WO2013098421A1

WO2013098421A1 - A medical injection device incorporating a dose sensing device and a method of providing such dose sensor

Info

Publication number: WO2013098421A1
Application number: PCT/EP2013/050027
Authority: WO
Inventors: Lars Peter Klitmose
Original assignee: Novo Nordisk A/S
Priority date: 2011-12-30
Filing date: 2013-01-02
Publication date: 2013-07-04

Abstract

The present invention relates to an injection device incorporating a dose sensing device and a method of providing such an injection device. The dose sensing device comprises a first component (8) having electrically conductive (51) and non-conductive areas and a second component having one or more contact elements to selectively engage the electrically conductive and non-conductive areas of the first component (8). The first (8) and the second components are relatively movable through a plurality of pre-defined rest-positions defined by means of a rotary increment positioning mechanism comprising a surface structure (10) unitarily formed by the first component (8) adapted to cooperate with a cooperating surface structure associated with the second component. The method of providing the first component comprises: a) providing the first component as a multi-injection molded body by: a1) molding a first molded body part (8.1) designated to comprise said electrically conductive (51) and non-conductive areas and made of a non-conductive thermoplastic support material suitable for forming an electric conductive pattern by metallic plating subsequent to laser patterning, and a2) molding a second molded body part (8.2) wherein the second molded body part is made from a reinforced polymer material.

Description

A MEDICAL INJECTION DEVICE INCORPORATING A DOSE SENSING DEVICE AND A METHOD OF PROVIDING SUCH DOSE SENSOR

The present invention relates to medical injection devices for setting and expelling doses of a medicament and incorporating dose sensing devices for sensing positional data of selected movable parts of the injection device. More specifically, the present invention relates to a dose sensing device and a method of providing such dose sensing device wherein a first component incorporates electrically conductive and non-conductive areas and where a second component incorporates one or more contact elements to selectively engage the electrically conductive and non-conductive areas of the first component. The invention provides improvements having regard to the accuracy in detecting positional data of selected parts of a medical injection device, having regard to the durability of the parts making up the dose sensing device and the manufacturability of the dose sensing device.

BACKGROUND OF THE INVENTION In the disclosure of the present invention reference is mostly made to the treatment of diabetes by injection or infusion of insulin, however, this is only a preferred use of the present invention.

In order to permit a patient to administer a proper dose of a medicament, various mechanical injection devices have been proposed such as the devices shown in WO 01/95959 and WO 2008/1 16766. Some devices incorporates additional electric circuitry for measuring and displaying the size of a dose which is being set during a dose setting procedure or which is being administered during an injection procedure. Examples of such devices are shown in WO 02/092153, WO 02/064196 and WO 2010/052275. To ensure that the devices are sufficiently safe, it is a key requirement that the electronic representation of the position of monitored components of the device fully corresponds to the exact positioning of the incorporated parts.

WO 02/092153 describes an injection pen that uses a sensor having electrical contacts to read a conductive rotatable matrix to determine how a dose setting mechanism has been rotationally arranged by a user in setting the pen for dose administration. In this reference, it is mentioned that the matrix may be fabricated by two shot molding a platable material, such as filled styrene plastic, into an electrically nonconductive or insulating sleeve, which molded material is then plated with a conductive material, such as successive layers of copper, nickel and then gold, so as to be electrically conductive. After plating, the sleeve is fixedly attached to a dial. Alternative methods include a sheet metal matrix insert molded onto a sleeve, via a metallic pattern on a non-conductive self-adhesive label or flexible circuit board attached to a dial, or by conductive paint or pad printed conductive ink applied directly to the dial.

In terms of safety, it is generally preferred that error detection circuitry is incorporated in the injection device so that if an incorporated dose sensing device fails, i.e. provides a non- consistent output, a warning indication is signalled to the user indicating that the device is potentially unsafe. However, in particular for the treatment of certain diseases, a failing injection device may be potentially injurious for the patient if no back-up device is at hand. Hence, the reliability and durability throughout the lifetime of the device is of major importance.

For state of the art injection devices where dose setting and expelling movements rely on precision components and where dose setting occurs in particular fine incremental rotational steps, the accuracy of the dose sensing systems becomes particularly challenging. This is mainly due to the number of parts involved where tolerances of the individual components stack up. Hence, there is a need of providing injection devices that are both accurate and reliable throughout the lifetime of the injection device.

In recent years Laser Direct Structuring (LDS) has become established on the market for the flexible design of conductor track structures, such as antennas for mobile phones and conductive structures in electronic subassemblies connecting two points on 3d surfaces. In the LDS process a plastic member (typically injection molded) doped with a metal-complex is irradiated by laser radiation to activate particular areas on which electrically conductive tracks are to be formed to activate the metal complex. Then the plastic member including the activated areas are metallized in a chemical bath using electroless deposition of copper which adheres to the laser activated areas. In typical applications, subsequently a layer of nickel and then a layer of flash gold are deposed by electroless deposition in the order specified. While such metallization process generally offers a flexible manufacturing method for static structures, it is not directly applicable to parts intended to be incorporated in position sensors, such as position encoders where contact elements wipe over areas having shifting non-conductive and conductive surface portions.

An alternative process generally is referenced as Microscopic Integrated Processing Technology (MIPTEC). This process uses chemical vapour deposition (CVD) or sputtering to coat plastic member with conductive material, then uses laser irradiation to pattern the conductive material and remove the conductive material from the non-metallized area, followed by chemical copper metallization.

The materials normally used in connection with the above processes (LDS or MIPTEC) for providing the plastic member are generally associated with drawbacks having regard to mechanical strength and durability.

In light of the above mentioned related art, it is an object of the invention to provide an improved injection device incorporating a dose sensing device that comprises a first component having electrically conductive and non-conductive areas and a second component having one or more contact elements to selectively engage the electrically conductive and non-conductive areas of the first component. Furthermore it is an object to provide an injection device wherein the dose sensing components provides a particular durable, wear-resistant and reliable design. In addition, it is an object to provide a method for providing such a dose sensing device which enables manufacture in a cost-effective way.

SUMMARY OF THE INVENTION In a first aspect of the invention a medical injection device incorporating an electronic control circuit and one or more dose sensing devices is provided. Each dose sensing device comprises a first component and a second component that are arranged for relative rotational movement, the extent of relative rotational movement being indicative of an amount of a set dose and/or an amount of an expelled dose. The first component comprises an electrically conductive code pattern defining electrically conductive and non-conductive areas. The second component comprises one or more contact elements configured to selectively engage the electrically conductive and non- conductive areas of the conductive code pattern as the first component and the second component rotate relative to each other. The one or more contact elements of the second component are coupled to the electronic control circuit to provide information indicative of the relative rotational position between the first component and the second component. Each of the dose sensing devices further defines a rotary increment positioning mechanism associated with the first component and the second component where the rotary increment positioning mechanism defines a plurality of pre-defined rest positions for relative rotational positions between the first component and the second component, wherein the rotary increment position mechanism is defined by a surface geometry associated with the first component that cooperates with a surface geometry associated with or defined by the second component. The first component of each of the dose sensing devices is formed as a unitary multi-shot injection molded component made by:

- a first molded body part made of a non-conductive thermoplastic support material wherein said conductive pattern is formed by plating subsequent to laser patterning of the thermoplastic support material, and - a second molded body part made from a reinforced polymer material, and wherein said surface geometry associated with the first component is formed unitarily with the first component.

In some embodiments, the second molded body part is made from a fibre reinforced polymer material. For the resultant dose sensing device, this provides superior durability and accuracy in reliably detecting the position of the relative position between the first component and the second component.

In the multi-injection molded component, the first molded body part and the second molded body part may be co-molded so that these two parts adhere together for providing a unitary component where relative movements between the first molded body part and the second molded body part are reduced to a minimum. In alternative embodiments, one or more additional injection shots are incorporated when providing the multi-injection molded body where said one or more additional injection shots may perform as an interface between the first molded body and the second molded body.

Hereby an accurate and durable fixation between the parts of the first component is provided. Also, in embodiments where the dose sensing device is configured as a cylindrical or planar rotational dose sensing device, such as a rotational position encoder where rotation occurs around an axis, the first component being formed as a multi-injection molded body enables a dose sensing device to be provided which obtains high coaxially tolerances, high rotational tolerances as well as high axial tolerances.

By forming the second molded body part from a high strength polymer material the functional surface parts, i.e. the parts which either define the relative movements between the first and the second component or transfer a substantial amount of torque, this provides superior durability and mechanical strength. At the same time, as the first molded body may be formed by a process ensuring low abrasion, low friction and conductivity/non-conductivity for the pattern forming the electrically conducting and non-conducting areas, a superior performance for the conductive dose sensing interface between the first component and the one or more contact elements of the second component are provided.

In some embodiments the surface geometry of the first component is defined by the first molded body part. In such an embodiment the rotary increment positioning mechanism may be configured as a rotatable detent mechanism, such as a one-way detent mechanism or a two-way detent mechanism.

