperature of the medication stored within barrel 30. The sensed temperature is then included in a continuous stream of wireless signals that are periodically broadcast.

[0111] In step 2812, the processing circuit compares the measured temperature to preset thresholds to determine whether the measured temperature meets certain predefined and pre-stored ideal injection temperature parameters. For example, a measured temperature may meet ideal injection temperature parameters when it is within an ideal temperature range for injection, e.g., 65-75°F or 18-24°C. In other, simpler embodiments, the processing circuit may simply determine whether the measured temperature is above a certain minimum temperature threshold (e.g., above 65°F or 18°C) without determining whether the measured temperature is below a certain maximum temperature threshold. If the measured temperature meets ideal injection temperature parameters, the processing circuit 2008 branches to step 2814 and sets an indicator to notify the user of this determination. Such indicators may include one or more LEDs, a light ring, a message on a display, or a panel that slides open to reveal a message or color on the injection device body. After setting such indicators, the processing circuit 2008 branches to step 2810. If the measured temperature does not meet the ideal injection temperature parameters, processing circuit 2008 branches directly to step 2810 without setting an indicator.

[0112] In step 2810, processing circuit 2008 checks to see if touch sensor 2706 detects contact with skin tissue. If touch sensor 2706 detects contact, processing circuit 2008 branches to step 2816. If touch sensor 2706 does not detect contact, processing circuit 2008 continues to loop back to step 2810 until skin contact is detected. Again, processing circuit 2008 automatically updates the wireless signal according to the output of touch sensor 2706.

[0113] In step 2816, processing circuit 2008 reads the output of accelerometer 2012. In some embodiments of process 2800, processing circuit 2008 does not read or evaluate the output of accelerometer 2012 unless skin contact is detected. This may be accomplished by cutting off power to accelerometer 2012 unless skin contact is detected, such that accelerometer 2012 does not output any acceleration signals unless skin contact is detected. Alternatively, accelerometer 2012 may receive power and output acceleration signals even if skin contact is not detected, and processing circuit 2008 may be configured to log the time and duration of skin contact in memory, but not otherwise take action based on the output signal from accelerometer 2012 until skin contact is detected. By requiring skin contact to be detected before determining that a dispense event has been detected, processing circuit 2008 reduces the occurrence of false positives, in which processing circuit 2008 records a dispense event when one has not occurred.

[0114] In step 2818, processing circuit 2008 determines whether a dispense event has been initiated and completed based on the output of accelerometer 2012. This determination can be made by various means, and example logic for making this determination is described in further detail below in FIGS. 29, 30, 31, and 32. If a completed dispense event is not detected, processing circuit 2008 branches back to step 2810. If processing circuit 2008 determines in step 2818 that a dispense event has both been initiated and completed, processing circuit 2008 records the initiation and / or completion of the dispense event in memory. Processing circuit 2008 may also communicate the initiation and / or completion of the dispense event to a user by setting an indicator, such as one or more LEDs, a light ring, or other visual and / or audible indicator. Processing circuit 2008 then branches to step 2820.

[0115] In step 2820, the processing circuitry sends a signal to the power latch circuitry 2716, causing the power latch circuitry 2716 to latch on. As described above, once the power latch circuitry 2716 is latched on, it will continue to route power from the battery 2002 to the processing circuitry 2008 until the battery 2002 is depleted. After the power latch circuitry 2716 is latched on, the processing circuitry 2008 continues to step 2822.

[0116] In step 2822, the processing circuit 2008 starts a time since dose counter. This time since dose counter can be a counter internal or external to the processing circuit 2008 that continuously counts up at regular periodic intervals, for example, every second, every 30 seconds, or every minute. In some embodiments, the time since dose counter may start counting only when the processing circuit 2008 reaches step 2822 (or when the power latch circuit 2716 is latched on in step 2820). In other embodiments, the time since dose timer starts counting from the moment the processing circuit 2008 receives power (e.g., at the battery enable event 2802), and the processing circuit 2008 records the current value of the time since dose counter when the processing circuit 2008 reaches step 2822.

[0117] In step 2824, processing circuit 2008 updates the broadcasted wireless signal to indicate that the dispense event was successfully initiated and completed. As discussed above, the wireless signal may include the detected dose start time and / or the amount of time that has elapsed since the initiated dose was completed. In embodiments in which the time since dose counter begins counting when processing circuit 2008 reaches step 2822, the broadcasted signal may include the current value of the time since dose counter. In embodiments in which the time since dose counter counts upward continuously from the moment processing circuit 2008 receives power, the broadcasted signal may include the difference between the current value of the time since dose counter and the value of the time since dose counter when processing circuit 2008 reaches step 2822.

[0118] The periodically broadcast wireless signals may be received by an external device, such as mobile device 1250. These wireless signals allow the external device to determine the type or configuration of device 20, the type of medication administered to the patient, the temperature of the medication at the time of administration (or whether the temperature of the medication met ideal injection temperature parameters at the time of administration), and / or the amount of time that has elapsed since the medication was administered. By subtracting the amount of time that has elapsed since the medication was administered from the current absolute time (e.g., determined by a clock integrated with or in communication with the external device), the external device may also determine the absolute time that the medication was administered. For example, if the external device receives a wireless signal from device 20 indicating that the medication was administered one hour ago, and the external device's clock currently indicates that it is December 21, 2018, 2:00 PM EST, the external device may determine that the medication was administered at 1:00 PM EST on December 21, 2018, by subtracting the elapsed time (one hour) from the current absolute time.

[0119] After each broadcast, the processing circuit 2008 monitors the remaining power level of the battery 2002 via the battery gauge 2710 (step 2826). The processing circuit 2008 then compares the remaining power level to a minimum low battery threshold (step 2828). If the remaining battery power level is greater than the low battery threshold, the processing circuit 2008 branches back to step 2824 to continue broadcasting the wireless signal. If the remaining battery power level is equal to or less than the low battery threshold, the processing circuit 2008 may determine that there will soon be insufficient power to continue actively broadcasting the wireless signal. As a result, the processing circuit 2008 branches to step 2830.

[0120] In step 2830, processing circuit 2008 writes its "last state" to NFC circuit 2004. This "last state" may include information indicating (i) that a dispense event was initiated and completed, and (ii) the current value of a time-since-dose counter (e.g., X hours, minutes, or seconds) when processing circuit reached step 2830. Because NFC circuit 2004 may be interrogated even when it is not fully powered by battery 2002, writing this "last state" to NFC circuit 2004 ensures that an external device will still be able to determine at least these two pieces of information by interrogating NFC circuit 2004. In other words, the external device will still be able to determine that device 20 (i) successfully dispensed its load of medication, and (ii) that this medication was dispensed at least X hours, minutes, or seconds ago.

[0121] Process 2800 may be modified by rearranging, removing, adding, or reconfiguring certain steps. For example, in some embodiments, process 2800 may be configured to refrain from broadcasting a wireless signal until after a successful dispense event is detected, i.e., rather than before reaching step 2824. By refraining from broadcasting a wireless signal before a dispense event is detected, process 2800 may conserve battery power and minimize signal interference or clutter in environments where other devices are also sending and receiving wireless signals. In some embodiments, process 2800 may not continually check battery level 2826 but may instead use a timer to determine when to write a “last state” to NFC circuit 2004 and when to shut down. Such a timer may be configured to instruct processing circuit 2008 to write a “last state” and shut down after a certain amount of time has elapsed since processing circuit 2008 was first powered on or when processing circuit 2008 first began transmitting wireless signals.

[0122] 29 illustrates an exemplary circuit diagram showing the logic for determining whether a dispense event has been initiated and completed (i.e., step 2818 of process 2800). While this logic is shown and described as a circuit diagram, it should be understood that this logic may be implemented as hardware logic circuitry, software or firmware instructions executing on a processing circuit, or some combination of hardware, software, and / or firmware.

[0123] As shown in FIG. 29 , the output signal from accelerometer 2012 first passes through a high-pass filter comprising a capacitor 2904 and a resistor 2906 connected to ground 2908. The high-pass filter is configured to filter out low-frequency acceleration signals due to gravity, but pass high-frequency signals from sharp shocks / accelerations that indicate the start or completion of a dispense event. The output of the high-pass filter is provided to a first input of a signal comparator 2912. A second input of signal comparator 2912 is connected to a reference voltage threshold 2910. Signal comparator 2912 outputs an on signal (e.g., a voltage high) when the output of the low-pass filter is greater than or equal to reference voltage threshold 2910; otherwise, signal comparator 2912 outputs an off signal (e.g., a voltage low). In other words, if an acceleration spike is detected, i.e., if the high-pass filtered signal from accelerometer 2012 is greater than or equal to reference voltage threshold 2910, the output of signal comparator 2912 is on. Otherwise, signal comparator 2912 outputs an off signal.

[0124] The output of signal comparator 2912 is coupled to a first input of AND gate 2916. A second input of AND gate 2916 is coupled to valid touch signal 2914. Valid touch signal 2914 may be turned on or off based on the output of touch sensor 2706, where an on signal may indicate that valid skin contact has been detected and an off signal may indicate that valid skin contact has not been detected. Some embodiments of device 20 having multiple skin contact sensors may require all skin contact sensors to detect valid skin contact before turning on valid touch signal 2914. Alternatively, some embodiments of device 20 may only require that one of the multiple skin contact sensors, or a designated number or designated subset of the multiple skin contact sensors, detect valid skin contact before turning on valid touch signal 2914. Therefore, the output of AND gate 2916 is on only if two conditions are met: (i) an acceleration spike is detected (i.e., the output of signal comparator 2912 is on), and (ii) valid touch signal 2914 is detected. The simultaneous occurrence of both conditions (i) and (ii) indicates that a dispense event has been initiated in which syringe assembly 22 is driven from the retracted position to the injection position by drive mechanism 24. By requiring that both conditions (i) and (ii) be met before determining that a dispense event has been initiated, this logic reduces false positive cases, where a dispense event is recorded when no dispense event has occurred.

[0125] The output of AND gate 2916 is coupled to a first input of OR gate 2918, which functions as a fire event latch. A second input of OR gate 2918 is coupled to the output of OR gate 2918. The output of OR gate 2918 remains off until the output of AND gate 2916 outputs an on signal. OR gate 2918 then stays on indefinitely until it is reset (e.g., by removing power to OR gate 2918). If the output of AND gate 2916 turns off again after turning on, the output of OR gate 2918 will stay on. Hence, OR gate 2918 is referred to as a fire event latch because it "latches" and remains on indefinitely after a fire event (e.g., the start of a dispense event) is detected.

[0126] The output of OR gate 2918 is coupled to debounce circuit 2932. Debounce circuit 2932 outputs an OFF signal until two conditions are met: (i) the fire event latch outputs an ON signal, indicating that the start of a dispense event has been detected, and (ii) the output of AND gate 2916 outputs an OFF signal. In other words, debounce circuit 2932 turns on only after the first acceleration spike, indicating the start of a dispense event, is detected, and that first acceleration spike has passed and is no longer detected. Once both conditions are met, the debounce circuit will stay on indefinitely until it is reset.

