Patent Description:
Hypodermic syringes are widely used to deliver fluids to the body. It is known to have hypodermic syringes applicable for manual operation. However, auto injectors, such as electronic auto injectors, have been developed and are widely used to aid the administering of fluid or medicaments to the body.

To avoid relying on users correctly performing certain tasks, it is of increasing interest that the auto injector automatically carries out as much as possible of the injection process.

It is generally known that air in a syringe should be depleted or minimized before injecting the medicament of the syringe. Injection of air may potentially cause problems such as air embolism e.g. in intra venous delivery. Thus, depletion or minimization of air in the syringe is usually performed before injecting the medicament. Also, for some injection systems minimized residual air trapped inside the syringe may positively influence resulting dose accuracy.

Depletion or minimization of air is usually done by performing an air-shot. An air-shot is generally performed by pointing the syringe upwards, such that the air is near the opening of the syringe, and performing an expelling action until medication is expelled. Thereby, the air is forced out of the syringe.

<CIT> shows injection devices that can inject materials at predetermined, user selected injection rates, allowing the operator more control than a traditional syringe. The devices can allow mixing of more than one substance and/or reconstitution of a solid substance for injection.

Further relevant prior art can be found in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

In spite of the known prior art, there is a need for an auto injector, such as an electronic auto injector, with an improved capability and accuracy of automatically performing an air-shot. The present invention, as defined in the appended claims, relates to a system, and a method improving the capability of automatically performing an air-shot.

Accordingly, an auto injector for administering a medicament is disclosed.

The auto injector comprises: a housing, a cartridge receiver, a code sensor, a drive module, and a processing unit.

The cartridge receiver is configured to receive a cartridge assembly comprising a cartridge and a cartridge code feature, the cartridge containing the medicament.

The code sensor is configured to read the cartridge code feature.

The drive module is coupled to move a plunger rod.

The processing unit is coupled to the code sensor and the drive module. The processing unit is configured to: receive from the code sensor a code signal indicative of the cartridge code feature; and control the drive module to move the plunger rod to a first plunger rod position, the first plunger rod position being based on the code signal.

The processing unit may further be configured to receive a trigger event, such as a trigger event after the plunger rod has been moved to the first plunger rod position; and control the drive module to move the plunger rod to a second plunger rod position following reception of the trigger event.

Also disclosed is a cartridge assembly for an auto injector, such as a cartridge assembly for the disclosed auto injector. The cartridge assembly comprising a cartridge and a cartridge code feature. The cartridge containing a medicament. The cartridge code feature being configured to be read by a code sensor of the auto injector for moving a plunger rod of the auto injector to a first plunger rod position based on the cartridge code feature.

Also disclosed is a system comprising a cartridge assembly, such as the disclosed cartridge assembly, and an auto injector, such as the disclosed auto injector. The cartridge assembly comprises a cartridge and a cartridge code feature, the cartridge containing a medicament. The auto injector comprises: a housing; a cartridge receiver configured to receive the cartridge assembly; a code sensor configured to read the cartridge code feature; a drive module coupled to move a plunger rod; and a processing unit coupled to the code sensor and the drive module. The processing unit being configured to: receive from the code sensor a code signal indicative of the cartridge code feature; and control the drive module to move the plunger rod to a first plunger rod position, the first plunger rod position being based on the code signal.

The processing unit may further be configured to: receive a trigger event, such as a trigger event after the plunger rod has been moved to the first plunger rod position; and control the drive module to move the plunger rod to a second plunger rod position following reception of the trigger event.

Also disclosed is a method for operating an auto injector comprising a plunger rod, such as the disclosed auto injector. The method comprising:
receiving a cartridge assembly comprising a cartridge and a cartridge code feature, the cartridge containing a medicament; reading the cartridge code feature; and moving the plunger rod to a first plunger rod position, the first plunger rod position being based on the cartridge code feature.

The method may further comprise: receiving a trigger event, such as receiving a trigger event after the plunger rod has been moved to the first plunger rod position; and moving the plunger rod to a second plunger rod position following reception of the trigger event.

It is an advantage of the present disclosure that the air-shot may be adapted to the specific cartridge inserted into the auto injector, thereby leading to a more precise air-shot, which may prevent or at least reduce expelling of medicament during the air-shot.

It is an advantage of the present disclosure that the air-shot may be performed without expelling medicament through the tip of the needle, such as a needle of the syringe and/or a needle attached to the syringe. In some situations, it may be important or desired, that dosages are known accurately. Hence, it may be desirable that the amount of medicament in the syringe is fully injected into the patient and it is therefore an advantage that the air-shot may be performed automatically, and without expelling medicament through the tip of the needle.

Furthermore, medicament on the tip of a needle may provide patient discomfort upon insertion of the needle. And, especially for some medicaments, it may be undesirable to spill medicament, e.g. on the floor. It is thus a further advantage of performing the air-shot without expelling medicament from the tip of the needle that patient discomfort may be reduced.

It is a further advantage of the present disclosure that residual air trapped in the cartridge compartment together with drug to be injected may be minimized.

It is thus advantageous that the present disclosure may increase dosage accuracy, decrease patient discomfort, and/or avoid spilled medicament.

It is envisaged that any embodiments or elements as described in connection with any one aspect may be used with any other aspects or embodiments, mutatis mutandis.

The cartridge receiver may be configured to receive the cartridge and/or cartridge assembly through a cartridge receiver opening. Thus, the cartridge and/or cartridge assembly may be inserted in the cartridge receiver through the cartridge receiver opening.

The cartridge may comprise a cartridge compartment. The cartridge compartment may contain the medicament.

The cartridge may comprise a cartridge outlet, e.g. at a first cartridge end. The cartridge outlet may be configured for fluid communication with the compartment, e.g. at the first cartridge end. The cartridge may be configured to expel medicament through the cartridge outlet. The cartridge outlet may be configured to be coupled with a needle, such as a hypodermic needle, to provide the medicament to be expelled through the needle.

The cartridge assembly may comprise the needle, such as a needle assembly comprising the needle. The needle assembly may comprise a needle cover and/or a needle hub. The cartridge assembly may comprise a cartridge holder. The cartridge holder may be configured to engage with the needle assembly. The cartridge holder may provide for attachment of the needle assembly to the cartridge.

