Status Sensing System for an Attached Injection Device

Abstract

A drug delivery system is described that is configured to generate an indication regarding a level of skill, familiarity, or experience of a user in operating the system. The system may include a syringe assembly, one or more skin contact sensors, and one or more syringe assembly sensors configured to detect the initiation and / or completion of a dispensing event. The system may further include one or more processing circuits configured to measure a duration between when the skin contact sensor detects contact with skin tissue and when the syringe assembly initiates a dispensing event, compare the measured duration to a threshold duration, and generate a user indication signal if the measured duration exceeds the threshold duration.

Description

Background Art

[0001] The present disclosure relates to a drug delivery device, and more particularly, to a status sensing system used in a connected drug delivery device.

[0002] Syringe-shaped or injection devices that include a syringe are widely used by medical professionals and self-administering patients. Patients suffering from several different diseases must frequently inject themselves with drugs, and various devices have been developed to facilitate such self-treatment. In one example, the use of an auto-injector device that includes a mechanism for performing some of the steps of the injection process makes self-treatment more convenient for patients, especially those with limited manual dexterity. Auto-injector 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 at least partially extends from the opening, one or more skin contact sensors disposed on the housing adjacent to the opening, each skin contact sensor being configured to detect contact with skin tissue, one or more syringe assembly sensors disposed within the housing and configured to output a syringe assembly sensor signal based on at least one of the position of at least a portion of the syringe assembly and the movement of at least a portion of the syringe assembly, and one or more processing circuits configured to determine when the one or more skin contact sensors detect contact with skin tissue, determine when the 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 to a first pre-programmed threshold duration, and generate a first user instruction signal when the first duration is greater than the first threshold duration. A drug delivery system is provided that includes the one or more processing circuits.

[0004] 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 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 has been removed from the opening, and one or more processing circuits configured to determine when the syringe assembly initiates a dispensing event based on data output from the one or more syringe assembly sensors and to 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 replaced to cover the opening before the syringe assembly subsequently initiates a dispensing event. A drug delivery system is provided that includes the one or more processing circuits.

[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 drug and a needle extending from the barrel, a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the drug from the needle when the needle at least partially extends from the opening, one or more skin contact sensors disposed on the housing adjacent to the opening, each skin contact sensor being configured to detect contact with skin tissue, one or more syringe assembly sensors disposed within the housing and configured to output a syringe assembly sensor signal based on at least one of the position of at least a portion of the syringe assembly and the movement of at least a portion of the syringe assembly, one or more processing circuits configured to determine when the syringe assembly initiates a dispensing event based at least in part on the syringe assembly sensor signal, count the number of approach events in which 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 approach events to a pre-programmed maximum threshold value, and generate a user instruction signal when the number of approach events is greater than the pre-programmed maximum threshold value. A drug delivery system is provided that includes one or more processing circuits configured to perform the above.

[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 drug and a needle extending from the barrel, a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the drug from the needle when the needle at least partially extends from the opening, one or more skin contact sensors disposed on the housing adjacent to the opening, each skin contact sensor being configured to output a skin detection signal when contact with skin tissue is detected, one or more syringe assembly sensors disposed within the housing and configured to output a syringe assembly sensor signal based on at least one of the position of at least a portion of the syringe assembly and the movement of at least a portion of the syringe assembly, and one or more processing circuits configured to determine when the syringe assembly initiates a dispensing event and when the syringe assembly completes a dispensing event based at least in part on the syringe assembly sensor signal, process one or more skin detection signals received from the one or more skin contact sensors after the dispensing event is initiated and before the dispensing event is completed to derive data indicative of the continuity of skin contact during the dispensing event, and generate a user instruction signal when the data meets one or more pre-programmed criteria. A drug delivery system is provided that includes the one or more processing circuits.

[0007] In yet another exemplary embodiment, 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 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 moved 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 dispensing event based on data output from the one or more syringe assembly sensors, and generate a user instruction signal when the syringe assembly does not initiate a dispensing event within a threshold time after the base cap is moved from the opening. A drug delivery system is provided that includes one or more processing circuits configured to perform the above. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above and other features of this disclosure, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the disclosure in conjunction with the accompanying drawings.

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[0009] Throughout the several views, corresponding reference numerals indicate corresponding parts. The illustrations described herein are illustrative of embodiments of the disclosure, but in some forms, 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.

Best Mode for Carrying Out the Invention

[0010] The present disclosure relates to a sensing system for a drug delivery device. The sensing system may be integrated within the delivery device or incorporated into a removable module that attaches to the delivery device. Such a sensing system may be configured to determine the current operating status of the device by sensing various parameters or signals representative of the operating 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 within the delivery device has been fully delivered. Such a sensing system may utilize various types of sensors such as a vision sensor that tracks the movement of the device component, an optical or radiation sensor that detects when the device component enters or exits a detection zone targeted by the sensing system, a magnetic field sensor that detects a sensed change in the 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 drug delivery device is properly oriented to deliver the drug. For example, the delivery device may warn the user or prevent drug delivery if the device is oriented upside down or in any orientation that makes safe and reliable delivery of the drug 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 pull. The sensing system may also include a processor circuit configured to determine the orientation of the device around 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 the drug stored within the drug delivery device. Certain drugs need to be stored within a first (e.g., lower) temperature range to avoid degradation, but may need to be brought to a second (e.g., higher) temperature range prior to delivery into the patient's body. The temperature sensing system may be used to monitor the temperature of the drug within the delivery device while stored and to ensure that the drug is not exposed to dangerous temperatures at which it may be rendered unfit for consumption. The temperature sensing system may also be used to warn the user when the temperature of the drug is approaching a dangerous level. When the device is ready for use, the sensing system may be used to determine when the temperature of the drug has reached the second temperature range. The drug delivery device may then notify the user that the drug is ready for delivery, for example, by using a visual indicator (e.g., by lighting and / or extinguishing one or more LEDs), an auditory indicator (e.g., an announcement or tone output from a speaker), or a wireless signal transmitted to an external mobile device and then notified to the user. Such a temperature sensing system may utilize any of a plurality of types of sensors, such as an infrared sensor or a thermistor, to measure the temperature of the drug.

[0014] In some embodiments, the sensing system can include one or more sensors configured to determine when and / or if the drug delivery device is in contact with the patient's skin. The drug delivery device can 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 can include one or more sensors configured to measure electrical resistance or capacitance, and a processing circuit 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 can be configured to determine which individual sensors of the multiple sensors are in contact with human tissue. Such a sensing system can also include a temperature sensor similar to those discussed above that is configured to determine when the sensor is in contact with human tissue.

[0015] The sensing system may determine the current operating status of the device. This current status may be communicated to the user via visual, auditory, or tactile indicators that are integrated with or physically attached to delivery devices 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, where the external device may then communicate the current status to the user. For example, in some embodiments, the drug 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 operating status of the delivery device to an external device. This external device may be an electronic computing device configured to execute software and / or firmware to receive and process the data and communicate the operating 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., smartwatches, or augmented or virtual reality devices), portable general-purpose computers (e.g., laptops), or desktop general-purpose computers. When the user is notified of the operating status of the device, the likelihood that the user will take actions that may impair the effective use of the device, such as removing the device from the injection site before completion of drug delivery or delivering the drug before the drug has warmed to the appropriate delivery temperature, is reduced. By way of example, the drug delivery device is described in the form of an auto-injector device. However, the drug delivery device may be any device used to deliver a dosage of a drug, such as a pen-type injector, an infusion pump, and a syringe. The drug may be any of the types that may 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 the needle guard present state, injection preparation state, needle insertion state, drug delivery state, and 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 requiring a change to the mechanical architecture of the drive mechanism of the delivery device.

[0017] In FIGS. 1-3, a drug injection device 20 is illustrated in various operating states. An example of such a device and its operation is described in U.S. Patent No. 8,734,394 (B2) issued to Adams et al. on May 27, 2014, 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 one or more main printed circuit boards (PCBs) 82 and / or one or more secondary PCBs 84, as shown later in FIGS. 8, 9A, 9B, 10A, and 10B, for example. The syringe assembly 22 includes a barrel 30 that forms a container body for holding a drug, and a piston 32 disposed within the barrel 30 for driving the drug outside 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 the piston 32 within the barrel 30 toward the needle 34 dispenses the drug through the needle 34.

[0018] Devices described in this specification, such as device 20, may further contain a medicament, such as within syringe barrel 30. In another embodiment, the system may include one or more devices including device 20 and a drug. The terms "medicament" or "drug" are not limited, but include 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, including, but not limited to, IL-23 antibody analogs or derivatives such as mirikizumab, IL-17 antibody analogs or derivatives such as ixekizumab, therapeutic antibodies, galcanezumab, drugs for pain-related treatment such as lasmiditan, and any therapeutic agent that can be delivered by the above-described devices, and refer to one or more therapeutic agents. A medicament as used in the device may be formulated with one or more excipients. The device is generally operated by a patient, caregiver, or healthcare professional in the manner generally described above for delivering a medicament to a human.

[0019] Figure 1 illustrates the device 20 in its initial pre-use configuration. Here, the end cap 36 is fixed to the injection device housing 38 and covers the proximal end opening 40 of the housing 38. As used herein, distal and proximal refer to the axial location relative to the 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 an injection site, and the distal end of the housing refers to the end of the housing farthest from such an injection site. The housing 38 is formed from a plastic material and can be shown to extend generally longitudinally between a distal end proximate to the actuation button 52 and a proximal end proximate to the proximal end opening 40 along the longitudinal axis 48. As shown in FIGS. 2 and 8, the housing 38 may include a user-gripable portion 37 configured to be gripped by the user's hand, and the user-gripable portion 37 extends outwardly from the longitudinal axis 48 by a radial distance 41. In some embodiments, the radial distance 41 can be 5 to 10 mm in length (e.g., in some embodiments, 5 to 8 mm can be a suitable length). Also, as shown in FIGS. 2 and 8, the housing 38 may also include an end portion 39 that extends outwardly beyond the proximal end of the housing adjacent to the proximal opening 40. The end portion extends outwardly from the longitudinal axis 48 by a radial distance 43 that is greater than the radial distance 41. In some embodiments, the radial distance 43 can be greater than 10 mm in length. For example, in some embodiments, the radial distance 43 can be 10 to 20 mm in length (e.g., in some embodiments, 15 to 20 mm can be a suitable length). The end portion 39 can smoothly slope radially outwardly from the user-gripable portion 37 as shown in FIGS. 1-3. In other embodiments, the end portion 39 may take other shapes. FIGS. 16A-16C show some exemplary alternative shapes of the end portion 39, but the end portion 39 can take any shape that extends away from the longitudinal axis 48 by a radial distance 43 that is greater than the radial distance 41 of the user-gripable portion.

[0020] The needle guard 42 is attached onto the syringe assembly 22 and covers and surrounds the needle 34. The end cap 36 and the 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 medicament, for example, when injecting a medicament into a patient, the end cap 36 and the needle guard 42 are first removed. FIG. 2 illustrates the device 20 after the end cap 36 and the needle guard 42 have been removed from the syringe assembly 22, with the syringe assembly in its retracted position and the device 20 ready for a dispensing event.

[0021] The syringe assembly 22 is movable relative to the injection device 20 between a retracted position and an injection position. FIG. 3 illustrates the device 20 after the syringe assembly 22 has been moved relative to the device 20 from its retracted position shown in FIG. 2 to the injection position. In the retracted position (FIGS. 1 and 2), the needle 34 is retracted to a position such that the needle 34 is disposed within the housing 38 of the device 20. In the injection position (FIG. 3), the needle 34 projects outwardly from the housing 38 beyond the proximal opening 40 in a proximal direction parallel to the longitudinal axis 48, whereby the needle 34 can be inserted into a patient.

[0022] The drive mechanism 24 includes a plunger 44 that engages a piston 32. The drive mechanism 24 includes a spring 46 that drives the plunger 44 in a translational motion. In an exemplary embodiment, the spring 46 advances the plunger 44 along a linear path defined by the longitudinal axis 48 of the device 20. As the plunger 44 advances, a foot 50 of the plunger 44 contacts the piston 32. As the plunger 44 further advances, the syringe assembly 22 advances along the axis 48 from its retracted position to its injection position. After the syringe assembly 22 has advanced to its injection position, continued proximal advancement of the plunger 44 advances the piston 32 within the 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 to dispense the medicament from the needle 34. Prior to any dispensing of the medicament and when the syringe barrel 30 holds the full volume of the original medicament, the piston 32 will be in its initial piston position. After advancing the piston 32 all the way to its travel length towards the needle assembly 33, the piston 32 will be in its final piston position proximate the needle assembly 33 and the medicament from within the barrel 30 will have been dispensed. For single use, the syringe assembly 22 holds a single dose of medicament to be delivered in a single dispensing event, and the piston 32 advances from its initial piston position to its final piston position during that single dispensing event, thereby delivering the entire single dose contents of the syringe assembly 22. Although the device is shown as a single use device, a multi-use device could also benefit from the status indication of the device during single use.

[0023] The advancement of the plunger 44 will generally not result in the dispensing of the drug from the syringe assembly 22 until the syringe assembly 22 advances to the injection position. There are factors that can prevent the drug from being dispensed before the syringe advances to the injection position. The factor can be the friction between the piston 32 and the barrel 30. Typically, the piston 32 is formed of a rubber material and the barrel 30 should be glass. The frictional resistance between these two components can be sufficient to prevent the forward movement of the piston 32 within the barrel 30 until the syringe assembly 22 advances to its injection position and engagement with a suitable stop member prevents further advancement of the syringe assembly 22. Additionally, the drug within the syringe can be somewhat viscous, and thus may be somewhat resistant to outflow from the needle 34. Optionally, modifications to the piston 32 and the syringe barrel 30 to vary the frictional resistance of the dispensing movement of the engagement member 32 with respect to the syringe barrel 30 can limit or prevent premature dispensing of the drug before the container 22 reaches its injection position.

