Drug delivery device with signal filtering - Patent application

Abstract

A method is provided for filtering a signal output from a sensor of a medication delivery device. In some embodiments, the sensor is operable to transition between an engaged state and a disengaged state. In some embodiments, the method includes detecting a first transition of the signal from a second logic state to a first logic state, the first transition occurring at a first time point; determining whether the signal is in the first logic state for an accumulated time period that is equal to or greater than a first threshold duration within a first time period beginning at the first time point; and determining that the sensor of the medication delivery device transitioned from the disengaged state to the engaged state at the first time point if the accumulated time period is equal to or greater than the first threshold duration.

Description

[Background technology]

[0001]

[0003] Patients suffering from various diseases frequently must inject themselves with medication. To enable individuals to conveniently and accurately self-administer medication, various devices, commonly known as pen-type injectors or injection pens, have been developed. These pens generally include a cartridge containing a piston and containing multiple doses of liquid medication. A drive member is movable forward to advance the piston within the cartridge and dispense the contained medication from an outlet at the distal cartridge end, typically through a needle.

[0002] Such devices may have components that physically interact with each other to effect a change of state or action by the device, for example, the device may have a dose button that can be rotated to a set dose and / or actuated to deliver a dose.

[0003] Such devices may include electronics such as integrated circuits with processing units and other components, For example, the electronics may include sensing devices in communication with the processing unit to detect the occurrence of such interactions. Summary of the Invention

[0004] According to an exemplary embodiment of the present disclosure, there is provided a method for filtering a signal output from a sensor of a medication delivery device, the sensor being operable to transition between an engaged state in which the signal output from the sensor is in a first logic state and a disengaged state in which the signal output from the sensor is in a second logic state, the method including: detecting a first transition of the signal from the second logic state to the first logic state, the first transition occurring at a first time point; determining, within a first time period beginning at the first time point, whether the signal is in the first logic state for an accumulated period equal to or greater than a first threshold duration; and determining that the sensor of the medication delivery device transitioned from the disengaged state to the engaged state at the first time point if the accumulated period is equal to or greater than the first threshold duration.

[0005] According to another embodiment of the present disclosure, there is provided a medication delivery device. The medication delivery device includes a housing with a reservoir large enough to hold a medication. The medication delivery device includes a printed circuit board. The medication delivery device includes a sensor mounted on the printed circuit board and operable to output a signal, the sensor operable to transition between an engaged state, in which the signal output from the sensor is in a first logic state, and a disengaged state, in which the signal output from the sensor is in a second logic state. The medication delivery device includes a microcontroller in electrical communication with the sensor via a logic input to the microcontroller. The microcontroller is configured to receive the signal output from the sensor and determine whether the sensor has transitioned between a disengaged state and an engaged state based at least in part on the received signal by: determining whether the signal is in the first logic state for an accumulated period that is greater than or equal to a first threshold duration within a first time period beginning at a first time point corresponding to a first transition of the signal from the second logic state to the first logic state; and determining that the sensor has transitioned from the disengaged state to the engaged state if the accumulated period is greater than or equal to the first threshold duration. [Brief explanation of the drawings]

[0006] Additional embodiments of the present disclosure, and its features and advantages, will become more apparent by reference to the description herein taken in conjunction with the accompanying drawings, in which components are not necessarily drawn to scale. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the different views. [Figure 1] FIG. 1 is a perspective view of a medication delivery device having a dose detection system according to an aspect of the present disclosure. [Figure 2] FIG. 2 is a partially exploded perspective view of the medication delivery device of FIG. 1 showing the dose button with a support and a cover, the cover shown separated from the support. [Figure 3] FIG. 2 is a partially exploded perspective view of the medication delivery device of FIG. 1 showing components of the dose detection system. [Figure 4] FIG. 2 is a cross-sectional view of the drug delivery device of FIG. 1. [Figure 5] 2 is a partial cutaway view of the proximal end of the medication delivery device of FIG. 1 showing components of the dose detection system. [Figure 6] FIG. 2 is a bottom view of a portion of the dose button of FIG. 1, showing a printed circuit board held within the dose button cover. [Figure 7] FIG. 7 is an exploded view of a portion of the dose button shown in FIG. 6. [Figure 8] FIG. 10 is a perspective view of a flange of a dose detection system of a medication delivery device. [Figure 9] FIG. 9 is a top view of the flange of FIG. 8. [Figure 10] FIG. 10 is a perspective view of a dose button support. [Figure 11] FIG. 11 is a top view of the dose button support of FIG. [Figure 12] 1 is an exemplary schematic diagram of a printed circuit board according to some embodiments. [Figure 13] 1 is an exemplary plot illustrating a signal received from a sensor of a medication delivery device, according to some embodiments. [Figure 14] 1 is an exemplary schematic diagram of a printed circuit board having a resistor-capacitor (RC) circuit according to some embodiments. [Figure 15] 10 is an exemplary plot showing a signal received from a sensor of a medication delivery device and filtered using an RC circuit, according to some embodiments. [Figure 16A] 10 is a flowchart illustrating an exemplary method for filtering a signal received from a sensor of a medication delivery device, according to some embodiments. [Figure 16B] 10 is a flowchart illustrating an exemplary method for filtering a signal received from a sensor of a medication delivery device, according to some embodiments. [Figure 17] 1 is an exemplary schematic diagram illustrating a system for detecting a transition in a signal received from a sensor of a medication delivery device, according to some embodiments. [Figure 18] 10 is an exemplary plot showing the integral of a signal received from a sensor of a medication delivery device, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0007] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same, it being understood nevertheless that no limitation of the scope of the invention is intended.

[0008] Techniques are provided herein for filtering signals received from a sensor of a medication delivery device. According to some embodiments, the sensor is operable to transition between an engaged state and a disengaged state. For example, the sensor may transition to the engaged state when it begins to interact with a sensed component of the medication delivery device. The sensor may transition to the disengaged state when it no longer interacts with the sensed component of the medication delivery device.

[0009] The engaged and / or disengaged states can be used to determine information about the medication delivery device, such as medication dosing information. In some embodiments, the transition of the sensor between the engaged and disengaged states may be used to determine the dosage of medication delivered using the medication delivery device. As a non-limiting example, the dosage of medication may be determined based on the number of times the sensor transitions to the engaged and / or disengaged states. Accordingly, the inventors have realized that accurately considering the number of times the sensor transitions to the engaged and / or disengaged states is important to accurately determine the dosage of medication delivered using the medication delivery device. For example, the medication delivery device may include a flange with teeth that rotates when a dose is being dispensed by the device. As the flange rotates, the teeth can interact with a mechanical switch, triggering the switch. Each time the switch is physically triggered by the teeth (e.g., when the switch contacts the teeth and / or when the switch no longer contacts the teeth), the switch can output an electrical signal that is counted by a processor of the medication delivery device. The processor can count these electrical signals to determine how much the flange has rotated and, optionally, determine how much insulin has been dispensed by the medication delivery device based on the rotation information. Alternatively, the processor may communicate the rotation information to another device that determines how much insulin has been dispensed by the medication delivery device based on the rotation information.

[0010] In some embodiments, the signal output by the sensor may be used to infer whether the sensor has transitioned between an engaged state and / or a disengaged state. For example, when the sensor is in an engaged state, the sensor may be configured to output a signal of a first logic state, and when the sensor is in a disengaged state, the sensor may be configured to output a signal of a second logic state different from the first logic state. Thus, when the sensor transitions between the engaged and disengaged states, the signal output by the sensor may transition between a first logic state and a second logic state. For example, the first logic state of the signal may be an assertion state (e.g., a logic 1, a high state, etc.), and the second logic state of the signal may be a deassertion state (e.g., a logic 0, a low state, etc.), or vice versa. Although embodiments herein are described assuming that the sensor outputs a signal in an assertion state when in an engaged state and a signal in a deassertion state when in a disengaged state, this can be easily reversed with appropriate modifications. For example, the signal may pass through an inverter before being processed to detect transitions between logic states.

[0011] However, the inventors recognize that this approach has limitations. In particular, there may be noise associated with the sensor's transitions between engaged and disengaged states. For example, as the sensor begins to transition to the engaged state, the interaction between the sensor and the sensed component may fluctuate (e.g., the sensor may momentarily lose contact with the sensed component). As another example, as the sensor transitions to the disengaged state, the sensor may bounce between the disengaged and engaged states. As a result, the signal output by the sensor may fluctuate between a first and a second logic state several times, even when the sensor is undergoing only a single transition. Therefore, counting the number of signal transitions to infer the number of sensor transitions may lead to an overestimation and, therefore, an inaccurate estimation of the dose delivered using the medication delivery device.

[0012] Therefore, the present inventors have developed a technique for filtering signals received from such sensors in medication delivery devices that addresses the above-mentioned limitations of the prior art. In some embodiments, the technique detects transitions of the signal between logic states and uses the detected transitions to determine whether the sensor has transitioned to an engaged and / or disengaged state. For example, in some embodiments, to determine whether the sensor has transitioned to an engaged state at a first time point, the technique determines the accumulated duration that the signal was in a first logic state, such as an asserted state, during a first period beginning at the first time point. If the accumulated duration is greater than or equal to a threshold duration, this may indicate that the sensor has transitioned to an engaged state at the first time point.

[0013] Additionally or alternatively, in some embodiments, the technique for filtering the signal includes processing the signal using one or more hardware components. For example, in some embodiments, the technique includes processing the signal using a resistor-capacitor (RC) circuit. For example, the RC circuit may act as a low-pass filter configured to remove high-frequency noise caused by interactions between the sensor and the sensed component as the sensor transitions between engaged and / or disengaged states.

[0014] While various embodiments have been described, it will be apparent to those skilled in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples and are not intended to be the only possible embodiments and implementations. Furthermore, the advantages described above are not necessarily the only advantages, and it is not necessarily expected that all of the described advantages will be achieved in each embodiment.

[0015] The devices described herein may further include a medication, such as in a reservoir or cartridge 20 (described below). In another embodiment, a system may include one or more devices, including device 10 (described below), and a drug. The term "medication" refers to one or more therapeutic agents, including, but not limited to, insulin, insulin analogs such as insulin lispro or insulin glargine, insulin derivatives, GLP-1 receptor agonists such as dalaglutide or liraglutide, glucagon, glucagon analogs, glucagon derivatives, gastric inhibitory polypeptide (GIP), GIP analogs, GIP derivatives, oxyntomodulin analogs, oxyntomodulin derivatives, therapeutic antibodies, and any therapeutic agent that can be delivered by a device described herein. Medication such as that used in the device may be formulated with one or more excipients. The device is operated by a patient, caregiver, or medical professional to deliver medication to a person in a manner generally as described above.

[0016] An exemplary medication delivery device 10 is shown in FIGS. 1-4 as a pen-type injector configured to inject a medication into a patient through a needle. The device 10 includes a body 11, which may include an elongated, pen-shaped housing 12 including a tip portion 14 and a proximal portion 16. As used herein, the term "distal" refers to the direction and / or portion of the medication delivery device that is directed toward (or located closer to) the injection site, while the term "proximal" refers to the direction and / or portion of the medication delivery device that is directed away from (or located further away from) the injection site. The distal portion 14 may be received within a pen cap 18. Referring to FIG. 4, the distal portion 14 may house a reservoir or cartridge 20 configured to hold a medication to be dispensed through an outlet 21 of the housing in a dispensing action. The outlet 21 of the distal portion 14 may be equipped with an injection needle 24. In some embodiments, the injection needle is removable from the housing. In some embodiments, the injection needle is replaced with a new injection needle after each use.

[0017] A piston 26 may be positioned within the reservoir 20. The medication delivery device may include an injection mechanism positioned within the proximal portion 16 that is operable to advance the piston 26 toward the outlet of the reservoir 20 and force the contained medication through the needle end during a dose-dispensing operation. The injection mechanism may include a drive member 28, illustratively in the form of a screw, that is axially movable relative to the housing 12 to advance the piston 26 through the reservoir 20.

[0018] The device may include a dose setting assembly coupled to the housing 12 for setting the dose to be dispensed by the device 10. As best seen in FIGS. 3 and 4, in the illustrated embodiment, the dose setting assembly includes a dose setting screw 32 and a flange 38. The dose setting screw 32 is in the form of a threaded element operable to move helically (i.e., move axially and rotationally simultaneously) relative to the housing 12 about a longitudinal axis of rotation AA during dose setting and dose dispensing. FIGS. 3 and 4 show the dose setting screw 32 fully threaded into the housing 12 at its home or zero dose position. The dose setting screw 32 is operable to unscrew proximally from the housing 12 until it reaches a fully extended position corresponding to the maximum dose deliverable by the device 10 in a single injection. The extended position can be any position between a position corresponding to an incremental extended position (such as a 0.5 or 1 unit dose setting) to a fully extended position corresponding to the maximum dose deliverable by the device 10 in a single injection, for screwing the housing 12 distally until a home or zero position corresponding to the minimum dose deliverable by the device 10 in a single injection is reached.