The cartridge may comprise a first stopper movable inside the cartridge compartment, e.g. towards the cartridge outlet, e.g. in a first stopper direction, such as towards the first cartridge end. For example, the medicament may be expelled through the cartridge outlet upon movement of the first stopper, e.g. in the first stopper direction and/or towards the cartridge outlet.

The cartridge may comprise a cartridge back face, e.g. at a second cartridge end, such as opposite the cartridge outlet. The cartridge back face may comprise a cartridge back end opening. The cartridge back end opening may provide access for the plunger rod to the first stopper.

The cartridge code feature may comprise one or more of a colour, a bar code, an RFID tag, an NFC tag, an identification number, and a QR code.

For example, the cartridge code feature may comprise a colour and/or a sequence of colours.

The cartridge code feature may be positioned surrounding or partly surrounding a part of the cartridge compartment wherein a stopper, such as the first stopper, is initially positioned. Such position of the cartridge code feature may increase readability of the cartridge code feature, e.g. since the stopper may form a background for the cartridge code feature. The stopper, such as the first stopper may be a light colour, such as light grey or white. The stopper, such as the first stopper, may be a dark colour, such as dark blue, dark grey, or black. The stopper may form a dark background for the cartridge code feature. The stopper, such as the first stopper, may reduce reflection of light, e.g. to further increase readability of the cartridge code feature. The cartridge code feature being positioned at a part of the cartridge compartment wherein a stopper is positioned may avoid unnecessarily covering of visible area into the cartridge compartment, e.g. for purpose of visual inspection of the medicament.

The cartridge code feature may be positioned at a specific position on the cartridge, e.g. independently of the stopper(s), such as the first stopper. For example, the cartridge code feature may be positioned at a code distance from the second cartridge end. All cartridges may have their cartridge code features positioned at the same position, e.g. positioned at the code distance from the second cartridge end. Such uniform position of the cartridge code feature may decrease complexity, and decrease size, of the auto injector, as the cartridge code feature is read in the same position for all suitable cartridges.

The cartridge and the cartridge code feature may be manufactured as one element. For example, the cartridge code feature may be a certain form of the cartridge. Alternatively, the cartridge code feature may be attached to the cartridge, such as fastened, e.g. by glue, to the cartridge. For example, the cartridge code feature may be a colour code printed on the cartridge.

The cartridge code feature may be indicative of one or more cartridge specifications, such as medicament in the cartridge, concentration of medicament in the cartridge, viscosity of medicament in the cartridge, volume and/or mass of medicament in the cartridge, positions of stopper(s) in the cartridge compartment, etc. The cartridge code feature may be indicative of a position of the first stopper wherein air in the cartridge compartment is reduced, such as minimized and/or reduced to an amount appropriate for injection. The cartridge code feature may be indicative of the amount of medicament contained in the cartridge. The cartridge code feature may be indicative of a specific type of cartridge, such as an ID number of the specific type of cartridge. The auto injector, such as the processing unit of the auto injector, may be configured to determine one or more cartridge specifications based on an ID number, e.g. by table lookup. The cartridge code feature may be indicative of a suitable speed of stopper movement. For example, the cartridge code feature may be indicative of the speed of movement of the plunger rod to the first plunger rod position and/or to the second plunger rod position and/or to a third plunger rod position. The cartridge code feature may be indicative of a suitable speed of stopper movement, such as stopper movement in different phases of movement, such as during air-shot and/or injection, such as towards the first plunger rod position and/or towards the second plunger rod position.

The cartridge code feature may be indicative of one or more delays, such as time delays, e.g. comprising a delay to elapse before initiating a movement of the plunger rod and/or first stopper and/or comprising a delay to elapse between completion of one movement of the plunger rod and/or first stopper and initiation of another movement of the plunger rod and/or first stopper.

The one or more delays may comprise a first delay. The first delay may be required to elapse before the plunger rod is moved to the first plunger rod position. For example, the first delay may be required to elapse before initiation of movement of the plunger rod to the first plunger rod position. For example, the first delay may be chosen to allow the medicament to settle before initiating the air-shot, e.g. after a reconstitution or mixing of the medicament, which may cause a foaming effect in the medicament. The first delay may allow the foaming effect in the medicament to settle.

The one or more delays may comprise a second delay. The second delay may be required to elapse before the plunger rod is moved to the second plunger rod position. For example, the second delay may be required to elapse after completion of movement of the plunger rod to the first plunger rod position and before initiation of movement of the plunger rod to the second plunger rod position.

The auto injector and/or the processing unit may be configured to determine the first delay and/or the second delay based on the code signal.

The auto injector may be an electronic auto injector. The auto injector may comprise a battery. The housing may accommodate the battery. The battery may be a rechargeable battery. For example, the battery may be a Li-ion battery or a NiCd battery or a NiMH battery. The battery may be configured to be charged by connection of a charger.

The drive module is coupled to move, such as actuate, such as advance, the plunger rod. The drive module may comprise one or more electrical elements. The drive module may be configured to receive electrical power from the battery. The drive module may be electrically connected to the battery for receiving electrical power. The drive module may be accommodated by the housing. The drive module may comprise a motor, such as an electro-mechanical motor, such as a DC motor, e.g. a DC motor with or without brushes. The drive module may comprise a solenoid motor.

The drive module may comprise a shape memory metal engine. The drive module may comprise an arrangement of springs configured to actuate the plunger rod. The drive module may comprise a pressurized gas configured to actuate the plunger rod.

The plunger rod may be configured to advance a first stopper, such as the first stopper of the cartridge. The advancement of the first stopper may be to expel medicament from the cartridge compartment through the cartridge outlet and/or to expel air from the cartridge compartment through the cartridge outlet. The plunger rod may be movable between a retracted plunger rod position and an extended plunger rod position.

The auto injector, such as the processing unit of the auto injector, may be configured to receive a trigger event, such as a trigger event indicating that the user initiates injection of the medicament. The auto injector, such as the processing unit of the auto injector, may be configured to receive the trigger event after the plunger rod has been moved to the first plunger rod position.

The trigger event may be used to start an injection sequence of the auto injector. The auto injector, such as the processing unit of the auto injector, may control the drive module to move the plunger rod to a second plunger rod position, such as a position wherein the medicament is injected and/or ejected from the cartridge compartment, following reception of the trigger event. The trigger event may initiate the movement of the plunger rod to expel medicament from the cartridge compartment through the cartridge outlet.