[0024] The plunger 44 can include a magnet 25 adjacent to the foot 50. As shown in FIGS. 1-3, the magnet 25 is configured to maintain a certain axial distance from the piston 32. The magnet 25 emits a magnetic field that is sensed by the magnetometers 118 and 112, which will be discussed below in connection with FIGS. 9A, 9B, and 11.

[0025] To activate the drive mechanism 24, the user depresses the activation button 52 at the distal end of the device 20. Depressing the button 52 disengages one or two elongate protrusions 54 on the plunger 44 (shown in FIG. 4) from the shuttle assembly 60, thereby allowing the spring 46 to axially advance the plunger 44. The spring 46 has a helical shape and surrounds the protrusion 54. The proximal end of the spring 46 is biasedly engaged with a flange 56 on the plunger 44.

[0026] The shuttle assembly 60 can 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 fixed together in the final assembly. In the final assembly, the upper shuttle member 62 captures the button 52 and the spring 46 and restricts the 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 engages a tab on the button 52 with the incline 55 of the protrusion 54, biasing the protrusion 54 inwardly to disengage the protrusion 54 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 the plunger 44 advances, it moves the syringe assembly 22 to the injection position and then advances the piston 32 to dispense the medicament as discussed above.

[0027] When the dispensing event is complete, the retraction mechanism 26 optionally moves the syringe assembly 22 back from the injection position shown in FIG. 3 to the retracted position. More specifically, the retraction mechanism is adapted to move the drug container in a retracting motion from the injection position to the retracted position. The retracted position may be similar to the storage position in that the syringe assembly is pulled back into the housing 38, whereby the needle 34 no longer protrudes proximally from the proximal opening 40 and is fully disposed within the housing 38. In some embodiments, the retracted position may be the same as the storage position. However, in other embodiments, the syringe assembly 22 in the retracted position may be located slightly proximal or distal to the syringe assembly in the storage 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, the device 20 may not include the retraction mechanism 26 such that the syringe assembly remains unrestrictedly in its injection position until the syringe assembly is manually removed or repositioned by the user after the medicament has been dispensed.

[0028] The plunger 44 may include an outrigger 58 that unlocks the rotating member 70 as the plunger 44 approaches the end of its proximal movement. The rotating member 70 is rotatably fixed to the lower shuttle member 64 by engagement between a latch and a latch recess of the lower shuttle member 64. The outrigger 58 unlocks the member 70 by depressing the latch. The spring 66 has a torsional preload applied thereto and has one end engaged with the member 70 and an opposite end engaged with the shuttle assembly 60. When the latch is depressed, the spring 66 rotates the member 70. Referring further 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. When 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. The radial flange of the rotating member 70 may engage an overhang within the housing member 38 to limit proximal movement of the member 70. The spring 66 exerts an axial force, a torsional force, or both forces proximally on the member 70 to bias the member 70 proximally, thereby maintaining the member 70 in an axial position where the radial flange of the member 70 engages the internal overhang of the housing member 38. The shuttle assembly 60 may include an axially extending channel or rib that engages a corresponding feature on the housing member 38 that allows the shuttle assembly 60 to move axially within the housing 38 but prevents relative rotation of the shuttle assembly 60 with respect to the housing member 38.

[0030] The spring 66 is also axially preloaded and exerts a biasing force oriented distally on the shuttle assembly 60. When the tab 78 reaches an axially extending channel, the spring 66 moves the shuttle assembly 60 distally within the housing 38 as the tab 78 slides axially through the channel. A damping composite is disposed adjacent to the rotating member 70 to decelerate the rotation of the member 70 and enable completion of the dispensing event before the tab 78 reaches the axially extending channel. For example, the rotating member 70 may include a skirt with a plurality of axially extending tabs disposed in a grease collar to provide damping.

[0031] When the shuttle assembly 60 moves distally, it transports the syringe assembly 22 distally and moves the syringe assembly 22 back to the stored position shown in FIG. 2. The spring 66 biases the retraction mechanism 26 distally, thereby maintaining the syringe assembly 22 in its retracted position after the dispensing event. Locking mechanisms such as a detent on the shuttle assembly 60 and a recess on the housing 38 member additionally provide a locking engagement to secure the syringe assembly 22 in its retracted position with the needle 34 disposed within the housing 38 after the dispensing event, thereby enabling the user to then dispose of or otherwise handle the device 20 in a safe manner.

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

[0033] Figures 1-7 illustrate an exemplary drive mechanism 24 and an exemplary retraction mechanism 26, although other mechanisms may also be used to drive syringe assembly 22 from a storage position to an injection position and / or from the injection position to a retracted position. Such drive and / or retraction mechanisms may (but are not required to) include one or more springs or deformable components that store energy when held in a pre-trigger state and release the stored energy when triggered to drive the syringe assembly from the storage position to the injection position and / or from the injection position to the retracted position. Such mechanisms may (but are not required to) include mechanisms that use a chemical reaction or process to generate power, such as 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 storage containers for chemical reagents, a trigger that pierces or opens the storage container to allow 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 an increase in gas pressure generated by the resulting chemical reaction. Such mechanisms may (but are not required to) include mechanisms that use stored electrical power (e.g., in a battery) to operate an electric motor that drives and / or retracts the syringe assembly or trigger another physical or chemical mechanism. Such mechanisms may (but are not required to) include a hydraulic or pneumatic system (e.g., a tube), gears, cables, pulleys, or other known components for transmitting kinetic energy from one component to another. In some embodiments, rather than having separate mechanisms for driving the syringe assembly and then retracting the syringe assembly, a single mechanism may be configured to perform both, driving the syringe assembly and then retracting the syringe assembly.

[0034] FIG. 8 illustrates an exemplary arrangement of one or more main PCBs 82 within the end portion 39 according to a first set of embodiments of the device 20. The one or more main PCBs may be arranged orthogonal to the longitudinal axis 48, may be stacked on top of each other, and / or may be arranged side by side on the same plane orthogonal to the longitudinal axis 48. The main PCB defines an opening 83 configured such that, for example, when the end cap 36 is removed and the injection needle is driven proximally during an injection event to inject a patient, the injection needle 34 of the syringe assembly 22 passes through. As shown, the main PCB extends away from the longitudinal axis 48 by a radial distance 45 that is greater than the radial distance 41 of the user grippable portion 37. FIG. 8 also shows one or more secondary PCBs 84 that are substantially orthogonal to the main PCB and extend parallel to the longitudinal axis 48, and the secondary PCBs may be communicatively coupled to the main PCB via one or more PCB connectors 114. Although the secondary PCB 84 may attach an additional sensing system, such a secondary PCB is optional and may be excluded in certain embodiments to reduce manufacturing complexity and cost.

[0035] The end portion 39 can be an advantageous location and size within the device 20 for placing the main PCB. The increased footprint of the end portion 39 is provided by the radial extension of the outer end portion away from the longitudinal axis 48 by a radial distance 43 that is greater than the radial distance 41 of the user grippable portion. From the increased footprint, the space for accommodating the main PCB and its various components becomes larger than other locations of the device 20. Thus, many components can be pre-assembled onto the main PCB, which is an advantageous location for many components disposed in the end portion 39. As a result, incorporating the main PCB into the end portion 39 requires little or no change to the shape of the housing of existing auto-injectors, reduces disruptions to the manufacturing process, and can reduce manufacturing costs. Further, placing the main PCB in the end portion 39 allows the skin contact sensors 122, 123, and 124 to be positioned further away from the longitudinal axis 48, improving the reliability of the skin contact readings received from these sensors.

[0036] FIG. 9A shows a top perspective view of the main PCB and the secondary PCB 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 a top view and a bottom view, 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, and 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 can take the form of a system on chip (SOC) integrated circuit that includes a processor, memory, and input / output ports. However, the processing circuit 108 may also be implemented using other types of components such as a microcontroller (MCU) or an application specific integrated circuit (ASIC). The processing circuit 108 may be configured to execute computer-executable instructions stored in a non-transitory storage medium. The main PCB may also include a plurality of different types of sensors such as a microswitch sensor 110, a magnetometer 112, an accelerometer 140, an 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, a magnetometer 118, and an infrared temperature sensor 120.

[0037] 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. Microswitch sensors 110 and 116 may be used to detect the position of components of the injection device 20. For example, 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 will be discussed in more detail below, depending on the output of microswitch sensor 110, the processing circuit 108 may indicate to the user whether the end cap 36 is attached to the device 20. Similarly, microswitch sensor 116 may be used to detect whether the syringe assembly 22 is in one of two states, such as (i) a stored position or (ii) an injection position. Microswitch sensor 116 may also be configured to detect whether the syringe assembly 22 is in one of three states, such as (i) a stored position, (ii) an injection position, or (iii) a retracted position. Depending on the output of microswitch sensor 116, the processing circuit 108 may indicate to the user the position of the syringe assembly 22.

[0038] 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 invalidate or endanger the drug stored in the barrel 30 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 the exposure to ambient light exceeds a predetermined threshold, the user may be notified that the drug should not be used.

[0039] The accelerometer 140 can be communicatively coupled to the processing circuit 108 and can determine the orientation of the injection device 20 (e.g., upright, upside down, or sideways). This can be important for certain types of drugs that can be significantly affected by gravity, such as sedimentation of particulate matter that requires the drug to be delivered in a specific orientation. The processing circuit 108 can also use the output of the accelerometer 140 to warn the user if the device 20 is improperly oriented with respect to injection (e.g., if the device is upside down). As described in more detail below, the accelerometer 140 can 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 and then warmed to a second, higher temperature (e.g., room temperature, 65 - 75°F or 18 - 24°C) before being injected into the patient's body. To ensure that the medication in the barrel 30 is stored at the appropriate storage temperature and / or to ensure that the medication is warmed to the appropriate injection temperature, the injection device 20 can include a mechanism for estimating the temperature of the medication. By ensuring that the medication has been warmed to the appropriate temperature, this information can be transmitted to a phone or the device itself can signal the patient that the device is ready for use. In some embodiments, this temperature measurement function can be implemented by an infra-red (IR) temperature sensor 120 on the secondary PCB 84. The IR sensor 120 can be communicatively coupled to the processing circuit 108. As best seen in FIG. 8, the IR sensor 120 can be disposed adjacent to and facing the barrel 30. The IR sensor 120 can detect and measure electromagnetic radiation within the IR spectrum from the barrel 30 and output an electrical signal based on the detected IR radiation. By sampling the electrical signal output by the IR sensor 120, the processing circuit 108 can estimate the temperature of the medication in the barrel 30.

[0041] The main PCB may also include one or more antennas for transmitting and receiving wireless communications. For example, FIGS. 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 the thick black line element) disposed on the bottom surface 82b of the main PCB. Other embodiments are possible where the main PCB includes only one antenna or only one type of antenna. As will be 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 or integrated with a plurality of sensors that detect contact with the skin tissue. The skin contact sensors may be used to verify proper contact with the user's skin before the user activates the injection device 20. The injection device 20 may also be able to indicate to the user which sensors detect skin contact and which do not. This allows the user to know in which direction to tilt or move the injection device 20 before injection. This function reduces the likelihood of injection failure where the needle 34 fails to penetrate the user's skin or penetrates at an inappropriately shallow angle.

[0043] Figures 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 symmetric three-leaf shape. 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. Although only two electrical terminals are shown for each sensor, other embodiments are possible where each sensor has three or more electrical terminals. Each skin contact sensor can measure the electrical resistance between its electrical terminals and output an electrical signal to the processing circuit 108 based on the measured resistance. The electrical resistance of skin tissue is generally lower than that of air. Thus, the processing circuit 108 can determine that a particular skin contact sensor is in contact with skin tissue when the measured resistance falls below a predetermined threshold.

[0044] Figures 9B and 10B illustrate each skin contact sensor 122, 123, and 124 as having two electrical terminals, but other embodiments are possible where each skin contact sensor has only one electrical terminal. In such a case, the electrical terminal of one skin contact sensor (e.g., sensor 122) can function as a reference electrode that outputs a predetermined voltage. The electrical terminals on each of the other two skin contact sensors (e.g., sensors 123 and 124) can function as sensor electrodes that measure the electrical resistance of the conductive path between themselves and the reference electrode. When the measured resistance between the reference electrode and a particular sensor electrode falls below a predetermined threshold, the processing circuit 108 can 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, the processing circuit 108 can 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 Figures 17A, 17B, 18A, and 18B, and a second set of embodiments of device 20.

[0045] As best shown in FIG. 10B, each of the skin contact sensors 122, 123, and 124 can be located at respective radial distances 128, 130, and 132 outward from the longitudinal axis 48 (extending in the plane of the paper in the view shown in FIG. 10B). The sensors 122, 123, and 124 can optionally be arranged to symmetrically surround the opening 83 such that the radial distances 128, 130, and 132 are equal to each other and the angular separation between each sensor is also equal (e.g., 120° in this case). The radial distances 128, 130, and 132 are greater than the radial distance 41 of the user grippable portion 37 (as shown in FIGS. 2 and 9) and may be longer than 10 mm in length. For example, in some embodiments, the radial distances 128, 130, and 132 can each be 10 mm to 20 mm in length, and in some cases, a distance of 15 mm to 20 mm may be appropriate. Although three skin sensors are shown, other embodiments having only one or two skin sensors are also possible. Conversely, embodiments having four or more skin contact sensors are also possible, and in such embodiments, the skin sensors can be arranged to symmetrically surround the opening 83 (not essential). For example, other embodiments including 4 to 20 skin sensors are also contemplated.