[0019] 3 and 4, the dose set screw 32 includes a helically threaded outer surface that engages a corresponding threaded inner surface 13 of the housing 12 to allow the dose set screw 32 to move helically (i.e., simultaneously rotate and translate) relative to the housing 12. The dose set screw 32 further includes a helically threaded inner surface that engages a threaded outer surface of a sleeve 34 (FIG. 4) of the device 10. The outer surface of the dose set screw 32 includes dose indicator markings, such as numbers that are visible through a dose window 36 to indicate the set dose to the user.

[0020] As mentioned above, in some embodiments, the dose setting assembly further includes a tubular flange 38 coupled to the open proximal end of the dose setting screw 32 and axially and rotationally locked to the dose setting screw 32 by a protrusion 40 received within an opening 41 in the dose setting screw 32. The protrusion 40 of the flange 38 can be seen in Figures 3, 8, and 9, and the opening 41 in the dose setting screw 32 can be seen in Figure 3.

[0021] As seen in Figures 3 and 4, the delivery device 10 may include an actuator assembly having a clutch 52 and a dose button 30. The clutch 52 is received within the dose setting screw 32, and the clutch 52 includes an axially extending stem 54 at its proximal end. The dose button 30 of the actuator assembly is positioned proximal to the dose setting screw 32 and flange 38. The dose button 30 includes a support 42, also referred to herein as the "under button," and a cover 56, also referred to herein as the "over button." As discussed, the support 42 and cover 56 enclose electronic components used to store and / or communicate data regarding the amount of the dose delivered by the medication delivery device.

[0022] The dose button support 42 may be attached to the stem 54 of the clutch 52, such as by an interference fit or ultrasonic welding, to axially and rotatably secure the dose button 30 and clutch 52 together.

[0023] In some embodiments, a portion of the clutch may pass through a lumen 39 in the flange 38. The flange lumen 39 is best seen in Figures 8 and 9. The lumen 39 may, in some embodiments, serve to assist in centering the clutch 52 in place.

[0024] The proximal face 60 of the dose button 30 may serve as a pressure surface against which force can be applied manually, i.e., directly by a user, to push the actuator assembly (dose button 30 and clutch 52) distally. A biasing member 68, illustratively a spring, may be disposed between a distal face 70 of the support 42 and a proximal face 72 of the tubular flange 38 (FIGS. 8 and 9) to bias the support 42 of the actuation assembly and the flange 38 of the dose setting assembly axially away from one another. The dose button 30 is depressible by a user to initiate a dose-dispensing operation. In some embodiments, the biasing member 68 may be seated against this proximal face 72 and surround a raised collar 37 of the flange 38.

[0025] The delivery device 10 is operable in a dose setting mode and a dose dispensing mode. In the dose setting mode of operation, the dose button 30 is rotated relative to the housing 12 to set the desired dose to be delivered by the device 10. In some embodiments, rotating the dose button 30 in one direction relative to the housing 12 translates the dose button 30 axially proximally relative to the housing 12, and rotating the dose button 30 in the opposite direction relative to the housing 12 translates the dose button 30 axially distally relative to the housing. In some embodiments, rotating the dose button clockwise moves the dose button 30 distally and rotating the dose button counterclockwise moves the dose button proximally, or vice versa.

[0026] In some embodiments, rotating the dose button 30 and axially translating the dose button 30 in a proximal direction serves to increase the set dose, and rotating the dose button 30 and axially translating the dose button 30 in a distal direction serves to decrease the set dose. The dose button 30 is adjustable in predefined rotational increments that correspond to minimum incremental increases or decreases in the set dose during the dose setting operation. The dose button may include a detent mechanism so that each rotational increment produces an audible and / or tactile "click." For example, one increment or "click" may be equivalent to one-half or one unit of medication.

[0027] In some embodiments, the set volume may be visible to the user via dial gauge markings shown through the dose window 36. During the dose setting mode, the actuator assembly, including the dose button 30 and clutch 52, moves axially and rotatably with the dose setting assembly, including the flange 38 and dose setting screw 32.

[0028] The dose-setting screw 32 and flange 38 are rotatably fixed to one another by a threaded connection between the dose-setting screw 32 and the housing 12, allowing them to rotate and move proximally during dose setting. During this dose-setting operation, the dose button 30 is rotatably fixed relative to the flange 38 and the dose-setting screw 32 by complementary splines 74 and clutch 52 ( FIG. 4 ) on the flange 38, which are biased together by a biasing member 68. During the dose-setting process, the dose-setting screw 32, flange 38, clutch 52, and dose button 30 move in a helical manner (i.e., simultaneous rotation and axial translation) relative to the housing 12 from a “start” position to an “end” position. This rotation and translation relative to the housing is proportional to the amount of the dose set by operation of the medication delivery device 10.

[0029] Once the desired dose is set, the device 10 is manipulated so that the injection needle 24 properly penetrates, for example, the user's skin. The dose-dispensing mode of operation is initiated in response to an axial distal force applied to the proximal face 60 of the dose button 30. The axial force is applied directly to the dose button 30 by the user. This causes axial movement of the actuator assembly (dose button 30 and clutch 52) in the distal direction relative to the housing 12.

[0030] Axial shifting of the actuator assembly compresses the biasing member 68, reducing or closing the gap between the dose button 30 and the tubular flange 38. This relative axial movement separates the clutch 52 and the complementary splines 74 on the flange 38, thereby disengaging the dose button 30 from rotatable fixation to the flange 38 and the dose set screw 32. Specifically, the dose set screw 32 is rotatably decoupled from the dose button 30 to allow back-drive rotation of the dose set screw 32 relative to the dose button 30 and housing 12. Additionally, rotation of the dose button 30 relative to the housing 12 is held by a user pressing the dose button 30 into engagement, while the dose set screw 32 and flange 38 are free to rotate relative to the housing 12.

[0031] As the dose button 30 and clutch 52 continue to be depressed axially without rotating relative to the housing 12, the dose set screw 32 is threaded back into the housing 12 as it rotates relative to the dose button 30. Dose markings indicating the amount remaining to be injected are visible through the window 36. As the dose set screw 32 is threaded distally, the drive member 28 advances distally, pushing the piston 26 through the reservoir 20 and expelling the medication through the needle 24.

[0032] During a dose-dispensing operation, the amount of medication released from the medication delivery device is proportional to the amount of rotational movement of the dose-setting screw 32 relative to the housing 12 as the dose-setting screw 32 is threaded back into the housing 12. In some embodiments, because the dose button 30 is rotatably fixed relative to the housing 12 during the dose-dispensing mode (e.g., due to engagement with a user's finger), the amount of medication released from the medication delivery device can be considered to be proportional to the amount of rotational movement of the dose-setting screw 32 relative to the dose button 30 as the dose-setting screw 32 is threaded back into the housing 12. The injection is complete when the internal threads of the dose-setting screw 32 reach the distal end of the corresponding external threads of the sleeve 34 ( FIG. 4 ). The device 10 is then repositioned in the ready or zero-dose position as shown in FIGS. 2 and 4 .

[0033] As discussed above, the delivered dose may be derived based on the amount of rotation of the dose setting assembly (flange 38 and dose setting screw 32) relative to the actuator assembly (clutch 52 and dose button 30) during dose delivery. This rotation may be determined by detecting incremental movement of the dose setting assembly, which is "counted" as the dose setting assembly rotates during dose delivery.

[0034] Further details of the design and operation of the exemplary delivery apparatus 10 can be found in U.S. Patent No. 7,291,132, entitled "Medication Dispensing Apparatus with Triple Screw Threads for Mechanical Advantage," the entire disclosure of which is incorporated herein by reference. Another example of a delivery device is an automatic injection device, which can be found in U.S. Patent No. 8,734,394, entitled "Automatic Injection Device With Delay Mechanism Including Dual Functioning Biasing Member," the entire disclosure of which is incorporated herein by reference, where such a device is modified with one or more of the various sensor systems described herein to determine the amount of medication delivered from the medication delivery device based on sensing relative rotation within the medication delivery device. Another example of a delivery device is a reusable pen-type device that can be found in U.S. Patent No. 7,195,616, entitled "Medication Injector Apparatus with Drive Assembly that Facilitates Reset," which is incorporated herein by reference in its entirety, and such a device is modified with one or more of the various sensor systems described herein to determine the amount of medication delivered from the medication delivery device based on sensing relative rotation within the medication delivery device.

[0035] Described herein is a dose detection system that may be operable to determine the amount of a delivered dose based on relative rotation between a dose setting member and a device body. The dose detection system utilizes a dose setting member attached to the device body and rotatable relative to the device body about an axis of rotation during dose delivery. A sensed element is attached to and rotatably fixed to the dose setting member. An actuator is attached to the device body and held against rotation relative to the device body during dose delivery. The sensed element thereby rotates relative to the actuator during dose delivery in relation to the amount of the dose to be delivered.

[0036] In some embodiments, the dose detection system comprises a rotational sensor attached to an actuator assembly and a sensed element including surface features evenly spaced radially about an axis of rotation of the sensing element.

[0037] In some embodiments, the dose detection system may include a sensor and a sensed component attached to a component of the medication delivery device. The term "attached" encompasses any manner of fixing the position of a component to another component or member of the medication delivery device such that they are operable as described herein. For example, the sensor may be attached to the component by being positioned directly on, received within, integrated with, or otherwise connected to the component of the medication delivery device. The connection may include, for example, a connection formed by frictional engagement, spline, snap or press fit, sonic welding, or adhesive.

[0038] The term "directly attached" is used to describe an attachment in which two components, or one structural application and one member, are physically secured together without the use of any intermediate members other than the attachment component. The attachment component may comprise a fastener, adapter, or other part of the fastening system, such as a compression membrane, that is interposed between the two components to facilitate the attachment. A "direct attachment" is distinguished from an attachment in which the components / members are joined by one or more intermediate functional members.

[0039] The term "fixed" is used to indicate that the indicated movement may or may not occur. For example, if two members are required to rotate and move together, a first member is "rotationally fixed" with a second member. In one aspect, a member may be "fixed" relative to another member functionally, rather than structurally. For example, one member may be pressed against another member so that frictional engagement between the two members rotationally locks them together, but the two members cannot be fixed together without the pressing of the first member.

[0040] Various sensor arrangements are contemplated herein. Generally, a sensor arrangement comprises a sensor and a sensed component. The term "sensor" refers to any component capable of detecting the relative position or movement of the sensed component. A sensor may be used with associated electrical components to operate the sensor. A "sensed component" is any component capable of detecting the position and / or movement of the sensed component relative to the sensor. In the case of a dose detection system, the sensed component rotates relative to the sensor, and the sensor is capable of detecting rotational movement of the sensed component. The sensor may comprise one or more sensing elements, and the sensed component may comprise one or more sensed elements. The sensor detects movement of the sensed component and provides an output representative of the movement of the sensed component.

[0041] Illustratively, the dose detection system includes an electronics assembly suitable for operation of the sensor arrangement as described herein. The medication delivery device may include a controller operably connected to the sensor to receive an output from the sensor. The controller begins receiving a generated signal from the sensor indicating a count from the first to the last count, with the total number of counts used to determine a total displacement, e.g., angular displacement. When detecting angular movement of the dose setting assembly, the controller may be configured to receive data indicative of the angular movement of the dose setting assembly, which can be used to determine from the output the amount of the dose delivered by operation of the medication delivery device. The controller may optionally be configured to determine from the output the amount of the dose delivered by operation of the medication delivery device. The controller may include conventional components such as a processor, power supply, memory, microcontroller, etc. Additionally or alternatively, at least some components may be provided separately, such as by a computer, smartphone, or other device. Means are then provided for operably connecting an external controller component with the sensor at the appropriate time, such as by a wired or wireless connection. For example, a controller onboard the medication delivery device may be configured to determine only the amount of angular movement of the dose setting assembly and communicate this angular movement to an external controller. The external controller can then be configured to determine the amount of the dose to be delivered based on the angular motion information.