The first component may be arranged so that it is rotatable around an axis. A further component of the medical injection device may be arranged coaxially with the first component so that the first component and the further component are locked to prevent relative rotational movements and wherein the further component of the medical injection device comprises one or more engagement elements that engages respective engagement elements formed by the second molded body part of the first component.

In some embodiments of a dose sensing device the dose sensing device comprises a first component that defines a rotatable dose setting item that rotates relative to the second component during dose setting, wherein the first dose sensing device and the control circuit are configured to provide an indication of the amount of a set dose. In some forms, the dose setting item is prevented from rotating during expelling of a set dose. The dose setting item may be a member which is manually operable by a user of the device, or may be a member which is accommodated within the device housing.

In other embodiments the surface geometry of the first component is defined by the second molded body part. In such an embodiment the rotary increment positioning mechanism may be configured as a rotatable lock mechanism.

The said surface geometry of the first component comprises one or more teeth formed as dog teeth adapted to cooperate with correspondingly formed structures defined by or associated with the second component. Alternatively, one or more saw teeth are provided. In some embodiments, the first component comprises a thread formed by the second molded body part and wherein the thread of the first component engages a threaded portion of a further component of the medical injection device. The first component may be provided with one or more rotational blocking surfaces formed by the second molded body part. Each of the rotational blocking surfaces is adapted to engage a respective rotational blocking surface of a further component of the medical injection device. The rotational blocking surfaces may be configured to provide a stop defining an end of dose movement stop. The rotational blocking surfaces may further define maximum and minimum dose setting limits for a dose setting item.

The injection device may further define a second dose sensing device also comprising a first component and a second component, wherein the first component defines a dosing member that rotates relative to the second component during expelling of a set dose and that is maintained nonrotatable relative to the second component during dose setting. In such configuration the second dose sensing device and the control circuit may be configured to provide an indication of the amount of an expelled dose. The injection device may further define a housing. In some embodiments, the housing is separate from the first and the second members. In other embodiments, the housing defines or may be associated with the first or the second member.

In further embodiments, a single dose sensing device may be similarly manufactured as the dose sensing device according to the first aspect and incorporated in the injection device but wherein such single dose sensing device is adapted to provide a measure of both set doses and expelled doses.

As the dose sensing device is provided as a rotational position encoder the first component of the dose sensing device may be cylindrical having either the inner surface or the outer surface providing the conductive and non-conductive areas that cooperate with the one or more contact elements of the second component. Alternatively, the dose sensing device is configured as a rotatable planar disc sensor.

The conductive pattern of the first component may in some embodiments be provided as a Gray code pattern. The Gray code pattern may define a code shift pattern that generally shifts midways between two neighbouring rest-position defined by the mechanical index mechanism. As such, the number of code pattern shifts along the direction of movement may correspond to the number of rest-positions defined by the index mechanism. In other embodiments, the number of pattern code shifts are selected as a multiple of the number of rest-positions, such as two times, three times or four times the number of rest-positions. In other embodimens code schemes other than Gray code patterns are used.

In some embodiments, the injection device is for setting and expelling set doses of a drug from a drug-filled cartridge of the kind comprising an outlet and a slideably arranged piston which is driveable in a distal direction to expel the drug through the outlet. The injection device further comprises a) a housing, b) a piston rod adapted to cooperate with the piston of the cartridge to cause a set dose to be expelled, c) a driver coupled to the piston rod, the driver being rotated during dose setting away from an initial position to effect the adjustment of the effective length of the piston rod and the driver, d) a dosing member mounted rotatably movable but axially fixed in the housing, the dosing member being prevented from rotating during dose setting and allowed to rotate during dose delivery, the dosing member controlling the distal movement of the piston rod during dose injection.

The initial position may correspond to a so-called end of dose state, i.e. the condition that the driver assumes after a complete expelling of a previously set dose. In some embodiments, a sensor of the type that exclusively provides one or more state changes senses the end of dose state when the driver is a pre-defined length from the end of dose state. By combining information from the third sensor and the information relating to the relative rotation between the driver and the dosing member, the end of dose state may be reliably detected by means of a relatively simple sensor configuration. Hence, the typical requirements relating to tolerances associated with components used for sensing the mechanical movements of the system becomes less of an issue. This allows for the device to be manufactured in a particular economical way. In the present context the term 'injection device' should be interpreted to mean a device which is suitable for injecting a drug, such as a liquid drug, into a human or animal body. The injection device is preferably of the kind being suitable for performing repetitive self injection of drug, e.g. insulin for persons having diabetes, or growth hormone. The injection device may be in the form of an injection pen, i.e. of a kind having an elongated shape similar to that of an ordinary pen. Such injection device generally is characterized in that the device part which is intended to rest against an injection site is only held against the skin of the patient during injection of the drug, such as for a duration of less than 1 minute for the complete expelling of a previously set dose.

As mentioned above, the drug is preferably a liquid drug suitable for injection into a human or animal body, e.g. subcutaneously or intravenously. Alternatively, the drug may be a dry drug which has to be reconstituted prior to injection.

The housing may in some embodiments be a part of the injection device which at least substantially encloses the remaining parts of the injection device. Thus, the housing defines an outer boundary of the injection device. The housing may be substantially closed, i.e. it may have substantially solid walls, or it may comprise more or less open parts, such as openings, grids, etc.

The driver of the medical injection device may provide a telescopic engagement to the piston rod. In some embodiments, the driver forms a dosage tube. Such dosage tube may be threadedly connected to the piston rod by means of an external thread or by means of an internal thread. In alternative embodiments, a telescopic engagement between the driver and the piston rod is provided by means of ratchet mechanism such as by means of ratchet teeth providing a one-way lengthening of the assembly formed by the driver and the piston rod.

In some embodiments, the injection mechanism is the part of the injection device which is used for injecting a desired dose once is has been set by means of the dose setting mechanism. The injection mechanism comprises a piston rod, and the piston rod is adapted to cooperate with a piston positioned in a cartridge. This typically takes place by causing the piston rod to move in an axial direction in the injection device during injection of a previously set dose. The piston rod is typically arranged in the injection device in such a manner that it abuts the piston arranged in the cartridge, and axial movement of the piston rod will therefore cause corresponding axial movement of the piston in the cartridge. Thereby drug is expelled from the cartridge and injected by the injection device. The injection mechanism preferably comprises a part which can be operated by an operator, e.g. an injection button or a release mechanism, e.g. for releasing energy which was previously stored in the spring member during dose setting (e.g. during dialling up a dose).

The driver may be axially movable in a proximal direction relatively to the housing during dose setting, and it is axially movable in a distal direction relatively to the housing during injection of a set dose. In the present context the term 'distal direction' should be interpreted to mean a direction substantially along a longitudinal axis of the injection device, and towards an end being adapted to receive an injection needle. Similarly, in the present context the term 'proximal direction' should be interpreted to mean a direction substantially along the longitudinal axis of the injection device, and substantially opposite to the distal direction, i.e. away from the end being adapted to receive an injection needle. The proximal direction is preferably in a direction towards the position of the rotatable dose knob. The driver is in some embodiments connected to the rotatable dose knob in such a manner that rotating the dose knob causes the driver to move axially in a proximal direction. Furthermore, the driver is preferably connected to the spring member in such a manner that moving the driver axially in a proximal direction causes energy to be stored in the spring member, and in such a manner that releasing energy stored in the spring member causes axial movement of the driver in a distal direction. Finally, the driver is preferably connected to the piston rod in such a manner that axial movement of the driver in a distal direction causes the piston rod to cooperate with the piston to cause a set dose to be delivered.

The retaining means is arranged to prevent axial movement of the driver in a distal direction relatively to the housing during injection of a set dose. In the case that the driver is connected to the spring member and the piston rod as described above, the retaining means, thus, prevents the spring member from releasing the stored energy and cause the piston rod to cooperate with the piston to inject drug during dose setting. Thus, it is prevented that drug is accidentally spilled, and it is ensured that a correct dose is being set. Controlling this by axially retaining the driver rather than locking the piston rod directly has the following advantage. When a cartridge is empty and therefore has to be replaced, it is necessary to return the piston rod to an initial position corresponding to a full cartridge. In the case that axial movement of the piston rod in a distal direction during dose setting is prevented by directly locking the piston rod, e.g. by means of a locking item or a dosing member, it may be difficult to return the piston rod during replacement of the cartridge. This is particularly the case when the piston rod and the locking item/dosing member are engaged in such a manner that they tend to jam. However, according to the present invention axial movement of the piston rod in a distal direction is prevented by axially retaining the driver, and the risk of jamming the piston rod during replacement of the cartridge is thereby minimised, since the piston rod is allowed to return freely to the initial position.

The retaining means may be a dosing member being axially fixed relatively to the housing, and the dosing member may be adapted to be rotationally locked relatively to the housing during dose setting, and it may be adapted to be able to perform rotational movement relatively to the housing during injection of a set dose. According to this embodiment, when the dosing member is rotationally locked relatively to the housing, it axially retains the driver, i.e. it prevents the driver from performing axial movements in a distal direction. However, when the dosing member is allowed to perform rotational movement relatively to the housing it allows the driver to move axially in a distal direction.