[0127] Debounce circuit 2932 includes an inverter 2920, an AND gate 2922, and an OR gate 2924. The output of AND gate 2916 is inverted by inverter 2920 before being passed to a first input of AND gate 2922. The output of the fire event latch (OR gate 2918) is passed to a second input of AND gate 2922. Therefore, the output of AND gate 2922 is on only when (i) the fire event latch output is on and (ii) the output of AND gate 2916 is off. The output of AND gate 2922 is coupled to a first input of OR gate 2924. The second input of OR gate 2924 is coupled to the output of OR gate 2924. Therefore, the output of OR gate 2924 is off until the output of AND gate 2922 is on. OR gate 2924 then stays on indefinitely until it is reset, for example, by removing power to OR gate 2924. If the output of AND gate 2922 turns on and then off again, the output of OR gate 2924 will stay on.

[0128] The output of debounce circuit 2932 is coupled to a first input of AND gate 2926. The second input of AND gate 2926 is coupled to the output of AND gate 2916. Therefore, the output of AND gate 2926 is ON only when two conditions are met: (i) debounce circuit 2932 is ON, indicating that a first acceleration spike indicating the start of a dispense event has been detected and that first acceleration spike has now passed, and (ii) the output of AND gate 2916 is ON, indicating that a second acceleration spike has been detected while valid skin contact was detected. This second acceleration spike indicates the completion of the dispense event, and syringe assembly 22 is driven by retraction mechanism 26 from the injection position to the retracted position in a retraction motion. Again, by requiring valid skin contact to be detected simultaneously with an acceleration spike before recording a retraction motion, this logic reduces false positives, where a retraction event is recorded when in fact no retraction event occurred.

[0129] The output of AND gate 2926 is coupled to a first input of OR gate 2928, which functions as a retraction event latch. The second input of OR gate 2928 is coupled to the output of OR gate 2928. Therefore, the output of OR gate 2928 remains off until the output of AND gate 2926 turns on, thus indicating the detection of a second acceleration spike indicative of retraction movement upon completion of a dispense event. Once the output of AND gate 2926 turns on, OR gate 2928 is latched to remain on indefinitely (even if the output of AND gate 2926 subsequently turns off) until reset by removing power to OR gate 2928. Thus, OR gate 2928 is referred to as a "retraction event latch" because it is latched on indefinitely after a retraction event, e.g., retraction movement in which syringe assembly 22 is driven from the injection position to the retracted position by retraction mechanism 26, is detected. The output of OR gate 2928 is coupled to dispense event output signal 2930.

[0130] Therefore, in summary, dispense event output signal 2930 turns ON and stays ON only when the following conditions are met: (i) a first acceleration spike is detected concurrently with valid skin contact, thus indicating that a dispense event has begun; (ii) that first acceleration spike has passed; and (iii) a second acceleration spike is detected concurrently with valid skin contact, thus indicating that the dispense event is complete and backward movement has been detected. When all of these conditions (i)-(iii) are met, dispense event output signal 2930 latches ON, thus indicating that the dispense event has both begun and completed. As discussed above in FIG. 28, once processing circuit 2008 determines that a dispense event has both begun and completed, processing circuit 2008 may record the start and / or completion of the dispense event in memory and may also communicate the completion of the dispense event.

[0131] 29 illustrates one exemplary means of detecting acceleration spikes that passes the accelerometer output signal through a high-pass filter and then compares the filtered signal to a reference voltage threshold, with an acceleration spike being detected if the filtered signal is greater than the reference threshold. However, it should be understood that other means of detecting acceleration spikes may also be used, either instead of or in addition to the method illustrated in FIG. 29 above.

[0132] Another exemplary process 3300 for detecting acceleration spikes is described and illustrated in Figure 33. In step 3302, processing circuit 2008 logs skin contact samples, denoted C[n], in a First-In-First-Out (FIFO) buffer. Processing circuit 2008 also logs S raw The raw accelerometer samples output from the accelerometer 2012, denoted by C[n], are logged in another FIFO buffer. In this example process 3300, C[n] and S raw [n] is a discrete digitally sampled signal. For example, C[n] may include data representing whether skin contact is detected each time touch sensor 2706 is sampled. Depending on the embodiment, C[n] may include a separate sample for each sampling time of each sensor of touch sensors, a single sample representing whether any of the sensors detected skin contact, a single sample representing whether all or a subset of the sensors detected skin contact, or other data derived or calculated from the output of one or more of touch sensors 2706. C[n] may include a binary indication of whether touch is detected or not, or data indicating the certainty of skin contact. S raw C[n] may contain the output signal from the accelerometer 2012 at each time sample. C[n] and S raw The sampling rate of C[n] may vary in different embodiments. For example, C[n] may be sampled at a rate of 20 Hz, while S[n] may be sampled at a rate of 20 Hz. raw C[n] and S[n] may be sampled at a rate of 1600 Hz. rawWhen the FIFO buffer [n] is full, the oldest sample is deleted to make room for the new sample.

[0133] In step 3304, the processing circuit 2008 raw [n] is passed through a filter such as a high-pass or band-pass filter, and then S f The filtered acceleration signal S is obtained by setting [n] equal to the magnitude of the filtered signal. f In some embodiments, the processing circuit 2008 may also further process the filtered signal to remove any detected acceleration due to the effects of gravity.

[0134] In step 3306, the processing circuitry f The integrated signal S is obtained by integrating [n]. int [n]. This integrated signal S int [n] is the S in a moving window before, after, or both before and after time n f The integrated signal S can be calculated by summing a certain number of samples [n]. int [n] may also optionally be S f It can be scaled using a scaling factor that varies according to [n]. int One exemplary means of calculating [n] is set forth in Equation 1 below.

[0135]

number

[0136] According to equation 1, S f [n] is a specific minimum acceleration signal threshold S min (e.g., 3.5Gs) int [n] will be set to 0. However, S f [n] is S min If it is greater than S int [n] is S fFirst integrate (e.g., sum) the next W samples of [n] (e.g., S f [n]+S f [n+1]+S f [n+2]...+S f [n+W]), and then multiplying the result of the integration by a scaling factor. The parameter W may be varied depending on the implementation; as an example, W may be set to 150 samples.

[0137] The scaling factor may be used to allow processing circuitry 2008 to adapt its sensitivity depending on how tightly device 20 is gripped by the user. f For example, in this embodiment, the scaling factor may be calculated based on the magnitude of the term S max -S f [n], where S max is a constant. max In some embodiments, S may be set equal to the maximum acceleration signal measurable by the accelerometer 2012 (e.g., 8 Gs). The scaling factor helps the processing circuit 2008 adapt its sensitivity to the acceleration sensed in different situations. For example, when the device 20 is tightly gripped by the user, the detected acceleration signal may be heavily attenuated, and in such a situation, the scaling factor will be larger. When the device 20 is loosely held, the detected acceleration may not be as heavily attenuated, and in such a situation, the scaling factor will be smaller. Other means of calculating the scaling factor are also possible. In general, S f Any method of calculating the scaling factor may be used where increasing [n] results in a smaller scaling factor (and vice versa).

[0138] In step 3308, processing circuit 2008 detects or logs acceleration spikes for all times n that satisfy the following condition: (1)S f [n]≧S min (2)D min ≦S int [n]≦D max (3) No acceleration spike is detected within the number N of samples prior to n.

[0139] The purpose of condition (1) is to obtain the filtered acceleration signal S f The goal is to ensure that acceleration spikes are detected only when [n] is greater than a minimum threshold (e.g., 3.5Gs).

[0140] The purpose of condition (2) is to ensure that the integrated signal S int [n] is a certain minimum threshold D min (e.g., 2.5) and a specific maximum threshold D max (e.g., 8). The values ​​2.5 and 8 are merely examples and may be changed depending on the implementation. int If [n] is too small (i.e., D min (less than 0.05), the acceleration detected in S[n] is unlikely to correspond to an acceleration spike because it is excessively transient and / or not large enough to be caused by the start and / or completion of a dispense event. int If [n] is too large (i.e., D max ), the acceleration detected in S[n] is also unlikely to correspond to an acceleration spike because the device is experiencing an acceleration force that is too large or too sustained and not caused by the initiation and / or completion of a dispense event. Such large and / or sustained acceleration may instead be caused, for example, by a user dropping device 20 onto a hard surface or device 20 being jostled during handling or transport.

[0141] The purpose of condition (3) is to ensure that once an acceleration spike is detected, processing circuit 2008 stops looking for another acceleration spike for at least N samples. For example, processing circuit 2008 may be configured to stop looking for acceleration spikes for 1 second after detecting the first acceleration spike. This reduces the occurrence of false positives, where noise or vibration from a single launch or retract event results in the detection of multiple acceleration spikes.

[0142] The process 3300 is merely illustrative and may be modified in various ways. For example, step 3304 may be implemented by converting the integrated signal S int [n] is S f S instead of [n] raw Step 3306 may be omitted, as it is calculated directly from S[n]. Step 3306 may be performed without using a scaling factor, or using a scaling factor different from that in Equation 1. int Step 3306 may also be modified by calculating S[n]. f [n] is S min For all values ​​of n, not just values ​​greater than int In some embodiments, the condition 2 may be changed by calculating S int When screening [n], the maximum threshold D max Only the minimum threshold D min Alternatively, the minimum threshold D min Only the maximum threshold D max Furthermore, S int [n] also means S after time n f In addition to or instead of integrating or summing the values ​​of [n], we can also integrate or sum the values ​​of S preceding time n. f It may be calculated by integrating or summing the values ​​of [n].

[0143] Process 3300 also includes f Only when the currently received value of [n] represents a recent peak, S int [n] is S in step 3306 fIt may be modified to be calculated by integrating (and optionally scaling) [n]. f The currently received sample of [n] represents the most recent peak when it is the highest sample received within the most recent N samples (e.g., N may be set to 1,000 accelerometer samples). f S only if [n] is the most recent peak int This requirement is calculated as S int The above conditions for calculating [n], e.g., S f [n] is S min These conditions may be imposed in addition to or instead of the above. f S only when the most recent peak value of [n] is received int By requiring [n] to be calculated, process 3300 may reduce the occurrence of false positives, where a bounce or subsequent vibration due to a device drop or impact is mistakenly identified as an acceleration spike indicating the start and / or completion of a dispense event. In other words, S does not represent a recent peak value and therefore may indicate a bounce or tapering vibration due to a device drop or impact. f [n] samples are deemed not worthy of consideration as potential acceleration spikes indicating the start and / or completion of a dispense event. min S, which is greater than but less than the recent peak f It may still be further modified so that if [n] further samples are received, the number of samples N may be extended. This means that instead of strictly considering only the last N samples when calculating the recent peak, the last few samples may be considered in S min If it is greater than , it means that the process 3300 can consider more recent samples.

[0144] Other methods of detecting acceleration spikes may also be used. For example, such acceleration spikes may be detected by analyzing the frequency components of the signal output by the accelerometer 2012, for example, by processing the output signal using a Fast Fourier Transform (FFT). If the frequency components of the accelerometer output signal exceed a preset threshold above a certain frequency threshold or within a certain frequency range, the processing circuit 2008 may determine that an acceleration spike has been detected. Yet another means of detecting an acceleration spike may be to differentiate the accelerometer output signal. If the derivative of the output signal has a magnitude greater than a certain threshold, the processing circuit may determine that an acceleration spike has been detected. In general, any process or algorithm for detecting acceleration spikes indicative of a sharp shock or vibration experienced by the device 20 may be used by the processing circuit 2008. Any of these processes or algorithms for detecting acceleration spikes may be used in the processes shown and described in FIGS. 30, 31, and 32.