The trigger event may, for example, be an effect of a push of a button, an effect of an elapsed timeout, and/or an effect of a predetermined user behaviour. The trigger event may be indicative of the auto injector being pressed against the injection site.

The auto injector may comprise an ejection sensor, e.g. configured to detect the ejection, such as the expelling, of medicament and/or air in the cartridge compartment. The ejection sensor may be configured to detect and/or determine the position of the plunger rod and/or the position of the first stopper. The ejection sensor may be configured to detect conditions indicative of the position of the plunger rod and/or the position of the first stopper. The ejection sensor may be configured to provide an ejection sensor signal. The ejection sensor signal may be indicative of the position of the plunger rod and/or the first stopper.

The ejection sensor may comprise a tachometer, e.g. a tachometer of the drive module. The tachometer may be configured to count the revolutions of the drive module, such as a motor of the drive module, such as the revolutions of the drive module from a set point, such as a point wherein the position of the plunger rod is known, such as a fully retracted position of the plunger rod. The count of revolutions of the drive module may be used to determine the actual position of the plunger rod, such as the first plunger rod position and/or the second plunger rod position.

The processing unit may be coupled to the ejection sensor, such as to the tachometer of the ejection sensor. The processing unit may receive from the ejection sensor a first ejection sensor signal, such as a tachometer signal, indicative of the count of revolutions of the drive module. The processing unit may determine the position of the plunger rod based on the first ejection sensor signal. The processing unit may receive a second ejection sensor signal, e.g. from the ejection sensor, indicative of the plunger rod being in a known position, such as a fully retracted position. The processing unit may determine the position of the plunger rod based on the first ejection sensor signal and the second ejection sensor signal.

The ejection sensor signal may include the first ejection sensor signal and/or the second ejection sensor signal.

The first plunger rod position may be selected to expel air from the cartridge. For example, the first plunger rod position may be selected to position the first stopper in a position wherein air in the cartridge compartment is reduced, such as minimized and/or reduced to an amount appropriate for injection. The first plunger rod position may be a position of the plunger rod wherein the air-shot has been completed. The first plunger rod position may be a position wherein air has been expelled from the cartridge compartment, such as wherein the first stopper is in a position wherein air has been expelled from the cartridge compartment. The first plunger rod position may be positioned between the retracted plunger rod position and the extended plunger rod position. The first plunger rod position may be based on the cartridge code feature. For example, the processing unit may be configured to determine the first plunger rod position based on the code signal.

The second plunger rod position may be selected to expel medicament from the cartridge. For example, the second plunger rod position may be selected to position the first stopper in a position wherein medicament in the cartridge compartment is reduced, such as minimized, such as in a position closest to the cartridge outlet. The second plunger rod position may be positioned between the first plunger rod position and the extended plunger rod position. The second plunger rod position may be the extended plunger rod position. The second plunger rod position may be based on the cartridge code feature. For example, the processing unit may be configured to determine the second plunger rod position based on the code signal.

The third plunger rod position may be selected to mix a plurality of components of the medicament, e.g. to reconstitute the medicament. For example, the third plunger rod position may be selected to position the first stopper in a position wherein a first medicament component is mixed with a second medicament component. The third plunger rod position may be positioned between the retracted plunger rod position and the first plunger rod position. The third plunger rod position may be based on the cartridge code feature. For example, the processing unit may be configured to determine the third plunger rod position based on the code signal.

A fourth plunger rod position may be configured to advance the first stopper to a position before mixing of the plurality of components of the medicament is commenced. The fourth plunger rod position may be positioned between the retracted plunger rod position and the third plunger rod position. The fourth plunger rod position may be based on the cartridge code feature. For example, the processing unit may be configured to determine the fourth plunger rod position based on the code signal.

Movements of the plunger rod may be separated and/or preceded and/or followed by the one or more delays.

The auto injector may comprise a user interface, such as a user interface allowing user input and/or provide visual and/or audible output to the user.

The auto injector may comprise a trigger member, such as a trigger member of the user interface. The trigger event may comprise activation of the trigger member. The trigger member may be a button of the user interface, such as a push-button. Alternatively or additionally, the trigger member may be a contact member, such as a skin sensor. The contact member may be configured to be pressed against the injection site for activation. For example, to activate the injection of the medicament. The contact member may be surrounding the cartridge outlet and/or the intended position of the cartridge outlet, such as the cartridge receiver opening. The contact member may be configured to activate a contact sensor when pressed against the skin, e.g. when moved relative to the housing. The contact sensor may be configured to transmit the trigger event. The processing unit may be coupled to the contact sensor. The processing unit may be configured to receive the trigger event from the contact sensor.

The auto injector may comprise an orientation sensor. The orientation sensor may be configured to detect an orientation of the cartridge and/or an orientation indicative of the orientation of the cartridge, such as an orientation of the auto injector. The orientation sensor may be configured to detect the direction of gravity, and/or if the direction of gravity is within a certain range of a predetermined direction. The orientation sensor may comprise an accelerometer. The orientation sensor may comprise a plurality of accelerometers, such as three accelerometers, such as three accelerometers arranged to detect acceleration in three dimensions, such as a three-dimensional accelerometer. The orientation sensor may comprise a tilt sensor, a tri-axial accelerometer, a single axis accelerometer, a magnetometer and/or any combination thereof, and the orientation sensor may provide a measure of roll, pitch and azimuth, a measure of acceleration and/or tilt in one or more directions.

The orientation sensor may be configured to detect if the cartridge is in a predetermined orientation. The orientation sensor may be configured to detect if the orientation of the auto injector is indicative of the cartridge being in the predetermined orientation. The predetermined orientation may be a vertical orientation. The predetermined orientation may be an orientation within <NUM> degrees of vertical, such as within <NUM> degrees of vertical. The predetermined orientation may be an orientation wherein the cartridge is orientated such that a longitudinal axis of the cartridge is within <NUM> degrees of vertical, such as within <NUM> degrees of vertical, and wherein the cartridge outlet is above the cartridge compartment, such as in a vertical position above the cartridge compartment.