[0042] According to one embodiment, the electronics assembly includes a sensor arrangement including one or more sensors in operative communication with a processor for receiving a signal from the sensor representing the sensed rotation. An exemplary electronics assembly 76 is shown in FIGS. 5-7 and can include a sensor 86 and a printed circuit board (PCB) 77 having multiple electronic components. The printed circuit board can be a flexible printed circuit board. The circuit board of the electronics assembly 76 can include a microcontroller unit (MCU) as a controller with at least one processing core and internal memory. The electronics assembly can include a power source 79, e.g., a battery, illustratively a coin cell, for powering the components. The controller of the electronics assembly 76 can include control logic operative to perform the operations described herein, including detecting angular movement of the dose setting assembly during dose setting and / or dose delivery and / or detecting the dose delivered by the medication delivery device 10 based on the detected rotation of the dose setting assembly relative to the actuator assembly. Some, but not all, of the components of the electronics assembly can be housed in a compartment 85 within the dose button 30. In some embodiments, the compartment 85 may be defined between the proximal surface 71 of the dose button support 42 and the distal surface 81 of the dose button cover 56. In the embodiment shown in Figure 5, the electronics assembly 76 is permanently integrated within the dose button 30 of the delivery device. In other embodiments, the electronics assembly is provided as a module that can be removably attached to the actuator assembly of the medication delivery device.

[0043] An underside view of electronics assembly 76 held within cover 56 is shown in Figure 6, and an exploded view of electronics assembly 76 is shown in Figure 7. As shown in Figures 6 and 7, electronics assembly 76 may include a printed circuit board (PCB) 77 and a sensor 86 having a contact surface 111. As shown in Figure 7, electronics assembly 76 may also include a battery 79 and a battery cage 87.

[0044] In some embodiments, at least a portion of the sensor 86 extends outside the compartment 85 of the dose button 30. As best seen in Figures 10 and 11, the support 42 of the dose button 30 may include one or more openings 45 through which the sensor 86 can extend. In some embodiments, during assembly of the medication delivery device, the contact surface 111 of the sensor 86 passes through the opening 45 in the support 42. This may allow the sensor contact surface 111 to interact with components external to the compartment 85 of the dose button 30. In some embodiments, only one of the openings 45 in the support 42 is required to accommodate the sensor, although a second opening may be provided, for example, due to symmetry of the support component, which aids in manufacturing the component and / or assembly of components with the medication delivery device.

[0045] The controller of the electronics assembly 76 may be operable to store the total angular movement used to determine dose delivery and / or the detected dose delivery in local memory (e.g., internal flash memory or on-board EEPROM). The controller may further be operable to wirelessly transmit a signal representing the total count, total angular movement, and / or the detected dose to an external device, such as a user's mobile device or a remote server. Transmission may be via, for example, Bluetooth Low Energy (BLE) or other suitable short-range or long-range wireless communication protocol. Illustratively, the BLE control logic and controller are integrated on the same circuit.

[0046] As discussed, according to one aspect, a dose detection system includes detecting relative rotational movement between two assemblies of a medication delivery device. The sensor operates to detect the amount of angular movement from the start of dose injection to the end of dose injection, with the degree of rotation having a known relationship to the amount of dose delivered. For example, in some embodiments, the relationship for a pen injector is such that an 18° angular displacement of the dose setting assembly corresponds to one dose unit, although other angular relationships are also suitable, such as 9°, 10°, 15°, 20°, 24°, or 36° for one or half units. The sensor system is operable to determine the total angular displacement of the dose setting member during dose delivery. Thus, if the angular displacement is 90°, five units of the dose have been delivered.

[0047] The angular displacement is determined by counting the dose increments as the injection progresses. For example, the sensing system can use a repeating pattern of sensed elements, with each repetition indicative of a predetermined degree of rotation angle. Advantageously, the pattern can be defined such that each repetition corresponds to the smallest dose increment that can be set using the medication delivery device.

[0048] The dose detection system components may be permanently or removably attached to the medication delivery device. In some embodiments, at least some of the dose detection system components are provided in the form of modules that are removably attached to the medication delivery device. In other embodiments, the dose detection system components are permanently attached to the medication delivery device.

[0049] In some embodiments, the sensor may detect relative rotation of a sensed component rotatably fixed to the dose setting screw 32 during dose delivery, which determines the amount of dose delivered by the medication delivery device. In one exemplary embodiment, the rotation sensor is attached to and rotatably fixed to the actuator assembly. The actuator assembly does not rotate relative to the device housing during dose delivery.

[0050] In some embodiments, the sensed component is attached to and rotatably fixed to the dose-setting screw 32 and rotates relative to the dose button 30 and device housing 12 during dose delivery. In some of the embodiments described herein, the sensed component includes a ring structure having a plurality of proximally extending projections circumferentially arranged relative to one another. The projections are shaped and sized to deflect a movable element of the rotation sensor. One exemplary embodiment of such a sensed component is a tubular flange 38, best seen in FIGS. 3, 5, 8, and 9. The embodiments described herein may be provided in the context of a module that is removably attachable to or integrated within the dose button of the delivery device.

[0051] During dose delivery, the dose setting screw 32 is free to rotate relative to the dose button 30. In an exemplary embodiment, the electronics assembly 76 is rotatably secured by the dose button 30 and does not rotate during dose delivery.

[0052] As seen in FIGS. 2, 3, and 5, the dose button 30 includes a cover 56 coupled to the support 42. The electronics assembly 76 may be at least partially housed within a compartment 85 defined between the cover 56 and the support. In some embodiments, the cover and the support have corresponding splines that engage with each other to couple the cover and the support together. For example, in some embodiments, the cover 56 may be coupled to the support 42 via one or more snaps 57 on the cover 56 that correspond to one or more protrusions 43 on the support. As seen in FIGS. 5 and 6, the snaps 57 on the cover 56 may be oriented radially inward from the inner circumferential sidewall 73. As seen in FIGS. 5, 10, and 11, the protrusions 43 of the support 42 may be oriented radially outward from the outer circumferential sidewall 75 of the support 42. The protrusions 43 may form a triangular ramp shape.

[0053] Snaps 57 on cover 56 are configured to snap over and mate with protrusions 43 on the support, coupling the cover to the support. In some embodiments, the protrusions on the support comprise a continuous annular protrusion around the outer peripheral sidewall of the support. Cover 56 may be attached to support 42 via frictional engagement, an interference fit, or any other suitable fit. In some embodiments, cover 56 is permanently secured to support 42 during assembly, for example, via ultrasonic welding, adhesive, or other suitable fastening technique.

[0054] As seen in Figures 8 and 9, the tubular flange 38 may include a plurality of axially oriented teeth 102 evenly spaced radially about the axis of rotation and arranged to correlate to the equivalent of one dosage unit. In this exemplary embodiment, the tubular flange 38 includes 20 teeth 102 that are rotatably spaced evenly from one another such that the rotational distance between two adjacent teeth corresponds to 18 degrees of rotation. Thus, with the tubular flange 38 of Figure 8, an 18-degree rotation of the tubular flange 38 may be used to represent one dosage unit or one-half dosage unit. It should be understood that in other embodiments, a different total number of teeth may be used to create other angular relationships, such as 9 degrees, 10 degrees, 15 degrees, 18 degrees, 20 degrees, 24 degrees, or 36 degrees for one unit or 0.5 units.

[0055] A recess 124 may be defined between each pair of adjacent teeth 102. Each tooth 102 may have a generally triangular-shaped profile and each may have a surface 120 against which the contact surface 111 of the sensor may slide.

[0056] In some embodiments, the sensor for detecting rotation of the tubular flange includes a spring-loaded movable element having a contact portion mountable to a tooth of the tubular flange such that the contact surface is configured to slide against and over the tooth during rotation of the flange relative to the actuator assembly during dose delivery. The sensor generates a signal corresponding to the flange in response to the contact portion moving over the tooth. The controller, in response to the signal generated by the sensor, determines a dose count for determining a delivered dose based on the detected rotation of the flange relative to the actuator assembly during dose delivery.

[0057] The contact surface may be biased against a physical feature of the tubular flange to ensure proper contact between the contact surface and the physical feature during rotation. In one embodiment, the movable member is a resilient member having one portion attached to the actuator at a position displaced from the contact surface. In one example, the movable member is a compliant member comprising a beam attached to the actuator at one end and having a contact surface at the other end. The beam is bent to bias the contact surface toward the surface feature. Alternatively, the movable member may be biased in any of a variety of other ways. In addition to using a resilient beam, biasing may be provided, for example, through the use of a spring component. Such spring components may comprise, for example, a compression, tension, or torsion coil spring. In yet other embodiments, the movable member may be biased against the surface feature of the sensed element by a separate resilient or spring component that supports the movable element.

[0058] 5 depicts an exemplary embodiment of a sensor 86 having a contact surface 111 that interacts with teeth 102 of a tubular flange 38. As the flange 38 rotates relative to the dose button 30 during delivery, the teeth 102 of the flange contact and slide against the contact surface 111 of the sensor 86, causing the contact surface 111 to move in an oscillatory manner. The movement of the contact surface 111 may be a combination of axial and lateral movement such that the contact surface 111 slides into and out of recesses 124 defined between the teeth 102 of the flange 38. The sensor 86 may be configured to track the movement of the contact surface 111 and associate the movement with an output signal that is sent to a controller.

[0059] As an alternative to teeth on the tubular flange, the surface feature that interacts with the sensor may comprise anything detectable by the sensor. The sensor arrangement may be based on a variety of sensed characteristics, including, for example, tactile, optical, electrical, and magnetic characteristics. In the exemplary embodiment shown in the figures, the surface feature is a physical feature that allows for detection of incremental movement as the dose setting assembly rotates relative to the actuator assembly. In alternative embodiments, the sensor may be a piezoelectric sensor, a magnetic sensor such as a Hall Effect sensor, an accelerometer for detecting vibrations, for example, vibrations of a ratchet or other detent mechanism, which vibrations can be correlated with rotational movement, an optical sensor such as a reflective sensor, a circuit breaker sensor, or an optical encoder, or any other sensor suitable for sensing rotation of a first component relative to a second component.

[0060] In some embodiments, when a user presses axially on the surface 60 of the dose button 30, the dose button 30 advances distally relative to the housing 12, compressing the spring 68. Continued distal pressing of the dose button 30 results in back-driving of the dose-setting screw 32 in a helical direction relative to the housing 12. As a result, axial pressing of the dose button 30 drives the dose-setting screw 32 and flange 38 to rotate. In some embodiments, the dose detection system is operable to detect a dose only while the dose button is pressed.

[0061] In some embodiments, the electronics assembly may include a clock or timer to determine the time elapsed between counts caused by the triggering of the rotational sensor from the surface features of the sensed element. If no counts are detected by the controller after a period of time, this may be used to indicate that the dose is complete.

[0062] In some embodiments, a single sensing system may be employed for both dose detection sensing and wake-up activation. For example, the controller may be configured to enable the electronics assembly to wake up or activate to a higher or full power state upon the sensor first sensing rotation of the sensed element. The wake-up feature is configured to enable power transfer from a power source (shown as a battery) to power up the electronic components and sense the dose, minimizing inadvertent power loss or usage when no dose dispensing event occurs. In other embodiments, a separate wake-up switch may be provided, disposed within the dose button housing, and triggered when the dose button is in its distal position. After actuation of the electronics assembly, the controller begins receiving a generated signal from the rotation sensor indicating the total angular displacement and, therefore, the total number of counts from start to finish used to determine the delivered dose.

[0063] In some embodiments, the electronics assembly may have a controller configured to receive the output signal from the rotation sensor. The controller of the electronics assembly may be programmed to convert the intermediate signal into a conditioned digital signal, which may be a single step / square wave with a predetermined width representing a predetermined time. In some embodiments, output signals below a predetermined level may be filtered out or ignored.

[0064] As described herein, the printed circuit board (e.g., printed circuit board 77) can include various processing circuits and / or logic that generate data based on the operation of the medication delivery device. For example, the processing circuit can count the number of times a sensor (e.g., sensor 86) is activated or triggered during an injection to determine the dose size of the injection (e.g., the dose of a particular insulin injection). As described herein, relative rotational movement between the dose setting assembly and the actuator of the medication delivery device can be sensed to determine the amount of the dose delivered by the medication delivery device, as the sensed relative rotational movement can be correlated to the amount of the dose delivered.

