Patent Description:
Patients suffering from various diseases must frequently inject themselves with medication. To allow a person to conveniently and accurately self-administer medicine, a variety of devices broadly known as pen injectors or injection pens have been developed. Generally, these pens are equipped with a cartridge including a piston and containing a multi-dose quantity of liquid medication. A drive member is movable forward to advance the piston in the cartridge to dispense the contained medication from an outlet at the distal cartridge end, typically through a needle. In disposable or prefilled pens, after a pen has been utilized to exhaust the supply of medication within the cartridge, a user discards the entire pen and begins using a new replacement pen. In reusable pens, after a pen has been utilized to exhaust the supply of medication within the cartridge, the pen is disassembled to allow replacement of the spent cartridge with a fresh cartridge, and then the pen is reassembled for its subsequent use.

Many pen injectors and other medication delivery devices utilize mechanical systems in which members rotate and/or translate relative to one another in a manner proportional to the dose delivered by operation of the device. Accordingly, the art has endeavored to provide reliable systems that accurately measure the relative movement of members of a medication delivery device in order to assess the dose delivered. Such systems may include a sensor which is secured to a first member of the medication delivery device, and which detects the relative movement of a sensed component secured to a second member of the device.

The administration of a proper amount of medication requires that the dose delivered by the medication delivery device be accurate. Many pen injectors and other medication delivery devices do not include the functionality to automatically detect and record the amount of medication delivered by the device during the injection event. In the absence of an automated system, a patient must manually keep track of the amount and time of each injection. Accordingly, there is a need for a device that is operable to automatically detect the dose delivered by the medication delivery device during an injection event. Further, there is a need for such a dose detection device to be removable and reusable with multiple delivery devices.

<CIT> discloses a data collection device comprises a first portion and a second portion, a sensor configured to detect rotation of the second portion relative to first portion and a processor arrangement configured to determine a medicament amount expelled by the injection device based on the detected movement. The first portion is mounted to a component of the injection device that rotates as medicament is expelled.

<CIT> discloses a sensor assembly comprising a first rotary sensor part having a plurality of individual electrically conducting code segments arranged in a circumferential pattern, and a plurality of electrically conducting reference segments between the code segments, and a second rotary sensor part arranged rotationally relative to the first part a plurality of contact structures, each contact structure being arranged to be in contact with either a code segment or a reference segment depending on the rotational position between the first and second rotary sensor part. The contact structures are configured to engage and connect to different sensor segments as the first and second rotary sensor part rotate relative to each, the created connections being indicative of a rotational position between the first and second rotary sensor part. For a given rotational position, at least one contact structure engages a code segment and at least one contact structure engages a reference segment.

The invention is defined in claims <NUM> and <NUM>. Aspects, embodiments and examples of the present disclosure which do not fall under the scope of the appended claims do not form part of the invention and are merely provided for illustrative purposes.

In accordance with an aspect of the present disclosure, a dose detection system is provided for a medication delivery device which includes a dose setting member which rotates relative to an actuator during dose delivery. The dose detection system comprises an electronics assembly attached to the actuator and a sensed element attached to the dose setting member. The electronics assembly includes a rotation sensor operable with the sensed element to detect the movement of the dose setting member relative to the actuator during dose delivery. The electronics assembly may further include various additional components such as one or more other sensors, memory, a processor, a controller, a battery, etc..

In another aspect, the dose detection system comprises a module which is removably attachable to the medication delivery device. Among other advantages, the attachable and detachable module is operative to detect a delivered medication amount without changing the functionality or operation of the medication delivery device to which it is attached. In some embodiments, the sensing system records the size of the delivered dose and communicates the information to an external device. The device may include a cartridge and a medication contained within said cartridge. Other advantages will be recognized by those of ordinary skill in the art.

The features and advantages of the present disclosure will become more apparent to those skilled in the art upon consideration of the following detailed description taken in conjunction with the accompanying figures.

The present disclosure relates to sensing systems for medication delivery devices. In one aspect, the sensing system is for determining the amount of a dose delivered by a medication delivery device based on the sensing of relative rotational movement between a dose setting member and an actuator of the medication delivery device. The sensed relative rotational movements are correlated to the amount of the dose delivered. By way of illustration, the medication delivery device is described in the form of a pen injector. However, the medication delivery device may be any device which is used to set and to deliver a dose of a medication, such as a pen injector, an infusion pump or a syringe. The medication may be any of a type that may be delivered by such a medication delivery device.