The processing unit may be coupled to the orientation sensor. The processing unit may be configured to receive from the orientation sensor an orientation signal indicative of the orientation of the cartridge when received in the cartridge receiver, and/or of the auto injector. The processing unit may be configured to control the drive module to move the plunger rod to the first plunger rod position based on the orientation signal. For example, the processing unit may be configured to control the drive module to move the plunger rod to the first plunger rod position only if the orientation signal indicates that a tilt angle between vertical and a longitudinal axis extending along the cartridge is within <NUM> degrees, such as within <NUM> degrees, of vertical and/or if the cartridge outlet is in a vertical position above the cartridge compartment.

The auto injector may comprise a code sensor, such as a code sensor configured to read the cartridge code feature. The code sensor may be configured to transmit a code signal indicative of the cartridge code feature. The code sensor may be configured to read the cartridge code feature in a plurality of positions. The cartridge code sensor may be movable. The cartridge code sensor may comprise a plurality of sensors, such as a plurality of transmitters and/or receivers.

The auto injector, such as the processing unit of the auto injector, may be configured to move the plunger rod based on the code signal and/or the cartridge code feature. The auto injector, such as the processing unit of the auto injector, may be configured to move the plunger rod to the first plunger rod position based on the code signal and/or the cartridge code feature. The first plunger rod position, e.g. wherein the air-shot is completed, may be determined based on the cartridge assembly, such as on the cartridge code feature, such as on the cartridge code signal. The movement of the plunger rod and/or the first stopper may be based on the cartridge assembly, e.g. on the cartridge code feature. Thus, the air-shot may be performed with reduced or no expelling of medicament, thereby increasing dosage accuracy and/or reduce patient discomfort.

Movement of the plunger rod may comprise movement having a plunger rod speed, such as a first plunger rod speed and/or a second plunger rod speed. The plunger rod speed may be based on the position of the plunger rod. The plunger rod may be moved to the first plunger rod position with a first plunger rod speed. The plunger rod may be moved to the second plunger rod position, such as from the first plunger rod position, with a second plunger rod speed. The second plunger rod speed may be faster or slower than the first plunger rod speed.

The plunger rod may be moved to the third plunger rod position with a third plunger rod speed. The plunger rod may be moved to the fourth plunger rod position with a fourth plunger rod speed.

The first plunger rod speed and/or the second plunger rod speed and/or the third plunger rod speed and/or the fourth plunger rod speed may be based on a cartridge specification, such as on the cartridge code feature, such as on the code signal. The processing unit may be configured to determine the first plunger rod speed and/or the second plunger rod speed and/or the third plunger rod speed and/or the fourth plunger rod speed, based on the code signal.

The processing unit may be configured to control the drive module to move the plunger rod to the first plunger rod position with the first plunger rod speed. The processing unit may be configured to control the drive module to move the plunger rod to the second plunger rod position, such as from the first plunger rod position, with the second plunger rod speed.

The code sensor may comprise an optical sensor. The code sensor may comprise an optical sensor comprising a transmitter and a receiver, such as a light transmitter and a light receiver. The code sensor may be configured to read the cartridge code feature. The code sensor may be configured to read QR codes, bar codes, colour codes, and/or any combination hereof.

The auto injector may comprise a temperature sensor. The temperature sensor may be configured to provide a temperature signal, such as a temperature signal indicative of the temperature of the auto injector and/or of the cartridge and/or of the medicament. The temperature sensor may comprise an infrared sensor, such as an optical infrared sensor. The temperature sensor and the code sensor may be the same sensor. For example, an optical infrared sensor for sensing temperature may be the same physical sensor as an optical sensor for reading the cartridge code feature.

The processing unit may be coupled to the temperature sensor. The processing unit may be configured to receive the temperature signal.

Movement of the plunger rod, e.g. to the first plunger rod position and/or to the second plunger position, may be based on the temperature of the auto injector and/or of the cartridge and/or of the medicament, e.g. on the temperature signal.

The auto injector, such as the processing unit, may be configured to control the drive module based on the temperature signal. For example, the processing unit may be configured to control the drive module to move the plunger rod to the first plunger rod position and/or to the second plunger rod position based on the temperature signal.

The first plunger rod speed and/or the second plunger rod speed and/or the third plunger rod speed and/or the fourth plunger rod speed may be determined based on temperature, such as the temperature of the auto injector and/or of the cartridge and/or of the medicament, e.g. on the temperature signal. The first plunger rod position and/or the second plunger rod position and/or the third plunger rod position and/or the fourth plunger rod position may be determined based on the temperature signal and/or temperature, such as the temperature of the auto injector and/or of the cartridge and/or of the medicament. For example, the volume of the medicament may be dependent on temperature, and therefore, the air-shot may be more precisely controlled when taking into account the temperature. Thus, the air-shot may be performed with reduced or no expelling of medicament, thereby, for example, increasing dosage accuracy and/or reducing patient discomfort.

The processing unit may be coupled to the orientation sensor, the code sensor, the ejection sensor, and/or the temperature sensor. The processing unit may be configured to receive the orientation signal, the code signal, the ejection sensor signal, and/or the temperature signal. The processing unit may be configured to control the drive module to move the plunger rod to the first plunger rod position and/or the second plunger rod position based on the orientation signal, the code signal, the ejection sensor signal, and/or the temperature signal.

The auto injector may comprise a cartridge sensor. The cartridge sensor may be configured to detect reception of a cartridge assembly in the auto injector and/or in the cartridge receiver of the auto injector. The cartridge sensor may provide a cartridge sensor signal indicative of reception of a cartridge assembly. The code sensor and the cartridge sensor may be the same sensor, e.g. the code sensor may be configured to detect reception of a cartridge assembly and subsequently read the cartridge code feature.

The processing unit may be coupled to the cartridge sensor. The processing unit may be configured to receive the cartridge sensor signal. The processing unit may be configured to control the drive module based on the cartridge sensor signal. For example, the processing unit may be configured to control the drive module to start movement of the plunger rod if a cartridge assembly is received, and/or only if a cartridge assembly is received.

The auto injector may comprise a needle sensor. The needle sensor may be configured to detect a needle, and/or a needle assembly, and/or a needle cover of a needle assembly, of the cartridge assembly, e.g. when the cartridge assembly is received in the auto injector and/or in the cartridge receiver of the auto injector. The needle sensor may provide a needle signal indicative of the presence of a needle, and/or a needle assembly, and/or a needle cover of a needle assembly.