[0065] 12 is an exemplary schematic diagram of a printed circuit board 1200 according to some embodiments. The printed circuit board 1200 (e.g., printed circuit board 77) includes various components, including a sensor 1202 (e.g., sensor 86 of FIG. 6) that is in electrical communication with a microcontroller 1204. The printed circuit board 1200 includes a set of pads 1206, 1208, 1210, 1212, 1214, 1216, 1218, 1220, and 1222 that are in electrical communication with the microcontroller 1204. The pads can be used to connect electrical components to the microcontroller 1204, such as for testing. Some of the pads, such as pads 1208, 1210, 1212, 1214, 1216, and 1218, may not be in communication with the microcontroller 1204 by default. For example, the microcontroller may be initially programmed (e.g., via associated registers) so that some of the pads are not in electrical communication with the microcontroller 1204 (e.g., via programmable switches or resistors). One or more of the pads may be placed in electrical communication with logic inputs, such as general-purpose input / output (GPIO) pin(s) of the microcontroller 1204. As an example, the microcontroller may be programmed to modify internal programmable components (e.g., one or more pull-up and / or pull-down resistors) to place the pads in electrical communication with the logic inputs.

[0066] In some embodiments, the GPIO pin input to the microcontroller 1204 may be a logic level input. The microcontroller 1204 may detect a logic 1 if a voltage above a certain maximum threshold is applied to the GPIO pin, and the microcontroller 1204 may detect a logic 0 if a voltage below a certain minimum threshold is applied to the GPIO pin. Some pads on the printed circuit board may be connected to voltage sources. For example, pad 1220 may provide a battery voltage Vbat. As another example, pad 1206 may provide a voltage Vdcdc from a DC / DC converter.

[0067] As described herein, the microcontroller 1204 (including, e.g., based on input from the sensor 1202) can operate to process dose data and / or other data of the medication delivery device. For example, the microcontroller 1204 can be configured to store in local memory (e.g., internal flash memory or on-board EEPROM) the total angular movement used to determine dose delivery and / or the detected dose delivery. The microcontroller 1204 can further be operable to wirelessly transmit signals representing the total count, total angular movement, and / or the detected dose to an external device, such as a user's mobile device or a remote server (e.g., via BLE control logic and controller integrated into the printed circuit board 1200).

[0068] As described herein, in some embodiments, the drug delivery device includes a sensor (e.g., sensor 86 in FIG. 6, sensor 1202 in FIG. 12) that detects movement of the sensed component and provides an output representative of the movement of the sensed component. For example, the sensor can generate a signal that indicates whether the sensor is in an engaged or disengaged state.

[0069] In some embodiments, the state of a sensor depends on physical contact between the sensor and the sensed component. For example, a sensor may be considered to be in an engaged state when it is in physical contact with the sensed component or with an intermediate component positioned between the sensor and the sensed component. In contrast, a sensor may be considered to be in a disengaged state when it is not in physical contact with the sensed component or with an intermediate component positioned between the sensor and the sensed component. As a non-limiting example, a sensor may be in an engaged state when a contact portion of the sensor contacts a tooth (e.g., tooth 102 in FIGS. 8-9 ) of a tubular flange (e.g., flange 38 in FIGS. 5 and 8-9 ) of a drug delivery device. The sensor may be in a disengaged state when a contact portion of the sensor is not in contact with the tooth, for example, when the contact portion is disposed within a recess (e.g., recess 124 in FIG. 5 ) between the teeth of the tubular flange.

[0070] Additionally or alternatively, in some embodiments, the state of the sensor depends on the sensor arrangement. As described herein, the sensor arrangement may be based on various sensed characteristics, including, for example, tactile, optical, electrical, and magnetic characteristics. The sensor may be a piezoelectric sensor, a magnetic sensor such as a Hall Effect sensor, an accelerometer for detecting vibration, an optical sensor, a circuit breaker sensor, or an optical encoder, or any other suitable sensor for sensing rotation of a first component relative to a second component. Thus, it should be understood that a sensor may be considered to be in an engaged state when it senses any suitable sensed characteristic, and may be considered to be in a disengaged state when it does not sense the sensed characteristic, or vice versa.

[0071] In some embodiments, the sensor generates a signal in response to interaction with the sensed component. For example, when the contact portion of the sensor is in contact with the teeth of the tubular flange (e.g., the sensor is in an engaged state), the sensor may generate a signal that is in a first logic state. When the contact portion of the sensor is not in contact with the sensed component (e.g., when the contact portion is positioned in a recess between the teeth or when the sensor is in a disengaged state), the sensor may generate a signal that is in a second logic state that is different from the first logic state. For example, the first logic state of the signal may be an assertion state (e.g., a logic 1, a high state, etc.), and the second logic state of the signal may be a deassertion state (e.g., a logic 0, a low state, etc.), or vice versa.

[0072] Thus, in some embodiments, the generated signal can be used to determine the rotation of the sensor relative to the sensed component. Continuing with the example of a tubular flange (e.g., tubular flange 38), when the signal transitions between a first logic state and a second logic state five times, this may indicate that the contact portion of the sensor has slid against and over five teeth of the medication delivery device. Taking into account the spacing between the aforementioned teeth, it may be possible to determine the rotation of a dose setting assembly within the medication delivery device. As described herein, the rotation of the dose setting assembly can then be used to determine a dose of medication delivered using the medication delivery device. The dose of medication may be determined by a controller of the medication delivery device or by a separate device in communication with the medication delivery device based on data indicative of the rotation of the dose setting assembly.

[0073] However, the signal output by the sensor can be noisy, making it difficult to use the signal to determine whether the sensor is engaged or disengaged. For example, as the sensor begins to engage with the sensed component, the sensor may momentarily lose contact with the sensed component, causing the signal output by the sensor to momentarily transition to a second logic state when it should have remained in a first logic state. For example, the leading edge of the sensor's contact portion may bounce as it begins to slide over the teeth of the tubular flange, causing it to momentarily lose contact with the teeth.

[0074] FIG. 13 is an exemplary plot showing a signal received from a sensor of a medication delivery device, according to some embodiments. Line 1310 indicates the time when the sensor of the medication delivery device actually transitioned between an engaged state (point “B” along the y-axis) and a disengaged state (point “A” along the y-axis). For example, this may correspond to the contact portion of the sensor sliding over two teeth on a tubular flange of the medication delivery device. Line 1320 indicates the time when the signal output by the sensor transitioned between an asserted state (e.g., a first logic state, or point “B” along the y-axis) and a deasserted state (e.g., a second logic state, or point “A” along the y-axis). As shown, the signal transitioned between the asserted and deasserted states more times than the switch actually transitioned between the engaged and disengaged states. Therefore, counting the number of times the signal is in the asserted state to infer the number of times the sensor is in the engaged state would lead to an overestimation of this value. This in turn leads to an inaccurate determination of the rotation of the dose setting assembly, resulting in an inaccurate estimation of the dose of medication delivered using the medication delivery device.

[0075] Therefore, the inventors have developed a technique for filtering the signal from the sensor so that the signal can be used to more reliably determine when the sensor has transitioned between an engaged and disengaged state. This technique can then more reliably and accurately estimate the rotation of the dose setting assembly and more reliably and accurately determine the dose of medication delivered using the medication delivery device.

[0076] In some embodiments, the technique for filtering the signal includes using one or more hardware components. For example, a printed circuit board of a medication delivery device (e.g., printed circuit board 1200 of FIG. 12) may include one or more components used to filter the signal received from the sensor. As a non-limiting example, the printed circuit board may include a resistor-capacitor circuit.

[0077] 14 is an exemplary schematic diagram of a printed circuit board having a resistor-capacitor (RC) circuit, according to some embodiments. As shown, the printed circuit board 1400 includes a dose detector component 1420 and a system clock 1430, each of which is in electrical communication with a microcontroller 1410. However, it should be understood that the printed circuit board 1400 may include one or more additional or alternative components as described herein, including with respect to at least FIGS. 5-7 and 12.

[0078] In some embodiments, the system clock 1430 is used by the microcontroller 1410 to keep track of time. The system clock 1430 may include an oscillator circuit, the frequency of which may be used to keep track of time. The oscillator circuit may include a resistor-capacitor (RC) oscillator circuit, an inductor-capacitor (LC) oscillator circuit, a crystal oscillator circuit, or any other suitable oscillator circuit, as aspects of the technology described herein are not limited in this respect. However, it should be understood that the system clock 1430 is not limited to an oscillator circuit, and may include any other suitable clock, as aspects of the technology are not limited in this respect.

[0079] In some embodiments, the dose detector component 1420 includes a switch 1422 and an RC circuit 1424. In some embodiments, the switch 1422 includes a portion of a sensor (e.g., sensor 86 in FIGS. 5-7 ) configured to detect the position and / or movement of a sensed component, such as a tooth on a tubular flange. For example, the switch may be configured to close when a contact portion of the sensor is in physical contact with the sensed component and open when the contact portion is not in physical contact with the sensed component, or vice versa.

[0080] Thus, in some embodiments, the RC circuit 1424 is configured to receive a signal from the sensor when the switch 1422 is closed and send a filtered signal to the microcontroller 1410. In an alternative embodiment, the microcontroller 1410 is configured to receive a signal directly from the sensor when the switch 1422 is closed.

[0081] In some embodiments, the RC circuit 1424 is configured to filter the signal received from the switch 1422. The RC circuit 1424 may include a resistor 1424a and a capacitor 1424b. The resistance of the resistor 1424a and the capacitance of the capacitor 1424b may be selected such that the RC circuit 1424 acts as a low-pass filter. For example, the RC circuit may be configured to remove noise in the signal, such as a momentary signal de-assertion that occurs when the sensor is actually engaged and / or a momentary signal assertion that occurs when the sensor is actually disengaged. Accordingly, it should be understood that the resistor may be any suitable resistance and the capacitor may be any suitable capacitance, as aspects of the present technology are not limited in this respect.

[0082] In some embodiments, the RC circuit is configured to function as a low-pass filter for only one or both types of signal transitions (e.g., signal transitions from the second logic state to the first logic state and / or signal transitions from the first logic state to the second logic state). For example, as shown in FIG. 15, the RC circuit acts as a low-pass filter for signal transitions from an asserted state to a de-asserted state. Thus, as described herein, the RC circuit in the example of FIG. 15 can be configured to filter out high frequency noise when the sensor transitions to a disengaged state.

[0083] In some embodiments, the RC circuit 1424 transmits the filtered signal to the microcontroller 1410. The microcontroller 1410 may include any suitable microcontroller, such as the microcontroller 1204 described herein with respect to at least FIG. 12 . In some embodiments, the microcontroller 1410 receives the filtered signal via a GPIO pin input. The GPIO pin input may be a logic level input. The microcontroller 1410 may detect a logic one (1) when a voltage above a certain maximum threshold is applied to the GPIO pin, and the microcontroller 1410 may detect a logic zero (0) when a voltage below a certain minimum threshold is applied to the GPIO pin.

[0084] While the RC circuit 1424 may function to filter out unwanted noise, there may be some limitations associated with the use of the RC circuit 1424, as described herein, including with respect to at least FIG.

[0085] 15 is an exemplary plot showing a signal received from a sensor of a medication delivery device and filtered using an RC circuit, according to some embodiments. As shown, line 1510 shows the time when the sensor of the medication delivery device actually transitions between an engaged and disengaged state. Line 1530 shows an analog signal output from an RC circuit, such as RC circuit 1424 shown in FIG. 14. Line 1520 shows a digital signal received and processed by a microcontroller of the medication delivery device, such as microcontroller 1410 shown in FIG. 14.

[0086] In some embodiments, when the contact portion of the sensor comes into contact with the sensed component, the switch 1422 closes, allowing the RC circuit 1424 to charge. The analog signal 1530 received by the microcontroller as the RC circuit charges is indicated by the portion of the analog signal 1530 transitioning in the positive y-direction to point "B."

[0087] In some embodiments, when analog signal 1530 exceeds threshold value 1560a, digital signal 1520 transitions to an assertion state. For example, as shown in FIG. 15, when analog signal 1530 crosses threshold value 1560a, digital signal 1520 transitions from point "A" to point "C" along the y-axis, which corresponds to a deassertion state and an assertion state of signal 1520, respectively. In some embodiments, threshold value 1560a may comprise any suitable threshold value, as aspects of the technology described herein are not limited in this respect.

[0088] In some embodiments, when the contact portion of the sensor is no longer in contact with the sensed component, the switch 1422 opens, discharging the RC circuit 1424. The analog signal 1530 received by the microcontroller as the RC circuit discharges is illustrated by the portion of the analog signal 1530 transitioning downward in the negative y-direction from point "B."

[0089] In some embodiments, when the analog signal 1530 falls below the threshold 1560b, the digital signal 1520 transitions to the deassertion state. For example, as shown in Figure 15, when the analog signal 1530 falls below the threshold 1560b, the digital signal 1520 transitions from point "C" to point "A" along the y-axis.