[0145] 30 is a flow chart illustrating another exemplary process 3000 that may be implemented by processing circuit 2008 to detect the start and completion of a dispense event (e.g., step 2818 of process 2800) according to a third set of embodiments. Process 3000 may be similar to the logic illustrated in FIG. 29, but may differ in certain respects.

[0146] After starting at step 3002, processing circuit 2008 branches to step 3004 and evaluates whether at least one skin contact sensor (e.g., at least one, a specified number, a specified subset, or all of touch sensors 2706) detects skin contact. If so, processing circuit 2008 branches to step 3006, where the processing circuit reads or analyzes acceleration signals output by accelerometer 2012 to detect acceleration spikes. If not, processing circuit 2008 continuously loops back to step 3004 until skin contact is detected. Because processing circuit 2008 does not read or analyze signals output by accelerometer 2012 until skin contact is detected, false positives are reduced. Again, this may be accomplished by cutting off power to accelerometer 2012 so that accelerometer 2012 does not output any signals unless skin contact is detected. Alternatively, the accelerometer 2012 may receive power and output an acceleration signal to the processing circuit 2008 even if skin contact is not detected, but the processing circuit 2008 may be configured not to proceed to step 3006 unless skin contact is detected.

[0147] In step 3006, processing circuit 2008 reads or analyzes the acceleration signal output by accelerometer 2012 to detect acceleration spikes. This may be done using any of the processes or methods for detecting acceleration spikes described above. After analyzing the accelerometer output signal, processing circuit 2008 may branch to step 3008.

[0148] In step 3008, processing circuit 2008 determines whether a first acceleration spike was detected while skin contact was detected. If not, processing circuit 2008 branches back to step 3004. If yes, processing circuit branches to step 3010, where processing circuit 2008 determines that the first acceleration spike was likely caused by the start of a dispense event. Therefore, processing circuit 2008 records the start of a dispense event by setting an indicator in memory or by setting a logic circuit and proceeds to step 3012.

[0149] In step 3012, processing circuit 2008 again evaluates whether at least one skin contact sensor (e.g., at least one, a specified number, a specified subset, or all of touch sensors 2706) detects skin contact. If so, processing circuit 2008 branches to step 3014. If not, processing circuit 2008 continually loops back to step 3012 until skin contact is detected. Again, processing circuit 2008 does not read or evaluate any signal output from accelerometer 2012 until skin contact is detected.

[0150] In step 3014, the processing circuit again reads or analyzes the acceleration signal output by the accelerometer 2012 to detect acceleration spikes. This analysis may be performed using any of the methods discussed above.

[0151] In step 3016, processing circuit 2008 determines whether a second acceleration spike was detected while skin contact was detected. If not, processing circuit 2008 branches back to step 3012. If yes, processing circuit 2008 branches to step 3018, where processing circuit 2008 determines that the second acceleration spike was likely caused by a backward movement at the completion of the dispense event. Therefore, processing circuit 2008 records the completion of the dispense event and proceeds to step 3020.

[0152] In step 3020, processing circuit 2008 logs and / or communicates the initiation and completion of the dispense event. This may be done by recording the dispense event in memory and / or broadcasting a wireless signal announcing the completion of the dispense event, as described above. Alternatively or additionally, processing circuit 2008 may indicate to the user that the dispense event is complete by turning on or off one or more LEDs, by emitting a sound, or via any other visual, tactile, or audio indicator.

[0153] 31 is a flowchart illustrating another exemplary process 3100 that may be implemented by processing circuit 2008 to detect the start and completion of a dispense event (e.g., step 2818 of process 2800) according to a third set of embodiments. Process 3100 may be similar to the logic illustrated in FIGS. 29 and 30, but may differ in certain respects. In particular, process 3100 uses a timer to ensure that a second acceleration spike is detected within a preset time after a first acceleration spike is detected before the dispense event is determined to be complete. If a second acceleration spike is not detected within the preset time, processing circuit 2008 ignores or deletes the first acceleration spike. Process 3100 also reverses the order of operations discussed in FIGS. 29 and 30 such that rather than continuously monitoring for skin contact from at least one touch sensor 2706 and reading / evaluating signals from accelerometer 2012 only if skin contact is detected, process 3100 instead continuously reads / evaluates signals from accelerometer 2012 for acceleration spikes and only reads / evaluates signals from at least one touch sensor 2706 if an acceleration spike is detected.

[0154] After starting at step 3102, the processing circuit 2008 proceeds to step 3104 and continuously or periodically reads, monitors, and / or evaluates the signal output from the accelerometer 2012, regardless of whether any skin contact is detected. This differs from the logic described above in FIG. 30 , in which the processing circuit does not read, monitor, or evaluate the signal from the accelerometer 2012 until skin contact is detected. The processing circuit 2008 may analyze the signal from the accelerometer 2012 for acceleration spikes using any of the techniques discussed above. Once a first acceleration spike is detected, the processing circuit 2008 proceeds to step 3105. The processing circuit 2008 may also, optionally, log the occurrence of this first acceleration spike in memory.

[0155] In step 3105, processing circuit 2008 determines whether at least one skin contact sensor (e.g., at least one, a specified number, a specified subset, or all of touch sensors 2706) detected skin contact when the first acceleration spike was detected. If not, processing circuit 2008 branches to step 3108 to ignore the first acceleration spike or delete the memory record logging the occurrence of the first acceleration spike, and then branches back to step 3104. If yes, processing circuit 2008 branches to step 3106.

[0156] In step 3106, processing circuit 2008 determines that the first acceleration spike was caused by the initiation of a dispense event, and syringe assembly 22 is driven by drive mechanism 24 from the retracted position to the injecting position. Processing circuit 2008 also starts a timer that counts down from a preset duration, e.g., a specified number of seconds. After starting the timer, processing circuit 2008 proceeds to step 3110.

[0157] In step 3110, the processing circuit 2008 determines whether the timer has expired. If so, the processing circuit 2008 branches to step 3108. If not, the processing circuit 2008 proceeds to step 3112.

[0158] In step 3112, processing circuit 2008 continuously or periodically reads, monitors, and / or evaluates the signal output from accelerometer 2012 for a second acceleration spike, regardless of whether any skin contact is detected. If a second acceleration spike is not detected, processing circuit 2008 returns to step 3110 and evaluates whether the timer has expired. If a second acceleration spike is detected, processing circuit 2008 branches to step 3114. Processing circuit 2008 may also, optionally, log the occurrence of this second acceleration spike in memory. Thus, processing circuit 2008 continues to loop back and forth between steps 3110 and 3112 until either the timer expires (in which case processing circuit 2008 branches to step 3108) or a second acceleration spike is detected (in which case processing circuit 2008 branches to step 3114).

[0159] In step 3114, processing circuit 2008 determines whether at least one skin contact sensor (e.g., at least one, a specified number, a specified subset, or all of touch sensors 2706) detected skin contact when the second acceleration spike was detected. If not, processing circuit 2008 branches to step 3116 and either ignores the second acceleration spike or deletes the memory record logging the occurrence of the second acceleration spike, and then branches back to step 3110. If yes, processing circuit 2008 branches to step 3118.

[0160] In step 3118, processing circuit 2008 determines that the second acceleration spike was caused by backward movement at the completion of the dispense event. Processing circuit 2008 then stops the timer, logs the start and completion of the dispense event to memory, and / or communicates the start and / or completion of the dispense event to an external device or user.

[0161] 32 is a flow chart illustrating yet another exemplary process 3200 that may be implemented by processing circuit 2008 to detect the initiation and completion of a dispense event (e.g., step 2818 of process 2800) according to a third set of embodiments. Process 3200 may be similar to the logic illustrated in FIGS. 29, 30, and 31, but may differ in certain respects. In particular, process 3200 imposes a requirement that two acceleration spikes fall within a specific time window before determining that a dispense event has been initiated and completed. Process 3200 also requires that at least one skin contact sensor detects skin contact during the period between the first and second acceleration spikes before determining that a dispense event has been successfully initiated and completed.

[0162] After starting at step 3202, the processing circuit 2008 proceeds to step 3204 and continuously reads, monitors, and / or evaluates the signal output from the accelerometer 2012 for acceleration spikes. The processing circuit 2008 may analyze the signal from the accelerometer 2012 to detect acceleration spikes using any of the techniques discussed above.

[0163] In step 3206, processing circuit 2008 determines whether two acceleration spikes that fall within a specified time window have been detected. If so, processing circuit 2008 branches to step 3212; if not, processing circuit 2008 branches back to step 3204. For example, processing circuit 2008 may determine whether two acceleration spikes that fall within a specified time window have been detected. min Only if two acceleration spikes occurring more than (e.g., 1 second) apart are detected may the processing circuit 2008 branch to step 3212. Alternatively, or additionally, the processing circuit 2008 may determine a maximum time threshold T max Only if two acceleration spikes are detected that occur less than or equal to a time apart (e.g., 5-10 seconds) may the branch to step 3212. In some embodiments, the time window is set to a maximum time threshold T max , and may not include the minimum time threshold T min may be set to 0 seconds.

[0164] In step 3212, processing circuit 2008 determines whether at least one skin contact sensor (e.g., at least one, a specified number, a specified subset, or all of touch sensors 2706) detected skin contact during the period between the first and second acceleration spikes. Some exemplary criteria for evaluating skin contact are listed below: (1) Skin contact detected during the entire period between the first and second acceleration spikes. (2) Skin contact detected at some point between the first and second acceleration spikes, but for a short period of time. (3) Detected skin contact for a specified duration at some point between the first and second acceleration spikes, e.g., 1-3 seconds, or 50-100% of the period between the first and second acceleration spikes. (4) Skin contact detected only during the first acceleration spike, but for a short period of time. (5) Detected skin contact for a specified period during the first acceleration spike. (6) Skin contact detected only during the second acceleration spike, but for a short period of time. (7) Detected skin contact for a specified period until the second acceleration spike.

[0165] Depending on the embodiment, processing circuit 2008 may evaluate any detected skin contact against any one or more of the criteria (1)-(7) listed above. For example, processing circuit 2008 may maintain a log or buffer in memory of the time and / or duration of recently sensed skin contact, and then examine this log in step 3212 to determine whether there was skin contact that met the applicable criteria. If the processing circuit detects skin contact that meets the applicable criteria, processing circuit 2008 branches to step 3216. If the applicable criteria are not met, processing circuit 2008 branches to step 3204.

[0166] In step 3216, processing circuit 2008 determines that the first acceleration spike was caused by the start of the dispense event and that the second acceleration spike was caused by the backward movement at the completion of the dispense event. Processing circuit 2008 then logs the start and completion of the dispense event in memory and / or communicates the start and / or completion of the dispense event to an external device or user.