[0046] The skin contact sensors 122, 123, and 124 are described above as measuring electrical resistance, but these skin contact sensors may alternatively be configured to detect skin contact by measuring electrical capacitance. A capacitance sensor may be configured to detect the proximity of human tissue by detecting the effect of such tissue on the electric field formed 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). Since capacitance sensors do not require metallic electrical terminals that make direct contact with skin tissue, they may be partially or fully encapsulated behind a protective non-conductive cover (e.g., made of plastic, etc.). This may improve the durability of the capacitance sensor by reducing the penetration of moisture or foreign objects into sensitive electrical components. Capacitance sensors may also reduce the risk of electrostatic discharge damaging sensitive electrical components within the device, since the capacitance sensor also does not require exposed metal contacts. Exemplary embodiments of the device 20 incorporating the capacitance sensor are discussed below in connection with FIGS. 21A, 21B, 22A, and 22B, and a third set of embodiments of the device 20.

[0047] The injection device 20 may also comprise 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 medicament remaining within the barrel 30 and / or, if any, the amount of medicament dispensed. In some embodiments, this may be achieved by providing a magnet above or near the piston 32 as the piston slides along the longitudinal axis 48 and one or more magnetometers that sense the magnetic field radiated by the magnet as the magnet 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, a magnetometer 112 on the main PCB 82 and a magnetometer 118 on the secondary PCB 84. As shown, the magnetometer 112 may be disposed radially further from the longitudinal axis 48 compared to the magnetometer 118. Further, instead of being positioned proximate to one end of the barrel 30, the magnetometer 118 may be disposed at an intermediate point along the length of the barrel 30.

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

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

[0050] Figure 12 provides a system architecture diagram of the electrical components within device 20 and the 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 a memory 1210 (e.g., an internal flash memory, an 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 a plurality of sensors such as ambient light sensor 106, end cap microswitch 110, magnetometer 112, accelerometer 140, and skin contact sensors 122, 123, and 124. Processing circuit 108 may also optionally be communicatively coupled to one or more secondary PCBs via flex connector 114. The secondary PCB may further incorporate microswitch 116, magnetometer 118, and IR temperature sensor 120. Processing circuit 108 may also be connected to means 1208 for user feedback that is integrated with 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 auditory indicator such as a speaker. Processing circuit 108 may be communicatively coupled to each of the components described above via one or more physical, electrical channels such as, but not limited to, General-Purpose Input / Output (GPIO) pins, Inter-Integrated Circuit (I2C) buses, Serial Peripheral Interface (SPI) connections, Universal Asynchronous Receiver / Transmitter (UART) connections, Controller Area Network (CAN) buses.In some cases, signals received by the processing circuit 108 from some or all of the sensors may also be converted from analog signals 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 (such as, for example, a mobile phone, a wearable device, a laptop, and / or a server database). 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 shows an exemplary external device 1250 that is physically separated from the injection device 20. In this embodiment, the exemplary external device 1250 can take the form of a mobile smartphone having a processor 1252 (e.g., a microprocessor or CPU) and a storage device 1258. The storage device 1258 can include a non-transitory computer-readable medium storing computer-executable instructions that, when executed by the processor 1252, cause the device 1250 to perform the operations described herein. These computer-executable instructions can include mobile applications such as medical mobile applications. The device 1250 can further include a display 1260 and a user input device 1262. The user input device 1262 can include physical buttons or switches integrated with the smartphone. Although shown separately in FIG. 12, all or a portion of the user input device 1262 can be integrated with the display 1260, e.g., within a touch-sensitive screen. The device 1250 can also include a vibration source 1264 such as a vibration motor.

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

[0054] FIG. 13 is a flow diagram illustrating an exemplary process 1300 for “pairing” or establishing a communication session between an injection device 20 and an external device 1250. Process 1300 may be used by any of a first set of embodiments of device 20, as well as any of a second and third set of embodiments of device 20 described below. To conserve power, 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 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 processing circuit 108 may be powered off, BLE circuit 1206 and BLE antenna 1207 may be powered off, some or all of processing core 1208 may be powered off, or may operate at a slower clock speed. When device 20 is in low-power sleep mode 1326, the device may need to be “awakened” before it can be paired with external device 1250.

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

[0056] Another way to activate the injection device 20 is to configure the device 20 to activate when it detects a specific vibration pattern (similarly step 1328). For example, to activate the device 20, the user can position the device 20 so that it contacts the external device 1250. For example, the device 20 can be placed on the upper surface of the external device 1250. The external device 1250 can then be instructed by the user to vibrate according to a specific predetermined pattern using the vibration source 1264. The vibration from the external device 1250 can be detected by the accelerometer 120 within the injection device 20. When the detected vibration matches the expected pattern, the processing circuit 108 can be configured to activate the injection device 20 from its low-power sleep mode.

[0057] When the injection device 20 first activates from its low-power sleep mode, the processing circuit 108 can participate in the BLE pairing process 1330 with the external device 1250. The BLE pairing process 1330 is the same as or similar to the BLE pairing process defined in the Bluetooth Core Specification v5.0 published by the Bluetooth SIG on December 6, 2016, the entire content of which is incorporated herein by reference. The BLE pairing process 1330 can start when the injection device 20 broadcasts one or more BLE advertisement packets using its BLE circuit 1206 and BLE antenna 1207. When the external device 1250 receives the BLE advertisement packet broadcast via the BLE circuit 1256 and BLE antenna 1257, the external device 1250 can respond with a wireless BLE transmission that initiates the communication flow between the injection device 20 and the external device 1250. The final result of this communication flow is a BLE communication session established between the injection device 20 and the external device 1250 where the two devices can exchange data.

[0058] Figures 14A and 14B are flowcharts showing an exemplary process 1400 implemented by a mobile medical application operating on an external device 1250. Process 1400 can be used in conjunction with any of the first set of embodiments of device 20, as well as any of the second and third sets of embodiments of device 20 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 above sensors 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 memory of device 20, or information derived from such data, such data may include the type of drug stored within the injection device 20, the expiration date of the drug, the prescribing doctor's identification information, the location or date of the drug manufacturer, the model of the injection device, etc.

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

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

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

[0062] Referring now to FIG. 14B, in step 1422, process 1400 may instruct the user to remove end cap 36. In step 1424, process 1400 determines whether the 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 injection device 20 for injection. This may include instructing the user to place the proximal opening 40 of device 20 in a coplanar arrangement with 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 ones of the plurality of skin contact sensors (e.g., sensors 122, 123, and 124) detected contact with the skin tissue and which individual ones did not detect contact with the skin tissue. As illustrated in FIG. 15, this may be done by displaying schematic 1502 on 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 arranged to mimic the physical arrangement of skin contact sensors 122, 123, and 124. For example, the indicators may be arranged symmetrically around a central opening. In embodiments where there are 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 the skin tissue, schematic 1502 may change the appearance of the corresponding indicator for that skin sensor. 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 the skin tissue. Accordingly, indicator 1524 corresponding to skin contact sensor 124 is filled with a color, pattern, or visual pattern different from the color, pattern, or visual pattern of indicators 1522 and 1523 corresponding to skin contact sensors 122 and 123 (as shown by cross-hatching with respect to indicator 1524). Other means of indicating the presence or absence of skin contact are also possible. For example, depending on whether a particular skin contact sensor detected any contact with the skin tissue, the shape of the indicator may change, or an icon or symbol may be displayed or not displayed.

[0065] Alternatively or additionally, device 20 may include a visual indicator (e.g., a light-emitting diode (LED)) that indicates to the user which skin contact sensors have detected skin contact and which have not. For example, device 20 may include a plurality of LEDs on the upper surface of main PCB 82a, with each LED corresponding to one of the skin contact sensors. The physical arrangement of the LEDs may correspond to the arrangement of the skin contact sensors so as to make clear to the user which LED corresponds to which skin contact sensor, and each LED may be disposed on the upper surface of the corresponding skin contact sensor. One such exemplary LED is illustrated as LED 142 in FIG. 11. Depending on whether the sensor has detected contact with skin tissue, the corresponding LED may be turned on, turned off, and / or change color. This provides another intuitive means for the user to quickly determine which skin contact sensors are not detecting 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 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 a top view and a bottom view, respectively, of the same PCB. Similar to main PCB 82 of the first set of embodiments, main PCB 1782 may also be positioned at end portion 39 of housing 38 of device 20, as illustrated in FIG. 8. Also similar to main PCB 82 described above, main PCB 1782 defines an opening 1703 (similar to opening 83 of PCB 82) configured for the injection needle 34 of syringe assembly 22 to pass through. Main PCB 1782 includes an upper surface 1782a and a bottom surface 1782b (the upper surface 1782a and the bottom surface 1782b are understood to be part of PCB 1782). The upper surface 1782a may include or support a power source 1702 that may include a battery such as a coin cell battery in some embodiments. The power source 1702 provides power to electrical components integrated or coupled with injection device 20. Main PCB 1782 may also include a processing circuit 1708 configured similarly to processing circuit 108 described above.

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

[0068] FIG. 19 shows a side view of the device 20 when the syringe assembly 22 is in the storage 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 each other. 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. Since the barrel 30 has a larger diameter than the needle 34 or the needle hub 35, the downward translation of the barrel 30 causes the barrel 30 to contact the angled portion of the angled arm 1710a and push the angled arm 1710a radially away from the longitudinal axis 48, whereby the angled arm 1710a contacts the straight arm 1710b. This completes the electrical circuit between the angled arm 1710a and the straight arm 1710b. Thus, the processing circuit 1708 can determine that the syringe assembly 22 is in either the storage or retracted position when detecting an open circuit between the arms 1710a and 1710b. The processing circuit 1708 can determine that the syringe assembly is in the injection position when detecting a closed circuit between the arms 1710a and 1710b.

[0069] The main PCB 1782 may also differ from the main PCB 82 in its configuration of the skin contact sensors. As best seen in the comparison of 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), the bottom surface 1782b of the main PCB 1782 of the second set of embodiments comprises only three single electrodes 1722, 1723, and 1724 that face distally from the distal surface of the PCB. These electrodes may be equally disposed radially from the longitudinal axis 48 and may be circumferentially equally spaced from each other. One of these three electrodes, for example, electrode 1722, may be connected to a voltage source that provides 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 the processing circuit 1708. If the voltage sensor connected to electrode 1723 senses a positive voltage above a reference threshold, the 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 the threshold, the 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 a voltage above the threshold, the processing circuit 1708 may determine that all three electrodes 1722, 1723, and 1724 are in contact with skin tissue. With respect to the main PCB 82 of the first set of embodiments, this arrangement of electrodes 1722, 1723, and 1724 reduces the number of electrodes required and thus reduces the complexity and cost of manufacturing and assembly.

[0070] The above description of the second set of embodiments of device 20 describes the differences between the second set of this embodiment and the first set of the above embodiments, but it should be understood that the second set of embodiments may also include features that exist in the first set of embodiments, as well as other features. For example, certain embodiments of the second set of this embodiment 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, several, or all of the sensors described above as being 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 the skin contact sensor, including configurations that are the same as or similar to the configurations 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, comprise electrode pairs similar to those described for 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 comprise one, two, three, or more sets of such electrode pairs.

[0071] FIG. 21A shows a top perspective view of the 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 a top view and a bottom view of the same PCB, respectively. Similar to the main PCB 82 of the first set of embodiments, the main PCB 2082 can also be positioned at the end portion 39, as illustrated in FIG. 8. Also, similar to the main PCB 82 of the first set of embodiments, the main PCB 2082 defines an opening 2003 (similar to the opening 83 of the PCB 82) configured such that the injection needle 34 of the syringe assembly 22 passes through. The main PCB 2082 includes a top surface 2082a and a bottom surface 2082b (the top surface 2082a and the bottom surface 2082b are understood to be part of the PCB 2082). The top surface 2082a includes or supports a power source 2002 that can include a battery such as a coin cell battery in some embodiments. The power source 2002 provides power to electrical components integrated or connected to the injection device 20. A battery door (not shown) within the housing 38 can be hinged or swing open to allow access to the power source 2002. The main PCB 2082 can also include a processing circuit 2008 configured similarly to the processing circuit 108 described above.

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

[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 can 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. Removing the secondary PCB 84 and / or the syringe position detector switch 1710 can reduce the manufacturing and assembly complexity and / or cost.

[0074] Second, the main PCB 2082 may attach 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 will be discussed in more detail below, when actuated by the user, this button 2001 sends an electrical and / or digital signal to the processing circuit 2008 to power on and cause the device 20 to check its temperature and indicate to the user whether the device 20 is at the correct temperature for drug administration, and may be a physical button.