[0090] In some embodiments, the RC circuit charges at a faster rate than it discharges. Thus, as shown in FIG. 15, the microcontroller can continue to receive a non-zero analog signal 1530 after the sensor transitions to a disengaged state, as indicated by line 1510. This can also result in a delay, such as delay 1550, between the time the sensor transitions to a disengaged state and the time the analog signal 1530 falls below threshold 1560b. The delay can depend on the characteristics of the RC circuit used to filter the signal received from the switch. For example, delay 1550 can be in the range of 20 to 120 μs.

[0091] In some embodiments, the signal transition delay does not affect the results of downstream processing of the signal 1520. For example, the first assertion of the digital signal 1520 corresponds to one occurrence of the sensor transitioning to the engaged state. If there is a delay 1550, the delay 1550 does not affect the calculation of the number of occurrences of the sensor transitioning to the engaged state during the period that the digital signal 1520 was in the asserted state.

[0092] However, in some embodiments, the signal transition delay affects the results of downstream processing of signal 1520. For example, the second assertion of digital signal 1520 corresponds to two occurrences of the sensor transitioning to the engaged state. As shown, because the RC circuit discharges too slowly after the sensor transitions from the engaged state to the disengaged state, analog signal 1530 decreases but does not decrease below threshold 1560b before the sensor transitions back to the engaged state. Therefore, digital signal 1520 does not transition to the deassertion state and, as a result, cannot be used to reliably detect both occurrences of the sensor transitioning to the engaged state.

[0093] In some embodiments, this limitation may be addressed by adjusting the RC circuit to allow higher frequencies to pass (e.g., so that line 1530 more closely follows line 1510). However, such adjustments may also allow more noise to pass through the RC circuit, resulting in inaccurate estimation of both the number of times the sensor transitions to the engaged state and the dose of drug delivered by the drug delivery device.

[0094] Therefore, the inventors have developed additional or alternative techniques for filtering signals received from sensors in medication delivery devices.

[0095] 16A-16B are flow charts illustrating an exemplary method 1600 for filtering signals received from a sensor of a medication delivery device, according to some embodiments. The method 1600 may be implemented on any suitable processor, such as, for example, the microcontroller 1204, the microcontroller 1410, and / or one or more processors external to the medication delivery device.

[0096] In step 1602, the processor receives data indicative of a signal from a sensor of the medication delivery device, such as, for example, sensor 86 of FIGS. 5-7 and sensor 1202 of FIG. 12. In some embodiments, the processor receives the signal directly from sensor 1202. For example, sensor 1202 may be disposed in electrical communication with an input (e.g., a logic input) of the processor, such as a GPIO pin input of the processor. Additionally or alternatively, in some embodiments, the processor receives the signal indirectly from sensor 1202. For example, the processor may receive the signal after it has been filtered using one or more components of the medication delivery device, such as an RC circuit (e.g., RC circuit 1424 of FIG. 14). Additionally or alternatively, the processor may receive data indicative of the signal after it has been processed using any suitable pre-processing steps. Additionally or alternatively, the processor may receive data indicative of the signal from a different processor. For example, the processor may be external to the medication delivery device and receive data indicative of the signal from a microcontroller included in the medication delivery device. In some embodiments, the raw or processed signals from the sensor 1202 may be stored in memory for a period of time before the processor receives the data.

[0097] In some embodiments, the processor continues to receive data indicative of the signal during subsequent steps of process 1600. For example, the steps of process 1600 may be performed as the signal is being generated, and the processor may receive and process data indicative of newly generated portions of the signal at any time during process 1600.

[0098] In step 1604, the processor detects a transition of the signal from a second logic state (e.g., a deassertion state) to a first logic state (e.g., an assertion state) based on the received data. For simplicity, a transition of the signal from the second logic state to the first logic state may be referred to herein as a “rising transition.” Note that the term “rising transition” is most appropriate for embodiments in which the first logic state corresponds to an asserted, or high, logic state and the second logic state corresponds to a deasserted, or low, logic state, such that the signal “rises” from a low state to a high state when the signal transitions from the first logic state to the second logic state. However, as previously mentioned, the present disclosure also contemplates embodiments in which the first logic state corresponds to a deassertion or low logic state and the second logic state corresponds to an assertion or high logic state. The use of the term “rising transition” herein as part of FIGS. 16A and 16B does not imply that such alternative embodiments are excluded.

[0099] In some embodiments, the processor is configured to determine a time point when the rising transition occurs (e.g., a first time point). The processor may determine the time point using any suitable technique. As an illustrative example, the processor may determine the time point using an interrupt handler implemented using software running or configured to run on the processor. In some embodiments, the interrupt handler is configured to record a timestamp indicating when the rising transition occurred. For example, the interrupt handler may record the timestamp according to a timer included in the medication delivery device. Additionally or alternatively, the processor may determine the time point by polling a timer included in the medication delivery device.

[0100] In step 1606, the processor determines whether a transition of the signal from a first logic state to a second logic state occurred within the first time period. For simplicity, a transition of the signal from a first logic state to a second logic state may be referred to herein as a “falling transition.” Similarly, it should be noted that the term “falling transition” is most appropriate for embodiments in which the first logic state corresponds to an asserted, or high, logic state and the second logic state corresponds to a deasserted, or low, logic state, such that the signal “falls” from a high state to a low state when the signal transitions from the first logic state to the second logic state. However, as previously mentioned, the present disclosure also contemplates embodiments in which the first logic state corresponds to a deasserted, or low, logic state and the second logic state corresponds to an asserted, or high, logic state. The use of the term “falling transition” herein as part of FIGS. 16A and 16B does not imply that such alternative embodiments are excluded.

[0101] In some embodiments, the first time period begins when the rising transition occurs (e.g., at a first time point), as determined in step 1604. In some embodiments, the duration of the first time period depends on the amount of time the sensor is expected to be in the engaged state. For example, when the sensor is expected to be in the engaged state for up to 1 second, the duration of the first time period may be approximately 1 second (e.g., 750 ms to 1.25 s, 800 ms to 1.2 s, 900 ms to 1.1 s, 1 s, etc.). However, aspects of the present technology are not limited in this respect, and the first time period may be of any suitable duration.

[0102] In some embodiments, if a downward transition is detected within the first period of time, process 1600 proceeds to step 1608. If a downward transition is not detected within the first period of time, process 1600 proceeds to step 1612.

[0103] In step 1608, the processor detects a falling transition of the signal based on the data received in step 1602 or data received at any time during process 1600. In some embodiments, the processor is configured to determine the time point when the falling transition occurs (e.g., the second time point). The processor may determine the time point using any suitable technique. For example, the processor may determine the time point using an interrupt handler implemented using software running on or configured to run on the processor. In some embodiments, the interrupt handler is configured to record a timestamp indicating when the falling transition occurred. For example, the interrupt handler may record the timestamp according to a timer included in the medication delivery device. Additionally or alternatively, the processor may determine the time point by polling a timer included in the medication delivery device.

[0104] In step 1610, the processor determines whether another rising transition of the signal occurs within the first time period and at a second time point (e.g., the time at which the falling transition occurred). In some embodiments, if another rising transition occurs within the first time period, process 1600 returns to step 1604 where a rising transition is detected. If no additional rising transitions occur within the first time period, process 1600 proceeds to step 1612.

[0105] In step 1612, the processor determines whether the signal is in the first logic state for an accumulation period equal to or greater than a first threshold duration within the first period. In some embodiments, the signal is considered to be in the first logic state during the time elapsed between a rising transition of the signal and a falling transition of the signal. For example, the accumulation period may include the amount of time elapsed between a first point in time (e.g., determined in step 1604) and a second point in time (e.g., determined in step 1608). If, in step 1610, there is another rising transition within the first period, the accumulation period may also include the amount of time elapsed between the time the rising transition occurred and either (a) the end of the first period, or (b) the time when another falling transition occurs within the first period. The logic described in the previous sentence may apply to any additional rising transitions in addition to the first and second rising transitions within the first period. In some embodiments, if it is determined in step 1606 that a downward transition did not occur within the first period of time, the accumulated amount of time may include the amount of time that elapsed between the first time point and the end of the first period of time.

[0106] In some embodiments, the first threshold duration may include any suitable duration that is less than or equal to the duration of the first period. By way of non-limiting example, the first threshold duration may be 70% of the duration of the first period, 75% of the duration of the first period, 80% of the duration of the first period, 85% of the duration of the first period, 90% of the duration of the first period, 100% of the duration of the first period, or any other suitable threshold duration. In some embodiments, the first threshold duration may depend on the expected duration of sensor engagement and / or the expected frequency of noise (e.g., momentary transitions of the signal to the second logic state) when the sensor engages with a sensed component (e.g., a tooth) of the medication delivery device. For example, a relatively low first threshold duration allows for more noise when determining that the sensor is engaged compared to a relatively high first threshold duration. In some embodiments, when the processor determines that the signal has been in the first logic state for an accumulated period equal to a first threshold duration within the first time period, the processor may discontinue measuring the accumulated period that the signal is in the first logic state.

[0107] In step 1614, the processor determines whether the sensor transitioned from a disengaged state to an engaged state at a first time point. If the cumulative period determined in step 1612 is greater than or equal to the first threshold duration, the processor determines that the sensor transitioned from a disengaged state to an engaged state at the first time point. In some embodiments, the occurrence of such a transition may be included in a count indicating the number of times the sensor transitioned between the disengaged and engaged states. In some embodiments, the count may be used to determine a dose of medication delivered by the medication delivery device. If the cumulative period is not greater than or equal to the first threshold duration, the processor determines that the sensor did not transition from a disengaged state to an engaged state.

[0108] In step 1616, the processor determines whether a downward transition occurred after the first period of time. If a downward transition did not occur after the first period of time, process 1600 ends. If a downward transition occurred after the first period of time, process 1600 proceeds to step 1618 shown in FIG. 16B. Additionally or alternatively, although not shown in FIG. 16A, if the cumulative period is greater than or equal to a first threshold duration, the processor can transition to step 1618 shown in FIG. 16B after the first threshold duration and / or after the first period of time.

[0109] In step 1618, the processor detects a falling transition of the signal based on the data received in step 1602 or data received at any time during process 1600. In some embodiments, the processor is configured to determine the time point at which the falling transition occurs (e.g., the third time point). The processor may determine the time point using any suitable technique. For example, the processor may determine the time point using an interrupt handler, such as the interrupts described herein, including at least those related to step 1608. Additionally or alternatively, the processor may determine the time point by polling a timer included in the medication delivery device.

[0110] In step 1620, the processor determines whether, within a second time period, the signal is in the second logic state for a cumulative period equal to or greater than the second threshold duration. In some embodiments, the second time period begins when a falling transition occurs (e.g., the third time point), as determined in step 1618. In some embodiments, the duration of the second time period depends on the amount of time the sensor is expected to be in a disengaged state. For example, when the sensor is expected to be in a disengaged state for up to 1 second, the duration of the second time period may be approximately 1 second (e.g., 300 ms to 1.7 s, 400 ms to 1.6 s, 500 ms to 1.5 s, 600 ms to 1.4 s, 700 ms to 1.3 s, 750 ms to 1.25 s, 800 ms to 1.2 s, 900 ms to 1.1 s, 1 s, etc.). However, aspects of the present technology are not limited in this respect, and the second time period may be of any suitable duration.

[0111] In some embodiments, the signal is considered to be in the second logic state during the time elapsed between the falling transition of the signal and the rising transition of the signal. For example, the accumulation period may include the amount of time elapsed between the third point in time (e.g., determined in step 1618) and a later point in time (e.g., a fourth point in time) during the second period at which the rising transition of the signal occurred. If there is another falling transition within the second period after the fourth point in time, the accumulation period may also include the amount of time elapsed between the point at which the falling transition occurred and the occurrence of either (a) the end of the second period, or (b) the point at which another rising transition occurs within the second period. The logic described in the previous sentence may apply to any additional falling transitions in addition to the first and second falling transitions within the second period. In some embodiments, if no rising transition occurs after the third point in time and within the second period, the accumulation period may include the amount of time elapsed between the third point in time and the end of the second period.

[0112] In some embodiments, the second threshold duration can be any suitable duration that is less than or equal to the duration of the second period. By way of non-limiting example, the second threshold duration can be 70% of the duration of the second period, 75% of the duration of the second period, 80% of the duration of the second period, 85% of the duration of the second period, 90% of the duration of the first period, 100% of the duration of the second period, or any other suitable second threshold duration. In some embodiments, the second threshold duration can depend on the expected duration of sensor disengagement and / or the expected frequency of noise (e.g., momentary transitions of the signal to the first logic state) expected when the sensor disengages from the sensed component (e.g., a tooth) of the medication delivery device. The second threshold duration can be the same as or different from the first threshold duration.