[0167] Each of processes 3000 ( FIG. 30 ), 3100 ( FIG. 31 ), and 3200 ( FIG. 32 ) have been described above as being implemented by processing circuitry 2008 within device 20. However, in some embodiments, some or all of the steps of each of these processes may be performed by or in cooperation with processing circuitry of an external device separate from device 20, such as processor 1252 of external device 1250 (see FIG. 12 ). For example, some or all of the steps of each of processes 3000, 3100, and 3200 may be performed by a processor within a mobile device (e.g., a smartphone or portable computer) or a server that receives skin contact data and accelerometer data from device 20. Such skin contact and accelerometer data may be derived from measurements or signals output from skin contact sensor 2706 and / or accelerometer 2012 and may be received via a wireless communication link between device 20 and the external device or via a network communication link (e.g., over the Internet or a cellular network). The external device may then log the completion of the dispense event in memory or in a report, notify and / or communicate the dispense event to a user, or perform other actions or steps based on the completion of the dispense event. Steps performed by the external device may be performed, for example, in real time as the data is being measured by device 20, or may be performed some time (e.g., hours, days, or years) after the skin contact and accelerometer data have been measured and recorded by device 20.

[0168] While the above description of the third set of embodiments of device 20 describes differences between this third set of embodiments and the first and second sets of embodiments above, it should be understood that the third set of embodiments may also include features present in either the first or second sets of embodiments, as well as other features. For example, certain embodiments of this third set of embodiments may include the secondary PCB 84 of the first set of embodiments, which includes some or all of the sensors described above mounted thereon. Certain embodiments of this third set of embodiments may also include the proximally extending arms 1710 a, 1710 b of the second set of embodiments.

[0169] 34 shows an exemplary sequence 3400 of user steps for using the medication injection device 20. This exemplary sequence 3400 may apply to any of the first, second, or third sets of embodiments of the device 20 described herein. The device 20 may begin at step 3402, where the device is kept at a cooler storage temperature (e.g., 36-46 degrees Fahrenheit, or 2-8 degrees Celsius) in a storage environment (e.g., a refrigerator) to protect the stored medication from degradation.

[0170] In step 3404, the user removes the device 20 from the storage environment.

[0171] In step 3406, the user may optionally press a temperature check button to wake up processing circuitry on device 20 to detect its temperature. For devices belonging to the first set of embodiments, this may be done by pressing the button to wake up processing circuitry 108 and read IR sensor 120. For devices belonging to the third set of embodiments, this may be done by pressing temperature check button 2001 and having processing circuitry 2008 read temperature sensor 2025.

[0172] In step 3408, one or more LEDs mounted on device 20 may illuminate or flash to indicate temperature status, thus indicating to the user whether the medication stored within device 20 is within an ideal temperature range for administration (e.g., at room temperature, or 65-75 degrees Fahrenheit, or 18-24 degrees Celsius). For medications that do not require a temperature check, steps 3406 and 3408 may be skipped.

[0173] In step 3410, device 20 may return to sleep to conserve battery power if no further activity is detected. Device 20 may enter sleep by powering down some or all of its electrical components or by operating some of its components in a low-power mode. For example, in some embodiments, device 20 goes to sleep by cutting off power to its processing circuitry. In some cases, power may be cut off from the processing circuitry the moment the user releases the temperature check button. In other cases, power may be cut off from the processing circuitry within a certain preset time (e.g., a few seconds or minutes) after the user releases the temperature check button. Other electrical components, such as LEDs and / or sensors, may also be powered down to conserve power.

[0174] In step 3412, device 20 detects when the user removes base cap 36. For devices belonging to the third set of embodiments, device 20 may detect that base cap 36 has been removed using base cap removal sensor 2010. This action may cause device 20 to wake up again, for example, by powering up its processing circuitry.

[0175] In step 3414, the user activates the device by pressing the device 20 against their body (e.g., the user's abdomen) and unlocking and depressing the activation button 52 on the distal end of the device 20. Unlocking and depressing the activation button 52 causes the drive mechanism 24 to drive the syringe assembly 22 from the retracted position to the injection position. For devices of the third set of embodiments, the device 20 senses contact with the user's skin and an acceleration spike associated with movement of the syringe assembly 22. As discussed above, these two sensed parameters may be interpreted by the device 20 to indicate the start of a dispensing event.

[0176] In step 3416, retraction mechanism 26 drives syringe assembly 22 from the injection position to the retracted position at the end of the dispense event. For devices of the third set of embodiments, device 20 senses contact with the user's skin and an acceleration spike associated with the retraction movement of syringe assembly 22. As discussed above, these two sensed parameters may be interpreted by device 20 to indicate the completion of the dispense event.

[0177] In step 3418, device 20 illuminates one or more LEDs mounted on the body of the device to indicate to the user that the dispense event was successfully initiated and completed.

[0178] In step 3420, device 20 repeatedly broadcasts injection data. This data may be received by an external device (e.g., mobile device 1250) and may indicate that the dispense event was successfully initiated and completed, the amount of time that has elapsed since the dispense event was completed, the type and / or configuration of device 20, the type of medication administered, or any other data or parameters sensed and / or stored by device 20. An application running on the external device may optionally confirm receipt of the data to device 20 by sending an acknowledgment message.

[0179] In step 3422, the device 20 may be disposed of in any suitable manner, for example, in a sharps container as shown.

[0180] Users of the disclosed injection devices may have varying levels of proficiency and / or experience in operating the devices. Users with a high level of proficiency and / or experience in operating the devices may require less instruction and / or supervision when dispensing medication using the disclosed devices. Conversely, users with a low level of proficiency and / or experience in operating the devices may require additional instructions and / or supervision. However, providing longer and / or more detailed instructions to all users may frustrate or tire users with a high level of proficiency and / or experience. Similarly, providing increased supervision from caregivers to all users, regardless of proficiency and / or experience level, may be unnecessarily costly because such supervision may not be required for experienced users. What is needed is a method for determining a user's level of proficiency and / or experience in properly operating the injection devices disclosed herein. This determination may enable the injection devices disclosed herein, mobile devices communicating with such injection devices, and / or caregivers to provide supplemental instructions, supervision, and / or training only to users who require such instructions or training. What is also needed is a method for assessing how a user's proficiency and / or experience level in operating the disclosed injection devices changes over time. With multiple uses, users may be expected to improve their proficiency with the disclosed devices. If a particular user does not improve their proficiency in using the disclosed devices over time, or does not improve as quickly as other users, a caregiver may provide such user with supplemental instructions, supervision, and / or training. Alternatively or additionally, if a user does not improve their proficiency over time or exhibits certain commonly repeated errors in operating the device, a caregiver, manufacturer, designer, distributor, and / or payer of such delivery devices may redesign the device and / or provide revised or supplemental instructions for use.

[0181] 35-40 illustrate various exemplary processes for gaining insight into whether a user of any of the injection devices disclosed herein has a high or low level of proficiency and / or experience in operating the injection device. Some or all of these processes may also be used to detect certain potential misuses of the injection device. Each process may be implemented on one or more processing circuits. The one or more processing circuits may be disposed entirely on the injection device (e.g., processing core 1208 within device 20, see FIG. 12), entirely on an external device in wireless communication with the injection device (e.g., processor 1252 on external device 1250 in wireless communication with device 20 via communication links 1232 and / or 1234, see FIG. 12), or may be distributed between both the injection device and the external device. In embodiments in which one or more processing circuits are distributed between the injection device and the external device, some steps of each process may be implemented on the injection device, while other steps of the process may be implemented on the external device. In some embodiments, some or all steps of each process may also be performed jointly by processing circuits on both the injection device and the external device. The processes illustrated in Figures 35-40 may be performed or implemented independently, sequentially one after the other, or in parallel with one another.

[0182] 35 is a flowchart illustrating an example process 3500 for generating an indication as to whether a user of any of the injection devices disclosed herein has a high or low level of proficiency or experience in operating the injection device. Process 3500 measures the amount of time that elapses between when one or more skin contact sensors detect contact with skin tissue and when the syringe assembly initiates a dispensing event. If the measured amount of time is greater than a threshold duration, one or more processing circuits on which process 3500 is implemented may generate a user-indicating signal indicating that the user likely has a relatively low level of proficiency or experience.

[0183] Process 3500 begins at step 3502, in which a drug delivery device is provided. One example of a suitable drug delivery device is device 20, including any of the embodiments thereof disclosed herein. The provided drug delivery device includes a device housing defining an internal volume and an opening in communication with the internal volume. The drug delivery device may include a syringe assembly disposed at least partially within the internal volume, the syringe assembly including a barrel configured to hold a medicament and an injection needle extending from the barrel, and a drive mechanism configured to move the syringe assembly from a retracted position to an injection position in which the injection needle at least partially extends from the opening. In some embodiments, as described herein, the drug delivery device may also optionally include a retraction mechanism configured to move the syringe assembly from the injection position to a retracted position.

[0184] The drug delivery device may further include one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue. Suitable skin contact sensors include both resistive and capacitive sensors, as discussed herein.

[0185] The drug delivery device may also include one or more syringe assembly sensors disposed within the device housing and configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly. In some embodiments, the syringe assembly sensors may include one or more sensors configured to determine the position of a piston that slides along the longitudinal axis of the syringe assembly barrel, such as magnetometers 112 and / or 118 configured to detect or measure a magnetic field generated by magnet 25 (see FIG. 11 ). In other embodiments, the syringe assembly sensors may include one or more sensors configured to detect the position of the syringe assembly. Suitable examples of such syringe assembly sensors include microswitch sensor 116 (see FIG. 9A ) and / or syringe position detector switch 1710 (see FIGS. 17A , 17B , 19 , and 20 ). In still other embodiments, the syringe assembly sensors may include one or more sensors configured to detect acceleration caused by the syringe assembly when the syringe assembly moves from the retracted position to the injection position or from the injection position to the retracted position. One suitable example of such a syringe assembly sensor includes an accelerometer 2012 (see FIG. 21A).

[0186] In step 3504, the processing circuit determines when one or more skin contact sensors detect contact with skin tissue. As discussed in detail herein, skin contact sensors may detect contact with skin tissue in different ways, for example, by measuring electrical resistance between two or more terminals and / or by measuring electrical capacitance. In some embodiments, step 3504 may include recording in memory a timestamp corresponding to the time when the one or more skin contact sensors detect contact with skin tissue. Alternatively or additionally, step 3504 may include starting a timer when the one or more skin contact sensors detect contact with skin tissue.

[0187] In step 3506, the processing circuit determines when the syringe assembly has initiated a dispense event. This determination may be made based on the position or movement of the piston within the barrel of the syringe assembly. For example, the processing circuit may determine that the syringe assembly has initiated a dispense event when a syringe assembly sensor detects that the piston begins to slide proximally along the longitudinal axis of the syringe assembly, or when the piston occupies a position proximal to its initial position when the syringe assembly is filled with medication. The position and / or movement of the piston may be determined using magnetometers 112 and / or 118 (see FIG. 11 ). Alternatively, or additionally, this determination may be made based on the position or movement of the entire syringe assembly. For example, the processing circuit may determine that the syringe assembly has initiated a dispense event when a syringe assembly sensor detects that the syringe assembly has moved from a retracted position to an injection position. This movement may be detected using any of the sensors or methods disclosed herein, such as microswitch sensor 116 (see FIG. 9A) and / or syringe position detector switch 1710 (see FIGS. 17A, 17B, 19, 20). In some embodiments, an accelerometer (such as accelerometer 2012, see FIG. 21A) can be used to detect impacts applied to the injection device when the syringe assembly is moved or driven from the retracted position to the injection position. Optionally, a skin contact sensor can be used in conjunction with an accelerometer to provide further accuracy in determining when the syringe assembly has initiated a dispense event; embodiments using a skin contact sensor in conjunction with an accelerometer to detect the start and / or completion of a dispense event are discussed above in connection with FIGS. 28-32. In some embodiments, step 3506 may include recording in memory a timestamp corresponding to when the syringe assembly initiated the dispense event. Alternatively or additionally, step 3506 may include stopping a timer that was started when one or more skin contact sensors detect contact with skin tissue.