Devices described herein, such as a device <NUM>, may further comprise a medication, such as for example, within a reservoir or cartridge <NUM>. In another embodiment, a system may comprise one or more devices including device <NUM> and a medication. The term "medication" refers to one or more therapeutic agents including but not limited to insulins, insulin analogs such as insulin lispro or insulin glargine, insulin derivatives, GLP-<NUM> receptor agonists such as dulaglutide or liraglutide , glucagon, glucagon analogs, glucagon derivatives, gastric inhibitory polypeptide (GIP), GIP analogs, GIP derivatives, oxyntomodulin analogs, oxyntomodulin derivatives, therapeutic antibodies and any therapeutic agent that is capable of delivery by the above device. The medication as used in the device may be formulated with one or more excipients. The device is operated in a manner generally as described above by a patient, caregiver or healthcare professional to deliver medication to a person.

An exemplary medication delivery device <NUM> is illustrated in <FIG> as a pen injector configured to inject a medication into a patient through a needle. Pen injector <NUM> includes a body <NUM> comprising an elongated, pen-shaped housing <NUM> including a distal portion <NUM> and a proximal portion <NUM>. Distal portion <NUM> is received within a pen cap <NUM>. Referring to <FIG>, distal portion <NUM> contains a reservoir or cartridge <NUM> configured to hold the medicinal fluid to be dispensed through its distal outlet end during a dispensing operation. The cartridge <NUM> of the medication delivery device the medication contained within the cartridge. The outlet end of distal portion <NUM> is equipped with a removable needle assembly <NUM> including an injection needle <NUM> enclosed by a removable cover <NUM>.

A piston <NUM> is positioned in reservoir <NUM>. An injecting mechanism positioned in proximal portion <NUM> is operative to advance piston <NUM> toward the outlet of reservoir <NUM> during the dose dispensing operation to force the contained medicine through the needled end. The injecting mechanism includes a drive member <NUM>, illustratively in the form of a screw, axially moveable relative to housing <NUM> to advance piston <NUM> through reservoir <NUM>.

A dose setting member <NUM> is coupled to housing <NUM> for setting a dose amount to be dispensed by device <NUM>. In the illustrated embodiment, dose setting member <NUM> is in the form of a screw element operative to spiral (i.e., simultaneously move axially and rotationally) relative to housing <NUM> during dose setting and dose dispensing. <FIG> and <FIG> illustrate the dose setting member <NUM> fully screwed into housing <NUM> at its home or zero dose position. Dose setting member <NUM> is operative to screw out in a proximal direction from housing <NUM> until it reaches a fully extended position corresponding to a maximum dose deliverable by device <NUM> in a single injection.

Referring to <FIG>, dose setting member <NUM> includes a cylindrical dose dial member <NUM> having a helically threaded outer surface that engages a corresponding threaded inner surface of housing <NUM> to allow dose setting member <NUM> to spiral relative to housing <NUM>. Dose dial member <NUM> further includes a helically threaded inner surface that engages a threaded outer surface of sleeve <NUM> (<FIG>) of device <NUM>. The outer surface of dial member <NUM> includes dose indicator markings, such as numbers that are visible through a dosage window <NUM> to indicate to the user the set dose amount. Dose setting member <NUM> further includes a tubular flange <NUM> that is coupled in the open proximal end of dial member <NUM> and is axially and rotationally locked to dose dial member <NUM> by detents <NUM> received within openings <NUM> in dial member <NUM>. Dose setting member <NUM> further includes a skirt or collar <NUM> positioned around the outer periphery of dial member <NUM> at its proximal end. Skirt <NUM> is axially and rotationally locked to dial member <NUM> by tabs <NUM> received in slots <NUM> formed by dose dial member <NUM>.

Dose setting member <NUM> therefore may be considered to comprise any or all of dose dial member <NUM>, flange <NUM>, and skirt <NUM>, as they are all rotationally and axially fixed together. Dose dial member <NUM> is directly involved in setting the dose and driving delivery of the medication. Flange <NUM> is attached to dose dial member <NUM> and, as described later, cooperates with a clutch to selectively couple dose dial member <NUM> with a dose button.

Skirt <NUM> provides a surface external of body <NUM> to enable a user to rotate dose dial member <NUM> for setting a dose. Skirt <NUM> illustratively includes a plurality of surface features <NUM> and an annular ridge <NUM> formed on the outer surface of skirt <NUM>. Surface features <NUM> are illustratively longitudinally extending ribs and grooves that are circumferentially spaced around the outer surface of skirt <NUM> and facilitate a user's grasping and rotating the skirt. In an alternative embodiment, skirt <NUM> is removed or is integral with dial member <NUM>, and a user may grasp and rotate dose dial member <NUM> for dose setting.