The processing unit may be coupled to the needle sensor. The processing unit may be configured to receive the needle signal. The processing unit may be configured to control the drive module based on the needle signal. For example, the processing unit may be configured to control the drive module to start movement of the plunger rod only if a needle is present, and/or only if a needle cover is not present.

The auto injector may comprise a resistance sensor. The resistance sensor may be configured to detect resistance against movement of the plunger rod. The resistance sensor may be configured to detect resistance against movement of the plunger rod based on measurements of the drive module. For example, the resistance sensor may be configured to detect the electrical current of a motor of the drive module. The resistance sensor may be configured to provide a resistance signal indicative of resistance against movement of the plunger rod.

The processing unit may be coupled to the resistance sensor. The processing unit may be configured to receive the resistance signal. The processing unit may be configured to determine the resistance against movement of the plunger rod based on the resistance signal. The processing unit may be configured to control the drive module based on the resistance signal. For example, the processing unit may be configured to control the drive module to adjust movement of the plunger rod based on the resistance signal. For example, the processing unit may be configured to control the drive module to start, stop or continue movement of the plunger rod based on the resistance signal.

A more detailed description follows below with reference to the drawing, in which:.

<FIG> illustrates an exemplary auto injector <NUM>. The auto injector <NUM> may be configured for administering a medicament. The auto injector <NUM> may be an electronic auto injector.

The auto injector <NUM> comprises a housing <NUM>. The auto injector <NUM> comprises a cartridge receiver <NUM>. The cartridge receiver is configured to receive a cartridge and/or a cartridge assembly comprising a cartridge. The cartridge may contain the medicament.

The cartridge receiver <NUM> has a cartridge receiver opening <NUM>. The cartridge receiver <NUM> is configured to receive the cartridge and/or the cartridge assembly through the cartridge receiver opening <NUM> in a cartridge receiving direction <NUM> along a longitudinal axis L.

The auto injector <NUM> may comprise a user interface <NUM>, as illustrated. The auto injector <NUM> comprises a trigger member, such as the contact member <NUM>. The contact member <NUM> may be configured to be pressed against an injection site. The contact member <NUM> may be movable in the cartridge receiving direction <NUM>, relative to the housing <NUM>, if pressed against the injection site. The contact member <NUM> may be part of the user interface <NUM>.

<FIG> illustrates an exemplary system <NUM>. The system <NUM> comprises an auto injector <NUM>, as described in relation to <FIG>, and an exemplary cartridge <NUM> received in the cartridge receiver <NUM>. The cartridge <NUM> is shown with a needle cover <NUM>. The needle cover <NUM> extending out of the contact member <NUM> to allow removal of the needle cover <NUM> from the cartridge <NUM>.

<FIG> schematically illustrates an exemplary cartridge <NUM>, such as a cartridge <NUM> being configured to be received in the cartridge receiver of an auto injector, such as the auto injector described in relation to previous figures.

The cartridge <NUM> comprises a cartridge compartment <NUM>. The cartridge compartment <NUM> may be configured for containing a medicament. The cartridge <NUM> has a first end <NUM> and a second end <NUM>. The cartridge <NUM> comprises a cartridge outlet <NUM> at the first cartridge end <NUM>. The cartridge <NUM> may be configured to expel medicament through the cartridge outlet <NUM>.

The cartridge <NUM> comprises a first stopper <NUM> movable inside the cartridge compartment <NUM>, e.g. in a first stopper direction <NUM>, e.g. towards the first cartridge end <NUM>. For example, the medicament may be expelled through the cartridge outlet <NUM> upon movement of the first stopper <NUM> in the first stopper direction <NUM>. The cartridge comprises a cartridge back face <NUM> at the second cartridge end <NUM>. The cartridge back face <NUM> comprises a cartridge back end opening for providing access to the first stopper <NUM> for a plunger rod.

As illustrated, the cartridge <NUM> may be a dual chamber cartridge. The cartridge comprises a second stopper <NUM> movable inside the cartridge compartment <NUM>, e.g. in the first stopper direction <NUM>, e.g. towards the first cartridge end <NUM>. The cartridge compartment <NUM> comprises a first cartridge subcompartment <NUM> and a second cartridge subcompartment <NUM>. The first cartridge subcompartment <NUM> is between the first stopper <NUM> and the second stopper <NUM>. The second cartridge subcompartment <NUM> is between the second stopper <NUM> and the cartridge outlet <NUM>. The cartridge comprises a bypass section <NUM> for providing fluid communication between the first cartridge subcompartment <NUM> and the second cartridge subcompartment <NUM>. The bypass section <NUM> provides fluid communication between the first cartridge subcompartment <NUM> and the second cartridge subcompartment <NUM> when the second stopper <NUM> is positioned in the bypass section <NUM>.

<FIG> schematically illustrates an exemplary cartridge assembly <NUM>. The cartridge assembly <NUM> comprises an exemplary cartridge <NUM> and an exemplary cartridge code feature <NUM>. The cartridge <NUM> has a first cartridge end <NUM> and a second cartridge end <NUM>. The first stopper direction <NUM> is from the second cartridge end <NUM> to the first cartridge end <NUM>. The cartridge code feature <NUM> is positioned near the second cartridge end <NUM>, e.g. closer to the second cartridge end <NUM> than the first cartridge end <NUM>. In another exemplary cartridge assembly, the cartridge code feature <NUM> may be positioned near the first cartridge end <NUM>.

<FIG> illustrates different types of exemplary cartridge code features <NUM>.

<FIG> illustrates an exemplary cartridge assembly <NUM>, wherein the cartridge code feature <NUM> comprises two strips. The two strips may be coloured, e.g. differently coloured. The combination and/or sequence of colours may be indicative of a code of the cartridge code feature <NUM>.

<FIG> illustrates an exemplary cartridge assembly <NUM>, wherein the cartridge code feature <NUM> comprises bar codes. The cartridge code feature <NUM> may comprise one or more bar codes. The bar code may be indicative of a number indicative of a code of the cartridge code feature <NUM>.

<FIG> illustrates an exemplary cartridge assembly <NUM>, wherein the cartridge code feature <NUM> comprises differently grated strips. For example, as illustrated, the cartridge code feature <NUM> may comprise two strips wherein the first strip is grated at <NUM> deg. , and the second strip is grated at - <NUM> deg. The grating, and/or the grating of the strips relative to each other, may be indicative of a code of the cartridge code feature <NUM>.