[0188] In step 3508, the processing circuit measures a first duration between when the at least one skin contact sensor detects contact with skin tissue and when the syringe assembly initiated the dispense event. This measurement may be made by subtracting a timestamp corresponding to when the one or more skin contact sensors detect contact with skin tissue from a timestamp corresponding to when the syringe assembly initiated the dispense event. Alternatively or additionally, step 3508 may include reading the value of a timer that is started when the one or more skin contact sensors detect contact with skin tissue and stopped when the syringe assembly initiated the dispense event.

[0189] In step 3510, the processing circuit compares the first duration with a first preprogrammed threshold duration (e.g., 1 second, 3 seconds, 5 seconds). In step 3512, when the first duration is greater than the first threshold duration, the processing circuit may generate a first user instruction signal. The user instruction signal may indicate that the user of the drug delivery device may have a relatively low level of proficiency and / or experience with operating the drug delivery device. This is because an experienced or skilled user of a drug delivery device may be expected to initiate a dispensing event immediately after placing the delivery device against skin tissue. The fact that the user delayed initiating a dispensing event after placing the device against skin may indicate that the user spent excessive time checking and double-checking whether the device was properly placed, re-reading the instructions for using the delivery device, and / or unlocking the device to initiate a dispensing event. In some embodiments, the first user instruction signal may be generated only if the first duration is greater than the first threshold duration.

[0190] FIG. 36 is a flowchart illustrating another exemplary process 3600 for generating an indication of whether a user of any of the injection devices disclosed herein has a high or low level of proficiency or experience in operating the injection device. Specifically, process 3600 generates an indication of whether the user is able to determine when the injection device has completed a dispensing event. Some of the injection devices disclosed herein incorporate mechanical features that allow the user to know when a dispensing event is complete. For example, when the syringe assembly moves from the injection position to the retracted position at the end of a dispensing event, the user can feel an impact in their hand from the movement of the syringe assembly and hear an audible click from the movement of the syringe assembly. In embodiments in which all or part of the device housing is transparent, the user may be able to visually view the movement of the syringe assembly as it moves from the injection position to the retracted position. Experienced or skilled users who can see, hear, and / or feel any of the aforementioned mechanical indicators may be expected to remove the injection device from the injection site immediately after the dispensing event is complete. If the user does not move the injection site within a period of time after the dispensing event is completed, this may indicate that the user is either unable to see, hear, and / or feel the aforementioned mechanical indicators (e.g., due to reduced sensory acuity), does not know to look for any of the aforementioned mechanical indicators, or does not know that the aforementioned indicators indicate that the dispensing event is completed.

[0191] Process 3600 begins at step 3614, where the processing circuit determines when the syringe assembly has completed a dispense event. This determination may be made based on the position or movement of the piston within the barrel of the syringe assembly. For example, the processing circuit may determine that the syringe assembly has completed a dispense event when a syringe assembly sensor detects that the piston has completed proximal movement along the barrel of the syringe assembly, or when the piston occupies a position along the barrel that indicates the completion of a dispense event. Alternatively, or additionally, this determination may be made based on the position or movement of the entire syringe assembly. For example, the processing circuit may determine that the syringe assembly has completed a dispense event when a syringe assembly sensor detects that the syringe assembly has moved from the injection position to the retracted position. This movement of the syringe assembly may be detected using any of the sensors or methods disclosed herein, such as microswitch sensor 116 (see FIG. 9A) and / or syringe position detector switch 1710 (see FIGS. 17A, 17B, 19, 20). In some embodiments, an accelerometer (such as accelerometer 2012, see FIG. 21A ) can be used to detect impacts applied to the injection device as the syringe assembly is moved or driven from the injection position to the retracted position. Optionally, as described above, a skin contact sensor can be used in conjunction with the accelerometer to provide further accuracy in determining when the syringe assembly has completed the dispense event. In some embodiments, step 3614 can include recording a timestamp in memory corresponding to when the syringe assembly has completed the dispense event. Alternatively or additionally, step 3614 can include starting a timer when the syringe assembly has completed the dispense event.

[0192] In step 3616, the processing circuit determines when the at least one skin contact sensor stops detecting contact with skin tissue. The processing circuit may make this determination by detecting when the skin contact sensor transitions from a state in which skin contact is detected to a state in which skin contact is not detected. In some embodiments, step 3616 may include recording in memory a timestamp corresponding to the time when the at least one skin contact sensor stops detecting contact with skin tissue. Alternatively or additionally, step 3616 may include stopping a timer when the syringe assembly completes a dispense event.

[0193] In step 3618, the processing circuit measures a second duration between when the syringe assembly completes the dispense event and when the at least one skin contact sensor stops detecting contact with skin tissue. This measurement may be made by subtracting the timestamp corresponding to when the syringe assembly completes the dispense event from the timestamp corresponding to when the at least one skin contact sensor stops detecting contact with skin tissue. This subtraction operation may be implemented either on the injection device or on a mobile device that wirelessly communicates with the injection device. In some embodiments, this measurement may be made by simply reading the value of the timer that was started in step 3614 and stopped in step 3616.

[0194] In step 3620, the processing circuit compares the second duration with a second preprogrammed threshold duration (e.g., 1 second, 3 seconds, 5 seconds, 10 seconds). In step 3622, when the second duration is greater than the second threshold duration, the processing circuit may generate a second user instruction signal. The second user instruction signal may indicate that a user of the drug delivery device is unable to see, hear, and / or feel any of the mechanical indicators that may accompany the completion of a dispensing event and / or that the user does not recognize the significance of said mechanical indicators. In some embodiments, the second user instruction signal may be generated only if the second duration is greater than the second threshold duration. In other embodiments, the second user instruction signal may be generated under other circumstances. In some embodiments, the second user instruction signal may be the same signal as the first user instruction signal.

[0195] FIG. 37 is a flowchart illustrating another exemplary process 3700 for generating an indication of whether a user of any of the drug delivery devices disclosed herein has a high or low level of proficiency or experience in operating the injection device. Specifically, process 3700 determines whether a user may be misusing the drug delivery device by attempting to replace the device's base cap. For some of the injection devices disclosed herein, a user may be instructed not to remove the base cap (e.g., base cap 36) that covers the injection device's needle and then replace it without initiating and / or completing a dispensing event. This is because replacing the base cap after removal could bend or damage the injection needle. With such injection devices, it is generally desirable not to remove the base cap until just before initiating and completing a dispensing event. If the base cap is prematurely removed before an injection is needed, the entire injection device should be discarded. Thus, removing the base cap and then replacing it without initiating and / or completing a dispensing event may constitute misuse of such an injection device. Instructions for using the device may make this clear to the user, but it would be preferable to implement means for automatically detecting such misuse of the injection device.

[0196] Process 3700 begins at step 3702, in which a drug delivery device is provided. One example of a suitable drug delivery device is device 20, including any of the embodiments thereof disclosed herein. The provided drug delivery device may include a device housing defining an interior volume, the interior volume being in communication with an opening (e.g., opening 40), and a syringe assembly at least partially disposed within the interior volume. The syringe assembly may include a barrel configured to hold a medicament and an injection needle extending from the barrel. The device may further include a movable base cap (e.g., base cap 36) configured to cover the opening. The device may also include one or more syringe assembly sensors configured to detect at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly, and one or more base cap sensors configured to detect when the movable base cap is removed from the opening. Suitable examples of syringe assembly sensors include, as previously described, magnetometers 112 and / or 118, microswitch 116 and / or syringe position detector switch 1710, and / or one or more accelerometers 2012. Suitable examples of base cap sensors include base cap removal sensor 2010.

[0197] In step 3704, the processing circuit monitors data output from one or more syringe assembly sensors to detect when the syringe assembly begins or completes a dispense event. Any of the methods for determining the start and / or completion of a dispense event described herein can be used. In step 3706, the processing circuit monitors data output from the one or more base cap sensors to determine whether the base cap covers the opening.

[0198] In step 3708, the processing circuit generates a misuse indication signal when data from one or more base cap sensors indicates that the movable base cap has been removed from the opening and then subsequently replaced over the opening before the syringe assembly has begun or completed a dispense event. The misuse indication signal may indicate that a user is misusing the injection device in a way that may damage the injection needle and impair device performance. In some embodiments, the misuse indication signal may be generated only if sensors in the injection device detect that the base cap has been removed and then replaced before the syringe assembly has begun or completed a dispense event.

[0199] In other embodiments, the misuse indicator signal may also be generated under other circumstances. For example, the one or more processing circuits may also generate a misuse indicator signal if the device detects that a user attempts to replace the base cap, even after a dispensing event has been completed. In other words, in some embodiments, a misuse indicator signal may be generated if a user attempts to replace the base cap after removing the base cap, regardless of whether a dispensing event has started and / or completed. This is because, in some embodiments, a user may be instructed to dispose of the injection device in a sharps container without attempting to replace the base cap, because attempting to replace the base cap may result in an accidental needlestick. If a user attempts to replace the base cap, even after a dispensing event has been completed, the device may detect such an attempt and flag or record it as misuse of the device. In some embodiments, replacing the base cap after a dispensing event has been completed may result in the generation of a second misuse indicator signal that is different from the first misuse indicator signal.

[0200] 38 is a flowchart illustrating another exemplary process 3800 for generating an indication as to whether a user of a drug delivery device has high or low proficiency or experience in operating the injection device. Specifically, process 3800 generates a user indication signal when the injection device detects multiple instances in which the skin contact sensor detects contact with skin tissue but a dispensing event is not initiated before skin contact is broken. This may indicate that the user is uncertain about which injection site to use and places the device and lifts it off the patient's body multiple times. An experienced user is expected to make firm contact between the device and the skin at one injection site and move quickly to initiate an injection or dispensing event. The fact that multiple skin contacts are detected without an injection indicates that the user may be inexperienced or uncertain.

[0201] Process 3800 begins at step 3802 where a drug delivery device is provided. The provided delivery device may be similar to the types of devices described above in connection with step 3502 of process 3500 of FIG.

[0202] In step 3804, the processing circuit counts the number of proximity events that occur before one or more syringe assembly sensors detect the start of a dispense event. As used herein, a proximity event is defined as an event in which one or more skin contact sensors detect contact with skin tissue and then subsequently stop detecting contact with skin tissue. Once the processing circuit detects the start of a dispense event, the processing circuit may stop counting the number of detected proximity events. The start of a dispense event can be determined using any of the methods described above in connection with step 3506 of process 3500.

[0203] In step 3806, the processing circuit compares the number of approach events to a pre-programmed maximum threshold, such as one, three, five, or more events.

[0204] In step 3808, the processing circuit generates a user indication signal when the number of proximity events is greater than a preprogrammed maximum threshold. For example, the processing circuit may generate a user indication signal when the number of proximity events exceeds 0, 1, 2, 3, or 4 proximity events.