Delivery device <NUM> includes an actuator <NUM> having a clutch <NUM> which is received within dose dial member <NUM>. Clutch <NUM> includes an axially extending stem <NUM> at its proximal end. Actuator <NUM> further includes dose button <NUM> positioned proximally of skirt <NUM> of dose setting member <NUM>. Dose button <NUM> includes a mounting collar <NUM> (<FIG>) centrally located on the distal surface of dose button <NUM>. Collar <NUM> is attached to stem <NUM> of clutch <NUM>, such as with an interference fit or an ultrasonic weld, so as to axially and rotatably fix together dose button <NUM> and clutch <NUM>.

Dose button <NUM> includes a disk-shaped proximal end surface or face <NUM> and an annular wall portion <NUM> extending distally and spaced radially inwardly of the outer peripheral edge of face <NUM> to form an annular lip <NUM> there between. Face <NUM> of dose button <NUM> serves as a push surface against which a force can be applied manually, i.e., directly by the user to push actuator <NUM> in a distal direction. Dose button <NUM> illustratively includes a recessed portion <NUM> centrally located on proximal face <NUM>, although proximal face <NUM> alternatively may be a flat surface. A bias member <NUM>, illustratively a spring, is disposed between the distal surface <NUM> of button <NUM> and a proximal surface <NUM> of tubular flange <NUM> to urge actuator <NUM> and dose setting member <NUM> axially away from each other. Dose button <NUM> is depressible by a user to initiate the dose dispensing operation.

Delivery device <NUM> is operable in both a dose setting mode and a dose dispensing mode. In the dose setting mode of operation, dose setting member <NUM> is dialed (rotated) relative to housing <NUM> to set a desired dose to be delivered by device <NUM>. Dialing in the proximal direction serves to increase the set dose, and dialing in the distal direction serves to decrease the set dose. Dose setting member <NUM> is adjustable in rotational increments (e.g., clicks) corresponding to the minimum incremental increase or decrease of the set dose during the dose setting operation. For example, one increment or "click" may equal one-half or one unit of medication. The set dose amount is visible to the user via the dial indicator markings shown through dosage window <NUM>. Actuator <NUM>, including dose button <NUM> and clutch <NUM>, move axially and rotationally with dose setting member <NUM> during the dialing in the dose setting mode.

Dose dial member <NUM>, flange <NUM> and skirt <NUM> are all fixed rotationally to one another, and rotate and extend proximally of the medication delivery device <NUM> during dose setting, due to the threaded connection of dose dial member <NUM> with housing <NUM>. During this dose setting motion, dose button <NUM> is rotationally fixed relative to skirt <NUM> by complementary splines <NUM> of flange <NUM> and clutch <NUM> (<FIG>), which are urged together by bias member <NUM>. In the course of dose setting, skirt <NUM> and dose button <NUM> move relative to housing <NUM> in a spiral manner from a "start" position to an "end" position. This rotation relative to the housing is in proportion to the amount of dose set by operation of the medication delivery device <NUM>.

Once the desired dose is set, device <NUM> is manipulated so the injection needle <NUM> properly penetrates, for example, a user's skin. The dose dispensing mode of operation is initiated in response to an axial distal force applied to the proximal face <NUM> of dose button <NUM>. The axial force is applied by the user directly to dose button <NUM>. This causes axial movement of actuator <NUM> in the distal direction relative to housing <NUM>.

The axial shifting motion of actuator <NUM> compresses biasing member <NUM> and reduces or closes the gap between dose button <NUM> and tubular flange <NUM>. This relative axial movement separates the complementary splines <NUM> on clutch <NUM> and flange <NUM>, and thereby disengages actuator <NUM>, e.g., dose button <NUM>, from being rotationally fixed to dose setting member <NUM>. In particular, dose setting member <NUM> is rotationally uncoupled from actuator <NUM> to allow backdriving rotation of dose setting member <NUM> relative to actuator <NUM> and housing <NUM>. Also, since dose setting member <NUM> and actuator <NUM> are free to relatively rotate, actuator <NUM> is held from rotating relative to device housing <NUM> by the user's engagement of dose button <NUM> by pressing against it.

As actuator <NUM> is continued to be axially plunged without rotation relative to housing <NUM>, dial member <NUM> screws back into housing <NUM> as it spins relative to dose button <NUM>. The dose markings that indicate the amount still remaining to be injected are visible through window <NUM>. As dose setting member <NUM> screws down distally, drive member <NUM> is advanced distally to push piston <NUM> through reservoir <NUM> and expel medication through needle <NUM> (<FIG>).

During the dose dispensing operation, the amount of medicine expelled from the medication delivery device is proportional to the amount of rotational movement of the dose setting member <NUM> relative to actuator <NUM> as the dial member <NUM> screws back into housing <NUM>. The injection is completed when the internal threading of dial member <NUM> has reached the distal end of the corresponding outer threading of sleeve <NUM> (<FIG>). Device <NUM> is then once again arranged in a ready state or zero dose position as shown in <FIG> and <FIG>.