[0075] Third, instead of using an NFC or BLE trace antenna disposed on the top and / or bottom surfaces of the PCB, the NFC or BLE connection may be provided by one or more chip antennas 2004 attached to the PCB 2082. Such a chip antenna 2004 may receive a signal from the processing circuit 2008 that causes the antenna to send wireless communications to an external device. FIG. 21A shows only one chip antenna 2004, but some embodiments of the third set of embodiments may include two or more chip antennas, for example, 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 has been removed by the user. The base cap removal sensor 2010 may be communicatively or electrically coupled to the processing circuit 2008. FIGS. 23A and 23B provide a more detailed perspective view of the base cap removal sensor 2010. The sensor 2010 includes 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 the proximal surface of the PCB. The arms may extend proximally away from the base 2302 and may be in a parallel relationship with each other. The first arm 2304 is connected to a horizontal lever 2310. In one example, the arm 2304 and the lever 2310 may form an L-shape and may be a single unit. The lever 2310 then supports an angled tab 2308 and a first contact surface 2309. The surface 2309 may be angled from the lever 2307 and may extend distally and / or radially inwardly. The tab 2308 is shown suspended from the lever 2310 and disposed between the arms 2304 and 2306. The tab 2308 may include an angled portion that extends radially inwardly toward the longitudinal axis 48. The lever 2310 is shown as having a multi-planar structure where a first portion that is continuous with the arm 2304 is along a first radial plane and a second portion that is continuous with the contact surface 2309 is along a second radial plane that is farther from the longitudinal axis 48 than the first radial plane. The second arm 2306 is connected to a second contact surface 2307. The contact surface 2307 may be angled from the body of the arm 2306 and, at some angles, may extend proximally and / or radially outwardly. The contact surfaces 2307, 2309 are shaped and configured to be in a contacting relationship in one configuration, such as when the base cap is removed, and in a separated configuration, or vice versa, in another configuration, such as when the base cap is attached. The first arm 2304, the second arm 2306, and the tabs and contact surfaces attached to both arms may be formed from metal or any other suitable flexible and conductive material.

[0077] Figure 24A shows the PCB 2082 and the base cap removal sensor 2010 associated with the end cap 36 when the end cap 36 is 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 attached onto the PCB 2082, the angled tab 2308 faces inwardly towards 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. Figure 24B shows the PCB 2082 and the end cap 36 when the end cap 36 is attached. When the end cap 36 is attached, the internal tab 2402 extends upwardly through the opening 2003 of the PCB 2082 and presses against the angled tab 2308. This presses the angled tab 2308, and the horizontal lever 2310 to which the angled tab 2308 is attached, radially outwardly in the direction of arrow 2406.

[0078] Figures 25A and 25B show the base cap removal sensor 2010 when the base cap removal sensor 2010 is viewed in the direction of the axis 2312 of FIGS. 23A and 23B. Figure 25A shows the base cap removal sensor 2010 when the base cap removal sensor 2010 is in its neutral state, for example, when the end cap 36 is removed and, therefore, the internal tab 2402 is not in contact with any part of the sensor 2010. When the sensor 2010 is in this neutral state, the first contact surface 2309 is biased to contact the second contact surface 2307 by the horizontal lever 2310. The 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 may determine that the end cap 36 has been removed.

[0079] FIG. 25B shows the base cap removal sensor 2010 when the end cap 36 is attached. When the end cap 36 is attached, the internal tab 2402 contacts and presses against the angled tab 2308 of the sensor 2010. This pressing force displaces the angled tab 2308, and the horizontal lever 2310 to which the angled tab 2308 is attached, outward in the direction of arrow 2406. This moves the first contact surface 2309 away from contact with the stationary 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 may determine that the end cap 36 is attached.

[0080] Fifth, instead of using electrodes that detect skin contact by measuring electrical resistance (as in the first and second sets of embodiments), the main PCB 2082 uses two capacitive pads 2022 and 2023 to detect skin contact instead. The pads 2022, 2023 are shown as separate planar structures disposed along the distal surface of the PCB. The capacitive pads 2022 and 2023 can be configured to detect the proximity of human tissue by measuring the effect of such tissue on the electric field formed by the sensor, e.g., the effect of such human tissue on the capacitance of the electrical circuit monitored or measured by the sensor. Since the capacitance sensor does not require a metallic electrical terminal in direct contact with the skin tissue, it can be partially or fully encapsulated behind a protective non-conductive cover (e.g., made of plastic, etc.). This can improve the durability of the capacitance sensor by reducing the penetration of moisture or foreign objects into sensitive electrical components. The capacitance sensor can also reduce the risk of electrostatic discharge damaging sensitive electrical components within the device since the capacitance sensor does not require exposed metal contacts either. The capacitive pads 2022 and 2023 can each independently detect contact with the skin tissue, whereby the processing circuit 2008 can determine when one pad has detected contact while the other has not. FIGS. 21B and 22B illustrate only the two capacitive pads 2022 and 2023, but other embodiments of the third set of embodiments may have fewer or more capacitive pads. For example, the 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 PCBs 2082 of this embodiment includes an accelerometer 2012 that detects an impact or acceleration caused by the start of a dispensing event in which the syringe assembly 22 is driven from a retracted position to an injection position by the drive mechanism 24. The accelerometer 2012 can also detect an impact or acceleration caused by a retraction movement at the completion of a dispensing event in which the syringe assembly 22 is driven from the injection position to the retracted position by the retraction mechanism 26. The accelerometer 2012 can send an output signal to the processing circuit 2008 via one or more electrical connections, enabling 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 the third set of embodiments. The vertical Y-axis of graph 2600 indicates the magnitude of the signal in volts. The x-axis of graph 2600 illustrates the passage of time, for example, in units of seconds. In this example, the signal from the accelerometer 2012 is concentrated around a voltage of approximately 1.75V. This 1.75 signal can represent a constant downward acceleration due to gravity. The deviation around this constant value indicates an acceleration or impact (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, an acceleration, vibration, or impact 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) can be detected by the accelerometer 2012.

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

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

[0085] Similarly, when the dispensing event is completed, the retraction mechanism 26 is actuated to drive the syringe assembly 22 from the injection position to the retracted position. This driving motion imparts one or more accelerations, which can also be detected by a signal output from the accelerometer 2012. For example, the pressing force imparted by the retraction mechanism 26 when the retraction mechanism 26 drives the syringe assembly 22 in the distal direction from the injection position can cause the accelerometer 2012 to detect an acceleration in the proximal direction along the longitudinal axis 48. When the syringe assembly reaches the retracted position, the sudden stop of the syringe assembly 22 can cause the accelerometer 2012 to detect an acceleration in the distal direction along the longitudinal axis 48. Either (or both) of this proximal or distal acceleration can cause the accelerometer 2012 to output a second acceleration spike (indicated by reference numeral 2068) that can be detected by the processing circuit 2008. This second acceleration spike can indicate the completion of the dispensing event. As used herein, "acceleration spike" is defined as any artifact of an 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 dispensing event.

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

[0087] The temperature sensor 2025 can include any of a plurality of types of temperature sensors that can 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 can be configured and positioned to measure the temperature of the thermal ballast. The thermal ballast can include all or a portion of the silicon substrate of the main PCB 2082 itself. Alternatively, the thermal ballast can include a suitable heat sink composed of other materials (e.g., polymers) mounted on the main PCB 2082. The thermal ballast can be in contact with the temperature sensor 2025 or can surround all or a portion thereof.

[0088] The material, size, shape, and location of the thermal ballast are such that the thermal ballast has a thermal time constant (τ drug ) that approximates that of the drug within the barrel 30 during heating (τ ballast ). As used herein and in the claims, the "thermal time constant (τ)" of the body (such as that of the thermal ballast or the drug within the barrel 30) should be understood to be a constant that satisfies Equation 1 below.

[0089]

Equation

[0090] In other words, the thermal time constant τ of the body characterizes the speed at which the temperature of the body adjusts to match the ambient temperature of its environment. A high thermal constant means that the temperature of the body adjusts quickly, and a low thermal constant means that the temperature of the body adjusts slowly. Therefore, the thermal time constant (τballast ) is close to the thermal time constant (τ drug ) of the drug in the barrel 30, it can be assumed that the temperature of the thermal ballast rises and falls so as to match the ambient temperature at approximately the same rate as the temperature of the drug. Since the thermal ballast can be attached to the main PCB 2082, the thermal ballast will generally be exposed to the same ambient temperature as the drug in the barrel 30. Therefore, the processing circuit 2008 can estimate the temperature of the drug in the barrel 30 by measuring the temperature of the thermal ballast and assuming that the temperature of the drug in the barrel 30 is equal to the measured temperature. Thus, the third set of main PCBs 2082 of this embodiment can estimate the temperature of the drug in the barrel 30 without the need to position an infrared (IR) sensor or other type of temperature sensor immediately adjacent to (or in physical contact with) the barrel 30. This reduces the manufacturing and assembly costs and complexity and also relaxes the space and form factor requirements of the device 20.

[0091] In some embodiments, the material, size, shape, and / or position of the thermal ballast is such that τ ballast is τ drug within 10% of. In other embodiments, the material, size, shape, and / or position of the thermal ballast is such that τ ballast is τ drug within 5% of. In some embodiments that require the temperature of the drug to be determined with high accuracy, the material, size, shape, and / or position of the thermal ballast is such that τ ballast is τ drug within 2% of. In still other embodiments, the material, size, shape, and / or position of the thermal ballast is such that when both the ballast and the drug are taken 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), the temperature of the ballast is always within a certain number of degrees (e.g., + / -2°C or + / -5°C) of the drug in the barrel 30.

[0092] FIG. 27 provides a system architecture diagram of electrical components within device 20 according to a third set of embodiments of device 20. Some or all of these components may be attached to main PCB 2082 already illustrated in FIGS. 21A, 21B, 22A, and 22B. As already considered 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 including a computing circuit (e.g., a microprocessor or an 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 computing circuit, and a BLE antenna 2714. Processing circuitry 2008 is configured to control and regulate the functions of the electrical components illustrated in FIG. 27.

[0093] According to a third set of embodiments, the processing circuit 2008 can be powered by one of two means, which can receive power from the battery 2002 via the battery enable circuit 2718, or which can receive power from the battery 2002 via the power latch circuit 2716. The battery enable circuit 2718 can be one or more physical circuits that route power from the battery 2002 to the processing circuit 2008 when certain conditions are met and cut off power to the processing circuit 2008 when those conditions are not met. In other words, the battery enable circuit 2718 can perform both power-on and power-off of the processing circuit 2008 depending on the sensed conditions. For example, in some embodiments, the battery enable circuit 2718 routes power to the processing circuit 2008 when either of two conditions are 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, depressed, and held by the user, or the temperature check button 2001 has been pressed within a certain past period, 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 consider only 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 the orientation of the device, 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 can be configured to cut off power to the processing circuit 2008.

[0094] The power latch circuit 2716 can be one or more physical circuits that receive an output signal from the processing circuit 2008 via a general-purpose input / output (GPIO) pin. When the power latch circuit 2716 receives a "power latch" signal from the processing circuit 2008 via the GPIO pin, it can be configured to route power from the battery 2002 to the processing circuit 2008. This power latch signal can be a simple voltage high or voltage low, or it can be a more complex coded signal that includes multiple voltage highs and / or voltage lows. When the power latch circuit 2716 receives the power latch signal, the power latch circuit 2716 will "latch," which means 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, when the power latch circuit 2716 is latched, power supply to the processing circuit 2008 will continue until the battery 2002 runs out (or a timer indicating the expected battery life of the battery 2002 expires, thus indicating that the battery 2002 is near depletion). Depending on the embodiment, the processing circuit 2008 can be configured to send a power latch signal to the power latch circuit 2716 under different circumstances.

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

[0096] The processing circuit 2008 can also be connected to an Inter-Integrated Circuit (I2C) bus 2724. The I2C bus can then be communicatively coupled to a plurality of electrical components, including the NFC circuit 2004, one or more touch sensors 2706, an accelerometer 2012, and a battery gauge 2710.

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

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

[0099] The accelerometer 2012 may take the form of any circuit configured to detect impacts, vibrations, and / or accelerations associated with the start and / or completion of a dispensing event, as described above. For example, the 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 can 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 connected to other electrical components via channels other than the I2C bus 2724. For example, the processing circuit 2008 may be connected to the temperature sensor 2025 via an analog input pin. The processing circuit may also be connected to the watchdog integrated circuit (IC) 2722 via a GPIO pin. The watchdog IC 2722 can be an integrated circuit that includes a continuously operating counter. The integrated circuit can be configured to reset or restart the processing circuit 2008 when the counter expires (e.g., by sending a "reset" signal or interrupting the 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 can then be configured to send the check-in signal to the watchdog IC 2722 periodically. The watchdog IC 2722 configured in this way helps to ensure that the processing circuit 2008 does not accidentally stack in a programming loop. By sending the check-in signal to the watchdog IC 2722 periodically, the processing circuit 2008 demonstrates that it is not stacked in an incorrect programming loop or some other fault condition. If the watchdog IC 2722 does not receive a check-in signal from the processing circuit 2008 before the counter expires, the watchdog IC 2722 will send a "reset" signal to the processing circuit 2008 (and / or cut off the power), causing the processing circuit 2008 to restart itself.

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

[0103] Process 2800 starts at step 2802 when the battery enable circuit 2718 powers the processing circuit 2008. As discussed above, this occurs when (i) the base cap removal sensor 2010 detects that the base cap 36 has been removed, and / or (ii) the temperature check button 2001 attached to the main PCB 2082 has been pressed within a specific period (e.g., within the past 45 minutes), or is depressed and held by the user. After starting to receive power, the processing circuit 2008 proceeds to step 2804.