The dosing member and the driver may be connected via mating threads formed on the driver and the dosing member, respectively. According to this embodiment the driver can be moved axially in a proximal direction by rotating the driver, thereby allowing it to climb the threaded connection between the dosing member and the driver. However, the threaded connection prevents that the driver is pushed in a purely axial movement in a distal direction as long as the dosing member is not allowed to rotate relatively to the housing. When the dosing member is subsequently allowed to rotate, the driver is allowed to move axially in a distal direction while causing the dosing member to rotate. The injection device may further comprise a locking item being movable between a locking position in which it prevents the dosing member from rotating relatively to the housing, and an unlocking position in which the dosing member is allowed to rotate relatively to the housing. According to this embodiment the locking item is in its locking position during dose setting and in its unlocking position during injection of a set dose. As discussed above mating teeth may be formed on the dosing member and the locking item, respectively, and these mating teeth may engage when the locking item is in the locking position. When the locking item is moved into its unlocking position, the mating teeth are, in this case, moved out of engagement, thereby allowing mutual rotational movement between the dosing member and the locking item.

The locking item may be moved from the locking position to the unlocking position in response to operation of the injection mechanism. According to this embodiment, the locking item is automatically moved into the unlocking position when a user operates the injection mechanism. Thereby the injection device is automatically shifted from a state where a dose can be set into a state where a dose can be injected when the user operates the injection mechanism. Thereby the user only has to perform a single operation in order to cause a set dose to be injected, and the injection device is thereby very easy to operate. As an alternative to a dosing member, the retaining means may, e.g., be or comprise a key and groove connection, one or more braking elements, one or more slidable locking elements, and/or any other means being suitable for axially retaining the driver as described above during dose setting.

The driver may be prevented from performing rotational movements relatively to the housing during injection of a set dose. According to this embodiment the driver moves in a purely axial manner relatively to the housing during injection of a set dose. This provides a very simple movement pattern, and the risk that the injection device jams during injection of a set dose is minimised.

The driver and the piston rod may be connected via mating threads formed on the driver and the piston rod, respectively. According to this embodiment, the driver is preferably moved along this threaded connection during dose setting. During injection the piston rod is preferably moved along the driver in an axial movement.

In a preferred embodiment the driver is threadedly connected to the piston rod as well as to a dosing member. For instance, the driver may comprise an inner thread arranged to engage an outer thread of the piston rod and an outer thread arranged to engage an inner thread of the dosing member. According to this embodiment, the piston rod, the driver and the dosing member are preferably arranged relatively to each other in such a manner that at least part of the driver surrounds at least part of the piston rod, and at least part of the dosing member surrounds at least part of the driver. As an alternative, the piston rod may be hollow, and the driver may, in this case comprise an outer thread arranged to engage an inner thread of the hollow piston rod.

The injection device may further comprise means for preventing rotational movement of the piston rod during dose setting. The means for preventing rotational movement of the piston rod may comprise a key and groove connection between the piston rod and a member being fixed relatively to the housing. Such a key and groove connection prevents the piston rod from rotating relatively to the housing, but relative axial movement is possible. The member is fixed relatively to the housing during normal operation, i.e. at least when a cartridge is inserted in the housing. However, the member may advantageously be fixed to the housing in such a manner that it is released, e.g. allowing rotational movements of the member relatively to the housing, during change of cartridge. Such an arrangement would allow the piston rod to be moved back during change of cartridge. This will be explained in more detail below with reference to the drawings.

Alternatively, the means for preventing rotational movement of the piston rod may comprise a third thread connection provided between the piston rod and a member being fixed relatively to the housing. The remarks set forth above relating to the member being fixed to the housing are equally applicable here. The third thread connection preferably has a pitch being directed in a direction which is opposite to the direction of the first thread. According to this embodiment the first thread connection between the dosing member and the piston rod and the third thread connection between the member and the piston rod in combination prevent rotational movement of the piston rod during dose setting, and thereby prevent axial movement of the piston rod during dose setting.

The driver may further be threadedly connected to the dose knob via a second thread connection. According to this embodiment the driver is preferably rotated along the second thread connection during setting of a dose. As an alternative, the driver may be connected to the dose knob via a key and groove connection. In this case the driver is simply rotated along with the dose knob during dose setting, and the dose knob and the driver are allowed to perform mutual axial movements.

The operation of the dose setting mechanism causes energy to be stored in a spring member, and the injection mechanism is driven by releasing energy previously stored in said spring member during dose setting. The spring member may, e.g., comprise a spring, such as a compressible spring or a torsion spring, or it may be or comprise any other suitable means capable of storing mechanical energy and subsequently releasing the stored energy. Such an injection device is very easy to use for persons having poor dexterity or low finger strength, e.g. elderly people or children, because only a relatively small force needs to be applied by the user in order to inject a set dose, since the necessary mechanical work is carried out by the spring member. Furthermore, in injection devices where the injection is performed by releasing energy previously stored in a spring member, the piston rod is normally moved during injection by applying a pushing force to the piston rod in a substantially axial direction.

The injection device may further comprise a release mechanism for releasing energy stored in the spring member, thereby causing a set dose to be injected. The release mechanism may, e.g., comprise a release button which the user operates. The release mechanism is preferably axially movable, and it may be operable by a user pressing a release button in a substantially axial direction. In this case the release button may be integral with the dose knob.

In a second aspect the present invention relates to a method of providing a medical injection device where the medical injection device incorporates a dose sensing device comprising a first component having electrically conductive and non-conductive areas and a second component having one or more contact elements to selectively engage the electrically conductive and non-conductive areas of the first component. The first and the second components are relatively movable through a plurality of pre-defined rest-positions defined by means of a rotary increment positioning mechanism associated with the first component and the second component comprising a surface structure of the first component adapted to cooperate with a cooperating surface structure associated with the second component. The method of providing the first component comprises the steps of: a) providing the first component as a unitary multi-injection molded body by: a1 ) molding a first molded body part designated to comprise said electrically conductive and non-conductive areas, wherein the first molded body part is mainly made of a non-conductive thermoplastic support material suitable for forming an electric conductive pattern by plating subsequent to laser patterning, and a2) molding a second molded body part, wherein the second molded body part is made from a reinforced polymer material, wherein the surface geometry of the first component is formed unitarily with the first component, b) irradiating areas of the first molded body part by laser patterning to define areas designated for said electrically conductive and non-conductive areas, and c) metallizing areas designated for said electrically conductive areas by a plating process.

For the resultant dose sensing device, this provides superior durability and accuracy in reliably detecting the position of the relative position between the first component and the second component.

In some embodiments the surface geometry of the first component is defined by the first molded body part. In such an embodiment the rotary increment positioning mechanism may be configured as a rotatable detent mechanism. In other embodiments the surface geometry of the first component is defined by the second molded body part. In such an embodiment the rotary increment positioning mechanism may be configured as a rotatable lock mechanism.

In some embodiments, the second molded body part is made from a fibre reinforced polymer material. In some embodiments, in step a1 ), the first molded body part is made from a thermoplastic support having at least one surface compounded with a radiation activatable metal complex, and in step b), the step of irradiating is provided by irradiating areas of said at least one surface on which electrically conductive areas are to be formed by laser radiation to activate said metal complex. Such process for forming an electrical conducting pattern on a non- conductive support may generally be performed as a LDS process.

In step b) the electromagnetic radiation may be subjected by means of laser irradiation such as by additive laser structuring.

Laser structuring can for example, be applied to PEI (polyetherimide), PA (polyamide), LCP (liquid-crystal polymer), ABS (acrylonitrile butadiene styrene), PC (polycarbonate), PC+ABS (polycarbonate+acrylonitrile butadiene styrene), PBT (polybutyleneterephthalate), PI (polyimide) or PET (polyethyleneterephthalate), in which case the material may need to be doped.

In step c), the step of metallizing the areas designated for said electrically conductive areas comprises the steps of sequentially providing one or more copper plating layers, a nickel plating layer and a metal plating layer having a constituent of gold, such as hard gold.

After laser irradiation, in step c) a copper layer may be applied electroless directly on top of the activated areas, where the electroless copper layer may have thickness in the range of 5 to 8 μιη. After the copper layer formed by the electroless copper deposition has taken place a nickel layer may be formed galvanically onto the underlying layer of copper. The thickness of the nickel layer may in some embodiments be provided with a thickness in the range of 3 to 5 μιη.

In step c), on top of the previously deposed metal layer(s), the metal plating layer having a constituent of gold is a layer being galvanically formed as a layer of hard gold having a layer thickness in the range of 0.25 to 2.5 μιη, preferably in the range of 1.25 to 2.5 μιη.

In some embodiments, after the first layer of copper has been formed be an electroless process, a second copper layer may be formed by a galvanic deposition. Such galvanic copper layer may be deposed with a layer thickness in the range of 2 to 25 μιη, preferably in the range of 20 to 25 μιη. Such measures provides for levelling the finished product to obtain a particular smooth surface of the conductive areas of the first component.