The dose delivered may be derived based on the rotation of dose setting member <NUM> relative to actuator <NUM> during dose delivery. This rotation may be determined by detecting the incremental movements of the dose setting member which are "counted" as the dose setting member is rotated during dose delivery.

Further details of the design and operation of an exemplary delivery device <NUM> may be found in <CIT>, entitled Medication Dispensing Apparatus with Triple Screw Threads for Mechanical Advantage.

The dose detection systems use a sensing component and a sensed component attached to members of the medication delivery device. The term "attached" encompasses any manner of securing the position of a component to another component or to a member of the medication delivery device such that they are operable as described herein. For example, a sensing component may be attached to a member of the medication delivery device by being directly positioned on, received within, integral with, or otherwise connected to, the member. Connections may include, for example, connections formed by frictional engagement, splines, a snap or press fit, sonic welding or adhesive.

The term "directly attached" is used to describe an attachment in which two components, or a component and a member, are physically secured together with no intermediate member, other than attachment components. An attachment component may comprise a fastener, adapter or other part of a fastening system, such as a compressible membrane interposed between the two components to facilitate the attachment. A "direct attachment" is distinguished from an attachment where the components/members are coupled by one or more intermediate functional members, such as the way dose dial member <NUM> is coupled in <FIG> to dose button <NUM> by clutch <NUM>.

The term "fixed" is used to denote that an indicated movement either can or cannot occur. For example, a first member is "fixed rotationally" with a second member if the two members are required to move together in rotation. In one aspect, a member may be "fixed" relative to another member functionally, rather than structurally. For example, a member may be pressed against another member such that the frictional engagement between the two members fixes them together rotationally, while the two members may not be fixed together absent the pressing of the first member.

Various sensor systems are contemplated herein. In general, the sensor systems comprise a sensing component and a sensed component. The term "sensing component" refers to any component which is able to detect the relative position or movement of the sensed component. The sensing component includes a sensing element, or "sensor", along with associated electrical components to operate the sensing element. The "sensed component" is any component for which the sensing component is able to detect the position and/or movement of the sensed component relative to the sensing component. For the dose detection system, the sensed component rotates relative to the sensing component, which is able to detect the rotational movement of the sensed component. The sensing component may comprise one or more sensing elements, and the sensed component may comprise one or more sensed elements.

The sensor system produces outputs representative of the movement of the sensed component. A controller is operably connected to the sensor to receive the sensor outputs. The controller is configured to determine from the sensor outputs the amount of dose delivered by operation of the medication delivery device.

Illustratively, the dose detection system includes an electronics assembly suitable for operation of the sensor system as described herein. A controller is operably connected to the sensor system to receive outputs from the rotation sensor. The controller is configured to determine from the sensor outputs the amount of dose delivered by operation of the medication delivery device. The controller may include conventional components such as a processor, power supply, memory, microcontrollers, etc. Alternatively, at least some components may be provided separately, such as by means of a computer, smart phone or other device. Means are then provided to operably connect the external controller components with the sensor system at appropriate times, such as by a wired or wireless connection.

An exemplary electronics assembly <NUM> comprises a flexible printed circuit board (FPCB) having a plurality of electronic components. The electronics assembly comprises a sensor system including one or more sensors operatively communicating with a processor for receiving signals from the sensor representative of the sensed rotation. Electronics assembly <NUM> further includes a microcontroller unit (MCU) comprising at least one processing core and internal memory. The system includes a battery, illustratively a coin cell battery, for powering the components. The MCU includes control logic operative to perform the operations described herein, including determining a dose delivered by medication delivery device <NUM> based on a detected rotation of the dose setting member relative to the actuator. Many of the components of the electronics assembly may be contained in a compartment <NUM> located proximal of the dose button <NUM>.

The MCU is operative to store the detected dose delivery in local memory (e.g., internal flash memory or on-board EEPROM). The MCU is further operative to wirelessly transmit a signal representative of the detected dose to a paired remote electronic device, such as a user's smartphone. Transmission may, for example, be over a Bluetooth low energy (BLE) or other suitable short or long range wireless communication protocol. Illustratively, the BLE control logic and MCU may be integrated on the same circuit.

Further disclosed herein is a medication delivery device including a dose detection system operable to determine the amount of dose delivered based on relative rotation between a dose setting member and the 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 rotationally fixed with the dose setting member. An actuator is attached to the device body and is 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 dose delivered.