[0205] 39 is a flowchart illustrating another exemplary process 3900 for generating an indication as to whether a user of any of the drug delivery devices disclosed herein has a high or low level of proficiency or experience in operating the injection device. Specifically, process 3900 determines whether the user is likely to improperly lift off the device from the patient's skin during a dispense event. A user indication signal (indicative of a user with a low level of proficiency or experience) may be generated if the skin contact sensor detects that contact with the skin is broken during an injection, i.e., after the dispense event has begun but before the dispense event is completed. Such a premature lift off event may indicate a potentially incomplete dose, as well as an inexperienced or uncertain user.

[0206] Process 3900 begins at step 3902 where a drug delivery device is provided. The provided delivery device may be similar to the types of devices described above in connection with step 3502 of process 3500 of FIG.

[0207] In step 3904, the processing circuit determines when the syringe assembly begins a dispense event and when the syringe assembly completes the dispense event. These determinations may be based at least in part on syringe assembly sensor signals output by one or more syringe assembly sensors disposed on the drug delivery device. The start of the dispense event may be detected by the processing circuit using any of the methods described above in connection with step 3506 of process 3500. The completion of the dispense event may be detected by the processing circuit using any of the methods described above in connection with step 3614 of process 3600 of FIG. 36.

[0208] In step 3906, the processing circuit processes one or more skin detection signals from one or more skin contact sensors on the drug delivery device. The processed signals may be received after a dispense event is initiated and before the dispense event is completed, i.e., the processed signals may be received during or while the dispense event is in progress. In step 3908, the processing circuit generates a user indication signal when data indicating continuity of skin contact meets one or more preprogrammed criteria.

[0209] The processing circuit processes such signals to generate data indicative of the continuity of skin contact during a dispense event. Different measures of the continuity of skin contact may be used by the processing circuit in this step. For example, the processing circuit may count the number of lift-off events, each of which includes an event in which one or more skin contact sensors transition from a state in which skin contact is detected to a state in which skin contact is not detected. In such an embodiment, the processing circuit may generate a user indication signal if the number of lift-off events exceeds a pre-programmed maximum threshold, such as 0, 1, 2, 3, 4, or 5 lift-off events.

[0210] Alternatively or additionally, the processing circuitry may calculate a ratio of the amount of time that skin contact is detected to the amount of time that skin contact is not detected, In such an embodiment, the processing circuitry may generate a user indication signal if the calculated ratio is lower than a preprogrammed threshold.

[0211] Alternatively or additionally, the processing circuitry may calculate a ratio between the amount of time that skin contact is detected and the total duration of the dispense event, In such embodiments, the processing circuitry may generate a user indication signal if the calculated ratio is less than a preprogrammed threshold.

[0212] Alternatively or additionally, the processing circuitry may calculate a ratio between the amount of time that no skin contact is detected and the total duration of the dispense event, In such embodiments, the processing circuitry may generate a user indication signal if the calculated ratio is greater than a preprogrammed threshold.

[0213] Alternatively or additionally, the processing circuitry may generate a user indication signal when the amount of time during a dispense event during which no skin contact is detected is greater than a pre-programmed threshold.

[0214] FIG. 40 is a flowchart illustrating yet another exemplary process 4000 for generating an indication of whether a user of any of the drug delivery devices disclosed herein has a high or low level of proficiency or experience in operating the injection device. Specifically, process 4000 determines whether the user initiates a dispense event within a certain threshold time after moving the base cap. A skilled or proficient user is expected to initiate a dispense event quickly after moving the base cap. However, a user with a lower level of proficiency or experience may wait a longer time after moving the base cap to initiate a dispense event, perhaps because the user is checking or rechecking the device's instructions for use to locate an appropriate injection site on the patient's body for use or because they are unsure how to operate the device. In particular, waiting a long time after moving the base cap to initiate a dispense event may increase the risk of contamination of the exposed sterile needle. Waiting a long time may also increase the risk that the liquid formulation stored in the barrel will dry out and partially or completely block the needle, potentially preventing delivery of the drug.

[0215] Process 4000 begins at step 4002 where a drug delivery device is provided. The provided delivery device may be similar to the type of device described above in connection with step 3702 of process 3700 of FIG.

[0216] In step 4004, the processing circuit monitors data output from the one or more syringe assembly sensors to detect when the syringe assembly begins a dispense event. Any of the methods for determining the start and / or completion of a dispense event described herein can be used. In step 4006, the processing circuit monitors data output from the one or more base cap sensors to determine whether the base cap has been moved from an opening in the housing through which the needle of the syringe assembly extends when the syringe assembly is moved to the injection position.

[0217] In step 4008, the processing circuit generates a user instruction signal when the syringe assembly does not initiate a dispense event within a threshold time after the base cap is moved from the opening. This may be done by starting a timer after the base cap sensor detects that the base cap has been moved. If the processing circuit does not detect the start of a dispense event by the time the timer expires (or by the time the timer reaches a certain threshold duration), the processing circuit may generate the user instruction signal. Alternatively or additionally, the processing circuit may log a first timestamp associated with when the base cap was moved and a second timestamp associated with when the syringe assembly initiated the dispense event. The processing circuit may then calculate the difference between the first and second timestamps. If the difference is greater than the threshold duration, the processing circuit may generate the user instruction signal.

[0218] As mentioned above, each of processes 3500, 3600, 3700, 3800, 3900, and 4000 may be implemented on one or more processing circuits disposed entirely on the injection device or disposed both on the injection device and on an external device that wirelessly communicates with the injection device. In embodiments in which processes are implemented by both the injection device and the external device, various types of data may be passed between the injection device and the external device to perform processes 3500, 3600, 3700, 3800, 3900, and 4000. For example, the injection device may periodically (e.g., every second, every few seconds, or multiple times per second) send data packets to the external device containing information regarding (a) whether a dispense event has been initiated, (b) whether a dispense event has been completed, (c) whether skin contact has been detected, and / or (d) the position of the base cap (e.g., whether it is attached or removed) at the time the data packet was sent. In some embodiments, the injection device may not begin transmitting such a data packet until the base cap is removed or after the dispense event has begun. In yet other embodiments, the injection device may wait until after the injection event is completed before transmitting a data packet. In such embodiments, the data packet may include a timestamp indicating when the base cap was removed and / or when the dispense event began. Upon receiving such a data packet, the external device then executes logic to determine whether the various conditions described above for processes 3500, 3600, 3700, 3800, 3900, and 4000 are met, and if so, generates the user instruction signal or misuse indication signal described above. In some embodiments, the logic for checking whether some or all of the various conditions described above for processes 3500, 3600, 3700, 3800, 3900, and 4000 are met is implemented on one or more processing circuits within the injection device, rather than on the external device. In such embodiments, the injection device may transmit one or more data packets including the user instruction signal and / or misuse indication signal described above.

[0219] Each of the user instruction signals (and / or misuse-indicating signals) generated by each of processes 3500, 3600, 3700, 3800, 3900, and 4000 may be sent to various destinations and / or may prompt different actions or responses from the processing circuit or from devices in communication with one or more processing circuits. Some of the aforementioned user instruction signals and / or misuse-indicating signals may be the same signal or may trigger the same response from one or more processing circuits. In some embodiments, each of these signals may cause one or more processing circuits to display or play instructions on how to properly use the injection device. For example, in process 3500, a first user instruction signal may prompt a mobile application on the user's mobile device (e.g., external device 1250) to display a screen showing instructions, or provide the user with one or more instructional video or audio messages on how to unlock, position, and activate the drug delivery device. Similarly, the second user instruction signal in process 3600 can prompt the mobile application to display a screen and / or message on how to communicate when the drug delivery device has completed a dispensing event. The misuse instruction signal in process 3700 may prompt the mobile application to display a screen and / or message warning the user that replacing the base cap after removing it may damage the needle, and / or advising the user that once the base cap is removed, they should activate the drug delivery device immediately thereafter. In some embodiments, the user instruction signal and / or misuse instruction signal may cause the user's mobile device to display a suggestion or prompt to put the user in contact with a help desk agent (e.g., via a phone line or chat line). The user instruction signal and / or misuse instruction signal may also prompt the injection device itself to provide additional instructions, such as via one or more pre-recorded audio messages played through a speaker attached to the injection device.

[0220] Alternatively or additionally, the user instruction signal and / or misuse indication signal may be transmitted over a network (e.g., via the Internet or a cellular network) to a remote server or device, for example, in the form of a text message, push notification, email, or other remote electronic notification. The remote server or device may be associated with a care provider to the user, such as a nurse, nurse practitioner, doctor, family member, or other care provider. In such cases, the user instruction signal and / or misuse indication signal may indicate to the care provider that the user may need additional supervision or assistance in using the drug delivery device. In yet other embodiments, the remote server or device may be associated with a manufacturer, designer, distributor, or payer of the injection device. In such cases, the user instruction signal and / or misuse indication signal may provide such entities with real-world evidence regarding how users are using the injection device. When aggregated across a population of injection device users, such real-world evidence can inform decisions regarding whether to reimburse such injection devices (and if so, at what rate and under what conditions), whether / how to redesign such injection devices, and / or whether additional instructions or training are required for effective use. User-indicative signals and / or misuse-indicative signals may also be recorded and tracked over time for individual users or groups of users. Ideally, the occurrence of user-indicative signals and / or misuse-indicative signals should decrease over time as users become more familiar and / or proficient with the injection device. If the occurrence of such signals does not decrease, or does not decrease as rapidly as expected, the injection device manufacturer, designer, distributor, and / or payer may consider taking additional action, such as redesigning the injection device or providing additional instructions or training.

[0221] While the present invention has been described as having exemplary designs, embodiments of the present disclosure may be further modified within the concept and scope of the present disclosure. This application is therefore intended to cover any variations, uses, or adaptations of embodiments of the present disclosure using its general principles.