[0113] In step 1622, the processor determines whether the sensor of the medication delivery device transitioned between an engaged state and a disengaged state at a third time. If the accumulated period determined in step 1620 is greater than or equal to the second threshold duration, the processor determines that the medication delivery device transitioned between an engaged state and a disengaged state. If the accumulated period is not greater than or equal to the second threshold duration, the processor determines that the medication delivery device did not transition between an engaged state and a disengaged state.

[0114] In step 1624, the processor determines whether another rising transition of the signal occurs after the second period of time. If a rising transition occurs, the process 1600 returns to step 1604 shown in Figure 16A. If a rising transition does not occur, the process 1600 ends.

[0115] For simplicity, FIGS. 16A and 16B illustrate an exemplary process for determining whether a sensor has transitioned from the aforementioned disengaged state to the aforementioned engaged state (or vice versa), where a first logic state corresponds to an assertion or high logic state and a second logic state corresponds to a deassertion or low logic state. This does not mean that the present disclosure excludes embodiments in which the first logic state instead corresponds to a deassertion or low logic state and the second logic state instead corresponds to an assertion or high logic state. In such alternative embodiments, appropriate modifications may be made to FIGS. 16A and 16B. For example, the term “rising transition” may be replaced with the term “falling transition” (or vice versa). Similarly, the term “assertion state” or “assertion threshold duration” may be replaced with the term “deassertion state” or “deassertion threshold duration” (or vice versa).

[0116] 17 is an exemplary schematic diagram illustrating a system 1700 for detecting rising and falling transitions in a signal received from a sensor of a medication delivery device, according to some embodiments. As shown, the system 1700 includes a clock 1702, a timer 1704, a rising transition interrupt handler 1716, and a falling transition interrupt handler 1718. However, it should be understood that the system for detecting rising and / or falling transitions may include one or more additional or alternative components, as aspects of the technology described herein are not limited in this respect.

[0117] In some embodiments, the rising transition interrupt handler 1716 is configured to detect a rising transition 1708 of the signal 1714 and record a timestamp 1706 indicating when the rising transition 1708 occurred. For example, the timestamp 1706 indicates that the rising transition 1708 occurred at count 158 ​​according to the timer 1704.

[0118] In some embodiments, the rising transition interrupt handler 1716 is an interrupt configured to detect the rising transition 1708 of the signal 1714 and / or record the timestamp that the rising transition 1708 occurred. The rising transition interrupt handler 1716 may be implemented using software running on or configured to run on a processor, such as, for example, a processor configured to execute the process 1600 shown in FIGS.

[0119] In some embodiments, the timer 1704 is any suitable timer, such as, for example, a timer configured to count up from an initial time. For example, the clock 1702 may cause the timer 1704 to count up from the time the medication delivery device was assembled. In some embodiments, the timer 1704 may be configured to count up at a rate (e.g., in one-second increments) to a particular value and then start over when that value is reached. For example, the clock 1702 may drive an 11-bit counter to count up to 2,047 in one-second increments. When the counter reaches 2,047, the counter restarts at 0. In some embodiments, to track the cumulative time that has elapsed since the initial time, the system 1700 is configured to record each time the counter restarts. In some embodiments, the timer 1704 is included in the medication delivery device. For example, the timer may be included on a printed circuit board (PCB) of the medication delivery device. In some embodiments, the timer 1704 is external to the medication delivery device.

[0120] In some embodiments, the clock 1702 includes any suitable clock, such as, for example, the system clock 1430 shown in FIG. 14 . In some embodiments, the clock 1702 is included in the medication delivery device. For example, the clock 1702 may be included on a PCB of the medication delivery device. In some embodiments, the clock 1702 is external to the medication delivery device.

[0121] In some embodiments, the falling transition interrupt handler 1718 is configured to detect a falling transition 1710 of the signal 1714 and record a timestamp 1712 indicating when the falling transition 1710 occurred. For example, the timestamp 1712 indicates that the falling transition 1710 occurred at count 297 according to the timer 1704.

[0122] In some embodiments, the falling transition interrupt handler 1718 is an interrupt configured to detect a falling transition 1710 of the signal 1714 and / or record a timestamp that the falling transition 1710 occurred. The falling transition interrupt handler 1718 may be implemented using software running on or configured to run on a processor, such as, for example, a processor configured to execute the process 1600 shown in Figures 16A-16B.

[0123] In some embodiments, the timestamps 1706, 1712 recorded by the interrupt handlers 1716, 1718 can be used to determine the duration that the signal 1714 was in a particular state. In the example of FIG. 17, the signal 1714 is in an asserted state for a duration defined by the difference between the point in time indicated by the timestamp 1706 and the point in time indicated by the timestamp 1712. As shown, the signal 1714 is in an asserted state for a count of 139, which is equal to the difference between 297 and 158. If the timer 1704 is configured to count up in 1 microsecond increments, the duration that the signal is in the asserted state is 139 microseconds. In some embodiments, if the timer 1704 restarts its count (e.g., restarts at 0) some time between the occurrence of the rising transition 1708 and the occurrence of the falling transition 1710, additional information can be used to determine the amount of time that has elapsed between the two occurrences. Such additional information may include, for example, the maximum value to which the timer 1704 is configured to count up, and / or the number of times the timer 1704 has restarted its count.

[0124] 18 is an exemplary plot showing the integral of a signal received from a sensor of a medication delivery device, according to some embodiments. As shown, line 1810 shows the time when the sensor of the medication delivery device actually transitioned between an engaged and disengaged state. Line 1820 shows the signal received from the sensor of the medication delivery device. Line 1830 shows the cumulative period that signal 1820 was in the asserted and / or deasserted state.

[0125] In some embodiments, the signal 1820 is received by a processor. In some embodiments, the processor is configured to process the signal by performing some or all of the process 1600 described herein, including at least those related to FIGS. 16A-16B.

[0126] For example, in some embodiments, the processor may detect or be configured to detect a first rising transition of the signal 1820. Upon detecting the first rising transition, the processor may determine a first time point at which the first rising transition occurred. For example, the processor may use a software-implemented interrupt handler to record a timestamp indicating the first time point at which the first rising transition occurred. Additionally or alternatively, in some embodiments, the first time point may not correspond to the first rising transition. For example, the first time point may include any suitable time point determined in any suitable manner, such as a time point before or after the occurrence of the first rising transition, as aspects of the technology described herein are not limited in this respect. For example, the first period of time may essentially slide upon detection of each rising transition of the signal to search for a first instance of a series of signals that results in the signal being in an asserted state for a first threshold duration (e.g., an assertion threshold duration).

[0127] In some embodiments, the first time point marks the start of a first time period, as shown in Figure 18. The processor may further detect, or be configured to detect, additional rising and / or falling transitions that occur within the first time period after the first time point. This may include, for example, determining the time at which each rising and / or falling transition occurs during the first time period, such as the second time at which the first falling transition occurred. As shown, three additional rising transitions and three falling transitions of signal 1820 occurred within the first time period.

[0128] In some embodiments, the processor may determine, or may be configured to determine, whether the sensor transitioned between a disengaged state and an engaged state at a first time. In some embodiments, this may be determined by determining whether the sensor transitioned between a disengaged state and an engaged state within a first time period for an assertion threshold duration (T A ) or more.

[0129] In some embodiments, determining the accumulation period includes (a) determining the amount of time elapsed between each rising transition and each falling transition within the first period and (b) summing the determined amounts of time. For example, line 1830 shows the integral of signal 1820 over the first period. Between each rising transition and each falling transition within the first period, when signal 1820 is in an asserted state, line 1830 rises by the amount of time elapsed during the signal assertion. That is, the amount of time is included in the accumulation period. However, between each falling transition and each rising transition, when signal 1820 is in a deasserted state, line 1830 does not increase. In other words, the amount of time elapsed during the signal deassertion is not included in the accumulation period. In some embodiments, when there is an upward transition within the first period that is not followed by a downward transition, as shown by the last upward transition in the first period of FIG. 18 , the accumulation period includes the time elapsed between when the upward transition occurred and when the first period ends.

[0130] In some embodiments, the cumulative period is the assertion threshold duration (T A), the processor determines that the sensor transitioned to the engaged state at the first time point. As shown in the example of FIG. 18, within the first time period, the cumulative time period indicated by line 1830 is equal to or greater than the assertion threshold duration (T A ) Thus, even if there is noise (e.g., a momentary signal de-assertion) within the first time period, the processor will still correctly determine that the sensor transitioned to the engaged state at the first time point.

[0131] In some embodiments, after determining that the sensor has transitioned to an engaged state at a first time, the processor may evaluate the quality of the signal 1820. In some embodiments, such evaluation may include determining the number of rising and / or falling transitions of the signal within a first time period. For example, during the first time period shown in FIG. 18, there were four rising transitions (including the first rising transition) and three falling transitions. In some embodiments, if the number of rising and / or falling transitions is equal to or greater than a specified threshold (e.g., the signal is very noisy), this may indicate that there may be a problem with the sensor, and therefore there may be a lower confidence associated with determining that the sensor has transitioned to an engaged state. In some embodiments, when this occurs, the processor may not consider that transition, even if the processor previously determined that the sensor had transitioned to an engaged state (e.g., prior to the quality evaluation).

[0132] In some embodiments, the processor may provide an output indicative of the quality of the signal. For example, when the number of rising and / or falling transitions exceeds a threshold, the processor may provide an output recommending that the user manually check the dose administered by the drug delivery device to confirm the accuracy of the estimation made based on the signal. Additionally or alternatively, the processor may provide the output as part of a quality control process. For example, during manufacturing, the processor may output a metric indicative of the number of rising and / or falling transitions in the signal, which can then be compared to an expected value. If there is a discrepancy between these two values, the tested drug delivery device and / or manufacturing process may be flagged for a potential problem.

[0133] In some embodiments, the processor may further detect, or be configured to detect, a falling transition of the signal 1820 that occurred after the first period of time. In the example of FIG. 18, the falling transition occurred at a third point in time after the first period of time. In some embodiments, upon detecting the falling transition, the processor may determine the third point in time at which the falling transition occurred. For example, the processor may use a software-implemented interrupt handler to record a timestamp indicating the third point in time at which the falling transition occurred. Additionally or alternatively, in some embodiments, the third point in time may not correspond to a falling transition. For example, the third point in time may correspond to the time at which the first period of time ended. For example, the second period of time may slide in time upon detection of each falling edge to essentially search for the first instance of a series of signals that result in the signal being in a deasserted state for a second threshold duration (e.g., a deassertion threshold duration). As described above, the first period of time may additionally or alternatively slide in time to perform the detections described herein.

[0134] In some embodiments, the third time point indicates the start of a second time period, as shown in Figure 18. The processor may further detect, or be configured to detect, additional falling and / or rising transitions that occur within the second time period after the third time point. This may include, for example, determining when each falling and / or rising transition occurred during the second time period. As shown, two additional falling transitions and two rising transitions of signal 1820 occurred within the second time period.

[0135] In some embodiments, the processor may determine, or be configured to determine, whether the sensor transitions between the engaged and disengaged states at a third time. In some embodiments, this occurs when the sensor transitions between the engaged and disengaged states for a de-assertion threshold duration (T D ) or more.

[0136] In some embodiments, determining the accumulation period includes (a) determining the amount of time elapsed between each falling transition and rising transition within the second period and (b) summing the determined amounts of time. For example, line 1830 shows the integral over signal 1820 during the second period. Between each falling transition and rising transition within the second period, when signal 1820 is in a deasserted state, line 1830 rises by the amount of time elapsed during the signal deassertion. That is, the amount of time is included in the accumulation period. However, between each rising transition and falling transition, when signal 1820 is in an asserted state, line 1830 does not increase. In other words, the amount of time elapsed during the signal assertion is not included in the accumulation period. In some embodiments, when there is a falling transition within the second period that is not followed by a rising transition, as shown by the last falling transition in the second period of FIG. 18 , the accumulation period includes the time elapsed between when the falling transition occurred and when the second period ends.

[0137] In some embodiments, the cumulative period is equal to the deassertion threshold duration (T D), the processor determines that the sensor transitioned to the disengaged state at a third time. As shown in the example of FIG. 18, within the second time period, the cumulative time period indicated by line 1830 is greater than or equal to the deassertion threshold duration (T D ) Thus, even if there is noise (e.g., a momentary signal assertion) within the second period of time, the processor will still correctly determine that the sensor transitioned to the disengaged state at the third time point.