<FIG> illustrates an exemplary cartridge assembly <NUM>, wherein the cartridge code feature <NUM> comprises an electromagnetically readable tag, such as an RFID tag or an NFC tag. The electromagnetically readable tag may contain data that is indicative of a code of the cartridge code feature <NUM>.

<FIG> illustrates an exemplary system <NUM>. The system <NUM> comprises an auto injector <NUM>, as described, for example, in relation to <FIG>, and an exemplary cartridge assembly <NUM>. The cartridge assembly <NUM> comprises a cartridge <NUM> with a cartridge compartment <NUM>, a needle assembly <NUM>, and a cartridge code feature <NUM>. The cartridge assembly <NUM> is received in the auto injector <NUM>.

The cartridge assembly <NUM> comprises a cartridge holder <NUM>. The cartridge holder <NUM> is configured for retention of the cartridge <NUM> in the cartridge receiver <NUM> of the auto injector <NUM>. The cartridge holder <NUM> comprises a cartridge retention member <NUM>. The cartridge retention member <NUM> engages with the cartridge receiver <NUM> for reception of the cartridge <NUM> and the cartridge assembly <NUM> in the cartridge receiver <NUM>.

The needle assembly <NUM> comprises a needle <NUM> and a needle hub <NUM>. The needle assembly <NUM> is attached to the cartridge <NUM>, e.g. by the needle hub <NUM> having a cartridge holder coupling portion <NUM>, e.g. a threaded coupling portion, being in engagement with a needle assembly coupling portion <NUM> of the cartridge holder <NUM>. The needle <NUM> extends through the cartridge outlet <NUM> of the cartridge <NUM>. The cartridge outlet <NUM> may be blocked by a resilient sealing being penetrated by the needle <NUM>, when the needle assembly <NUM> is attached to the cartridge <NUM>.

The auto injector <NUM> comprises a code sensor <NUM> configured to read the cartridge code feature <NUM>. When the cartridge assembly <NUM> is inserted, as shown, the cartridge code feature <NUM> is lined up with the code sensor <NUM>.

The auto injector <NUM> comprises a plunger rod <NUM>. The plunger rod <NUM> is configured to advance a first stopper of the cartridge <NUM>. The plunger rod <NUM> comprises an outer plunger rod <NUM> with an inner thread, and an inner plunger rod <NUM> with an outer thread. The thread of the inner plunger rod <NUM> is in engagement with the thread of the outer plunger rod <NUM>. The outer plunger rod <NUM> is prevented from rotating relative to the housing of the auto injector. The movement of the plunger rod <NUM> comprises rotation of the inner plunger rod <NUM>. The rotation of the inner plunger rod <NUM> results in translational movement of the outer plunger rod <NUM>, due to the outer plunger rod <NUM> being rotationally restricted. The outer plunger rod <NUM>, when moved translationally in the first stopper direction <NUM>, is configured to abut the first stopper of the cartridge <NUM>, and to move the first stopper in the first stopper direction <NUM>.

The drive module <NUM> is coupled to actuate the plunger rod <NUM>. The drive module <NUM> is electrically connected to a battery for receiving electrical power. The drive module <NUM> comprises a motor <NUM>, such as an electro-mechanical motor, such as a DC motor. The drive module <NUM> comprises a transmission <NUM> for coupling the motor <NUM> to the inner plunger rod <NUM> of the plunger rod <NUM>.

Although the example shown comprises a motor <NUM>, which may be an electro-mechanical motor, it will be readily understood that the auto injector <NUM> may be realised having an alternative drive module, such as comprising a solenoid motor, a shape memory metal engine, an arrangement of springs and/or a pressurized gas configured to actuate the plunger rod <NUM>.

The auto injector <NUM> comprises an ejection sensor <NUM>, such as a plunger rod position sensor. The ejection sensor <NUM> is configured to detect the position of the plunger rod <NUM>. In the illustrated example, the ejection sensor <NUM> comprises a tachometer configured to count/detect the revolutions of the motor <NUM>. Thus, the position of the plunger rod <NUM> may be determined. The ejection sensor <NUM> may, based on the detection of the position of the plunger rod <NUM>, detect the expelling of medicament and/or air in the cartridge compartment. The position of the plunger rod <NUM> is indicative of the position of the first stopper of the cartridge <NUM>.

<FIG> schematically illustrates an exemplary cartridge assembly <NUM> and a plunger rod <NUM> in exemplary positions.

The cartridge assembly <NUM> comprises a cartridge <NUM>, a cartridge holder <NUM>, and a needle assembly <NUM>.

The cartridge <NUM> comprises a cartridge compartment <NUM>, a first stopper <NUM> and a cartridge outlet <NUM>. The cartridge compartment <NUM> is configured for containing a medicament (not shown). The cartridge <NUM> shown in <FIG> is a single chamber cartridge. However, it may be a dual chamber cartridge as, for example, explained in relation to <FIG>.

The cartridge holder <NUM> comprises a cartridge retention member <NUM>. The cartridge retention member <NUM> is configured for engagement with a cartridge receiver of the auto injector. The cartridge holder <NUM> comprises a needle assembly coupling portion <NUM>. The needle assembly coupling portion <NUM> is configured for engagement with a cartridge holder coupling portion <NUM> of the needle assembly <NUM>. The needle assembly coupling portion <NUM> allows attachment of a needle to the cartridge <NUM>.

The needle assembly <NUM> comprises a needle <NUM> and a needle hub <NUM>. The needle assembly <NUM> is attached to the cartridge <NUM>, e.g. by the needle hub <NUM> having a cartridge holder coupling portion <NUM>, e.g. a threaded coupling portion, being in engagement with a needle assembly coupling portion <NUM> of the cartridge holder <NUM>. The needle <NUM> extends through the cartridge outlet <NUM> of the cartridge <NUM>.

<FIG> shows the first stopper <NUM> in an exemplary initial stopper position, and the plunger rod <NUM> in an exemplary initial plunger rod position. The plunger rod <NUM> is moved towards the cartridge outlet <NUM>, e.g. in the first stopper direction <NUM>, such that a plunger rod front end <NUM> of the plunger rod <NUM> abuts the first stopper <NUM>.