[0222] Several embodiments are disclosed, including but not limited to the following. [Aspect 1] a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue; and a skin contact sensor disposed within the housing and configured to detect at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly. one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on one or more of the one or more skin contact sensors; and one or more processing circuits configured to: determine when the one or more skin contact sensors detect contact with skin tissue; determine when a syringe assembly initiates a dispensing event based at least in part on the syringe assembly sensor signal; measure a first duration between when the one or more skin contact sensors detect contact with skin tissue and when the syringe assembly initiates a dispensing event; compare the first duration with a first preprogrammed threshold duration; and generate a first user instruction signal when the first duration is greater than the first threshold duration. [Aspect 2] The drug delivery system of aspect 1, wherein the syringe assembly further comprises a piston configured to slide within the barrel along the longitudinal axis to push the medication out of the injection needle, the syringe assembly sensor signal being based on the position of the piston, and the one or more processing circuits being configured to determine when the syringe assembly has initiated a dispensing event based on the position of the piston. [Aspect 3] 2. The drug delivery system of embodiment 1, wherein the drive mechanism is configured to move the syringe assembly from a retracted position to an injection position in which the injection needle extends at least partially from the opening. [Aspect 4] A drug delivery system as described in aspect 3, wherein the one or more processing circuits are configured to determine when the syringe assembly has initiated a dispensing event by determining when the syringe assembly has moved from a retracted position to an injection position. [Aspect 5] 5. The drug delivery system of embodiment 4, wherein the one or more syringe assembly sensors comprise a syringe position detector switch. [Aspect 6] 6. The drug delivery system of aspect 4 or 5, wherein the one or more syringe assembly sensors comprise an accelerometer configured to output a syringe assembly sensor signal based on a sensed acceleration caused by movement of the syringe assembly, and the one or more processing circuits are configured to determine when the syringe assembly has initiated a dispensing event based at least in part on the sensed acceleration. [Aspect 7] Aspect 7. The drug delivery system of any one of aspects 1-6, wherein at least one of the one or more processing circuits is disposed within the device housing. [Aspect 8] Aspect 8. The drug delivery system of any one of aspects 1-7, wherein at least one of the one or more processing circuits is disposed in a mobile device separate from the device housing and in wireless communication with a wireless transmitter disposed in the device housing. [Aspect 9] A drug delivery system as described in aspects 1 to 8, wherein the one or more processing circuits are further configured to display or play instructions on how to use the drug delivery system in response to the first user instruction signal. [Aspect 10] Aspect 10. The drug delivery system of any one of aspects 1-9, wherein the one or more processing circuits are configured to transmit the first user instruction signal to a remote device over a network. [Aspect 11] 11. The drug delivery system of any one of aspects 1-10, wherein the one or more processing circuits are further configured to: determine, based at least in part on the syringe assembly sensor signal, when the syringe assembly completes a dispensing event; determine when the one or more skin contact sensors stop detecting contact with the skin tissue; measure a second duration between when the syringe assembly completes the dispensing event and when the one or more skin contact sensors stop detecting contact with the skin tissue; compare the second duration to a second preprogrammed threshold duration; and generate a second user instruction signal when the second duration is greater than the second threshold duration. [Aspect 12] A drug delivery system as described in aspect 11, wherein the one or more processing circuits are further configured to display or play instructions for use regarding how to determine when the syringe assembly has completed a dispensing event in response to a second user instruction signal. [Aspect 13] 13. The drug delivery system of any one of aspects 11-12, wherein the one or more processing circuits are configured to transmit the second user instruction signal to a remote device over a network. [Aspect 14] 14. The drug delivery system of any one of aspects 1-13, wherein the barrel holds a medicament. [Aspect 15] 1. A method for generating instructions for a user of a drug delivery device, the device comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly disposed at least partially within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly ejects the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue; and a drive mechanism disposed within the device housing and coupled to at least a portion of the syringe assembly. and one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of the syringe assembly and a movement of at least a portion of the syringe assembly, the method including: determining when the one or more skin contact sensors detect contact with skin tissue; determining, based at least in part on the syringe assembly sensor signal, when the syringe assembly initiates a dispensing event; measuring a first duration between when the at least one skin contact sensor detects contact with skin tissue and when the syringe assembly initiates a dispensing event; comparing the first duration to a first preprogrammed threshold duration; and generating a first user instruction signal when the first duration is greater than the first threshold duration. [Aspect 16] 16. The method of embodiment 15, further comprising, in response to the first user instruction signal, displaying or playing instructions on how to use the drug delivery device. [Aspect 17] 17. The method of embodiment 15 or 16, further comprising transmitting the first user instruction signal to the remote device over a network. [Aspect 18] 18. The method of any one of aspects 15-17, further comprising: determining, based at least in part on the syringe assembly sensor signal, when the syringe assembly completes the dispensing event; determining when the one or more skin contact sensors stop detecting contact with the skin tissue; measuring a second duration between when the syringe assembly completes the dispensing event and when the one or more skin contact sensors stop detecting contact with the skin tissue; comparing the second duration to a second preprogrammed threshold duration; and generating a second user instruction signal when the second duration is greater than the second threshold duration. [Aspect 19] 20. The method of embodiment 18, further comprising, in response to the second user instruction signal, displaying or playing instructions regarding how to determine when the syringe assembly has completed a dispensing event. [Aspect 20] 20. The method of embodiment 18 or 19, further comprising transmitting the second user instruction signal to the remote device over a network. [Aspect 21] A non-transitory computer-readable medium storing instructions operable, when executed by at least one processing circuit, to cause the at least one processing circuit to implement a method according to any one of aspects 15-20. [Aspect 22] a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; one or more base cap sensors configured to detect when the movable base cap is removed from the opening; and one or more processing circuits configured to: determine when the syringe assembly initiates a dispense event based at least in part on the syringe assembly sensor signal; and generate a misuse indication signal when the one or more base cap sensors detect that the movable base cap has been removed from the opening and then subsequently replaced over the opening before the syringe assembly initiates a dispense event. [Aspect 23] 23. The drug delivery system of claim 22, wherein the one or more processing circuits are further configured to generate an abuse indication signal when the one or more base cap sensors detect that the movable base cap is removed from the opening and then subsequently replaced to cover the opening after the syringe assembly has initiated a dispensing event. [Aspect 24] 24. The drug delivery system of aspect 22 or 23, wherein the syringe assembly further comprises a piston configured to slide within the barrel along the longitudinal axis to force the medication out of the injection needle, the syringe assembly sensor signal being based on the position of the piston, and the one or more processing circuits being configured to determine when the syringe assembly initiates a dispensing event based on the position of the piston. [Aspect 25] 24. The drug delivery system of claim 22 or 23, wherein the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event by determining when the syringe assembly moves from a storage position to an injection position. [Aspect 26] 26. The drug delivery system of embodiment 25, wherein the one or more syringe assembly sensors comprise a syringe position detector switch. [Aspect 27] 27. The drug delivery system of aspect 25 or 26, wherein the one or more syringe assembly sensors comprise an accelerometer configured to output a sensed acceleration caused by movement of the syringe assembly, and the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event based at least in part on the sensed acceleration. [Aspect 28] Aspect 28. The drug delivery system of any one of aspects 22-27, wherein at least one of the one or more processing circuits is disposed within the device housing. [Aspect 29] 29. The drug delivery system of any one of aspects 22-28, wherein at least one of the one or more processing circuits is disposed in a mobile device separate from the device housing and in wireless communication with a wireless transmitter disposed in the device housing. [Aspect 30] A drug delivery system described in any one of aspects 22 to 29, wherein the one or more processing circuits are further configured to display or play instructions for using the drug delivery system in response to the misuse indication signal. [Aspect 31] Aspect 31. The drug delivery system of any one of aspects 22-30, wherein the one or more processing circuits are configured to transmit the misuse indication to a remote device over a network. [Aspect 32] A drug delivery system according to any one of aspects 22 to 31, wherein the one or more processing circuits are further configured to generate a second type of misuse indication signal when the one or more base cap sensors detect that the movable base cap has been removed from the opening and then subsequently replaced to cover the opening after the syringe assembly has initiated a dispensing event. [Aspect 33] Aspect 33. The drug delivery system of any one of aspects 22 to 32, wherein the barrel holds a medicament. [Aspect 34] 1. A method for generating instructions for a user of a drug delivery device, the device being a drug delivery system comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; and one or more base cap sensors configured to detect when the syringe assembly initiates a dispensing event, the method including: monitoring signals output from the one or more syringe assembly sensors to detect when the syringe assembly initiates a dispensing event; monitoring syringe assembly sensor signals from the one or more base cap sensors to determine if the base cap covers the opening; and generating a misuse indication to a user of the drug delivery system when data from the one or more base cap sensors indicates that the movable base cap has been removed from the opening and then subsequently replaced back over the opening before the syringe assembly initiates a dispensing event. [Aspect 35] 35. The method of aspect 34, further comprising: generating a misuse indication to a user when data from the one or more base cap sensors indicates that the movable base cap was removed from the opening and then subsequently replaced to cover the opening after the syringe assembly initiated a dispensing event. [Aspect 36] 36. The method of any one of aspects 34 or 35, further comprising, in response to the misuse-indicating signal, displaying or playing instructions for using the drug delivery system. [Aspect 37] 37. The method of any one of aspects 34-36, further comprising transmitting the misuse indication to a remote device over a network. [Aspect 38] Aspect 38. The method of any one of aspects 34-37, further comprising: generating a second type of misuse indication signal when the one or more base cap sensors detect that the movable base cap has been removed from the opening and then subsequently replaced over the opening after the syringe assembly has initiated a dispensing event. [Aspect 39] A non-transitory computer-readable medium storing instructions operable, when executed by at least one processing circuit, to cause the at least one processing circuit to implement a method according to any one of aspects 34-38. [Aspect 40] The drug delivery system includes a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue; and a sensor disposed within the housing and configured to detect a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly. one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of the sensor signals; and one or more processing circuits configured to: determine, based at least in part on the syringe assembly sensor signal, when the syringe assembly initiates a dispensing event; count a number of proximity events in which the one or more skin contact sensors detect contact with skin tissue and then subsequently stop detecting contact with skin tissue before the syringe assembly initiates a dispensing event; compare the number of proximity events to a pre-programmed maximum threshold; and generate a user instruction signal when the number of proximity events is greater than the pre-programmed maximum threshold. [Aspect 41] A drug delivery system as described in aspect 40, wherein the syringe assembly further comprises a piston configured to slide along the longitudinal axis within the barrel to push the medication out of the injection needle, the syringe assembly sensor signal is based on the position of the piston, and the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event based on the position of the piston. [Aspect 42] 41. The drug delivery system of embodiment 40, wherein the drive mechanism is configured to move the syringe assembly from a retracted position to an injection position in which the injection needle extends at least partially from the opening. [Aspect 43] A drug delivery system as described in aspect 42, wherein the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event by determining when the syringe assembly moves from a storage position to an injection position. [Aspect 44] 44. The drug delivery system of embodiment 43, wherein the one or more syringe assembly sensors comprise a syringe position detector switch. [Aspect 45] 45. The drug delivery system of aspect 43 or 44, wherein the one or more syringe assembly sensors comprise an accelerometer configured to output a syringe assembly sensor signal based on a sensed acceleration caused by movement of the syringe assembly, and the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event based at least in part on the sensed acceleration. [Aspect 46] Aspect 46. The drug delivery system of any one of aspects 40-45, wherein at least one of the one or more processing circuits is disposed within the device housing. [Aspect 47] 47. The drug delivery system of any one of aspects 40-46, wherein at least one of the one or more processing circuits is disposed within a mobile device separate from the device housing and in wireless communication with a wireless transmitter disposed within the device housing. [Aspect 48] A drug delivery system described in any one of aspects 40 to 47, wherein the one or more processing circuits are further configured to display or play instructions on how to use the drug delivery system in response to a user instruction signal. [Aspect 49] Aspects 49. The drug delivery system of any one of aspects 40-48, wherein the one or more processing circuits are configured to transmit user instruction signals to a remote device over a network. [Aspect 50] 50. The drug delivery system of any one of aspects 40 to 49, wherein the barrel holds a medicament. [Aspect 51] A method for generating instructions for a user of a drug delivery device, the device comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly disposed at least partially within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; and one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor detecting contact with skin tissue. and one or more syringe assembly sensors disposed within the device housing and configured to detect the initiation of a dispensing event using the syringe assembly, the method including counting a number of proximity events in which the one or more skin contact sensors detect contact with skin tissue and then thereafter the one or more syringe assemblies cease detecting contact with skin tissue before detecting the initiation of a dispensing event; comparing the number of proximity events to a pre-programmed maximum threshold; and generating a user indication signal when the number of proximity events is greater than the pre-programmed maximum threshold. [Aspect 52] 52. The method of embodiment 51, further comprising, in response to a user instruction signal, displaying or playing instructions on how to use the drug delivery device. [Aspect 53] 53. The method of embodiment 51 or 52, further comprising transmitting the user instruction signal to the remote device over a network. [Aspect 54] A non-transitory computer-readable medium storing instructions operable, when executed by at least one processing circuit, to cause the at least one processing circuit to implement a method according to any one of aspects 51-53. [Aspect 55] a syringe assembly disposed at least partially within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to output a skin detection signal when contact with skin tissue is detected; and a device housing disposed within the housing and configured to position at least a portion of the syringe assembly and the syringe assembly. and one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of: a movement of at least a portion of the syringe assembly; and one or more processing circuits configured to: determine, based at least in part on the syringe assembly sensor signal, when the syringe assembly initiates a dispense event and when the syringe assembly completes the dispense event; process one or more skin detection signals from the one or more skin contact sensors received after the dispense event has been initiated and before the dispense event has been completed to derive data indicative of continuity of skin contact during the dispense event; and generate a user indication signal when the data meets one or more pre-programmed criteria. [Aspect 56] A drug delivery system as described in aspect 55, wherein the derived data includes a number of lift-off events, each lift-off event including an event in which one or more skin contact sensors transition from a state in which skin contact is detected to a state in which skin contact is not detected, and wherein one or more processing circuits generate a user instruction signal when the number of lift-off events exceeds a preprogrammed threshold. [Aspect 57] A drug delivery system as described in embodiment 55, wherein the derived data includes a ratio of the amount of time during which skin contact is detected to the amount of time during which skin contact is not detected, and wherein the one or more processing circuits generate a user instruction signal when the ratio is below a preprogrammed threshold. [Aspect 58] A drug delivery system as described in aspect 55, wherein the derived data includes a ratio of the amount of time skin contact is detected to the total duration of the dispensing event, and wherein the one or more processing circuits generate a user instruction signal when the ratio is less than a preprogrammed threshold. [Aspect 59] the derived data includes a ratio of the amount of time during which no skin contact is detected to the total duration of the dispense event; 56. The drug delivery system of embodiment 55, wherein the one or more processing circuits generate a user-indicating signal when the ratio is greater than a preprogrammed threshold. [Aspect 60] the derived data includes an amount of time during the dispense event during which no skin contact is detected; 56. The drug delivery system of embodiment 55, wherein the one or more processing circuits generate a user instruction signal when the amount of time is greater than a preprogrammed threshold. [Aspect 61] the syringe assembly further comprising a piston configured to slide within the barrel along the longitudinal axis to expel the medication from the needle, the syringe assembly sensor signal being based on a position of the piston; A drug delivery system described in any one of aspects 55 to 59, wherein the one or more processing circuits are configured to determine when the syringe assembly starts a dispensing event and completes a dispensing event based on the position of the piston. [Aspect 62] A drug delivery system described in any one of aspects 55 to 59, wherein the one or more processing circuits are configured to determine when the syringe assembly starts a dispensing event and completes a dispensing event based on the position of the syringe assembly. [Aspect 63] 63. The drug delivery system of embodiment 62, wherein the one or more syringe assembly sensors comprise a syringe position detector switch. [Aspect 64] A drug delivery system as described in aspect 62 or 63, wherein the one or more syringe assembly sensors comprise an accelerometer configured to output a syringe assembly sensor signal based on a sensed acceleration caused by movement of the syringe assembly, and the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event and completes a dispensing event based at least in part on the sensed acceleration. [Aspect 65] A drug delivery system according to any one of aspects 55-64, wherein at least one of the one or more processing circuits is disposed within the device housing. [Aspect 66] 66. The drug delivery system of any one of aspects 55 to 65, wherein at least one of the one or more processing circuits is disposed within a mobile device separate from the device housing and in wireless communication with a wireless transmitter disposed within the device housing. [Aspect 67] A drug delivery system described in any one of aspects 55 to 66, wherein the one or more processing circuits are further configured to display or play instructions on how to use the drug delivery system in response to a user instruction signal. [Aspect 68] 68. The drug delivery system of any one of aspects 55-67, wherein the one or more processing circuits are configured to transmit user instruction signals to a remote device over a network. [Aspect 69] 69. The drug delivery system of any one of aspects 55-68, wherein the barrel holds a medicament. [Aspect 70] 1. A method for generating instructions for a user of a drug delivery device, the device comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly ejects the medicament from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent the opening, each skin contact sensor configured to detect contact with skin tissue; and a syringe assembly disposed within the device housing and configured to drive the syringe. one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the assembly and a movement of at least a portion of the syringe assembly, the method including: determining, based at least in part on the syringe assembly sensor signal, when the syringe assembly initiates a dispensing event and when the syringe assembly completes the dispensing event; processing one or more skin detection signals from the one or more skin contact sensors received after the dispensing event is initiated and before the dispensing event is completed to derive data indicative of continuity of skin contact during the dispensing event; and generating a user indication signal when the data meets one or more pre-programmed criteria. [Aspect 71] The method of embodiment 70, wherein the derived data includes a number of lift-off events, each lift-off event including an event in which one or more skin contact sensors transition from a state in which skin contact is detected to a state in which skin contact is not detected, and wherein a user indication signal is generated when the number of lift-off events exceeds a pre-programmed threshold. [Aspect 72] The method of embodiment 70, wherein the derived data includes a ratio of the amount of time during which skin contact is detected to the amount of time during which skin contact is not detected, and the user indication signal is generated when the ratio is below a preprogrammed threshold. [Aspect 73] The method of embodiment 70, wherein the derived data includes a ratio of the amount of time that skin contact is detected to the total duration of the dispensing event, and the user indication signal is generated when the ratio is below a preprogrammed threshold. [Aspect 74] The method of embodiment 70, wherein the derived data includes a ratio of the amount of time no skin contact is detected to the total duration of the dispensing event, and a user indication signal is generated when the ratio is greater than a preprogrammed threshold. [Aspect 75] The method of embodiment 70, wherein the derived data includes an amount of time during the dispensing event during which no skin contact is detected, and the user indication signal is generated when the amount of time is greater than a pre-programmed threshold. [Aspect 76] Aspect 75. The method of any one of aspects 70-74, further comprising displaying or playing instructions on how to use the drug delivery system in response to a user instruction signal. [Aspect 77] 77. The method of any one of aspects 70-76, further comprising transmitting the user instruction signal to the remote device over a network. [Aspect 78] A non-transitory computer-readable medium storing instructions operable, when executed by at least one processing circuit, to cause the at least one processing circuit to implement a method according to any one of aspects 70-77. [Aspect 79] a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; one or more base cap sensors configured to detect when the movable base cap is removed from the opening; and one or more processing circuits configured to: determine when the movable base cap is removed from the opening based on data output from the one or more base cap sensors; determine when the syringe assembly initiates a dispense event based at least in part on the syringe assembly sensor signal; and generate a user indication signal when the syringe assembly does not initiate a dispense event within a threshold time after the base cap is moved from the opening. [Aspect 80] A drug delivery system as described in aspect 79, wherein the syringe assembly further comprises a piston configured to slide along the longitudinal axis within the barrel to push the medication out of the injection needle, the syringe assembly sensor signal is based on the position of the piston, and the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event based on the position of the piston. [Aspect 81] A drug delivery system as described in aspect 79 or 80, wherein the one or more processing circuits are configured to determine when the syringe assembly initiates a dispensing event by determining when the syringe assembly moves from a storage position to an injection position. [Aspect 82] 82. The drug delivery system of embodiment 81, wherein the one or more syringe assembly sensors comprise a syringe position detector switch. [Aspect 83] 83. The drug delivery system of aspect 81 or 82, wherein the one or more syringe assembly sensors comprise an accelerometer configured to output a sensed acceleration caused by movement of the syringe assembly, and the one or more processing circuits are configured to determine, based at least in part on the sensed acceleration, when the syringe assembly initiates a dispensing event. [Aspect 84] A drug delivery system according to any one of aspects 79 to 83, wherein at least one of the one or more processing circuits is disposed within the device housing. [Aspect 85] 85. The drug delivery system of any one of aspects 79 to 84, wherein at least one of the one or more processing circuits is disposed within a mobile device separate from the device housing and in wireless communication with a wireless transmitter disposed within the device housing. [Aspect 86] A drug delivery system described in any one of aspects 79 to 85, wherein the one or more processing circuits are further configured to display or play instructions for using the drug delivery system in response to an misuse indication signal. [Aspect 87] 87. The drug delivery system of any one of aspects 79-86, wherein the one or more processing circuits are configured to transmit the misuse indication to a remote device over a network. [Aspect 88] 88. The drug delivery system of any one of aspects 79-87, wherein the barrel holds a medicament. [Aspect 89] a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; and one or more base cap sensors configured to detect when the movable base cap is removed from the opening, the method comprising: monitoring the syringe assembly sensor signals output from the one or more syringe assembly sensors to detect when the syringe assembly initiates a dispensing event; monitoring data output from the one or more base cap sensors to determine when the movable base cap has been moved from the opening; and generating a user instruction signal when the syringe assembly does not initiate a dispensing event within a threshold time after the base cap has been moved from the opening. [Aspect 90] 90. The method of embodiment 89, further comprising displaying or playing instructions for using the drug delivery system in response to the misuse indication signal. [Aspect 91] 91. The method of embodiment 89 or 90, further comprising transmitting the misuse indication to a remote device over a network. [Aspect 92] A non-transitory computer-readable medium storing instructions operable, when executed by at least one processing circuit, to cause the at least one processing circuit to implement a method according to any one of aspects 89-91.