In other embodiments, the galvanic copper layer may be omitted whereby the nickel layer may be deposed directly on the electroless formed copper layer.

In other embodiments, as an alternative to the LDS process, prior to step b) a step of forming a metal thin film layer is provided on a surface of the first molded body part designated to comprise said electrically conductive and non-conductive areas. In step b), the step of irradiating is provided by irradiating areas of the metal thin film layer with laser radiation to remove the metal thin film in areas designated for said non-conductive areas. Such process for forming an electrical conducting pattern on a non-conductive support may generally be performed as a MIPTEC process. Other process parameters suitably to be used for the manufacture may be selected along the directions disclosed in US patent application No. 2010/0263921 A1 . The layer thicknesses defined above in connection with the LDS related processes may be provided as well in a process where laser patterning is performed as a material removal process, e.g. where a laser beam removes traces of the metal thin film layer to define the non-conductive areas.

The above methods may include a further step of providing the second component and configuring the first component and the second component for relative movement along a direction through said plurality of pre-defined rest-positions so that said one or more contact elements of the second component selectively engages the electrically conductive and non- conductive areas of the first component as the first and the second components are moved relative to each other. The one or more contact elements of the second component and the first component may in some embodiments be arranged relatively movable so that said relative movement occurs in a direction normal to the general surface defined by the electrically conductive and non- conductive areas of the first component. In dose sensing devices manufactured by this method, where contact elements of the second component wipe over areas having shifting non-conductive and conductive surface portions, e.g. where the contact element(s) move substantially parallel with the top surface of the conducting and non-conducting areas and where the dose sensing device provides a measure as to the relative position between the first component and the second component, a particular durable and wear resistant solution is provided. In step a2), the surface structure of the first component comprises one or more surface portions adapted to cooperate with corresponding surface portions associated with said second component and wherein respective surface portions of the first and second components are configured so that the first component and the second component are movable relative to each other through said plurality of pre-defined rest positions along said direction of movement from a first relative position to a second relative position. The predefined rest positions may in some embodiments be provided by means of a click- mechanism, e.g. an index mechanism for providing the relative movement between the first and the second component to occur mainly stepwise from the first relative position to the second relative position or vice versa. The click-mechanism may be provided by a detent mechanism incorporating a spring element which biases the first and second component relative to each other for the components to assume any of the pre-defined rest positions.

Alternatively, as discussed above, the rest positions are provided by means of a rotational lock mechanism that can be engaged and released by means of an additional action. In any case, by forming the surface portions of the first component integrally with the part of the first component which provides the conductive and non-conductive areas, a particular accurate device may be obtained having very low tolerance variations.

The above method of providing an electronic dose sensing device may be used for providing electronic dose sensing devices of various types such as on/off switches, translational position encoders, linear encoders, planar rotary position encoders or cylindrical rotary position encoders. The encoders may be formed to provide switch detection signals along a single direction or to provide switch detection signals in more dimensions, such as along two different directions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in further detail with reference to the accompanying drawings in which Fig. 1 a and 1 b shows cross sectional and top views of mechanical parts of an injection device suitable for use with an electronic sensing system according to the present invention, the injection device being in a position where it is ready to set a dose,

Fig. 2a and 2b shows similar views of the injection device of Fig. 1 in a position where a dose has been set,

Fig. 3a and 3b shows similar views of the injection device of Figs. 1 and 2 in a position where a dose has been set and the injection button has been pushed,

Fig. 4a and 4b shows similar views of the injection device of Figs. 1 -3 in a position where a dose has been injected and the injection button is still pushed, Fig. 5 is an exploded view of selected parts of the injection device of Figs. 1 -4,

Fig. 6 is a perspective view of device similar to the device shown in Figs. 1 -5, including a first subset of sensor elements of the electronic sensing system according to the present invention,

Fig. 7 is a perspective view similar to Fig. 6 and including first and second subsets of sensor elements of the electronic sensing system,

Fig. 8 is a perspective view similar to correspond to Fig. 7 and further showing a switch frame,

Fig. 9 is a top view of components shown in Fig. 6 and including a housing component,

Fig. 10 is a top view corresponding to Fig. 7, Fig. 1 1 a shows a schematic representation of a sensor system associated with a dosage tube,

Fig. 1 1 b shows a schematic representation of a sensor system associated with a locking nut, Figs. 12a and 12b represent tables of sensor values of the sensor systems of Fig. 1 1 a and Fig. 1 1 b respectively,

Fig. 13a shows a perspective view of an embodiment of a locking nut comprising a Gray code pattern for use in an injection device, Fig. 13b is a plan view of the locking nut shown in Fig. 13a,

Fig. 13c is a cross sectional view of the locking nut shown in Fig. 13b along section C-C,

Fig. 14 is a schematic view of the metal layers disposed on the locking nut shown in fig. 13a, and

Fig. 15 shows a cross sectional side view of selected components of the drive mechanism including a locking nut and a dose setting item,

Fig. 16a shows a perspective view of an embodiment of a dose setting item comprising a Gray code pattern for use in an injection device,

Fig. 16b is a plan view of the dose setting item shown in Fig. 16a, and

Fig. 16c is a cross sectional view of the dose setting item shown in Fig. 16b along section G- G.

DETAILED DESCRIPTION OF THE DRAWINGS

Figs. 1 through 5 illustrate an injection device 1 comprising a dose setting mechanism for setting a dose of a drug and a dose injection mechanism for injecting previously set doses. In accordance with the present invention, such device mechanism is suitable for use with a sensing system described in connection with Figs. 6 through 12. The device shown in Figs. 1 -5 generally corresponds to the embodiment shown in figs. 1 1 -15 of WO 2008/1 16766, this document being incorporated herein by reference.

The dose setting and injection mechanism included in injection device 1 is adapted to operate in two mechanical operational modes, respectively designated Dose Setting Mode and Dosing Mode. In Dose Setting Mode, dose setting may be performed by dialling up and down a manually operable dose setting member. In this mode, the piston rod of the device is held stationary so that no dose will be expelled. In Dosing Mode, altering an already set dose is prevented while the expelling of an already set dose can be performed. The mechanism may include a mechanical transition zone between the Dose Setting Mode and the Dosing Mode, the transition zone being designated Safe Mode. Safe Mode is a zone ensuring that neither dose setting nor dose expelling can be performed.

In Fig. 1 , the injection device 1 is shown in a position where it is ready for setting a dose. In Fig. 1 a the injection device 1 is shown in a cross sectional view, and in Fig. 1 b the injection device 1 is shown in a top view with some of the parts omitted for the sake of clarity and in order to show parts arranged in the interior of the injection device and to illustrate their operation.

The injection device 1 of Fig. 1 comprises a driver which in the following will be referred to as a dosage tube 6 and a dosing member which in the following will be referred to as a locking nut 8. The device 1 further comprises a piston rod 7. In this embodiment the dosage tube 6 is threadedly connected to the piston rod 7 via inner thread 21 formed on the dosage tube 6 and a corresponding outer thread 14 formed on the piston rod 7. The dosage tube 6 is further provided with an outer thread 22. The dosage tube 6 and the locking nut 8 are threadedly connected via the outer thread 22 of the dosage tube 6 and inner thread 23 formed on the locking nut 8. The outer thread 22 of the dosage tube 6 covers only part of the length of the dosage tube 6. Thereby the distance which the dosage tube 6 is allowed to travel relatively to the locking nut 8 is limited, and the ends of the outer thread 22 of the dosage tube 6 define end positions of the relative movement between the dosage tube 6 and the locking nut 8. Accordingly, it is not possible to set a dose which is smaller than a dose corresponding to one end position, and it is not possible to set a dose which is larger than a dose corresponding to the other end position. The minimum dose setting limit may be defined by rotational stop surfaces 6a and 8a respectively being formed by dosage tube 6 and locking nut 8. In the shown embodiment, a corresponding rotational stop (not visible in Figs. 1 -4) is associated with the dosage tube 6 and locking nut 8 for defining the maximum allowable dose setting (cf. Figs. 5 and 15). A set of teeth 10 formed on the locking nut 8 and a set of teeth 1 1 formed on the locking item 12 engage as can be seen in Fig. 1 b. The locking item 12 is rotationally locked to the housing component 2, and the engagement of the teeth 10, 1 1 thereby prevents the locking nut 8 from rotating. By means of the teeth 10, 1 1 the locking nut 8 is designed to be locked rotationally relative to the housing in a number of pre-defined rest-positions. Hence, the engagement between locking item 12 and locking nut 8 defines a rotary increment positioning mechanism.