The dose detection system involves detecting relative rotational movement between two members. With the extent of rotation having a known relationship to the amount of a delivered dose, the sensor system operates to detect the amount of angular movement from the start of a dose injection to the end of the dose injection. For example, a typical relationship for a pen injector is that an angular displacement of a dose setting member of <NUM>° is the equivalent of one unit of dose, although other angular relationships are also suitable. The sensor system is operable to determine the total angular displacement of a dose setting member during dose delivery. Thus, if the angular displacement is <NUM>°, then <NUM> units of dose have been delivered.

The angular displacement is determined by counting increments of dose amounts as the injection proceeds. For example, a sensing system may use a repeating pattern of a sensed element, such that each repetition is an indication of a predetermined degree of angular rotation. Conveniently, the pattern may be established such that each repetition corresponds to the minimum increment of dose that can be set with the medication delivery device.

The sensor system components may be permanently or removably attached to the medication delivery device. In an illustrative embodiment, at least some of the dose detection system components are provided in the form of a module that is removably attached to the medication delivery device. This has the advantage of making these sensor components available for use on more than one pen injector.

The sensor system detects during dose delivery the relative rotation of the sensed component, and therefore of the dose setting member, from which is determined the amount of a dose delivered by the medication delivery device. In an illustrative embodiment, a rotation sensor is attached, and rotationally fixed, to the actuator. The actuator does not rotate relative to the body of the medication delivery device during dose delivery. In this embodiment, a sensed component is attached, and rotationally fixed, to the dose setting member, which rotates relative to the actuator and the device body during dose delivery.

Disclosed herein is a medication delivery device including a dose detection system operable to determine the amount of dose delivered based on relative rotation between a dose setting member and the 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. A sensed element is attached to and rotationally fixed with the dose setting member. An actuator is attached to the device body and is 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 dose delivered.

The sensor system includes a rotation sensor attached to the actuator. The sensed element includes surface features radially-spaced about the axis of rotation of the dose setting member. The rotation sensor includes a following member having a contact portion resting against and spring-biased in the direction of the surface features of the sensed element. The contact surface is thereby positioned to move over the surface features during rotation of the sensed element relative to the actuator during dose delivery. The rotation sensor is responsive to the movement of the contact portion over the surface features and generates signals corresponding to the amount of dose delivery. A controller is responsive to the signals generated by the rotation sensor to determine the amount of dose delivery based on the detected rotation of the dose setting member relative to the actuator during dose delivery.

The surface features may comprise anything detectable by the rotation sensor. As previously indicated, sensor systems may be based on a variety of sensed characteristics, including tactile, optical, electrical and magnetic, for examples. In one aspect, the surface features are physical features which allow for detection of incremental movements as the dose setting member rotates relative to the actuator.

The contact surface is biased against the physical features to ensure proper contact between the contact surface and the physical features during rotation. In one embodiment, the following member is a resilient member having one portion attached to the actuator at a location displaced from the contact surface. For example, the following member may comprise a flexible beam attached at one end to the actuator and having the contact surface at the other end. The beam is flexed to urge the contact surface in the direction of the surface features.

Alternatively, the following member may be biased in any of a variety of other ways. In addition to the use of a resilient beam, the biasing may be provided, for example, by use of a spring component. Such spring component may for example comprise a compression, tension, or torsion coil spring. In yet other embodiments, the following member may be biased against the surface features of the sensed element by a separate resilient member or spring component bearing against the following member.

In one embodiment, the surface features are uniform elements which are spaced intermittently around the axis of rotation of the sensed element. In a particular aspect, the surface features are equi-radially spaced projections separated by intervening recesses. The contact surface of the following member is positioned to ride over the projections, and to move inwardly relative to the intervening recesses. The following member may, for example, be a resilient beam which flexes outwardly along the projections.

In one aspect, the projections are ramped upward in the direction opposite to rotation of the sensed element during dose delivery to facilitate movement of the contact surface along and over the projections. In another aspect, the projections are provided with differing profiles in opposed angular directions to provide for detecting the direction of rotation of the sensed element relative to the actuator. The projections may extend in any direction detectable by the following member. For example, the projections may extend axially or radially. Axial projections may extend proximally or distally. Radial projections may extend inwardly or outwardly.

The sensed element is attached to the dose setting member. Depending on the medication delivery device, the sensed element may be attached to the skirt, the flange or the dose dial, or any other component that rotates relative to the device body during dose delivery in relation to the amount of dose delivered.

In one aspect, the sensing system of dose detection system <NUM> is originally incorporated into a medication delivery device as an integrated system. In another aspect, there is disclosed a modular form of the dose detection system. The use of a removably attached module is particularly adapted to use with a medication delivery device in which the actuator and/or the dose setting member include portions external to the medication device housing. These external portions allow for direct attachment of the module to the actuator, such as a dose button, and/or attachment of a sensed element to a dose setting member, such as a skirt, flange, or dose dial member, as described herein. Alternately, the sensed element is integral with the medication delivery device and the module is removably attached. This has the advantage that the more complex and expensive electronics, including the rotation sensor and controller, may be reused with different medication delivery devices. By comparison, the sensed element may use relatively simple features, for example radially-spaced projections, which do not add significantly to the cost of the medication delivery device.