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

[0105] A UUID can include a serial number or an array of alphanumeric symbols. Depending on the embodiment, the UUID can be unique to a particular device 20, a particular manufacturing lot of the 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 can also specify the type of drug contained within the device 20. Alternatively, the memory may store a data field separate from the UUID that specifies the type of drug contained within the device 20. In some embodiments, the processing circuit 2008 can 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) can be stored in a memory coupled or integrated with the NFC circuit 2004 instead of the processing circuit 2008 to simplify the manufacturing and assembly process. In some embodiments, depending on the configuration of the device 20, programming the memory coupled or integrated with the processing circuit 2008 may require the processing circuit 2008 to be powered on. This programming operation can consume valuable power stored in the battery 2002 and thus shorten the effective battery life of the completed device. On the other hand, the memory coupled or integrated with the NFC circuit 2004 can be programmed using some or all of this data via passive NFC communication without requiring any power draw from the battery 2002. Thus, to conserve power, the instructions executed by the processing circuit 2008 can be programmed into the NFC circuit 2004 via passive NFC communication during manufacturing. The processing circuit 2008 can then be configured to read the stored data / instructions from the memory of the NFC circuit 2004 when powered on. After the processing circuit 2008 reads the UUID, drug type, and / or any other data or programming instructions from the memory, the processing circuit 2008 proceeds to step 2805.

[0107] In step 2805, processing circuit 2008 begins to periodically broadcast a wireless signal communicating the status of injection device 20 via BLE antenna 2714. These wireless signals can take the form of BLE advertising packets in some embodiments, although other types of wireless signals and wireless protocols can also be used. This wireless signal can be broadcast at specific periodic intervals, such as once per second or once every five seconds, and can include data related to (i) the UUID of the device, (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 elapsed since the base cap was first removed (e.g., in seconds), (v) the skin contact duration (e.g., the amount of time the device has been in contact with the skin), (vi) an indication of whether administration has been started and / or whether administration has been started and completed, (vii) the detected administration start time and / or the amount of time elapsed since the started administration was completed, (viii) in some embodiments, the administration duration, which can be defined as the amount of time between the start and completion of an administration event, (ix) the temperature sensed by temperature sensor 2025, (x) the device orientation when measured by the accelerometer, (xi) the temperature check count, e.g., the number of times the user has pressed the temperature check button, (xii) the device orientation during administration, (xiii) any detected faults or error conditions related to 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) through (xiii), and / or (xv) any other device or ambient conditions observed or measured by the device.

[0108] These wireless signals can be periodically broadcast by the processing circuit 2008 throughout the process 2800. At this point in step 2805, some or all of the fields included in the wireless signal may be null or blank until the processing circuit 2008 begins to receive and process data from the on-board sensors of device 20. The processing circuit 2008 continuously updates the transmitted wireless signal to reflect the latest state of the device in order to receive and process signals from the on-board sensors of device 20 (such as the base cap removal sensor 2010, the touch sensor 2706, the accelerometer 2012, the temperature sensor 2025, etc.). The processing circuit 2008 then proceeds to step 2806.

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

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

[0111] In step 2812, the processing circuit compares the measured temperature with a pre-set threshold value to determine whether the measured temperature meets specific pre-defined and pre-stored ideal injection temperature parameters. For example, when the measured temperature is within the ideal temperature range for injection, such as 65 - 75 degrees Fahrenheit or 18 - 24 degrees Celsius, the measured temperature may meet the ideal injection temperature parameters. In other simpler embodiments, the processing circuit may simply determine whether the measured temperature exceeds a specific minimum temperature threshold (e.g., exceeds 65 degrees Fahrenheit or 18 degrees Celsius) without determining whether the measured temperature is below a specific maximum temperature threshold. If the measured temperature meets the ideal injection temperature parameters, the processing circuit 2008 branches to step 2814 and sets an indicator to notify the user of this decision. Such an indicator 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 an indicator, the processing circuit 2008 branches to step 2810. If the measured temperature does not meet the ideal injection temperature parameters, the processing circuit 2008 branches directly to step 2810 without setting an indicator.

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

[0113] In step 2816, the processing circuit 2008 reads the output of the accelerometer 2012. In some embodiments of process 2800, the processing circuit 2008 does not read or evaluate the output of the accelerometer 2012 unless skin contact is detected. This can be achieved by cutting off the power to the accelerometer 2012 unless skin contact is detected so that the accelerometer 2012 does not output any acceleration signals unless skin contact is detected. Alternatively, the accelerometer 2012 may receive power and output an acceleration signal even when skin contact is not detected, and the processing circuit 2008 may be configured to log the skin contact time and duration in memory, but no separate measures are taken based on the output signal from the accelerometer 2012 until skin contact is detected. By requiring that skin contact be detected before determining that a dispensing event has been detected, the processing circuit 2008 reduces the occurrence of false positives where the processing circuit 2008 records a dispensing event when no dispensing event is occurring.

[0114] In step 2818, the processing circuit 2008 determines, based on the output of the accelerometer 2012, whether a dispensing event has been started and completed. This determination can be made by various means, and exemplary logic for making this determination is described in more detail below with reference to FIGS. 29, 30, 31, and 32. If a completed dispensing event is not detected, the processing circuit 2008 branches back to step 2810. If the processing circuit 2008 determines in step 2818 that both the start and completion of a dispensing event have occurred, the processing circuit 2008 records the start and / or completion of the dispensing event in memory. The processing circuit 2008 may also communicate the start and / or completion of the dispensing event to the user by setting an indicator, such as one or more LEDs, a light ring, or other visual and / or auditory indicators. Thereafter, the processing circuit 2008 branches to step 2820.

[0115] In step 2820, the processing circuit sends a signal to the power latch circuit 2716 to latch the power latch circuit 2716 on. As described above, when the power latch circuit 2716 is latched on, it will continue to route power from the battery 2002 to the processing circuit 2008 until the battery 2002 runs out. After the power latch circuit 2716 is latched on, the processing circuit 2008 proceeds to step 2822.

[0116] In step 2822, the processing circuit 2008 starts a time counter from administration. This time counter from administration can be an internal or external counter of the processing circuit 2008 that continuously counts up at regular intervals, such as every second, every 30 seconds, or every minute. In some embodiments, the time counter from administration 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 timer from administration 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 counter from administration when the processing circuit 2008 reaches step 2822.

[0117] In step 2824, the processing circuit 2008 updates the broadcast wireless signal to indicate that the dispensing event has started and completed successfully. As discussed above, the wireless signal may include the detected administration start time and / or the amount of time elapsed since the started administration was completed. In embodiments where the time counter from administration starts counting when the processing circuit 2008 reaches step 2822, the broadcast signal may include the current value of the time counter from administration. In embodiments where the time counter from administration continuously counts up from the moment the processing circuit 2008 receives power, the broadcast signal may include the difference between the current value of the time counter from administration and the value of the time counter from administration when the processing circuit reaches step 2822.

[0118] Wireless signals that are periodically broadcast can be received by external devices such as mobile device 1250. These wireless signals enable an external device to determine the type or configuration of device 20, the type of drug administered to a patient, the temperature of the drug at the time of administration (or whether the temperature of the drug meets the ideal injection temperature parameters at the time of administration), and / or the amount of time elapsed since the drug was administered. By subtracting the amount of time elapsed since the drug was administered from the current absolute time (e.g., determined by a clock integrated with or communicating with the external device), the external device can also determine the absolute time at which the drug was administered. For example, if the external device receives a wireless signal from device 20 indicating that the drug was administered 1 hour ago, and the clock of the external device indicates that it is currently 2:00 PM on December 21, 2018 in Eastern Standard Time, the external device can determine that the drug was administered at 1:00 PM on December 21, 2018 in Eastern Standard Time by subtracting the elapsed time (1 hour) from the current absolute time.

[0119] After each broadcast, processing circuit 2008 monitors the remaining power level of battery 2002 via battery gauge 2710 (step 2826). 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, processing circuit 2008 branches back to step 2824 and continues to broadcast the wireless signal. If the remaining battery power level is below the low battery threshold, processing circuit 2008 may determine that power will soon be insufficient to continue actively broadcasting the wireless signal. As a result, processing circuit 2008 branches to step 2830.

[0120] In step 2830, the processing circuit 2008 writes its "last state" to the NFC circuit 2004. This "last state" may include information indicating (i) that the dispensing event has been started and completed, and (ii) the current value of the time counter from administration (e.g., X hours, minutes, or seconds) when the processing circuit reaches step 2830. Writing this "last state" to the NFC circuit 2004 ensures that the external device can still determine at least these two pieces of information by querying the NFC circuit 2004, even when the NFC circuit 2004 is not fully powered by the battery 2002. In other words, the external device will still be able to determine that (i) the device 20 has normally dispensed the loaded dose of the drug, and (ii) this drug was dispensed at least X hours, minutes, or seconds ago.

[0121] The process 2800 can be changed by rearranging, deleting, adding, or reconfiguring certain steps. For example, in some embodiments, the process 2800 can be configured to refrain from broadcasting a wireless signal until after a normal dispensing event is detected, i.e., not before reaching step 2824. By refraining from broadcasting a wireless signal before the dispensing event is detected, the process 2800 can conserve battery power and minimize signal interference or disruption in an environment where other devices are also transmitting and receiving wireless signals. In some embodiments, the process 2800 may not need to continuously check the battery level 2826 and instead may use a timer to determine when to write the "last state" to the NFC circuit 2004 and when to shut down. Such a timer can be configured to instruct the processing circuit 2008 to write the "last state" and shut down after a specific time has elapsed since the processing circuit 2008 was first powered on, or when the processing circuit 2008 first starts transmitting a wireless signal.

[0122] FIG. 29 illustrates an exemplary circuit diagram showing the logic (i.e., step 2818 of process 2800) for determining whether a dispensing event has started and completed. Although this logic is illustrated and described as a circuit diagram, it should be understood that this logic can be implemented as a hardware logic circuit, software or firmware instructions executed 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 resistor 2906 connected to capacitor 2904 and ground 2908. The high-pass filter is configured to filter out low-frequency acceleration signals due to gravity, but passes high-frequency signals from sharp impacts / accelerations indicating the start or completion of a dispensing event. The output of the high-pass filter is supplied to a first input of 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 high voltage) when the output of the low-pass filter is above the reference voltage threshold 2910, and otherwise, signal comparator 2912 outputs an off signal (e.g., a low voltage). In other words, if an acceleration spike is detected, i.e., if the high-pass filtered signal from accelerometer 2012 is above the reference voltage threshold 2910, the output of signal comparator 2912 turns on. Otherwise, signal comparator 2912 outputs an off signal.

[0124] The output of the signal comparator 2912 is coupled to the first input of the AND gate 2916. The second input of the AND gate 2916 is coupled to the valid touch signal 2914. The valid touch signal 2914 can be turned on or off based on the output of the touch sensor 2706. The on signal can indicate that a valid skin contact has been detected, and the off signal can indicate that no valid skin contact has been detected. Some embodiments of the device 20 having a plurality of skin contact sensors may require that all skin contact sensors detect a valid skin contact before turning on the valid touch signal 2914. Alternatively, some embodiments of the device 20 may require only one, or a specified number or subset of the plurality of skin contact sensors, to detect a valid skin contact before turning on the valid touch signal 2914. Therefore, the output of the AND gate 2916 is on only when two conditions are met: (i) an acceleration spike is detected (i.e., the output of the signal comparator 2912 is on), and (ii) a valid touch signal 2914 is detected. The simultaneous occurrence of both conditions (i) and (ii) indicates that a dispensing event has been initiated in which the syringe assembly 22 is driven from the retracted position to the injection position by the drive mechanism 24. By requiring that both conditions (i) and (ii) be met before determining that a dispensing event has been initiated, this logic reduces false positive cases that are recorded when no dispensing event is occurring.

[0125] The output of AND gate 2916 is connected to the first input of OR gate 2918, which functions as a firing event latch. The second input of OR gate 2918 is connected 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. Thereafter, OR gate 2918 remains on indefinitely until it is reset (e.g., by cutting power to OR gate 2918). If the output of AND gate 2916 goes off again after going on, the output of OR gate 2918 remains on. Therefore, OR gate 2918 is called a firing event latch because it remains on indefinitely after it "latches" and a firing event (e.g., the start of a dispensing event) is detected.

[0126] The output of OR gate 2918 is connected to a debounce circuit 2932. The debounce circuit 2932 outputs an off signal until two conditions are met: (i) the firing event latch outputs an on signal, indicating that the start of a dispensing event has been detected, and (ii) the output of AND gate 2916 outputs an off signal. In other words, the debounce circuit 2932 turns on only after the first acceleration spike indicating the start of a dispensing event is detected, and the first acceleration spike passes and is no longer detected. When both conditions are met, the debounce circuit remains on indefinitely until it is reset.

[0127] The debounce circuit 2932 includes an inverter 2920, an AND gate 2922, and an OR gate 2924. The output of the AND gate 2916 is inverted by the inverter 2920 before being passed to the first input of the AND gate 2922. The output of the firing event latch (OR gate 2918) is passed to the second input of the AND gate 2922. Therefore, the output of the AND gate 2922 becomes on only when (i) the firing event latch output is on and (ii) the output of the AND gate 2916 is off. The output of the AND gate 2922 is connected to the first input of the OR gate 2924. The second input of the OR gate 2924 is connected to the output of the OR gate 2924. Therefore, the output of the OR gate 2924 is off until the output of the AND gate 2922 becomes on. Thereafter, the OR gate 2924 remains on indefinitely until reset, for example, by cutting off the power to the OR gate 2924. If the output of the AND gate 2922 turns off again after turning on, the output of the OR gate 2924 remains on.