In the injection device 1 , the dose setting member forms a dose knob 5. When it is desired to set a dose the dose knob 5 is rotated. The dose knob 5 is rotationally locked to injection button 24 via a first spline connection. The injection button 24 is rotationally locked to dose setting item 15 via a second spline connection 15d/24d (see Figs. 5 and 16a). The dose setting item 15 is rotationally locked to the dosage tube 6 via a third spline connection. Accordingly, when the dose knob 5 is rotated, the dosage tube 6 is rotated along. Due to the threaded connection between the dosage tube 6 and the locking nut 8, and because the locking nut 8 is prevented from rotating, due to the engagement between teeth 10, 1 1 , the dosage tube 6 is thereby moved axially in a proximal direction relative to the locking nut 8, and in a spiralling movement. Simultaneously, the dosage tube 6 climbs along the piston rod 7 which remains fixed relative to the housing component 2. In the shown embodiment, the injection device includes a spring device in the form of a helical compression spring 19 arranged internally between the dosage tube 6 and the dose setting item 15. During dose setting, the axial movement of the dosage tube 6 causes compressible spring 19 to be compressed, i.e. energy is stored in the compressible spring 19. The distance travelled by the dosage tube 6 corresponds to the dose being set. An initially set dose may be dialled down fully or partly by reversing the direction of rotation of dose knob 5. Such dialling down may be performed all the way to the zero dose dial position to thereby return the dosage tube 6 to the initial relative rotational position between the dosage tube 6 and the locking nut 8. The injection device 1 may include a rotary increment positioning mechanism in the form of an indexing mechanism whereby the dose knob 5 is configured to move in discrete rotational steps corresponding to the desired dose increments, i.e. providing a number of pre-defined rest-positions which may correspond to the number of rotational rest-positions, (i.e. locking positions) between locking nut 8 relative to the housing 2. Referring to Fig. 5, such an indexing mechanism may be provided as a spring biased click-mechanism including a knurled ring surface 15b on dose setting item 15 which engages a corresponding knurled surface 16b on a ring shaped surface defined by indexing member 16. Indexing member 16 is mounted within housing component 2 so as to be rotationally locked but axially movable. Click spring 17 provides a biasing force for biasing the knurled ring surface 15b on dose setting item 15 against the corresponding knurled surface 16b on ring-shaped indexing member 16. In the shown embodiment, the dose knob 5 is adapted to rotate in 24 rotational steps during each revolution that the dose knob 5 undergoes during dose setting, i.e. corresponding to 24 dose increments. In the shown embodiment the knurled surfaces 15b and 16b are provided as toothed surface geometries having cooperating inclined surface portions to provide a two-way rotatable detent mechanism. Movement of the dose setting item 15 from one particular rest position to a neighbour rest position is adapted to occur when a torque exceeding a pre-defined limit is exerted on the dose knob 5 via button 24. The minimum and maximum limit stops defined between dosage tube 6 and locking nut 8 are decisive for the relative rotational and axial movement between these components and may be defined to a total of say 80 or 100 dose increments. In the shown embodiment the rotary increment positioning mechanism formed by locking item 12 and locking nut 8 is designed to provide a number of rotational rest positions corresponding to that of the dose knob 5/dose setting item 25, i.e. 24 rotational steps during each revolution of locking nut 8.

In some embodiments, the force originating from the compressible spring 19, when compressed, may tend to automatically dial down an initially set dose. However, the inclusion of an indexing mechanism may prevent this by adequately designing the indexing mechanism to provide reluctance against self-returning of the dose knob 5. Figs. 2a and 2b show the injection device 1 of Figs. 1 a and 1 b in a position where a dose has been set. In Fig. 2a the injection device 1 is shown in a cross sectional view, and in Fig. 2b the injection device 1 is shown in a top view with some of the parts omitted for the sake of clarity, similar to Fig. 1 b.

Comparing Figs. 1 a +1 b and Figs. 2a +2b it is clear that the dosage tube 6 has been moved in a proximal direction and that the compressible spring 19 has been compressed. In Fig. 2a it can be seen that the dosage tube 6 is arranged in such a manner that the inner thread 23 of the locking nut 8 is positioned very close to one of the ends of the outer thread 22 of the dosage tube 6. Thus, the dose which has been set is very close to the maximum settable dose. In Fig. 2b the outer thread 22 of the dosage tube 6 is visible. In Fig. 2b it can be seen that the teeth 10 formed on the locking nut 8 and the teeth 1 1 formed on the locking item 12 are still engaged, i.e. the locking nut 8 is still prevented from rotating relatively to the hosing 2. Thus, the dosage tube 6 is retained in the position shown in Fig. 2.

When it is desired to inject the set dose, the injection button 24 is pushed in a distal direction, i.e. towards the housing component 2. The injection button 24 is connected to the locking item 12 via connecting part 25. Accordingly, pushing the injection button 24 causes the locking item 12 to move along in a distal direction, thereby moving the teeth 10, 1 1 out of engagement, allowing the locking nut 8 to rotate. The injection button 24 is configured in such a manner that it automatically returns to its initial distal position when external pressure acting on the injection button 24 is released. In the shown embodiment this is obtained by means of click spring 17.

The locking nut 8 may be mounted relative to the housing by means of a ball bearing or similar to provide a low-frictional rotation of the locking nut 8 during dosing.

Figs. 3a and 3b show the injection device 1 of Figs. 1 and 2 in a position where the injection button 24 has been pushed in a distal direction as described above. In Fig. 3b it can be seen that the teeth 10, 1 1 have been moved out of engagement. The position of the dosage tube 6 is the same as in Fig. 2, i.e. the injection device 1 has not yet started injecting the set dose.

The compressed spring 19 pushes against the dosage tube 6, thereby urging it in a distal direction. Since the locking nut 8 is now allowed to rotate, the dosage tube 6 is allowed to move in a distal direction, while forcing the locking nut 8 to rotate due to the connection between the outer thread 22 of the dosage tube 6 and the inner thread 23 of the locking nut 8. The energy stored in the compressed spring 19 will cause the dosage tube 6 to perform this movement. Due to the connection between the inner thread 21 of the dosage tube 6 and the outer thread 14 of the piston rod 7, the piston rod 7 is moved along in this movement. The piston rod 7 is arranged in abutment with a piston (not shown) arranged in a cartridge. Accordingly, moving the piston rod 7 as described above causes the set dose of drug to be expelled from the injection device 1. The injection movement may be halted at any time during injection by releasing the injection button 24. The dose movement may be continued by once again pushing the injection button 24 in the distal direction. In the shown embodiment, the injection button 24 is provided with a plurality of axially extending teeth (not shown) arranged to releasably engage corresponding teeth (not referenced) formed in the housing component 2 (cf. Figs. 2a, 3a and 9). The engagement of the two sets of teeth is initiated upon pressing in of the injection button 24, and the engagement is released when the injection button 24 moves into its proximal position. Hence, manipulation of the dose knob 5 to alter a set dose during the injection movement is prevented.

Figs. 4a and 4b show the injection device 1 of Figs. 1 -3 in a position where injection of the set dose has been completed. Comparing Fig. 3 and Fig. 4 it can be seen that the dosage tube 6 has been returned to the position shown in Fig. 1 . However, the piston rod 7 has been moved in a distal direction as compared to the position shown in Fig. 1 , thereby indicating that a dose has been injected.

In accordance with the above, as the locking nut 8 only rotates during the injection process, i.e. from the start of the dosing movement of dosage tube 6 till the end of dose state is reached, the locking nut 8 performs as a dosing member for metering doses expelled from the device.

In the shown embodiment, the piston rod 7 is rotationally locked with respect to the housing component 2 during dose setting and injection operations. However, in an alternative embodiment, the piston rod 7 may be configured to rotate during the dosing movement in a manner as described in WO 2006/1 14395. As known in the art, the rotational lock or the rotational guiding of piston rod 7 relative to housing component 2 may be provided by means of a locking disc 9 which engages a track or thread on piston rod 7 and which is locked relative to the housing during the dose setting and dose injection process.

Fig. 5 is an exploded view of the injection device 1 of Figs. 1 -4. For the sake of clarity, only the parts necessary for explaining the operation of the injection device 1 are shown. In Fig. 5 the connecting part 25, the indexing member 16, the click spring 17 and the ball bearing 18 are clearly visible.

Turning now to Figs. 6 through 10 a dose setting and injection mechanism is shown which in most aspects are similar to the one of the device shown in Figs. 1 -5 but which include electronic components enabling the position detection of specific mechanical components incorporated in the device and allowing the monitoring of the mechanical components during operation of the device 1 . Further, the electronic components may include an electronically controlled display and/or communication means for utilizing information relating to the detected position data, e.g. a number of set and/or expelled doses. In Figs. 6-10, the parts that are shown which correspond to similar parts shown in Figs. 1 -5 have been provided with identical reference numerals. Likewise, only the parts necessary for explaining the operation of the electric components of the injection device 1 are shown.

In an exemplary embodiment and as identified in Fig. 6, four switch arrangements are provided for detecting the individual mechanical movements and states within the device mechanism. A first sensor arrangement 40 is associated with the dosage tube 6 to provide positional data relating to the rotational position of the dosage tube 6 relative to the device housing. A second sensor arrangement 50 is associated with the locking nut 8 to provide positional data relating to the rotational position of the locking nut 8 relative to the device housing. A third sensor arrangement 60 is also associated with the dosage tube 6 and provides information relating to the axial position of dosage tube 6, i.e. whether the dosage tube 6 is within a predefined amount of axial travel distance from the end of dose position. Further, a fourth sensor arrangement 70 may include a switch which provides data relating to the axial position of the injection button 24, thus also the axial position of connecting part 25 and locking item 12. Hence, sensor arrangement 70 provides data as to whether the injection device 1 is in the Dose Setting Mode or in the Dosing Mode as defined above.