<FIG> shows the first stopper <NUM> in an exemplary first stopper position, and the plunger rod <NUM> in an exemplary first plunger rod position. Compared to <FIG>, the plunger rod <NUM> has moved towards the cartridge outlet <NUM>, e.g. in the first stopper direction <NUM>, to the first plunger rod position. The first stopper <NUM> has moved to the first stopper position by the movement of the plunger rod <NUM>. The first stopper <NUM> has been pushed by the plunger rod front end <NUM> of the plunger rod <NUM>.

The first stopper position and/or the first plunger rod position may have been determined by a cartridge code feature (see <FIG>), of the cartridge assembly <NUM>.

The first stopper position and/or the first plunger rod position may be the position of the first stopper <NUM> and/or the plunger rod <NUM> after completion of an air-shot. Thus, the first stopper position and/or the first plunger rod position may be the position of the first stopper <NUM> and/or the plunger rod <NUM> wherein air in the cartridge compartment <NUM> has been expelled, e.g. through the cartridge outlet <NUM> and/or the needle <NUM>.

<FIG> shows the first stopper <NUM> in an exemplary second stopper position, and the plunger rod <NUM> in an exemplary second plunger rod position. Compared to <FIG>, the plunger rod <NUM> has moved towards the cartridge outlet <NUM>, e.g. in the first stopper direction <NUM>, to the second plunger rod position. The first stopper <NUM> has moved to the second stopper position by the movement of the plunger rod <NUM>. The first stopper <NUM> has been pushed by the plunger rod front end <NUM> of the plunger rod <NUM>.

The second stopper position and/or the second plunger rod position may be the position of the first stopper <NUM> and/or the plunger rod <NUM> after completion of ejection of medicament, such as after completion of injection of medicament. Thus, the second stopper position and/or the second plunger rod position may be the position of the first stopper <NUM> and/or the plunger rod <NUM> wherein medicament in the cartridge compartment <NUM> has been expelled, e.g. through the cartridge outlet <NUM> and/or the needle <NUM>.

<FIG> shows a block diagram of an exemplary auto injector <NUM>. The auto injector comprises a plurality of sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, a processing unit <NUM>, a drive module <NUM>, and a trigger member <NUM>. The sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are coupled to the processing unit <NUM>. The trigger member <NUM> is coupled to the processing unit <NUM>. The processing unit is coupled to the drive module <NUM>.

The processing unit <NUM> receives signals from the sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and the trigger member <NUM>. The processing unit <NUM> is configured to control the drive module <NUM>. The processing unit <NUM> may control the drive module <NUM> based on one or more of the received signals from the sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

The auto injector <NUM> comprises an orientation sensor <NUM>. The orientation sensor <NUM> is configured to provide an orientation signal indicative of the orientation of a cartridge received in the auto injector <NUM>. For example, the orientation sensor <NUM> may be configured to detect the orientation of the auto injector <NUM>. The orientation of the cartridge may be determined based on the orientation of the auto injector <NUM>. The orientation sensor <NUM> may be configured to detect the direction of gravity. For example, the orientation sensor <NUM> may comprise an accelerometer.

The processing unit <NUM> is coupled to the orientation sensor <NUM>. The processing unit <NUM> is configured to receive the orientation signal. The processing unit <NUM> may determine the orientation of the cartridge based on the orientation signal. The processing unit <NUM> may control the drive module <NUM> based on the orientation signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to move the plunger rod to the first plunger rod position based on the orientation signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to move the plunger rod to the first plunger rod position only if the cartridge outlet is pointing upwards, e.g. such that air is expelled from the cartridge compartment upon movement of the plunger rod to the first plunger rod position.

The auto injector <NUM> comprises a code sensor <NUM>. The code sensor <NUM> is configured to read a cartridge code feature, and provide a code signal indicative of the cartridge code feature. For example, the code sensor may be configured to read/detect a colour code.

The processing unit <NUM> is coupled to the code sensor <NUM>. The processing unit <NUM> is configured to receive the code signal. The processing unit <NUM> may determine the cartridge code feature of the cartridge assembly based on the code signal. The processing unit <NUM> may control the drive module <NUM> based on the code signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to move the plunger rod to the first plunger rod position and/or the second plunger rod position based on the code signal. For example, the processing unit <NUM> may be configured to determine the position of the first plunger rod position based on the code signal.

The auto injector <NUM> comprises an ejection sensor <NUM>, such as a plunger rod position sensor. The ejection sensor <NUM> is configured to detect the position of the plunger rod of the auto injector <NUM> and/or the position of the first stopper of the cartridge, and provide an ejection sensor signal indicative of the position of the plunger rod and/or first stopper.

The processing unit <NUM> is coupled to the ejection sensor <NUM>. The processing unit <NUM> is configured to receive the ejection sensor signal. The processing unit <NUM> may determine the position of the plunger rod based on the ejection sensor signal. The processing unit <NUM> may control the drive module <NUM> based on the ejection sensor signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to start, stop or continue movement of the plunger rod based on the ejection sensor signal. For example, the processing unit <NUM> may be configured to determine that the plunger rod is moved to the first plunger rod position based on the ejection sensor signal.

The auto injector <NUM> comprises a cartridge sensor <NUM>. The cartridge sensor <NUM> is configured to detect reception of a cartridge assembly in the auto injector <NUM>. The cartridge sensor <NUM> provides a cartridge sensor signal indicative of reception of a cartridge assembly.

The processing unit <NUM> is coupled to the cartridge sensor <NUM>. The processing unit <NUM> is configured to receive the cartridge sensor signal. The processing unit <NUM> may control the drive module <NUM> based on the cartridge sensor signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to start movement of the plunger rod if a cartridge assembly is received, and/or only if a cartridge assembly is received.

The code sensor <NUM> and the cartridge sensor <NUM> may be the same sensor, e.g. the code sensor <NUM> may be configured to detect reception of a cartridge assembly and subsequently read the cartridge code feature.

The auto injector <NUM> comprises a needle sensor <NUM>. The needle sensor <NUM> is configured to detect a needle, and/or a needle assembly, and/or a needle cover of a needle assembly, of the cartridge assembly, when the cartridge assembly is received in the auto injector <NUM>. The needle sensor <NUM> provides a needle signal indicative of the presence of a needle, and/or a needle assembly, and/or a needle cover of a needle assembly, of the cartridge assembly.