Referring to <FIG>, there is shown in diagrammatic form a dose detection system <NUM> including a module <NUM> useful in combination with a medication delivery device, such as device <NUM>. Module <NUM> carries a sensor system, shown generally at <NUM>, including a sensing component <NUM> comprising a rotation sensor <NUM> and other associated components such as a processor, memory, battery, etc. Module <NUM> is provided as a separate component which may be removably attached to the actuator.

Dose detection module <NUM> includes a body <NUM> attached to dose button <NUM>. Body <NUM> illustratively includes an inner wall <NUM>, an outer wall <NUM>, and a top wall <NUM>, spanning over and sealing inner wall <NUM>. By way of example, in <FIG> inner wall <NUM> is diagrammatically shown having inwardly-extending tabs <NUM> attaching module <NUM> to dose button <NUM>. Module <NUM> is thereby attached to dose button <NUM> such that pressing on the module delivers a set dose.

Dose detection module <NUM> may alternatively be attached to dose button <NUM> via any suitable fastening means, such as a snap or press fit, threaded interface, etc., provided that in one aspect module <NUM> may be removed from a first medication delivery device and thereafter attached to a second medication delivery device. The attachment may be at any location on dose button <NUM>, provided that dose button <NUM> is able to move any required amount axially relative to dose setting member <NUM>, as discussed herein.

During dose delivery, dose setting member <NUM> is free to rotate relative to dose button <NUM> and module <NUM>. In the illustrative embodiment, module <NUM> is rotationally fixed with dose button <NUM> and does not rotate during dose delivery. This may be provided structurally, such as with tabs <NUM> of <FIG>, or by having mutually-facing splines or other surface features on the module body <NUM> and dose button <NUM> engage upon axial movement of module <NUM> relative to dose button <NUM>. In another embodiment, the distal pressing of the module provides a sufficient frictional engagement between module <NUM> and dose button <NUM> as to functionally cause the module <NUM> and dose button <NUM> to remain rotationally fixed together during dose delivery.

Top wall <NUM> is spaced apart from face <NUM> of dose button <NUM> and thereby provides with inner wall <NUM> a compartment <NUM> containing some or all of electronics assembly <NUM>. Compartment <NUM> defines a chamber <NUM> and may be open at the bottom, or may be enclosed, such as by a bottom wall <NUM>. Bottom wall <NUM> may be positioned to bear directly against face <NUM> of dose button <NUM>. Alternatively, bottom wall <NUM>, if present, may be spaced apart from dose button <NUM>, and other contacts between module <NUM> and dose button <NUM> may be used such that an axial force applied to module <NUM> is transferred to dose button <NUM>.

Referring to <FIG>, there is diagrammatically shown dose detection system <NUM> comprising a pair of sensor arms <NUM> attached at proximal ends to inner wall <NUM> and configured to operate in connection with sensed element <NUM>. Sensor arms <NUM> include distal portions <NUM> having contact surfaces <NUM>. Contact surfaces <NUM> of sensor arms <NUM> are positioned in contact with surface features <NUM> of skirt <NUM>. These surface features <NUM> detected by contact surfaces <NUM> may be the same as surface features <NUM> previously described. Sensor arms <NUM> are attached to inner wall <NUM> in a manner which allows contact surfaces <NUM> to deflect inwardly and outwardly along the surface features <NUM> as skirt <NUM> rotates. For example, skirt <NUM> is shown in <FIG> to have a circumferential ridge <NUM> and a series of equally spaced axial ridges <NUM> with recessed surfaces <NUM> therebetween.

The deflection of sensor arms <NUM> may be accommodated in a variety of ways. For example, the sensor arms may be made of a flexible material which flexes in response to the ridges and recessed surfaces encountered as skirt <NUM> rotates. Alternatively, sensor arms <NUM> may be secured to the inner wall with a "living hinge" which spring biases sensor arms <NUM> in the direction of skirt <NUM>, optionally by including a spring member (not shown).

An accelerometer <NUM> is mounted to each sensor arm <NUM>, and is electrically connected with the electronics assembly <NUM>. As skirt <NUM> rotates, contact surfaces <NUM> successively ride up over each ridge <NUM> and down into the following recessed surface <NUM>. This deflecting movement results in repeated vibrations that are sensed by the accelerometers and the rotation of skirt <NUM> is thereby determined.