In the shown embodiment, the sensor arrangements 40, 50, 60 and 70 are formed as conductive switch based sensors which are coupled to an electronic control circuit incorporating a processor and being powered by a power source (the control circuit and the power source is not shown in figures). In Fig. 6, a switch frame 80 is visible which is configured to hold and retain various contact elements in the form of contact arms of the sensor arrangements 40, 50, 60 and 70 in fixed relationship with the housing component 2.

The first sensor arrangement 40 used for detecting a set dose is based on a principle of detecting the rotational motion between the dosage tube 6 and the switch frame 80. As the dose setting item 15 rotates together with the dosage tube 6 and as the dose setting item 15 is mounted axially fixed in the device 1 , the dose setting item 15 is utilized for detecting rotational movements during a dose setting operation. By keeping track of the rotation of dose setting item 15 it is possible to determine the dose set. The sensor arrangement 40 is implemented as a Gray code pattern (referenced first Gray code pattern 41 ) which is fixedly arranged relative to dose setting item 15. It is to be noted that within the context of this application suitable coding schemes other than the Gray code schemes described below may alternatively be used. The first Gray code pattern 41 is formed as a cylindrical drum being swept by a set of contact arms comprised within the switch frame 80 as the dosage tube 6 is rotated. Hence, it is possible to detect direction and keep count of the net dose set. The set of contact arms are formed as a group of eight contact arms below referred to as the first group of contact arms 42.

The second sensor arrangement 50 used for detecting the amount dosed is based on the same principle utilizing a first Gray code pattern 51 provided as a cylindrical drum fixedly arranged relative to the locking nut 8. This Gray code pattern 51 is being swept by a second group of contact arms 52 which in the shown embodiment consist of six contact arms.

The first and second gray code patterns 41 and 51 are provided as galvanically conducting patterns having a series of electrically insulating fields disposed thereon. Alternatively, the first and second Gray code patterns may be formed as a generally electrically insulating base material having a plurality of galvanically conducting fields disposed thereon. In the shown embodiment the code patterns 41 and 51 are provided as metallic or metallized sleeves which are fixedly attached to dose setting item 15 respectively to locking nut 8.

In alternative embodiments, the first Gray code pattern 41 and/or the second Gray code pattern 51 may be provided as unitarily formed into dose setting item 15 respectively to locking nut 8, such as being fabricated using MID technology (Molded Interconnect Devices). Typical known methods for producing conductor tracks on three-dimensional products include, for example, two-component injection molding, hot-stamping, mask- exposure methods and thin-film insert molding. In a particular embodiment, the first Gray code pattern 41 and/or the second Gray code pattern 51 are formed by Laser Direct Structuring (LDS) whereby the dose setting item 15 and/or the locking nut 8 are formed by an initially non-conductive doted thermoplastic material. The thermoplastic material on which the conductive areas are to be formed are activated by means of targeted laser radiation and then metallized in a chemical bath. Typically, the LDS process involves forming a first copper layer on the activated areas by means of a chemical metal-deposition process in a current-free copper bath, then a chemical nickel layer is applied electroless on top of the copper layer and finally a flash gold layer is applied electroless on top of the nickel layer to provide a corrosion resistant surface.

Figs. 13a, 13b and 13c show the locking nut 8 which has been provided as a multi-injection molded body component having a first molded body part 8.1 comprising the areas that carries the electrically conductive and non-conductive areas of the Gray code pattern 51 and a second molded body part 8.2 comprising the surface geometries 10 described above which is configured to cooperate with corresponding surface geometries 1 1 defined by locking item 12. The second body part 8.2 further comprises the internal surface geometries (23, 8a, 8b) configured for cooperating with corresponding geometric structures defined by the dosage tube 6, namely, i.e. outer thread 22 and rotational stop surfaces 6a/6b (see Fig. 5).

The first molded body part 8.1 is made of a non-conductive thermoplastic support material suitable for forming an electric conductive pattern by plating subsequent to laser patterning. The second molded body part 8.2 is made from a reinforced polymer material such as by a fibre reinforced polymer material.

In one embodiment the first body part 8.1 is formed by a non-conductive thermoplastic support material having at least the surface portion intended for holding the Gray code pattern 51 compounded with a radiation activatable metal complex. Figs. 13a and 13b further show the Gray code pattern 51 comprising electrically non-conductive areas and conductive areas. Gray code pattern 51 is provided onto the first body part 8.1 by an LDS process. However, in order to provide a superior wear resistance as well as an effective electrical conductivity, an outer layer of hard gold is formed on top of the previously formed metallic layers of the laser activated areas. The hard gold (around 99.7% pure) is made hard during the plating process by adding cobalt and/or nickel at levels of approximately 0.1 % to 0.3%. The hard gold layer is applied by a galvanical process.

In this embodiment, and as indicated in fig. 14, the laser activated areas are firstly deposed electroless with copper in a layer thickness in the range of approximately 5 to 8 μιη. Then a copper layer is deposed galvanically on top of the electroless copper layer, the galvanic copper layer having a thickness of approximately 20 to 25 μιη. Subsequently, a layer of nickel is deposed galvanically on top of the galvanic copper layer, the nickel layer having a thickness of approximately 3 to 5 μιη. Finally the hard gold layer is applied galvanically with a layer thickness of 0.25 to 2.5 μιη, preferably in the range of 1 .25 to 2.5 μιη.

The galvanic copper layer is optional and provides for levelling the finished product to obtain a particular smooth surface of the conductive areas of the Gray code pattern. In other embodiments, this layer may be omitted.

Figs. 16a, 16b and 16c show the dose setting item 15/ Gray code 41 which may be manufactured by a similar process as described above in connection with the locking nut 8/ Gray code pattern 51 , including the forming of a multi-injection molded body component. The multi-injection molded body component has a first molded body part 15.1 comprising the areas that carries the electrically conductive and non-conductive areas of the Gray code pattern 41 and a second molded body part 15.2 comprising internal surface geometries tracks 15c and 15d adapted to respectively engage protrusions 6c of dosage tube 6 and splines 24d of injection button 24 (see figs. 5, 15 and 16c). Hence, the dose setting item 15 being formed as a unitary co-molded component, exhibit superior strength for the parts which transfer a substantial part of the torque being exerted on dose knob 5. The first molded body part 15.1 also defines surface geometries 15b configured to cooperate with corresponding surface geometries 16b of indexing member 16 and splines of injection button 24. This design provides an abrasion resistant solution where the surface geometries 15b forming teeth having inclined surfaces that cooperate with corresponding teeth on indexing member 16 obtain superior wear resistance.

Reference is now made to Fig. 15 which shows a cross sectional side view of selected components of an embodiment injection device 1. In this drawing, the parts that are shown that correspond to similar parts in the embodiments shown in Figs. 1 -5, 6-10 and 13-14 have been provided with identical reference numerals. Fig. 15 offers a cross sectional view of the locking nut 8 and the dose setting item 15. In the drawing, the distribution of each of the first molded body parts 8.1 and 15.1 respectively the second molded body parts 8.2 and 15.2 is visible.

Also visible from Fig. 15 is that the dosage tube 6 is provided with radially extending protrusions 6c positioned at the proximal end of the dosage tube (see also fig. 5). Each protrusion 6c is adapted to be received in a corresponding longitudinal extending track 15c formed in dose setting item 15 thereby forming sets of tracks and track followers. Hence, the dosage tube 6 is configured to be rotationally locked to the dose setting item 15 so that the dosage tube 6 follows rotation of the dose setting item 15. The longitudinally extending tracks 15c may be formed in the second molded body part 15.2. Also the functional surfaces of the second spline connection that connects the injection button 24 with the dose setting item 15 may be formed in the second molded body part 15.2.

By the above process a particular durable surface for the Gray code pattern is achieved which, especially for switch devices having contact elements wiping the surface of the code surface containing the non-conductive and conductive areas, provides superior wear resistance, durability and electrical conductivity. At the same time, due to the locking nut 8 and the dose setting item 15 each are being formed as multi-injection molded components having first and second co-molded body parts, the mechanical strength of the functional surfaces of these components are high. Hence, in the particular application for the locking nut 8 above and/or for the dose setting item 15, a particular reliable and durable encoder solution is provided. As an alternative for the LDS process described above, the locking nut 8 and/or the dose setting item may in another embodiment be provided by means of the above mentioned MIPTEC process. In such a process the respective first molded body parts designated for the Gray code sensor are provided with a metal thin film layer. Before forming the metal thin film on the first molded body part an initial plasma treatment is provided in order to activate the surface of the insulating substrate. After the metal thin film layer has been proved on the first molded body part an irradiation process is provided by irradiating areas of the metal thin film layer with laser radiation to remove the metal thin film in areas designated for the non- conductive areas. Hereafter metal plating is performed with metal layers that may generally correspond to the layers provided by the above described LDS process. Other process parameters suitably to be used for the manufacture may be selected along the directions disclosed in US patent application No. 2010/0263921 A1 .