Claims

1. 1. A method for generating instructions for a user of a drug delivery device comprising: a device housing defining an internal volume and an opening in communication with the internal volume; a syringe assembly at least partially disposed within the internal volume, the syringe assembly including a barrel configured to hold a medicament and a needle extending from the barrel; a movable base cap configured to cover the opening; one or more syringe assembly sensors configured to output a syringe assembly sensor signal based on at least one of a position of at least a portion of the syringe assembly and a movement of at least a portion of the syringe assembly; and one or more base cap sensors configured to detect when the movable base cap is removed from the opening, the method comprising: monitoring the syringe assembly sensor signals output from the one or more syringe assembly sensors to detect when the syringe assembly initiates a dispense event; monitoring data output from the one or more base cap sensors to determine when the movable base cap is moved from the opening; generating a user indication signal when the syringe assembly does not initiate the dispensing event within a threshold time after the movable base cap is moved from the opening; The method further includes transmitting the user instruction signal over a network to a remote device.

2. The method of claim 1, further comprising displaying or playing instructions for using the drug delivery system in response to the user instruction signal.

3. the syringe assembly further comprising a piston configured to slide within the barrel along a longitudinal axis to expel the medicament from the injection needle; the syringe assembly signal is based on the position of the piston; detecting the start of the dispense event based on the position of the piston; The method of claim 1.

4. The method of any one of claims 1 to 3, wherein detecting the start of the dispense event is based on determining when the syringe assembly moves from a retracted position to an injection position.

5. The method of claim 4 , wherein the one or more syringe assembly sensors comprise a syringe position detector switch.

6. the one or more syringe assembly sensors comprising an accelerometer configured to output a sensed acceleration caused by movement of the syringe assembly; detecting the start of the dispense event based at least in part on the sensed acceleration; 6. The method according to claim 4 or 5.

7. A non-transitory computer-readable medium storing instructions operable, when executed by at least one processing circuit, to cause the at least one processing circuit to implement the method of any one of claims 1 to 6.

Images