[0128] The output of the debounce circuit 2932 is connected to the first input of the AND gate 2926. The second input of the AND gate 2926 is connected to the output of the AND gate 2916. Therefore, the output of the AND gate 2926 becomes on only when two conditions are met: (i) the debounce circuit 2932 is on, a first acceleration spike indicating the start of the dispensing event is detected, and it indicates that the first acceleration spike has currently passed, and (ii) the output of the AND gate 2916 is on and a second acceleration spike is detected while a valid skin contact is detected. This second acceleration spike indicates the completion of the dispensing event, and the syringe assembly 22 is driven by the retraction mechanism 26 in a retraction motion from the injection position to the retraction position. Again, by requiring that a valid skin contact be detected simultaneously with the acceleration spike before recording the retraction motion, this logic reduces the false positive cases where a retraction event is recorded when no retraction event is actually occurring.

[0129] The output of the AND gate 2926 is connected to the first input of the OR gate 2928 which functions as a retraction event latch. The second input of the OR gate 2928 is connected to the output of the OR gate 2928. Therefore, the output of the OR gate 2928 remains off until the output of the AND gate 2926 turns on, thus indicating that a second acceleration spike indicating the retraction movement at the completion of the dispensing event has been detected. When the output of the AND gate 2926 turns on, the OR gate 2928 is latched to remain on indefinitely (even if the output of the AND gate 2926 later turns off) until it is reset by cutting off the power to the OR gate 2928. Therefore, the OR gate 2928 is called a "retraction event latch" because it is latched on indefinitely after a retraction event, such as a retraction movement in which the syringe assembly 22 is driven from the injection position to the retraction position by the retraction mechanism 26, has been detected. The output of the OR gate 2928 is connected to the dispensing event output signal 2930.

[0130] Therefore, in summary, the dispensing event output signal 2930 turns on and remains on only when the conditions that (i) a first acceleration spike is detected simultaneously with a valid skin contact, thus indicating that the dispensing event has started, (ii) the first acceleration spike has passed, and (iii) a second acceleration spike is detected simultaneously with a valid skin contact, thus indicating that the dispensing event has been completed and a retraction movement has been detected, are satisfied. When all of these conditions (i) to (iii) are satisfied, the dispensing event output signal 2930 is latched on, thus indicating both that the dispensing event has started and been completed. As discussed above in FIG. 28, when the processing circuit 2008 determines that both the start and completion of the dispensing event have occurred, the processing circuit 2008 may record the start and / or completion of the dispensing event in the memory and also communicate the completion of the dispensing event.

[0131] FIG. 29 illustrates one exemplary means for detecting acceleration spikes by passing the output signal of an accelerometer through a high-pass filter and then comparing the filtered signal to a reference voltage threshold, where the acceleration spike is detected when the filtered signal is greater than the reference threshold. However, it should be understood that other means for 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 FIG. 33. In step 3302, the processing circuit 2008 logs a skin contact sample denoted as C[n] into a First-In-First-Out (FIFO) buffer. The processing circuit 2008 also raw logs the raw accelerometer sample output from the accelerometer 2012, denoted as S raw [n], into another FIFO buffer. In this exemplary process 3300, C[n] and S raw [n] are discrete digitally sampled signals. For example, C[n] may include data representing whether skin contact was detected each time the touch sensor 2706 is sampled. Depending on the embodiment, C[n] may include a separate sample for each sampling time of each sensor of the touch sensor, 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 the touch sensors 2706. C[n] may include a binary indication of whether contact was detected or data indicating the certainty of skin contact. S raw [n] may include the output signal from the accelerometer 2012 at each time sample. The sampling rates of C[n] and S raw [n] may vary depending on the embodiment. For example, C[n] may be sampled at a rate of 20 Hz, while S raw [n] may be sampled at a rate of 1600 Hz. C[n] and S rawWhen the [n] FIFO buffer is full, the oldest sample is deleted to create space for new samples.

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

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

[0135]

Equation

[0136] According to Equation 1, when S f [n] is less than a specific minimum acceleration signal threshold S min (e.g., 3.5 Gs), S int [n] will be set to 0. However, when S f [n] is greater than S min , S int [n] is S fIntegrate (e.g., sum) the next W samples of [n] first (e.g., S f [n]+S f [n + 1]+S f [n + 2]...+S f [n + W]), and then it will be derived by multiplying the result of the integration by a scaling factor. The parameter W can be changed depending on the embodiment. As an example, W can be set to 150 samples.

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

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

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

[0140] The purpose of condition (2) is to ensure that the integrated signal S int [n] is between a specific 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 exemplary and can be changed depending on the embodiment. S int If S[n] is too small (i.e., less than D min ), the acceleration detected by S[n] is too transient and / or not large enough to be caused by the start and / or completion of the dispensing event, so it is unlikely to correspond to an acceleration spike. S int If S[n] is too large (i.e., greater than D max ), the acceleration detected by S[n] is also likely to be due to an acceleration force that is too large or overly persistent and not caused by the start and / or completion of the dispensing event, so it is unlikely to correspond to an acceleration spike. Such large and / or persistent accelerations can instead be caused, for example, by the user dropping the device 20 onto a hard surface or by the device 20 being pushed during handling or transportation.

[0141] The purpose of condition (3) is to ensure that when an acceleration spike is detected, the processing circuit 2008 stops looking for another acceleration spike for at least N samples. For example, the 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 vibrations from a single firing or recoil event result in the detection of multiple acceleration spikes.

[0142] Process 3300 is merely illustrative and can be varied by various means. For example, step 3304 may be omitted such that the integrated signal S int [n] is calculated directly from S f [n] instead of S raw [n]. Step 3306 may be changed by not using a scaling factor or by using a scaling factor different from that of Equation 1 to calculate S int [n]. Step 3306 may also be changed by calculating S f [n] for all values of n rather than only for values where S min is greater than. Some embodiments may utilize only the maximum threshold D int when screening S int [n] and not utilize the minimum threshold D max . Other embodiments may utilize only the minimum threshold D min and not utilize the maximum threshold D min . Further, S max [n] may also be calculated by integrating or summing the values of S int [n] after time n in addition to or instead of integrating or summing the values of S f [n] preceding time n. f [n].

[0143] Process 3300 may also be such that S f [n] is only when the currently received value of S int [n] represents the most recent peak, S fIt may be modified to be calculated by integrating (and optionally scaling) [n]. S 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 can be set to 1,000 accelerometer samples). S f Only when [n] is the most recent peak S int This requirement that is calculated S int The above conditions for calculating [n], e.g., S f [n] is S min In addition to, or instead of, the condition that it is greater than or equal to, it can be imposed. S f Only when the most recent peak value of [n] is received S int By requiring that [n] be calculated only when the most recent peak value of [n] is received, process 3300 can reduce the occurrence of false positives where rocking back or subsequent vibrations due to a drop or impact of the device are misrecognized as acceleration spikes indicating the start and / or completion of a dispensing event. In other words, samples of [n] that do not represent the most recent peak value, and thus, can indicate rocking back or damped vibrations due to a drop or impact of the device S f The sample of [n] is considered not worthy of consideration as a potential acceleration spike indicating the start and / or completion of a dispensing event. In some embodiments, step 3306 is S min Greater than but less than the most recent peak S f If a further sample of [n] is received, it may still be further modified such that the sample number N can be extended. This means that instead of strictly considering only the last N samples when calculating the most recent peak, the process 3300 can consider more recent samples if the last few samples are S min Greater than, which means that process 3300 can consider more recent samples.

[0144] Other methods of detecting acceleration spikes may also be used. For example, such acceleration spikes can 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 specific frequency threshold or are within a specific frequency range and exceed a preset threshold, the processing circuit 2008 may determine that an acceleration spike has been detected. Yet another means of detecting acceleration spikes can be to differentiate the accelerometer output signal. If the derivative of the output signal has a magnitude greater than a specific threshold, the processing circuit may determine that an acceleration spike has been detected. In general, any process or algorithm for detecting acceleration spikes indicating sharp impacts or vibrations received by the device 20 can be used by the processing circuit 2008. Any of these processes or algorithms for detecting acceleration spikes can be used in the processes illustrated and described in FIGS. 30, 31, and 32.

[0145] FIG. 30 is a flowchart showing another exemplary process 3000 that may be implemented by the processing circuit 2008 to detect the start and completion of a dispensing 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, the 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 the touch sensors 2706) has detected contact with the skin. If affirmative, the processing circuit 2008 branches to step 3006, where the processing circuit reads or analyzes the acceleration signal output by the accelerometer 2012 to detect an acceleration spike. If negative, the processing circuit 2008 continuously loops back to step 3004 until skin contact is detected. Since the processing circuit 2008 does not read or analyze the signal output by the accelerometer 2012 until skin contact is detected, false positives are reduced. Again, this can be achieved by shutting off power to the accelerometer 2012 so that the accelerometer 2012 does not output any signal 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] At step 3006, the processing circuit 2008 reads or analyzes the acceleration signal output by the accelerometer 2012 to detect an acceleration spike. This can be done using any of the processes or methods for detecting the acceleration spike described above. After analyzing the accelerometer output signal, the processing circuit 2008 may branch to step 3008.

[0148] In step 3008, the processing circuit 2008 determines whether a first acceleration spike has been detected while skin contact is detected. If the determination is negative, the processing circuit 2008 branches back to step 3004. If the determination is positive, the processing circuit branches to step 3010, and the processing circuit 2008 determines that the first acceleration spike is likely caused by the start of the dispensing event. Therefore, the processing circuit 2008 records the start of the dispensing event by setting an indicator in the memory or by setting the logic circuit, and proceeds to step 3012.

[0149] In step 3012, the processing circuit 2008 re-evaluates whether at least one skin contact sensor (e.g., at least one, a specified number, a specified subset, or all of the touch sensors 2706) is detecting contact with the skin. If the determination is positive, the processing circuit 2008 branches to step 3014. If the determination is negative, the processing circuit 2008 continuously loops back to step 3012 until skin contact is detected. Repeatedly, the processing circuit 2008 does not read or evaluate any signal output from the accelerometer 2012 until skin contact is detected.

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

[0151] In step 3016, the processing circuit 2008 determines whether a second acceleration spike has been detected while skin contact is detected. If the determination is negative, the processing circuit 2008 branches back to step 3012. If the determination is positive, the processing circuit 2008 branches to step 3018, and the processing circuit 2008 determines that the second acceleration spike is likely caused by the backward movement at the completion of the dispensing event. Therefore, the processing circuit 2008 records the completion of the dispensing event and proceeds to step 3020.

[0152] In step 3020, the processing circuit 2008 logs and / or communicates the start and completion of the dispensing event. This can be done, as described above, by recording the dispensing event in memory and / or by broadcasting a wireless signal notifying of the completion of the dispensing event. Alternatively or additionally, the processing circuit 2008 can indicate to the user that the dispensing event has been completed by turning one or more LEDs on or off, by emitting a sound, or via any other visual, tactile, or auditory indicator.

[0153] FIG. 31 is a flowchart showing another exemplary process 3100 that can be implemented by the processing circuit 2008 to detect the start and completion of a dispensing event (e.g., step 2818 of process 2800) according to a third set of embodiments. Process 3100 can be similar to the logic illustrated in FIGS. 29 and 30 but can 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 the first acceleration spike is detected and before it is determined that the dispensing event has been completed. If the second acceleration spike is not detected within the preset time, the processing circuit 2008 ignores or deletes the first acceleration spike. Process 3100 also reverses the order of operations considered in FIGS. 29 and 30, continuously monitoring skin contact from at least one touch sensor 2706 and reading / evaluating the signal from the accelerometer 2012 only if skin contact is detected. Instead, process 3100 continuously reads / evaluates the signal from the accelerometer 2012 for acceleration spikes and, when an acceleration spike is detected, reads / evaluates only the signal from at least one touch sensor 2706.

[0154] After starting at step 3102, the processing circuit 2008 proceeds to step 3104, where it continuously or periodically reads, monitors, and / or evaluates the signal output from the accelerometer 2012, regardless of whether any skin contact is detected. This is different from the logic described above in FIG. 30, where 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. When 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] At step 3105, when the first acceleration spike is detected, the 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 the touch sensors 2706) has detected skin contact. If negative, the processing circuit 2008 branches to step 3108, ignores the first acceleration spike, or deletes the memory record that logged the occurrence of the first acceleration spike, and then branches back to step 3104. If positive, the processing circuit 2008 branches to step 3106.

[0156] At step 3106, the processing circuit 2008 determines that the first acceleration spike was caused by the start of a dispensing event, and the syringe assembly 22 is driven by the drive mechanism 24 from the retracted position to the injection position. The processing circuit 2008 also starts a timer that counts down from a pre-set duration, e.g., a specified number of seconds. After starting the timer, the processing circuit 2008 proceeds to step 3110.

[0157] At step 3110, the processing circuit 2008 determines whether the timer has expired. If positive, the processing circuit 2008 branches to step 3108. If negative, the processing circuit 2008 proceeds to step 3112.

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

[0159] In step 3114, when the second acceleration spike is detected, the 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 the touch sensors 2706) has detected skin contact. If negative, the processing circuit 2008 branches to step 3116 to either ignore the second acceleration spike or delete the memory record that logged the occurrence of the second acceleration spike, and then branches back to step 3110. If positive, the processing circuit 2008 branches to step 3118.

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

[0161] FIG. 32 is a flowchart showing yet another exemplary process 3200 that may be implemented by processing circuit 2008 to detect the start and completion of a dispensing 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 dispensing event has started and completed. Process 3200 also requires that at least one skin contact sensor detect skin contact during the period between the first and second acceleration spikes before determining that the dispensing event has started and completed normally.