[0138] In some embodiments, the techniques may be configured to process signals as they are being received (e.g., in real time during signal reception and / or processing). Such an approach may achieve memory savings, for example, because the entire signal does not need to be stored for the medication delivery device. In some embodiments, the techniques may be configured to store received signals and process the stored signals at a later point in time (i.e., not in real time during signal reception and / or processing) in accordance with the techniques described herein. While such techniques may require more memory compared to processing signals as they are received, such techniques may allow signals to be processed in multiple passes, etc., so that the signals can be processed in various manner(s) to determine the best way to analyze the signals to determine assertion and deassertion states.

[0139] It should be understood that the various periods, such as the first period and / or second period, are configurable and may vary over time as the signal is processed. In some embodiments, the first period is different from the second period. In some embodiments, the first period is the same as the second period. In some embodiments, multiple different first periods and / or second periods may be used in accordance with the techniques described herein.

[0140] While FIG. 18 is illustrated in the context of an embodiment in which a first logic state corresponds to an assertion or high logic state and a second logic state corresponds to a deassertion or low logic state, other embodiments are possible in which a first logic state corresponds to a deassertion state and a second logic state corresponds to a deassertion state. In such alternative embodiments, appropriate modifications may be made to FIG. 18. For example, signal line 1820 may be inverted so that whenever line 1810 indicates that the sensor is in an engaged state, signal 1820 occupies the deassertion state, and similarly, whenever line 1810 indicates that the sensor is in a disengaged state, signal 1820 occupies the assertion state. The assertion threshold duration (T A ) is the deassertion threshold duration (T D ) within the first period, the cumulative period indicated by line 1830 may correspond to the cumulative amount of time that signal 1820 spends in the deassertion state instead of the assertion state. D ) is the assertion threshold duration (T A ) Within the second period, the cumulative period indicated by line 1830 may correspond to the cumulative amount of time that signal 1820 spends in the asserted state instead of the deasserted state.

[0141] In some embodiments, the processor may determine a quality metric based on processing of the signal 1820. The metric may include any suitable metric, such as, for example, the ratio between the number of times the sensor is determined to have transitioned to an engaged state and the number of rising transitions in the signal. Additionally or alternatively, the metric may include the ratio between the number of times the sensor has transitioned to a disengaged state and the number of falling transitions in the signal.

[0142] In some embodiments, the quality metric may be output to a user, such as, for example, a user of the medication delivery device, a healthcare provider, and / or a user involved in manufacturing and / or testing the medication delivery device. In some embodiments, the quality metric may indicate a problem with a sensor of the medication delivery device, such as, for example, when the ratio between the signal transitions and the sensor transitions is large (e.g., indicating a noisy signal). Additionally or alternatively, when the quality metric indicates a problem, a recommendation to check the sensor, a recommendation to manually check the dose delivered using the medication delivery device, and / or any other suitable recommendation may be output to the user, since aspects of the present technology are not limited in this respect.

[0143] The device described herein is what is commonly referred to as a reusable pen-type medication injection device that a user manually manipulates to selectively set a dose and then injects the set dose. This type of injection device is well known, and the description of the device is merely exemplary, as the sensing system can be adapted for use with variously configured medication delivery devices, including otherwise constructed pen-type medication injection devices, alternatively shaped injection devices, and infusion pump devices. The medication can be any of the types that can be delivered by such medication delivery devices. The sensing system, described further below, can be used with other, otherwise configured devices, so the device is intended to be exemplary and not limiting.

[0144] Techniques operating according to the principles described herein may be implemented in any suitable manner. The processing and decision blocks of the flowcharts above represent steps and acts that may be included in algorithms that perform these various processes. The algorithms derived from these processes may be implemented as software integrated with and directing the operation of one or more single-purpose or multi-purpose processors, as functionally equivalent circuitry such as digital signal processing (DSP) circuits or application-specific integrated circuits (ASICs), or in any other suitable manner. It should be understood that the flowcharts included herein do not depict any particular circuitry or the syntax or operation of any particular programming language or type of programming language. Rather, the flowcharts illustrate functional information that one skilled in the art may use to fabricate circuits that perform the processing of, or implement computer software algorithms that perform the processing of, a particular device that implements the types of techniques described herein. It should also be understood that, unless otherwise indicated herein, the specific sequence of steps and / or acts set forth in each flowchart is merely illustrative of algorithms that may be implemented and varied in implementations and embodiments of the principles described herein.

[0145] Thus, in some embodiments, the techniques described herein may be embodied in computer-executable instructions implemented as software, including application software, system software, firmware, middleware, embedded code, or any other suitable type of computer code. Such computer-executable instructions may be written using any of a number of suitable programming languages ​​and / or programming or scripting tools, and may be compiled as executable machine code or intermediate code that runs on a framework or virtual machine.

[0146] When the techniques described herein are embodied as computer-executable instructions, these computer-executable instructions may be implemented in any suitable manner, including as several functional facilities, each of which provides one or more operations for completing the execution of an algorithm operating according to these techniques. A "functional facility" is an instantiated structural component of a computer system that is integrated with one or more computers and, when executed by one or more computers, causes the one or more computers to perform a specific operational role. A functional facility may be part or all of a software element. For example, a functional facility may be implemented as a function of a process, as a separate process, or as other suitable processing units. When the techniques described herein are implemented as multiple functional facilities, each functional facility may be implemented in its own way and need not all be implemented in the same way. Additionally, these functional facilities may execute in parallel and / or serially as desired and may pass information between each other using shared memory on the computers on which they are executing, using a message-passing protocol, or other suitable methods.

[0147] Generally, functional facilities include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of functional facilities may be combined or distributed as desired in the systems in which they operate. In some implementations, one or more functional facilities that implement the techniques herein may together form a complete software package. These functional facilities may, in alternative embodiments, be adapted to interact with other, unrelated functional facilities and / or processes to implement a software program application.

[0148] Several exemplary functional facilities for performing one or more tasks are described herein. However, it should be understood that the described functional facilities and divisions of tasks are merely exemplary of types of functional facilities that may implement the exemplary techniques described herein, and that embodiments are not limited to being implemented with any particular number, division, or type of functional facilities. In some implementations, all functionality may be implemented in a single functional facility. It should also be understood that in some implementations, some of the functional facilities described herein may be implemented together with others or separately (i.e., as a single unit or separate units), or some of these functional facilities may not be implemented.

[0149] Computer-executable instructions implementing the techniques described herein (when implemented as one or more functional facilities or in any other manner) may, in some embodiments, be encoded on one or more computer-readable media to provide functionality thereon. Computer-readable media include magnetic media such as hard disk drives, optical media such as compact discs (CDs) or digital versatile discs (DVDs), persistent or non-persistent solid-state memory (e.g., flash memory, magnetic RAM, etc.), or any other suitable storage media. Such computer-readable media may be implemented in any suitable manner. As used herein, "computer-readable media" (also referred to as "computer-readable storage media") refers to tangible storage media. Tangible storage media are non-transitory and have at least one physical structural component. In "computer-readable media," as used herein, the at least one physical structural component has at least one physical characteristic that can be altered in some way during the process of creating information-embedded media, recording information thereon, or any other process of encoding information-bearing media. For example, the magnetization state of portions of the physical structure of the computer-readable medium may be altered during the recording process.

[0150] Furthermore, some of the technologies described above involve the act of storing information (e.g., data and / or instructions) in a particular manner for use by those technologies. In some implementations of these technologies, such as those in which the technologies are implemented as computer-executable instructions, the information may be encoded on a computer-readable storage medium. Where particular structures are described herein as advantageous formats for storing this information, those structures may be used to impart a physical organization to the information when encoded on the storage medium. These advantageous structures may then provide functionality to the storage medium by affecting the operation of one or more processors that interact with the information, e.g., by increasing the efficiency of computer operations performed by the processor(s). For example, by increasing the efficiency of computer operations performed by the processor(s).

[0151] In some, but not all, implementations where the techniques may be embodied as computer-executable instructions, these instructions may be executed on one or more suitable computing device(s) operating in any suitable computer system, or one or more computing devices (or one or more processors of one or more computing devices) may be programmed to execute the computer-executable instructions. A computing device or processor may be programmed to execute the instructions when the instructions are stored in a manner accessible to the computing device or processor, such as a data store (e.g., an on-chip cache or instruction register, a computer-readable storage medium accessible via a bus, a computer-readable storage medium accessible via one or more networks and accessible by the device / processor, etc.). The functional facility containing these computer-executable instructions may be integrated with and direct the operation of a single general-purpose programmable digital computing device, a cooperative system of two or more general-purpose computing devices that share processing power and jointly implement the techniques described herein, a single computing device or cooperative system of computing devices (co-located or geographically distributed) dedicated to performing the techniques described herein, one or more field programmable gate arrays (FPGAs) for implementing the techniques described herein, or any other suitable system.

[0152] A computing device may include at least one processor, a network adapter, and a computer-readable storage medium. The computing device may be, for example, a desktop or laptop personal computer, a personal digital assistant (PDA), a smart mobile phone, a server, or any other suitable computing device. The network adapter may be any suitable hardware and / or software that enables the computing device to communicate wired and / or wirelessly with any other suitable computing device over any suitable computing network. The computing network may include wireless access points, switches, routers, gateways, and / or other network equipment, as well as any suitable wired and / or wireless communication medium for exchanging data between two or more computers, including the Internet. The computer-readable medium may be adapted to store data to be processed and / or instructions to be executed by the processor. The processor enables the processing of data and the execution of instructions. The data and instructions may be stored on the computer-readable storage medium.

[0153] A computing device may additionally have one or more components and peripherals, including input and output devices. These devices may be used, among other things, to present a user interface. Examples of output devices that may be used to provide a user interface include a printer or display screen for visual presentation of output and a speaker or other sound-generating device for audible presentation of output. Examples of input devices that may be used for a user interface include pointing devices such as a keyboard, mouse, touchpad, or digitizer tablet. As another example, a computing device may receive input information through voice recognition or in other audible forms.

[0154] Embodiments have been described in which the present technology is implemented in circuits and / or computer-executable instructions. It should be understood that some embodiments may be in the form of a method, of which at least one example is provided. The acts performed as part of this method may be ordered in any suitable manner. Thus, while shown as sequential acts in the exemplary embodiments, embodiments may be constructed in which acts are performed in an order different from that illustrated, which may include performing some acts simultaneously.

[0155] Various aspects of the above-described embodiments may be used alone, in combination, or in various arrangements not specifically discussed in the foregoing embodiments, and therefore are not limited in their application to the details and arrangements of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0156] The use of ordinal terms such as "first," "second," "third," etc. to modify claim elements in the claims does not, by itself, imply any priority, precedence, or order of a claim element relative to another or the temporal order in which the actions of a method are performed, but is used solely as a label to distinguish a claim element having a particular name from another element having the same name (but due to the use of ordinal terms) to distinguish between claim elements.

[0157] Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0158] The term "exemplary" is used herein to mean serving as an example, instance, or illustration. Thus, any embodiment, implementation, process, feature, etc. described herein as exemplary is to be understood as an exemplary example and not as a preferred or advantageous example, unless otherwise specified.

[0159] By clarifying the use of the following and notifying the public: 、 , ...and <n> At least one of the following" or "< / n> 、 、... <n> , or at least one of these combinations," or "< / n> 、 , ... and / or <n>The phrase "is defined by applicant in its broadest sense and supersedes any other implied definition above or below unless expressly asserted to the contrary by applicant, and means one or more elements selected from the group including A, B... and N. In other words, this phrase means any combination of one or more of the elements A, B,... or N, including any one element alone or that one element in combination with one or more of the other elements, which may also include additional, unlisted elements.

[0160] While various embodiments have been described, it will be apparent to those skilled in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples and are not intended to be the only possible embodiments and implementations. Furthermore, the advantages described above are not necessarily the only advantages, and it is not necessarily expected that all of the described advantages will be achieved in each embodiment.