The processing unit <NUM> is coupled to the needle sensor <NUM>. The processing unit <NUM> is configured to receive the needle signal. The processing unit <NUM> may control the drive module <NUM> based on the needle signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to start movement of the plunger rod only if a needle is present, and/or only if a needle cover is not present.

The auto injector <NUM> comprises a temperature sensor <NUM>. The temperature sensor <NUM> is configured to detect a temperature, such as a temperature of the auto injector and/or of the cartridge and/or of the medicament. The temperature sensor <NUM> is configured to provide a temperature signal indicative of the temperature.

The processing unit <NUM> is coupled to the temperature sensor <NUM>. The processing unit <NUM> is configured to receive the temperature signal. The processing unit <NUM> may be configured to determine the temperature, such as the temperature of the auto injector and/or of the cartridge and/or of the medicament based on the temperature signal. The processing unit <NUM> may control the drive module <NUM> based on the temperature signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to move the plunger rod to the first plunger rod position and/or the second plunger rod position based on the temperature signal. For example, the processing unit <NUM> may be configured to determine the position of the first plunger rod position based on the temperature signal.

The auto injector <NUM> comprises a resistance sensor <NUM>. The resistance sensor <NUM> is configured to detect resistance against movement of the plunger rod of the auto injector <NUM>. The resistance sensor <NUM> may be configured to detect resistance against movement of the plunger rod based on measurements of the drive module <NUM>. For example, the resistance sensor <NUM> may be configured to detect the electrical current of a motor of the drive module <NUM>. The resistance sensor <NUM> is configured to provide a resistance signal indicative of resistance against movement of the plunger rod.

The processing unit <NUM> is coupled to the resistance sensor <NUM>. The processing unit <NUM> is configured to receive the resistance signal. The processing unit <NUM> may be configured to determine the resistance against movement of the plunger rod based on the resistance signal. The processing unit <NUM> may control the drive module <NUM> based on the resistance signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to adjust movement of the plunger based on the resistance signal. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to start, stop or continue movement of the plunger rod based on the resistance signal.

The auto injector <NUM> is illustrated comprising all of the above mentioned sensors. However, alternatively, the auto injector may comprise only one or any combination of one or more of the above mentioned sensors.

The auto injector comprises a trigger member <NUM>. The trigger member <NUM> is configured to provide a trigger event upon activation. For example, the trigger member <NUM> may be a contact member configured to be pressed against the injection site for activation.

The processing unit <NUM> is coupled to the trigger member <NUM>. The processing unit <NUM> is configured to receive the trigger event. The processing unit <NUM> may control the drive module <NUM> based on the trigger event. For example, the processing unit <NUM> may be configured to control the drive module <NUM> to move the plunger rod to the second plunger rod position following reception of the trigger event. The processing unit <NUM> may be configured to control the drive module <NUM> to move the plunger rod to the second plunger rod position, e.g. to inject the medicament, only after receiving the trigger event from the trigger member <NUM>.

The auto injector comprises a housing <NUM> accommodating the sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, processing unit <NUM>, trigger member <NUM> and drive module <NUM>.

<FIG> shows a flow chart of an exemplary method <NUM> for operating an auto injector, such as the auto injector as described in relation to the previous figures. The method <NUM> comprises receiving <NUM> a cartridge assembly; reading <NUM> a cartridge code feature of the cartridge assembly; moving <NUM> a plunger rod of the auto injector to a first plunger rod position, wherein the first plunger rod position is based on the cartridge code feature; receiving a trigger event <NUM>; and moving <NUM> the plunger rod to a second plunger rod position following reception of the trigger event.

The method <NUM> furthermore comprises an optional step of determining <NUM> an orientation of the cartridge. This step may be performed simultaneously with reading <NUM> the cartridge code feature. However, alternatively the determining <NUM> of the orientation may be performed before or after the reading <NUM> of the cartridge code feature. If determining <NUM> the orientation, movement <NUM> of the plunger rod to the first plunger rod position may be based on the determined orientation. For example, the movement <NUM> may require that the determined orientation is within a predefined range, e.g. of vertical.

The method <NUM> furthermore comprises an optional step of detecting <NUM> a temperature. This step may be performed simultaneously with reading <NUM> the cartridge code feature and/or determining <NUM> the orientation. However, alternatively the detecting <NUM> of the temperature may be performed before or after the reading <NUM> of the cartridge code feature and/or before or after the determining <NUM> of the orientation. If detecting <NUM> the temperature, the first plunger rod position may further be based on the detected temperature. Movement <NUM> of the plunger rod to the second plunger rod position may be based on the detected temperature. For example, the speed of the movement <NUM> may be based on the detected temperature.

Claim 1:
A system comprising an auto injector (<NUM>) for administering a medicament and a cartridge assembly (<NUM>);
wherein the cartridge assembly (<NUM>) comprises a cartridge (<NUM>) and a cartridge code feature (<NUM>), the cartridge (<NUM>) comprises a cartridge compartment (<NUM>) containing the medicament, and a cartridge outlet (<NUM>); and
wherein the auto injector (<NUM>) comprises:
• a housing (<NUM>);
• a cartridge receiver (<NUM>) configured to receive the cartridge assembly (<NUM>);
• a code sensor (<NUM>) configured to read the cartridge code feature (<NUM>);
• a drive module (<NUM>) coupled to move a plunger rod (<NUM>);
• an ejection sensor (<NUM>) configured to provide an ejection sensor signal indicative of the position of the plunger rod (<NUM>); and
• a processing unit (<NUM>) coupled to the code sensor (<NUM>); the drive module (<NUM>) and the ejection sensor (<NUM>);
wherein the processing unit (<NUM>) is configured to:
- receive from the code sensor (<NUM>) a code signal indicative of the cartridge code feature (<NUM>);
- receive from the ejection sensor (<NUM>) an ejection sensor signal indicative of the position of the plunger rod (<NUM>); and
- control the drive module (<NUM>) to move the plunger rod (<NUM>) to a first plunger rod position based on the ejection sensor signal, the first plunger rod position being based on the code signal;
wherein air is expelled from the cartridge (<NUM>) upon movement of the plunger rod (<NUM>) to the first plunger rod position,
wherein by expelling air from the cartridge (<NUM>), the air in the cartridge compartment (<NUM>) is reduced to an amount appropriate for injection, and
wherein the plunger rod (<NUM>) is only moved to the first plunger rod position if the cartridge outlet (<NUM>) is pointing upwards.