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

[0163] At step 3206, processing circuit 2008 determines whether two acceleration spikes that fall within a specified time window have been detected. If affirmative, the processing circuit branches to step 3212, and if negative, processing circuit 2008 branches back to step 3204. For example, processing circuit 2008 may branch to step 3212 only if two acceleration spikes that occur more than a minimum time threshold T min (e.g., 1 second) apart are detected. Alternatively or additionally, processing circuit 2008 may branch to step 3212 only if two acceleration spikes that occur less than a maximum time threshold T max (e.g., 5 - 10 seconds) apart are detected. In some embodiments, the time window may include only the maximum time threshold T max and may not include a minimum time threshold. In other words, 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 points, but for a short time, between the first and second acceleration spikes. (3) Skin contact detected for a specified duration at some points between the first and second acceleration spikes, e.g., 1 - 3 seconds, or between 50 - 100% of the period between the first and second acceleration spikes. (4) Skin contact detected only at the first acceleration spike, but for a short time. (5) Skin contact detected for a specified period at the first acceleration spike (6) Skin contact detected only at the second acceleration spike, but for a short time (7) Skin contact detected 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 maintains a log or buffer in memory of the time and / or duration of the most recently sensed skin contact, and then examines this log in step 3212 to determine whether there was a skin contact that meets the applicable criteria. If the processing circuit detects a 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, the processing circuit 2008 determines that the first acceleration spike was caused by the start of the dispensing event and that the second acceleration spike was caused by the retraction movement at the completion of the dispensing event. The processing circuit 2008 then logs the start and completion of the dispensing event in memory and / or communicates the start and / or completion of the dispensing event to an external device or user.

[0167] Each of processes 3000 (FIG. 30), 3100 (FIG. 31), and 3200 (FIG. 32) has heretofore been described as being implemented by the processing circuit 2008 within device 20. However, in some embodiments, some or all of the steps of each of these processes may be implemented by, or in cooperation with, a processing circuit 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 implemented by a processor within a mobile device (e.g., a smartphone or a portable computer), or by 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., by the Internet or a cellular network). The external device may then log the completion of the dispensing event in memory or in a report, notify and / or communicate the dispensing event to the user, or perform other actions or steps based on the completion of the dispensing event. The steps performed by the external device may be performed, for example, in real time while data is being measured by device 20, or at some time (e.g., hours, days, or years) after the skin contact and accelerometer data has been measured and recorded by device 20.

[0168] The above description of the third set of embodiments of device 20 describes the differences between this third set of embodiments and the first and second sets of the above embodiments, but it should be understood that the third set of embodiments may also include features that exist in either the first or second sets of embodiments, as well as other features. For example, a particular embodiment 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 as being attached thereto. A particular embodiment of this third set of embodiments may also include arms 1710a, 1710b that extend proximally to the second set of embodiments.

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

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

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

[0172] In step 3408, one or more LEDs attached to device 20 may be lit or blink to indicate the temperature status, and thus show the user whether the drug stored in device 20 is within the ideal temperature range for administration (e.g., at room temperature, or between 65 - 75 degrees Fahrenheit, or between 18 - 24 degrees Celsius). For drugs that do not require a temperature check, steps 3406 and 3408 may be skipped.

[0173] In step 3410, if no further activity is detected, device 20 may return to sleep to conserve battery power. Device 20 may enter sleep by powering off 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 power to its processing circuit. In some cases, power may be cut from the processing circuit the moment the user releases the temperature - check button. In other cases, power may be cut from the processing circuit within a certain pre - set time (e.g., several seconds or minutes) after the user releases the temperature - check button. Other electrical components, such as LEDs and / or sensors, may also be powered off to conserve power.

[0174] In step 3412, device 20 detects when the user removes the base cap 36. For devices belonging to a third set of embodiments, device 20 may use a base - cap removal sensor 2010 to detect that the base cap 36 has been removed. This measure, for example, restarts device 20 by powering on its processing circuit.

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

[0177] In step 3418, device 20 lights one or more LEDs mounted on the body of the device to indicate to the user that the dispensing event has started and completed successfully.

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

[0179] In step 3422, device 20 can be disposed of in any suitable manner, for example, within a sharps container as illustrated.

[0180] Users of the disclosed injection device may have various levels of proficiency and / or experience in operating the device. Users with a high level of proficiency and / or experience in operating the device may require less instruction and / or supervision when using the disclosed device to dispense a medicament. Conversely, users with a low level of proficiency and / or experience in operating the device may require additional instructions and / or supervision. However, providing all users with longer and / or more detailed instructions may frustrate or fatigue users with a high level of proficiency and / or experience. Similarly, providing all users with enhanced supervision from a caregiver, regardless of proficiency and / or experience level, may be costly and unnecessary when such supervision may not be required for experienced users. What is needed is a method for determining the level of a user's proficiency and / or experience in correctly operating the injection device disclosed herein. This determination may enable the disclosed injection device, a mobile device in communication with such an injection device, and / or a caregiver to provide supplementary instructions, supervision, and / or training only to those users who require such instructions or training. Also needed is a method for assessing how the level of a user's proficiency and / or experience in operating the disclosed injection device changes over time. With multiple uses, a user may be expected to improve their proficiency in using the disclosed device. If a particular user does not improve their proficiency over time in using the disclosed device, or does not improve as quickly as other users, a caregiver may provide such a user with supplementary 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, seller, and / or payer of such a delivery device may redesign the device and / or provide revised or supplemental instructions for use.

[0181] Figures 35 - 40 illustrate various exemplary processes for gaining insight into whether any user of an injection device disclosed herein has a high or low level of proficiency and / or experience when 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 implemented entirely on the injection device (e.g., the processing core 1208 within device 20, see FIG. 12), entirely on an external device wirelessly communicating with the injection device (e.g., the processor 1252 on external device 1250 wirelessly communicating 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 where the one or more processing circuits are distributed between the injection device and the external device, certain 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, certain steps or all steps of each process may also be jointly executed by processing circuits on both the injection device and the external device. The processes shown in FIGS. 35 - 40 may be executed or implemented independently, sequentially one after the other, or in parallel with each other.

[0182] FIG. 35 is a flowchart illustrating an exemplary process 3500 for generating an indication as to whether any user of an injection device disclosed herein has a high or low level of proficiency or experience when operating the injection device. Process 3500 measures the amount of time elapsed 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, the one or more processing circuits on which process 3500 is implemented may generate a user indication signal indicating that the user may have a relatively low level of proficiency or experience.

[0183] Process 3500 begins with step 3502 where a drug delivery device is provided. An example of a suitable drug delivery device is device 20, including any of its embodiments disclosed herein. The provided drug delivery device includes a device housing that defines an internal volume and an opening in communication with the internal volume. The drug delivery device is 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, and a drive mechanism configured to move the syringe assembly from a retracted position to an injection position where the needle at least partially extends from the opening. In some embodiments, as described herein, the drug delivery device may optionally further 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 to the opening, each skin contact sensor being configured to detect contact with skin tissue. Suitable skin contact sensors include both resistive sensors 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 the position of at least a portion of the syringe assembly and the movement of at least a portion of the pre-syringe assembly. In some embodiments, the syringe assembly sensor may include one or more sensors configured to determine the position of a piston that slides along the longitudinal axis of the barrel of the syringe assembly, 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 sensor 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, 20). In yet other embodiments, the syringe assembly sensor may include one or more sensors configured to detect an acceleration caused by the syringe assembly when the syringe assembly moves from a storage position to an injection position or from an injection position to a retracted position. A suitable example of such a syringe assembly sensor includes 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, the skin contact sensors may detect contact with skin tissue in different ways, such as by measuring the electrical resistance between two or more terminals and / or by measuring the capacitance. In some embodiments, step 3504 may include recording a timestamp in memory corresponding to the time when one or more skin contact sensors detect contact with skin tissue. Alternatively or additionally, step 3504 may include starting a timer when 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 dispensing event. This determination can 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 dispensing event when the syringe assembly sensor detects that the piston has begun 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 can be determined using magnetometers 112 and / or 118 (see FIG. 11). Alternatively or additionally, this determination can 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 dispensing event when the syringe assembly sensor detects that the syringe assembly has moved from the storage position to the injection position. This movement can 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 the impact applied to the injection device when the syringe assembly is moved or driven from the storage position to the injection position. Optionally, a skin contact sensor can be used in combination with the accelerometer to provide additional accuracy in determining when the syringe assembly has initiated a dispensing event, and embodiments that use a skin contact sensor in combination with the accelerometer to detect the start and / or completion of a dispensing event are discussed above in connection with FIGS. 28-32. In some embodiments, step 3506 may include recording a timestamp in memory corresponding to the time when the syringe assembly initiated a dispensing event. Alternatively or additionally, step 3506 may include stopping a timer that was started when one or more skin contact sensors detected contact with skin tissue.

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

[0189] In step 3510, the processing circuit compares the first duration with a first pre-programmed 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 regarding the operation of the drug delivery device. This is because it can be expected that an experienced or skilled user of the drug delivery device will start a dispensing event immediately after placing the delivery device against the skin tissue. The fact that the user delays the start of the dispensing event after placing the device against the skin may indicate that the user has spent excessive time checking and double-checking whether the device is properly positioned, re-reading the instructions for using the delivery device, and / or unlocking the device to start the 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 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. Specifically, process 3600 generates an indication as to whether a user can determine when the injection device has completed a dispensing event. Some of the injection devices disclosed herein incorporate mechanical features that enable the user to know when the dispensing event has been completed. For example, when the syringe assembly moves from the injection position to the retracted position at the end of the dispensing event, the user can feel the impact from the movement of the syringe assembly with their hand and can hear an audible click sound from the movement of the syringe assembly. In embodiments where all or a portion of the device housing is transparent, the user may be able to visually see the movement of the syringe assembly as it moves from the injection position to the retracted position. An experienced or skilled user 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 has been completed. If the user does not move the injection site within a period of time after the dispensing event has been completed, this may indicate that the user is unable to see, hear, and / or feel any of the aforementioned mechanical indicators (e.g., due to a decrease in sensory acuity), does not know to look for any of the aforementioned mechanical indicators, or does not know that any of the indicators indicate that the dispensing event has been completed.

[0191] Process 3600 begins at step 3614 where a processing circuit determines when the syringe assembly has completed a dispensing event. This determination can be made based on the position or movement of a piston within the barrel of the syringe assembly. For example, the processing circuit may determine that the syringe assembly has completed a dispensing event when the syringe assembly sensor detects that the piston has completed its proximal movement along the barrel of the syringe assembly, or when the piston occupies a position along the barrel indicating completion of the dispensing event. Alternatively or additionally, this determination can be made based on the position or movement of the syringe assembly as a whole. For example, the processing circuit may determine that the syringe assembly has completed a dispensing event when the syringe assembly sensor detects that the syringe assembly has moved from an injection position to a 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 an impact applied to the injection device when the syringe assembly is moved or driven from an injection position to a retracted position. Optionally, as described above, a skin contact sensor can also be used in combination with the accelerometer to provide additional accuracy in determining when the syringe assembly has completed a dispensing event. In some embodiments, step 3614 may include recording a timestamp in memory corresponding to the time when the syringe assembly has completed a dispensing event. Alternatively or additionally, step 3614 may include starting a timer when the syringe assembly completes a dispensing event.

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

[0193] In step 3618, the processing circuit measures a second duration between when the syringe assembly completes a dispensing event and when at least one skin contact sensor stops detecting contact with the skin tissue. This measurement may be performed by subtracting the time stamp corresponding to when the syringe assembly completes the dispensing event from the time stamp corresponding to when at least one skin contact sensor stops detecting contact with the skin tissue. This subtraction operation can 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 performed simply by reading the value of a 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 pre-programmed 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 the user of the drug delivery device cannot see, hear, and / or feel any of the mechanical indicators that may accompany the completion of the dispensing event, and / or that the user does not recognize the importance of the aforementioned 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 as to whether a user of any of the drug delivery devices disclosed herein has a high or low level of proficiency or experience when operating an injection device. Specifically, process 3700 determines whether a user may be misusing a drug delivery device by attempting to replace a base cap of the device. For some of the injection devices disclosed herein, a user may be instructed not to replace a base cap (e.g., base cap 36) that covers the injection needle of the injection device and then, without starting and / or completing a dispensing event thereafter. This is because replacing the base cap after removal may cause the injection needle to bend or become damaged. In such injection devices, it is generally desirable not to remove the base cap until immediately before starting and completing a dispensing event. If the base cap is prematurely removed before an injection is required, the entire injection device should be discarded. Thus, replacing the base cap without starting and / or completing a dispensing event after removal can be a misuse of such an injection device. Instructions for using the device may clarify this to the user, but it may be preferable to implement means for automatically detecting such misuse of the injection device.

[0196] Process 3700 begins at step 3702 where a drug delivery device is provided. An example of a suitable drug delivery device is device 20, including any of its embodiments disclosed herein. The provided drug delivery device may comprise a device housing defining an internal volume, the internal volume being in communication with an opening (e.g., opening 40), and a syringe assembly at least partially disposed within the internal volume. The syringe assembly may include a barrel configured to hold a medicament and a syringe needle extending from the barrel. The device may further comprise a movable base cap (e.g., base cap 36) configured to cover the opening. The device may also comprise one or more syringe assembly sensors configured to detect at least one of the position of at least a portion of the syringe assembly and at least a portion of the movement of the syringe assembly, and one or more base cap sensors configured to detect when the movable base cap has been removed from the opening. Suitable examples of syringe assembly sensors include, as described above, magnetometers 112 and / or 118, microswitches 116 and / or syringe position detector switches 1710, and / or one or more accelerometers 2012. A suitable example of a base cap sensor includes a 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 starts or completes a dispensing event. Any of the methods described herein for determining the start and / or completion of a dispensing event can be used. In step 3706, the processing circuit monitors data output from one or more base cap sensors to determine whether the base cap is covering 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 later returned to cover the opening before the syringe assembly starts or completes a dispensing event. The misuse indication signal may indicate that the user is misusing the injection device in a way that could damage the needle and impair the performance of the device. In some embodiments, the misuse indication signal may be generated only if the sensor of the injection device detects that the base cap has been removed and then returned before the syringe assembly starts or completes a dispensing event.