In the process of being mounted to the medication delivery device, contact surfaces <NUM> pass over circumferential ridge <NUM> on skirt <NUM>. This deflection may be separately detected by the accelerometers to signal that module <NUM> has been pressed axially to or beyond this point. This detection in one embodiment is used to activate the dose detection system.

In <FIG> there is shown an alternate dose detection system <NUM> including module <NUM> generally constructed in a manner similar to <FIG>. Module <NUM> includes inner wall <NUM>, outer wall <NUM> and top wall <NUM>. Inner wall <NUM> is secured in a snap fit to dose button <NUM> by tabs <NUM>. Cantilevered sensor arms <NUM> are attached to inner wall <NUM> and extend to distal portions <NUM>, terminating in contact surfaces <NUM>. Module <NUM> is shown in <FIG> in the at rest position. In this position, contact surfaces <NUM> rest within upper portions of recessed surfaces <NUM>. When module <NUM> is pressed distally to initiate a dose, contact surfaces <NUM> slide distally within the respective recessed surfaces <NUM> to a lowered position, but still adjacent to surface features <NUM>.

Illustratively, module <NUM> shown in <FIG> includes an outer wall <NUM> which extends axially distally of inner wall <NUM>. In this manner, outer wall <NUM> covers the interior components in order to facilitate their operation as described herein. Outer wall <NUM> may further extend axially distally to fully cover sensor arms <NUM> and even skirt <NUM>.

Electronics assembly <NUM> includes a printed circuit board ("PCB") <NUM> attached to the inner wall by fasteners <NUM>. PCB <NUM> may be provided with a cutout area <NUM> radially aligned with a respective sensor arm. An accelerometer <NUM> may be positioned within the cutout area, which enhances the sensing of vibrations of the sensor arms.

Illustratively shown in <FIG> and <FIG>, the surface features <NUM> may have nonuniform profiles to allow for additional information to be obtained by the sensor system. For example, skirt <NUM> is shown with angularly-spaced, axially-extending ridges <NUM>. Each ridge has a profile surface <NUM> facing in one direction which is sloped significantly different from the slope of the profile surface <NUM> facing in the opposite angular direction. In this manner, rotation of skirt <NUM> creates characteristic vibrations which differ depending upon the direction of rotation. The sensor system may thereby be used to identify the characteristic vibration in order to determine the direction of rotation of skirt <NUM>.

Contact surface <NUM> of sensor arm <NUM> is provided with a generally U-shaped distal portion <NUM>. Distal portion <NUM> includes a central portion <NUM> which is shaped to generally conform with the recessed surfaces <NUM> of skirt <NUM>. Extending in opposite directions from central portion <NUM> are side portions <NUM> and <NUM>. The side portions are configured to accommodate rotation of sensor arm <NUM> in either direction relative to the surface features <NUM> of skirt <NUM>.

By way of illustration there is shown in <FIG> yet another embodiment of a dose detection system. Dose detection system <NUM> similarly comprises a module <NUM> including inner wall <NUM>, outer wall <NUM>, top wall <NUM> and bottom wall <NUM>. Top wall <NUM> is shown as a compliant material which flexes upon pressing the module in the distal direction. Microswitch <NUM> is operatively attached to electronics assembly <NUM> adjacent the center of top wall <NUM>. Pressing module <NUM> causes top wall <NUM> to flex inwardly and to thereby trigger microswitch <NUM> in order to activate the system electronics.

PCB <NUM> is attached to bottom wall <NUM> by fasteners <NUM>. Supports <NUM> extend outwardly from PCB <NUM> and carry sensor arms <NUM>. Strain gauges <NUM> extend over supports <NUM> and are thereby affected by flexing of the support relative to PCB <NUM> as sensor arms <NUM> ride over surface features <NUM> of skirt <NUM>. The axially-extending ridges <NUM> are shown in <FIG> as having identical profiles in both angular directions. However, based upon different reactions of the strain gauges based on the direction of rotation, the direction of rotation may still be discerned for this embodiment.

<FIG> provides another illustration of a dose detection system. System <NUM> includes module <NUM>, inner wall <NUM>, outer wall <NUM>, and top wall <NUM>. Sensor arms <NUM> are secured by fasteners <NUM> to PCB <NUM>. In lieu of the sensors of the previous embodiments, sensor system <NUM> includes microswitches <NUM> to detect rotation of skirt <NUM>. Microswitches <NUM> are attached to mounting extensions <NUM> of PCB <NUM> and include buttons <NUM> positioned to be engaged by sensor arms <NUM> as they flex inwardly.

Module <NUM> is shown in <FIG> with the contact surfaces <NUM> received against the recessed surfaces <NUM> and with microswitch button <NUM> thereby depressed. As skirt <NUM> rotates, the distal portions <NUM> will move in and out relative to button <NUM> as the contact surfaces <NUM> successively ride over the ridges <NUM> and into the recessed surfaces <NUM>. The sensor system operates to detect the rotation of skirt <NUM> and therefore the amount of dose delivered.