The layer thicknesses defined above in connection with the LDS related processes may be provided as well in a process where laser patterning is performed as a material removal process, e.g. where a laser beam removes traces of the metal thin film layer to define the non-conductive areas. As for the contact elements, the state of each individual contact arm is detected by the switch sensor interface of the electronic control circuit and the information is processed by an algorithm implemented in the switch sensor interface. In this way the switch sensor interface counts the amount set, counts the amount dosed, and presents the value of these counters to the processor for further processing the data.

Electrically the sensors are configured as switches connected to ground, and the corresponding inputs to the electronic control circuit are held high by pull-up resistors to ensure a well-defined signal level. An open switch will not consume any power, but a closed switch will consume power as its pull-up resistor connects supply voltage and ground. A power conservation strategy is implemented that disables the pull-up resistors for the switches that are closed in the same manner as described in WO 2010/052275.

Such sensor system will not consume power continuously, but with this strategy only transitions that results in switches being closed can be detected. A switch that opens will not generate a rising voltage on its corresponding input since the pull-up resistor for that input has been disabled.

Fig. 7 and Fig. 9 show perspective and top views similar to the view as shown in Fig. 6 but where the switch frame 80 has been omitted to reveal the first Gray code pattern 41 and the second Gray code pattern 51 .

Further, Fig. 8 and Fig. 10 show similar perspective and top views where the contact arms of the switch frame 80 are visible.

The first Gray code pattern 41 is schematically represented in Fig. 1 1 a and the second Gray code pattern 51 is schematically represented in Fig. 1 1 b. The Gray code patterns 41 and 51 are based on a click mechanism associated with the dose setting item wherein 24 rotational steps are provided for each full revolution of dose knob 5 relative to the housing component 2. In this embodiment, the Gray code patterns have a rotational resolution corresponding to the dose increments defined by the click-mechanism, i.e. a pattern which changes state every 15 deg. angle of rotation. In other embodiments, the resolution of the Gray code patterns may be provided as two or three times the resolution defined by the click mechanism. The first and second Gray code patterns have a code length of 8 codes (Index 0 through Index 7) and are each disposed within a 120 deg. span pr. sequence. Hence, for each full revolution that the dose setting item 15 and locking nut 8 undergoes, the contact arms will swipe the respective Gray codes three times. Each of the first and second Gray code patterns comprises separate tracks formed as a number of circular bands. A first circular band defines a continuous electrically conducting ground pattern (designated Ground SW). A set of two contact arms provides for redundant galvanic coupling to the first circular band of the Gray code patterns. The Gray code patterns further comprises two circular patterned bands each defining generally isolating fields of angular width 75 deg. spaced apart by 45 deg. conductive traces. The first of the two circular patterned bands is offset by an angle of 15 deg relative to the other of the two circular patterned bands. Contact arms designated SW 1 , SW 2 are arranged to cooperate with the first circular patterned bands and contact arms designated SW 3 and SW 4 are arranged to cooperate with the other. The contact arms SW 1 and SW 2 are positioned 30 deg. apart. Also the contact arms SW 3 and SW 4 are positioned 30 deg. apart.

The first Gray code pattern further includes a further track forming a circular band of alternating conducting and isolating fields each having an angular width of 15 deg. This circular band is provided as a wake-up track. Also for this track a set of two contact arms spaced 30 deg. apart swipes this circular band and provides for redundant electrical connection.

Figs. 12a and 12b show table values of the first and the second sensor arrangement for each of the sequences Index 0 through Index 7 for a Gray code lay-out as shown in Figs. 1 1 a and 1 1 b respectively. Both Gray code patterns provide an absolute measure of the rotational position within a sequence of 8 rotational positions. As noted above, a switch that opens will not generate a rising voltage on its corresponding input since the pull-up resistor for the input has been disabled. Hence, having a Gray code pattern as defined in Figs. 1 1 b and 12b only the transitions 0-1 , 2-3, 4-5 and 6-7 can be detected when rotating that particular Gray code pattern clockwise, and 0-7, 2-1 , 4-3 and 6-5 can be detected when rotating counter-clockwise. Hence, by means of the additional wake- up track referred to above it is ensured that the pull-up resistors are enabled when needed. Referring to the table shown in Fig. 12a, for the first Gray code pattern 41 shown in Fig. 1 1 a, it is noted that there will always be a switch that closes when going from an index to its neighbour index in either rotational direction. Hence a detectable level will always occur.

For the second Gray code pattern 51 which is associated with the locking nut 8 another implementation is chosen. Here all pull-up resistors are enabled whenever the fourth sensor arrangement 70 detects that the injection button 24 is pressed in; and deactivated when the fourth sensor arrangement 70 detects that the injection button is in its non-depressed state. In this way the second sensor arrangement 50 associated with the locking nut 8 and relating to dosing is only consuming power when the device 1 is actually in Dosing Mode.

As noted above, the third sensor arrangement 60 provides information as to whether the dosage tube 6 is within a pre-defined axial distance from the position the dosage tube 6 assumes at the end of dose position. In one form, the third sensor arrangement 60 may be based on a simple principle of two contact arms being connected by a conductive circular band 61 arranged fixedly relative to dosage tube 6 wherein the conductive circular band is provided between adjacent regions of electrically insulating material. When the conductive circular band is not in the proximity of its end of dose position, i.e. further away than 0 to 7 index positions from the end of dose position the conductive circular band connect the two contact arms and consequently the switch will remain in an open state. When the dosage tube 6 reaches a point in the proximity of its end of dose position (an arbitrary point that is within 0-7 index positions from the end of dose position), the cylinder will connect the switch arms and cause the third sensor arrangement 60 to enter a closed state.

In the shown embodiment, the third sensor arrangement 60 is provided as three contact arms 62 cooperating with conductive cylinder 61 , providing two separate state changes occurring at two mutual offset axial positions of dosage tube 6 relative to the locking member 8. Such configuration provides increased reliability in safely detecting whether or not the dosage tube 6 is within close proximity to its end of dose position.

Electrically, the sensor is configured as a switch connected to ground, and the corresponding input to the electronic control circuit is held high by a pull-up resistor to ensure a well-defined signal level.

The fourth sensor arrangement 70 is based on a switch being closed. In the depicted embodiment a contact arm 72 is manipulated by a flange (not shown) on the connecting part 25. When the injection button is not activated (not pushed in) the flange will not activate the switch and consequently the switch will remain in an open state. When the injection button 24 is pushed in, the flange will perform an axial movement and cause the fourth sensor arrangement 70 to enter a closed state. Electrically the sensor is configured as a switch connected to ground, and the corresponding input to the electronic control circuit is held high by a pull-up resistor to ensure a well-defined signal level.

In other embodiments, the third sensor arrangement 60 and/or the fourth sensor arrangement 70 may include a similar manufacturing process using LDS as described above having a hard gold layer provided on the outer surface. For example, the conductive cylinder 61 may be disposed on a non-conductive thermoplastic support either integrally formed with dosage tube 6 or fixedly attached to dosage tube 6, where the above described metal layer distribution (see fig. 14) is used.

The mechanical coupling between the dosage tube 6 and the locking nut 8 during dose setting (dialling up and dialling down) as well as during dosing means that the first and second Gray code patterns 41 and 51 will always end up at the same relative rotational position after a complete dosing has taken place. Hence, in the end of dose state of the device 1 , the index of the first Gray code pattern 41 will be the same as the index of the second Gray code pattern 51 provided that the two Gray code patterns during manufacture have been aligned corresponding to an alignment in the end of dose state of the device 1 . As noted above, the dose setting mechanism may be designed to cover a dosable range that may be chosen as 80 or 100 index positions. Due to this and due to the fact that the shown embodiment utilizes Gray code patterns which only provide an absolute detection of the rotational position within a sequence of 8 rotational positions (corresponding to 120 deg. of rotation) the monitoring during operation of the device 1 is based on counting the number of full sequences as well as fractional sequences of rotation performed during relative rotational movement between the dosage tube 6 and the locking nut 8. Hence, there will be a multitude of relative rotational positions between dosage tube 6 and locking nut 8 where the signals from the first and second sensor arrangements are the same. Likewise, there will be a number of relative rotational positions between dosage tube 6 and locking nut 8 which correspond to the relative rotational position at the end of dose state of the device 1. Therefore, the synchronization between the first and the second sensor arrangements are being monitored. In the above sensor configuration, the exact adjusted dose size and/or the total amount of an expelled dose will not be detectable when basing the monitoring solely on instantaneous data provided by the first sensor arrangement 40 and the second sensor arrangement 50. Should one or more interrupts be missed during operation of the device there will be a risk that the synchronization between the electronic sensor system and the mechanical system may fail.