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

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

[0201] Process 3800 begins at step 3802 where a drug delivery device is provided. The delivery device provided may be similar to the types of devices described above in relation to step 3502 of process 3500 of FIG. 35.

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

[0203] At 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 instruction signal when the number of proximity events is greater than a pre-programmed maximum threshold. For example, the processing circuit may generate a user instruction signal when the number of proximity events exceeds zero, one, two, three, or four proximity events.

[0205] FIG. 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 an injection device. Specifically, process 3900 determines whether a user may inappropriately lift the device off the patient's skin during a dispensing event. A user instruction signal (indicating a user with a low level of proficiency or experience) may be generated when a skin contact sensor detects a break in contact with the skin during an injection, i.e., after the dispensing event has started but before the dispensing event is complete. Such an early lift-off event may potentially indicate an incomplete dose, as well as an inexperienced or unsure user.

[0206] Process 3900 begins at step 3902 where a drug delivery device is provided. The delivery device provided may be similar to the types of devices described above in connection with step 3502 of process 3500 of FIG. 35.

[0207] In step 3904, the processing circuit determines when the syringe assembly starts a dispensing event and when the syringe assembly completes a dispensing 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 a dispensing 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 a dispensing 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 signal may be received after the dispensing event has started and before the dispensing event is completed, i.e., the processed signal may be received during the dispensing event or while the dispensing event is in progress. In step 3908, the processing circuit generates a user instruction signal when data indicating the continuity of skin contact meets one or more pre-programmed criteria.

[0209] The processing circuit processes such signals to generate data indicating the continuity of skin contact during the dispensing event. Different measures indicating 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, where each lift-off event includes an event in which one or more skin contact sensors transition from a state where skin contact is detected to a state where skin contact is not detected. In such an embodiment, the processing circuit may generate a user instruction signal when 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 circuit may calculate the ratio of the amount of time during which skin contact is detected to the amount of time during which skin contact is not detected. In such an embodiment, the processing circuit may generate a user instruction signal when the calculated ratio is lower than a pre-programmed threshold.

[0211] Alternatively or additionally, the processing circuit may calculate the ratio of the amount of time during which skin contact is detected to the total duration of the dispensing event. In such an embodiment, the processing circuit may generate a user instruction signal when the calculated ratio is less than a pre-programmed threshold.

[0212] Alternatively or additionally, the processing circuit may calculate a ratio of the amount of time during which skin contact is not detected to the total duration of the dispensing event. In such embodiments, the processing circuit may generate a user instruction signal if the calculated ratio is greater than a pre-programmed threshold value.

[0213] Alternatively or additionally, the processing circuit may generate a user instruction signal if the amount of time during which skin contact is not detected during the dispensing event is greater than a pre-programmed threshold value.

[0214] FIG. 40 is a flowchart illustrating yet another exemplary process 4000 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 an injection device. Specifically, process 4000 determines whether the user starts a dispensing event within a certain threshold time after moving the base cap. A skilled or experienced user is expected to start the dispensing event quickly after moving the base cap. However, a user with a low level of proficiency or experience may likely wait a longer time after moving the base cap to start the dispensing event because the user is checking or re-checking the device's instructions for use, looking for the appropriate injection site on the patient's body for use, or is unsure how to operate the device. In particular, waiting a long time after moving the base cap to start the dispensing event can increase the risk that the exposed sterile needle becomes contaminated. Waiting a long time can also increase the risk that the liquid formulation stored in the barrel dries out and partially or completely blocks the needle, preventing drug delivery.

[0215] Process 4000 begins at step 4002 where a drug delivery device is provided. The delivery device provided may be similar to the types of devices described above in connection with step 3702 of process 3700 of FIG. 37.

[0216] In step 4004, the processing circuit monitors data output from one or more syringe assembly sensors to detect when the syringe assembly starts a dispensing event. Any of the methods described herein for determining the start and / or completion of a dispensing event can be used. In step 4006, the processing circuit monitors data output from 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 start a dispensing event within a threshold time after the base cap has been moved from the opening. This can 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 dispensing event by the time the timer expires (or by the time the timer reaches a specific threshold duration), the processing circuit may generate a user instruction signal. Alternatively or additionally, the processing circuit may log a first timestamp associated with the time the base cap was moved and a second timestamp associated with the time the syringe assembly started a dispensing event. The processing circuit may then calculate the difference between the first timestamp and the second timestamp. If the difference is greater than a threshold duration, the processing circuit may generate a user instruction signal.

[0218] As described above, each of processes 3500, 3600, 3700, 3800, 3900, and 4000 may be implemented on one or more processing circuits that are either disposed entirely on the injection device or disposed on both the injection device and an external device that wirelessly communicates with the injection device. In embodiments where the process is 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 execute 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) transmit a data packet to the external device that includes information regarding (a) whether a dispensing event has been initiated, (b) whether the dispensing 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 is transmitted. In some embodiments, the injection device may not initiate transmission of such data packets until the base cap is removed or after a dispensing event has been initiated. In yet other embodiments, the injection device may wait until after an injection event prior to transmitting the data packet has been completed. In such embodiments, the data packet may include a timestamp indicating when the base cap was removed and / or when the dispensing event was initiated. 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 instruction 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 instruction signal described above.

[0219] Each of the user instruction signals (and / or misuse instruction signals) generated by processes 3500, 3600, 3700, 3800, 3900, and 4000 can be sent to various destinations and / or can prompt different actions or responses from the processing circuitry or from a device communicating with one or more processing circuits. Some of the aforementioned user instruction signals and / or misuse instruction 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 can cause one or more processing circuits to display or reproduce instructions regarding how to properly use the injection device. For example, in process 3500, the first user instruction signal can prompt a mobile application on the user's mobile device (e.g., external device 1250) to display a screen showing instructions or to provide the user with one or more instructional videos or audio messages regarding how to unlock, position, and operate 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 regarding how to indicate when the drug delivery device has completed a dispensing event. The misuse instruction signal in process 3700 can prompt the mobile application to display a screen and / or message warning the user that the needle may be damaged if the base cap is removed and then replaced, and / or can advise the user that the drug delivery device should be operated immediately after the base cap is removed. In some embodiments, the user instruction signal and / or misuse instruction signal can cause the user's mobile device to display a proposal or prompt to contact a help desk agent (e.g., via a phone line or chat line). The user instruction signal and / or misuse instruction signal can 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 the misuse instruction signal may be transmitted via a network (e.g., via the Internet or a cellular network) to a remote server or device in the form of, for example, a text message, a push notification, an email, or other remote electronic notification. The remote server or device may be associated with a care provider to a user such as a nurse, nurse practitioner, physician, family member, or other care provider. In such a case, the user instruction signal and / or the misuse instruction signal may indicate to the care provider that the user may require additional supervision or assistance when using the drug delivery device. In still other embodiments, the remote server or device may be associated with a manufacturer, designer, distributor, or payer of the injection device. In such a case, the user instruction signal and / or the misuse instruction signal can provide real-world data to such an entity regarding how the user is using the injection device. When aggregated across a population of injection device users, such real-world data can inform decisions regarding whether (and if so, at what rate and under what conditions) to reimburse such injection devices, whether and / or how to redesign such injection devices, and / or whether additional usage instructions or training are required for effective use. The user instruction signal and / or the misuse instruction signal may also be recorded and tracked over time for individual users or groups of users. Ideally, the occurrence of the user instruction signal and / or the misuse instruction signal should decrease over time as the user becomes more proficient and / or familiar with the injection device. If the occurrence of such signals does not decrease or does not decrease as rapidly as expected, the manufacturer, designer, distributor, and / or payer of the injection device may consider taking additional actions such as redesigning the injection device or providing additional usage instructions or training.

[0221] The present invention has been described as having an exemplary design, but embodiments of the present disclosure may be further modified within the concept and scope of the present disclosure. Therefore, this application is intended to cover any variations, uses, or adaptations of the embodiments of the present disclosure using its general principles.

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

Claims

1. 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 drug and a syringe needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly expels the drug from the syringe needle when the syringe needle at least partially extends from the opening; one or more skin contact sensors disposed on the housing adjacent to the opening, each skin contact sensor being configured to detect contact with skin tissue; one or more syringe assembly sensors disposed within the 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; one or more processing circuits configured to: determine when the one or more skin contact sensors detect contact with skin tissue; determine when the syringe assembly initiates the 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 the dispensing event; compare the first duration to a first pre-programmed threshold duration; and transmit a first user instruction signal to an external device when the first duration is greater than the first threshold duration.

2. The drug delivery system of claim 1, wherein the syringe assembly further comprises a piston configured to slide along a longitudinal axis within the barrel to extrude the drug from the syringe needle. The syringe assembly sensor signal is based on the position of the piston. The one or more processing circuits are configured to determine when the syringe assembly initiates the dispensing event based on the position of the piston.

3. The drug delivery system according to claim 1, wherein the drive mechanism is configured to move the syringe assembly from a storage position to an injection position where the injection needle extends at least partially from the opening.

4. The drug delivery system according to claim 3, wherein the one or more processing circuits are configured to determine when the syringe assembly has started the dispensing event by determining when the syringe assembly has moved from the storage position to the injection position.

5. The drug delivery system according to claim 4, wherein the one or more syringe assembly sensors comprise a syringe position detector switch.

6. The one or more syringe assembly sensors comprise an accelerometer configured to output the syringe assembly sensor signal based on a sensed acceleration caused by movement of the syringe assembly, The drug delivery system according to claim 4 or 5, wherein the one or more processing circuits are configured to determine when the syringe assembly has started the dispensing event based at least in part on the sensed acceleration.

7. The drug delivery system according to any one of claims 1 to 6, wherein at least one of the one or more processing circuits is disposed within the device housing.

8. The drug delivery system according to any one of claims 1 to 7, wherein at least one of the one or more processing circuits is disposed within a mobile device separate from the device housing and wirelessly communicates with a wireless transmitter disposed within the device housing.

9. The drug delivery system according to any one of claims 1 to 8, wherein the one or more processing circuits are further configured to display or reproduce instructions on how to use the drug delivery system in response to the first user instruction signal.

10. The drug delivery system according to any one of claims 1 to 9, wherein the one or more processing circuits are configured to transmit the first user instruction signal to a remote device via a network.

11. The one or more processing circuits are determining when the syringe assembly has completed the dispensing event based at least in part on the syringe assembly sensor signal; determining when the one or more skin contact sensors cease detecting contact with skin tissue; measuring a second duration between when the syringe assembly completes the dispensing event and when the one or more skin contact sensors cease detecting contact with skin tissue; comparing the second duration to a second pre-programmed threshold duration; further configured to generate a second user indication signal when the second duration is greater than the second threshold duration, the drug delivery system of any one of claims 1-10. **Claim 12** The drug delivery system of claim 11, wherein the one or more processing circuits are further configured to display or reproduce instructions regarding how to determine when the syringe assembly has completed the dispensing event in response to the second user indication signal. **Claim 13** The drug delivery system of claim 11 or 12, wherein the one or more processing circuits are configured to transmit the second user indication signal to a remote device via a network. **Claim 14** The drug delivery system of any one of claims 1-13, wherein the barrel holds the medicament. **Claim 15** 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 drug and a needle extending from the barrel; a drive mechanism configured to initiate a dispensing event in which the syringe assembly discharges the drug from the needle when the needle extends at least partially from the opening; one or more skin contact sensors disposed on the housing adjacent to the opening, each skin contact sensor being configured to detect contact with skin tissue; and 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 the position of at least a portion of the syringe assembly and the movement of at least a portion of the syringe assembly, the method comprising: determining when the one or more skin contact sensors detect contact with skin tissue; determining when the syringe assembly initiates the dispensing event, based at least in part on the syringe assembly sensor signal; measuring a first duration between when the at least one skin contact sensor detects contact with skin tissue and when the syringe assembly initiates the dispensing event; comparing the first duration to a first pre-programmed threshold duration; transmitting a first user instruction signal to an external device when the first duration is greater than the first threshold duration. **Claim 16** The method of claim 15, further comprising displaying or reproducing instructions on how to use the drug delivery device in response to the first user instruction signal. **Claim 17** The method of claim 15 or 16, further comprising transmitting the first user instruction signal to a remote device via a network. **Claim 18** determining when the syringe assembly completes the dispensing event, based at least in part on the syringe assembly sensor signal; determining when the one or more skin contact sensors cease 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 cease detecting contact with the skin tissue; comparing the second duration to a second pre-programmed threshold duration; generating a second user indication signal when the second duration is greater than the second threshold duration; The method according to any one of claims 15 to 17, further comprising.

19. The method according to claim 18, further comprising displaying or playing an instruction on how to determine when the syringe assembly has completed the dispensing event in response to the second user indication signal.

20. The method according to claim 18 or 19, further comprising transmitting the second user indication signal to a remote device via a network.

21. A non-transitory computer-readable medium storing instructions that, when executed by at least one processing circuit, cause the at least one processing circuit to implement the method according to any one of claims 15 to 20.

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