Referring to <FIG>, there is shown an alternate dose detection system utilizing electrical conductors for detecting rotation of the dose setting element relative to the actuator. Dose detection system <NUM> includes a sensor system <NUM> attached to dose button <NUM>, such as by tabs <NUM>. Sensor system <NUM> includes an electronics assembly <NUM> including, for example, PCB <NUM>, battery <NUM>, and first and second electrical conductors <NUM>, <NUM>, respectively, operably connected with PCB <NUM>.

Sensed element <NUM> comprises a cylindrical member <NUM> attached to the dose setting member, for example skirt <NUM>. Sensed element <NUM> includes radially spaced conductive portions <NUM> which operate with conductors <NUM>, <NUM> to enable sensor system <NUM> to detect relative rotation of dose setting member. The electrical conductors are spring-biased against sensed element <NUM> to facilitate electrical communication between the conductors and conductive portions <NUM>.

As shown in <FIG>, sensor system <NUM> is contained by a module <NUM> in a manner as previously described. Module <NUM> is shown in <FIG> in a depressed condition during dose delivery. In this position, electrical conductors <NUM>, <NUM> are located radially-opposed to conductive portions <NUM>. In one angular, "coupled" position, as shown in <FIG>, contact portions <NUM>, <NUM> of electrical contacts <NUM>, <NUM> both contact the same conductive portion <NUM> such that direct electrical communication between the two electrical contacts is accomplished. Upon rotation of sensed element <NUM> relative to dose button <NUM>, a second angular, "uncoupled" position is reached in which only one of the two contact portions <NUM>, <NUM> is in contact with a conductive portion <NUM>. In this uncoupled condition, direct electrical connection between the two electrical conductors <NUM>, <NUM> is not provided by a conductive portion. Thus, sensor system <NUM> is able to detect the successive coupled and uncoupled conditions to detect rotation of the sensed element.

A cylindrical support <NUM> may be provided to further support electrical contacts <NUM>. Support <NUM> may facilitate providing a spring bias of the contact portions <NUM>, <NUM> against sensed element <NUM>, particularly during axial movement of module <NUM> between dose setting and dose delivery positions. Support <NUM> may be provided as a separate component attached to module <NUM>, or may be formed integrally with module <NUM>.

Conductive portions <NUM> may be provided by sensed element <NUM> in various fashions, such as by co-molding of the conductive portions with a supporting material <NUM>. As a further feature of dose detection system <NUM>, sensed element <NUM> may be used to identify the type of medication or delivery device. For this purpose, support material <NUM> is provided with a predetermined conductivity representative of a particular medication or delivery device. When the sensed element is positioned such that electrical conductors are not directly electrically connected by conductive portions <NUM>, there is still provided a sufficient electrical connection of conductors <NUM>, <NUM> as to be detected by sensor system <NUM>. Thus, support material <NUM> is selected to provide an electrical property in the uncoupled condition to identify the type of medication or delivery device.

Claim 1:
A medication delivery device (<NUM>) comprising:
a device body (<NUM>) comprising an elongated pen shaped housing (<NUM>) including a distal portion (<NUM>) and a proximal portion (<NUM>), the distal portion containing a reservoir (<NUM>) configured to hold a medicinal fluid to be dispensed through a distal outlet end of the reservoir during dose delivery;
a dose setting member (<NUM>) attached to said device body and rotatable relative to said device body about an axis of rotation during dose delivery;
a sensed element (<NUM>) attached to and rotationally fixed with said dose setting member, said sensed element including alternating first and second surface features (<NUM>) radially-spaced about the axis of rotation of said dose setting member, the surface features facing radially;
an actuator (<NUM>) attached to said device body, said actuator being axially and rotationally fixed with said dose setting member in a first operating mode during dose setting, said actuator being non-rotatable relative to said device body in a second operating mode during dose delivery, said sensed element and said dose setting member rotating relative to said actuator during dose delivery in relation to the amount of dose delivered;
a rotation sensor (<NUM>) attached to said actuator during dose delivery, said rotation sensor including a following member (<NUM>) attached to said actuator, the following member extending distally and including a contact surface (<NUM>) resting against and spring-biased radially in the direction of the first and second surface features of said sensed element, the contact surface being positioned to move over the surface features during rotation of said sensed element relative to said actuator during dose delivery, said rotation sensor being responsive to the movement of the contact surface over the surface features to detect the rotation of the dose setting member; and
a controller responsive to said rotation sensor to determine the amount of dose delivery based on the detected rotation of said dose setting member relative to said actuator during dose delivery.