[0161] Various aspects are described in this disclosure, including but not limited to the following aspects. 1. A method for filtering a signal output from a sensor of a medication delivery device, the sensor being operable to transition between an engaged state in which the signal output from the sensor is in a first logic state and a disengaged state in which the signal output from the sensor is in a second logic state, the method comprising: detecting a first transition of the signal from the second logic state to the first logic state, the first transition occurring at a first time point; determining whether, within a first time period beginning at the first time point, the signal is in the first logic state for an accumulated period of time that is greater than or equal to a first threshold duration; and determining that the sensor of the medication delivery device has transitioned from the disengaged state to the engaged state at the first time point if the accumulated period is greater than or equal to the first threshold duration. 2. The method of claim 1, further comprising determining that the sensor of the medication delivery device has not transitioned from a disengaged state to an engaged state if the accumulated period is not greater than or equal to a first threshold determination. 3. The method of claim 1 or 2, further comprising receiving data indicative of a signal from a sensor of the medication delivery device. 4. The method of any one of claims 1 to 3, further comprising detecting a second transition of the signal from the first logic state to a second logic state, the second transition occurring at a second time point after the first time point and within the first time period, and the accumulated time period comprising a first amount of time elapsed between the first time point and the second time point. 5. The method of claim 4, further comprising: detecting a third transition of the signal from the second logic state to the first logic state, the third transition occurring at a third time point after the second time point and within the first time period; and detecting a fourth transition of the signal from the first logic state to the second logic state, the fourth transition occurring at a fourth time point after the third time point and also within the first time period; and wherein the accumulation period includes a second amount of time elapsed between the third time point and the fourth time point, but excludes an amount of time elapsed between the second time point and the third time point. 6. The method of claim 4 or 5, wherein detecting the second transition includes using the first interrupt handler to record a second time when the second transition occurs. 7. The method of any one of claims 1 to 6, wherein detecting the first transition includes using a second interrupt handler to record a first time point at which the first transition occurs. 8. The method of any one of claims 1 to 7, wherein determining that the sensor of the medication delivery device has transitioned between states further comprises: determining whether a number of signal transitions occurring within a first period of time exceeds a threshold; and determining that the sensor of the medication delivery device has transitioned from a disengaged state to an engaged state only if the number of signal transitions does not exceed the threshold. 9. The method of any one of claims 1-8, further comprising detecting a fifth transition of the signal from the first logic state to the second logic state, the fifth transition occurring at a fifth time point after the first period of time. 10. The method of claim 9, further comprising: determining whether the signal is in a second logic state for a second cumulative period that is greater than or equal to a second threshold duration within a second period beginning at a fifth time point; and determining that the sensor of the medication delivery device has transitioned from an engaged state to a disengaged state at the fifth time point if the second cumulative period is greater than or equal to the second threshold duration. 11. The method of claim 10, further comprising detecting a sixth transition of the signal from the second logic state to the first logic state, the sixth transition occurring at a sixth time point after the fifth time point and within the second period of time, and the second accumulation period comprising the amount of time elapsed between the fifth time point and the sixth time point. 12. The method of claim 10 or 11, wherein the first duration of the first period is different from the second duration of the second period, or the first threshold duration is different from the second threshold duration, or both. 13. The method of any one of claims 1 to 12, further comprising: detecting a seventh transition from the second logic state to the first logic state, wherein the seventh transition occurs at a seventh time point; determining, within a third time period beginning at the seventh time point, whether the signal is in the first logic state for a third cumulative period that is greater than or equal to a first threshold duration; and determining that the sensor of the medication delivery device transitioned from a disengaged state to an engaged state at the seventh time point if the third cumulative period is greater than or equal to the first threshold duration. 14. The method of any one of claims 1 to 13, further comprising determining a number of sensor transitions that occur within a fourth time period beginning at the first time point, the number of sensor transitions indicating an amount of drug delivered using the drug delivery device. 15. The method of any one of claims 1-14, wherein the first logic state comprises an assertion state and the second logic state comprises a deassertion state. 16. A non-transitory computer-readable storage medium containing instructions that, when executed by one or more processors on a computing device, are operable to cause the one or more processors to perform the method of any one of claims 1 to 15. 17. A medication delivery device comprising: a housing including a reservoir large enough to hold a medication; a printed circuit board; a sensor mounted on the printed circuit board and operable to output a signal, the sensor operable to transition between an engaged state, in which the signal output from the sensor is in a first logic state, and a disengaged state, in which the signal output from the sensor is in a second logic state; and a microcontroller in electrical communication with the sensor via a logic input to the microcontroller, wherein the microcontroller is configured to: receive the signal output from the sensor; and determine whether the sensor has transitioned between the disengaged state and the engaged state based on the received signal, at least in part, by: determining whether the signal is at the first logic state for an accumulated period that is equal to or greater than a first threshold duration, within a first time period beginning at a first time corresponding to a first transition of the signal from the second logic state to the first logic state; and determining that the sensor has transitioned from the disengaged state to the engaged state if the accumulated period is equal to or greater than the first threshold duration. 18. The medication delivery device of claim 17, wherein the microcontroller is configured to determine that the sensor has not transitioned from a disengaged state to an engaged state when the accumulated period is not greater than or equal to a first threshold duration. 19. A medication delivery device as claimed in claim 17 or 18, further comprising a rotatable element that is rotatable relative to the printed circuit board, the rotatable element having a series of protrusions spaced apart from one another, the rotatable element positioned to allow the protrusions to slide relative to the sensor to move the sensor between engaged and disengaged states as the rotatable element rotates. 20. The medication delivery device of any one of claims 17 to 19, further comprising a resistor-capacitor (RC) circuit electrically coupled to the sensor and the microcontroller, wherein the signal is a filtered signal, and the RC circuit is configured to receive an unfiltered signal from the sensor and transmit a filtered signal to the microcontroller. 21. The medication delivery device of any one of claims 17 to 19, further comprising a timer configured to count up from an initial point in time. 22. The medication delivery device of claim 21, wherein determining whether the sensor has transitioned between a disengaged state and an engaged state further comprises detecting a first transition of the signal and using a timer to determine a first time point at which the first transition occurred. 23. The medication delivery device of claim 21 or 22, wherein determining whether the sensor has transitioned between the disengaged state and the engaged state further comprises detecting a second transition of the signal from a first logic state to a second logic state, the second transition occurring at a second time point after the first time point and within the first period of time; determining using a timer the second time point at which the second transition occurred; and determining the amount of time that has elapsed between the first time point and the second time point. 24. The drug delivery device of any one of claims 17 to 23, further comprising a drug held in the reservoir. 25. The drug delivery device of claim 24, wherein the drug is insulin.< / n>

Claims

1. 1. A method for filtering a signal output from a sensor in a medication delivery device, the sensor being operable to transition between an engaged state, in which the signal output from the sensor is in a first logic state, and a disengaged state, in which the signal output from the sensor is in a second logic state, the method comprising: detecting a first transition of the signal from the second logic state to the first logic state, the first transition occurring at a first time; determining, within a first time period beginning at the first time point, whether the signal is in the first logic state for an accumulation period equal to or greater than a first threshold duration; determining that the sensor of the medication delivery device transitioned from the disengaged state to the engaged state at the first time if the accumulated period is greater than or equal to the first threshold duration.

2. 2. The method of claim 1, further comprising determining that the sensor of the medication delivery device has not transitioned from the disengaged state to the engaged state when the cumulative period does not equal or exceed the first threshold determination.

3. The method of claim 1 or 2, further comprising receiving data indicative of the signal from the sensor of the medication delivery device.

4. detecting a second transition of the signal from the first logic state to the second logic state, the second transition occurring at a second time point within the first time period after the first time point; The method of any one of claims 1 to 3, wherein the cumulative period comprises a first amount of time that elapsed between the first time point and the second time point.

5. detecting a third transition of the signal from the second logic state to the first logic state, the third transition occurring at a third time point within the first time period after the second time point; detecting a fourth transition of the signal from the first logic state to the second logic state, the fourth transition occurring at a fourth time point after the third time point and also within the first time period; 5. The method of claim 4, wherein the cumulative period includes a second amount of time elapsed between the third time point and the fourth time point, but excludes an amount of time elapsed between the second time point and the third time point.

6. 6. The method of claim 4, wherein detecting the second transition comprises using a first interrupt handler to record the second time that the second transition occurs.

7. 7. The method of claim 1, wherein detecting the first transition comprises using a second interrupt handler to record the first time that the first transition occurred.

8. determining that the sensor of the medication delivery device has transitioned between the states; determining whether a number of signal transitions occurring within the first period of time exceeds a threshold; 8. The method of claim 1, further comprising determining that the sensor of the medication delivery device has transitioned from the disengaged state to the engaged state only if the number of signal transitions does not exceed the threshold.

9. 9. The method of claim 1, further comprising detecting a fifth transition of the signal from the first logic state to the second logic state, the fifth transition occurring at a fifth time point after the first period of time.

10. determining, within a second time period beginning at the fifth time point, whether the signal is in the second logic state for a second accumulation time period that equals or exceeds a second threshold time duration; 10. The method of claim 9, further comprising determining that the sensor of the medication delivery device transitioned from the engaged state to the disengaged state at the fifth time point if the second cumulative period equals or exceeds the second threshold duration.

11. detecting a sixth transition of the signal from the second logic state to the first logic state, the sixth transition occurring at a sixth time point within the second period of time after the fifth time point; The method of claim 10 , wherein the second cumulative period comprises the amount of time that elapsed between the fifth time point and the sixth time point.

12. a first duration of the first period is different from a second duration of the second period; or The method of claim 10 or 11, wherein the first threshold duration is different from the second threshold duration, or both.

13. detecting a seventh transition from the second logic state to the first logic state, the seventh transition occurring at a seventh time; determining, within a third time period beginning at the seventh time point, whether the signal is in the first logic state for a third accumulation time period that is greater than or equal to the first threshold time duration; 13. The method of claim 1, further comprising determining that the sensor of the medication delivery device has transitioned from the disengaged state to the engaged state at the seventh time point if the third cumulative period equals or exceeds the first threshold duration.

14. 14. The method of claim 1, further comprising determining a number of sensor transitions that occur within a fourth time period beginning at the first time point, the number of sensor transitions indicating an amount of drug delivered using the drug delivery device.

15. the first logic state comprises an assertion state; The method of any preceding claim, wherein the second logic state comprises a deassertion state.

16. 16. A non-transitory computer-readable storage medium comprising instructions that, when executed by one or more processors on a computing device, are operable to cause the one or more processors to perform the method of any one of claims 1 to 15.

17. 1. A drug delivery device comprising: a housing having a reservoir large enough to hold the medicament; a printed circuit board; a sensor mounted on the printed circuit board and operable to output a signal, the sensor operable to transition between an engaged state, in which the signal output from the sensor is in a first logic state, and a disengaged state, in which the signal output from the sensor is in a second logic state; a microcontroller in electrical communication with the sensor via logic inputs to the microcontroller, the microcontroller comprising: receiving the signal output from the sensor; At least in part, determining, within a first time period beginning at a first time point corresponding to a first transition of the signal from the second logic state to the first logic state, whether the signal is in the first logic state for an accumulation period that is greater than or equal to a first threshold duration; determining that the sensor has transitioned from the disengaged state to the engaged state if the cumulative period is greater than or equal to the first threshold duration, thereby determining whether the sensor has transitioned between the disengaged state and the engaged state based on the received signal.

18. 18. The medication delivery device of claim 17, wherein the microcontroller is configured to determine that the sensor has not transitioned from the disengaged state to the engaged state when the accumulated period is not greater than or equal to the first threshold duration.

19. 19. The medication delivery device of claim 17 or 18, further comprising a rotatable element that is rotatable relative to the printed circuit board, the rotatable element having a series of protrusions spaced apart from each other, the rotatable element being positioned to allow the protrusions to slide relative to the sensor to move the sensor between the engaged state and the disengaged state when the rotatable element rotates.

20. a resistor-capacitor (RC) circuit electrically coupled to the sensor and the microcontroller, the signal being a filtered signal, the RC circuit comprising: receiving an unfiltered signal from the sensor; A medication delivery device according to any one of claims 17 to 19, configured to transmit the filtered signal to the microcontroller.

21. 20. The medication delivery device of any one of claims 17 to 19, further comprising a timer configured to count up from an initial point in time.

22. determining whether the sensor has transitioned between the disengaged state and the engaged state; detecting the first transition of the signal; 22. The medication delivery device of claim 21, further comprising: using the timer to determine the first time point at which the first transition occurs.

23. determining whether the sensor has transitioned between the disengaged state and the engaged state; detecting a second transition of the signal from the first logic state to the second logic state, the second transition occurring at a second time point within the first time period after the first time point; using the timer to determine the second time at which the second transition occurs; 23. The medication delivery device of claim 21 or 22, further comprising: determining an amount of time that has elapsed between the first time point and the second time point.

24. A drug delivery device according to any one of claims 17 to 23, further comprising a drug held within the reservoir.

25. The drug delivery device of claim 24, wherein the drug is insulin.

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