In order to ensure synchronization between the mechanical system and the electronic system, the information provided by the third sensor arrangement 60 is utilized which provides a detection that the relative rotation between dosage tube 6 and locking nut 8 is within 1 sequence (0 - 7 Index positions) from the end of dose state. Combining this information and the differential information from the first sensor arrangement 40 and the second sensor arrangement 50 a detection of the exact end of dose state is deductible. If a discrepancy should occur between the continuous monitoring and instantaneous information obtained from the sensor arrangements 40, 50, 60 and 70, the electronic control circuit will detect this as a failure and provide a warning indication to the user of the device. If the error is one of a recoverable kind, the device may be reset by means of the signals from the first sensor arrangement 40, the second sensor arrangement 50 and the third sensor arrangement 60 and the synchronization between the mechanical system and the electronic system may be recovered. If the error is irrecoverable, a warning as to this instance may be indicated to the user.

Due to the rotational stop surfaces of the dosage tube 6 relative to the locking nut 8 at the end of dose state, the relative position are well defined and thus allows the device to reset itself during normal operation, e.g. during operation of the injection button 24 and/or the dose knob 5. Hence, the device may be so adapted that the first and the second sensor arrangements synchronizes automatically when the device is in the end of dose state.

The above described sensor values are used for estimating the dose as set and the dose as expelled so as to provide an indication on a display of the device (not shown). In the shown embodiment, during a dosing operation, the display may be configured to continuously show the part of a set dose that remains to be injected, e.g. as defined by the display refresh rate. The electronic control circuit of the injection device 1 may further include a memory circuit adapted to hold information relating to a plurality of set and/or injected doses and the timing information relating to each such dose. Hereby the dosing history may be browsed through for example by utilizing the injection button 24 as a means for stepping through the injection history.

The electronic control circuit of the injection device 1 may in addition, or as an alternative, be provided with means for communicating the contents of the memory to an external apparatus, such as a personal computer, a mobile communication terminal such as a Smartphone or such as a glucose meter (BGM/CGM). Such means for communication may be provided by means of an optical port such as an IR port, an RF communication antenna such as for communicating via Bluetooth or NFC, or via cable connection, etc. It is to be noted that the dose setting and injection mechanism described above only relates to one particular embodiment according to the invention. Other dose setting and injecting mechanisms such as the dose setting and injection mechanism incorporated in the device shown in Figs. 1 -7 of WO 2007/134954 may be utilized in accordance with the present invention.

Claims

1 . A medical injection device (1 ) configured for setting and expelling doses of a drug from a drug-filled cartridge, the medical injection device comprising an electronic control circuit and comprising one or more dose sensing devices, each dose sensing device defining: a first component (8, 15) and a second component (12, 80), wherein the first component (8, 15) and the second component (12, 80) are arranged for relative rotational movement, the extent of relative rotational movement being indicative of an amount of a set dose and/or an amount of an expelled dose, wherein the first component (8, 15) comprises a conductive code pattern (41 , 51 ) defining electrically conductive and non-conductive areas, wherein the second component (12, 80) comprises one or more contact elements (42, 52) configured to selectively engage the electrically conductive and non-conductive areas of the conductive code pattern ( 41 , 51 ) as the first component (8, 15) and the second component (80) rotate relative to each other, said one or more contact elements (42, 52) of the second component (12, 80) are coupled to the control circuit to provide information indicative of the relative rotational position between the first component (8, 15) and the second component (12, 80), and wherein the dose sensing device further defines a rotary increment positioning mechanism associated with the first component (8, 15) and the second component (12, 80), the rotary increment positioning mechanism defining a plurality of pre-defined rest positions for relative rotational positions between the first component (8, 15) and the second component (12, 80), wherein the rotary increment position mechanism is defined by a surface geometry (10, 15b) associated with the first component (8, 15) that cooperates with a surface geometry (1 1 , 16b) associated with the second component (12, 80), characterized in that the first component (8, 15) of each respective dose sensing device is formed as a unitary multi-shot injection molded component made by: - a first molded body part (8.1 , 15.1 ) made of a non-conductive thermoplastic support material wherein said conductive pattern (41 , 51 ) is formed by plating subsequent to laser patterning of the thermoplastic support material, and

- a second molded body part (8.2, 15.2) made from a reinforced polymer material, and wherein said surface geometry (10, 15b) associated with the first component (8, 15) is formed unitarily with the first component (8, 15).

2. A medical injection device as defined in claim 1 , wherein the surface geometry (15b) of the first component (15) is defined by the first molded body part (15.1 ) and wherein the rotary increment positioning mechanism is configured as a rotatable detent mechanism.

3. A medical injection device as defined in claim 2, wherein the first component (15) is rotatable around an axis and wherein a further component of the medical injection device (6, 24) is arranged coaxially with the first component (15), wherein the first component (15) and the further component (6, 24) are locked to prevent relative rotational movements and wherein the further component (6, 24) of the medical injection device (1 ) comprises one or more engagement elements (6c, 24d) that engages respective engagement elements (15c, 15d) formed by the second molded body part (15.2) of the first component (15).

4. An injection device as defined in any of the claims 1 -3, defining a first dose sensing device comprising a first component (15) and a second component (80), wherein the first component (15) defines a rotatable dose setting item that rotates relative to the second component (80) during dose setting, wherein the first dose sensing device and the control circuit are configured to provide an indication of the amount of a set dose.

5. A medical injection device as defined in claim 1 , wherein said surface geometry (10) of the first component (8) is defined by the second molded body part (8.2) and wherein the rotary increment positioning mechanism is configured as a rotatable lock mechanism.

6. A medical injection device as defined in claim 5, wherein said surface geometry (10) of the first component (8) comprises one or more teeth formed as dog teeth or saw teeth.

7. A medical injection device as defined in any of the claims 5-6, wherein the first component (8) comprises a thread (23) formed by the second molded body part (8.2) and wherein the thread (23) of the first component (8) engages a threaded portion (22) of a further component (6) of the medical injection device (1 ).

8. A medical injection device as defined in claim 7, wherein the first component (8) comprises one or more rotational blocking surfaces (8a, 8b) formed by the second molded body part (8.2) each adapted to engage a respective rotational blocking surface (6a, 6b) of the further component (6) of the medical injection device (1 ).

9. An injection device as defined in any of the claims 4-8, and further defining a second dose sensing device comprising a first component (8) and a second component (12), wherein the first component (8) defines a dosing member that rotates relative to the second component (12) during expelling of a set dose and that is maintained nonrotatable relative to the second component (12) during dose setting, wherein the second dose sensing device and the control circuit are configured to provide an indication of the amount of an expelled dose.

10. A method of providing a medical injection device (1 ) as defined in any of the claims 1 - 9, wherein the injection device comprises a dose sensing device comprising a first component (8, 15) and a second component (12, 80), wherein the first component (8, 15) comprises a conductive code pattern (41 , 51 ) defining electrically conductive and non- conductive areas and comprises a surface geometry (10, 15b) formed by the first component (8, 15) adapted to cooperate with a surface geometry (1 1 , 16b) associated with the second component (12, 80), wherein the method of providing the first component comprises the steps of: a) providing the first component (8, 15) as a unitary multi-injection molded component by: a1 ) molding a first molded body part (8.1 , 15.1 ) designated to comprise said electrically conductive and non-conductive areas, wherein the first molded body part (8.1 , 15.1 ) is mainly made of a non-conductive thermoplastic support material suitable for forming an electric conductive pattern by plating subsequent to laser patterning, and a2) molding a second molded body part (8.2, 15.2) made from a reinforced polymer material, wherein the surface geometry (10, 15b) of the first component (8, 15) is formed unitarily with the first component (8, 15), b) irradiating areas of the first molded body part (8.1 , 15.1 ) by laser patterning to define areas designated for said electrically conductive and non-conductive areas, and c) metallizing areas designated for said electrically conductive areas by a plating process.

1 1 . The method as in claim 10, wherein in step a1 ), the first molded body part (8.1 , 15.1 ) is made from a thermoplastic support having at least one surface compounded with a radiation activatable metal complex, and wherein in step b), the step of irradiating is provided by irradiating areas of said at least one surface on which electrically conductive areas are to be formed by laser radiation to activate said metal complex.

12. The method as in claim 10, wherein prior to step b) a step of forming a metal thin film layer is provided on a surface of the first molded body part (8.1 , 15.1 ) designated to comprise said electrically conductive and non-conductive areas, and wherein in step b), the step of irradiating is provided by irradiating areas of the metal thin film layer with laser radiation to remove the metal thin film in areas designated for said non-conductive areas.

13. The method as in any of the previous claims 10-12, wherein in step c), the step of metallizing the areas designated for said electrically conductive areas comprises the steps of sequentially providing one or more copper plating layers, a nickel plating layer and a metal plating layer having a constituent of gold.

14. The method as in claim 13, wherein in step c) the metal plating layer having a constituent of gold is a layer being galvanically formed as a layer of hard gold having a layer thickness in the range of 0.25 to 2.5 μιη, preferably in the range of 1.25 to 2.5 μιη.

15. The method as in any of the previous claims 10-14, wherein in step a2), the second molded body part (8.2, 15.2) is made from a fibre reinforced polymer material.