Patent Description:
A variety of diseases exists that require regular treatment by injection of a medicament. Such injection can be performed by using injection devices, which are applied either by medical personnel or by patients themselves. As an example, type-<NUM> and type-<NUM> diabetes can be treated by patients themselves by injection of insulin doses, for example once or several times per day. For instance, a pre-filled disposable insulin pen can be used as an injection device. Alternatively, a re-usable pen may be used. A re-usable pen allows replacement of an empty medicament cartridge by a new one. Either pen may come with a set of one-way needles that are replaced before each use. The insulin dose to be injected can then for instance be manually selected at the insulin pen by turning (dialling) a dosage knob and observing the actual dose from a dose window or display of the insulin pen. The dose is then injected by inserting the needle into a suited skin portion and pressing an injection button of the insulin pen. To be able to monitor insulin injection, for instance to prevent false handling of the insulin pen or to keep track of the doses already applied, it is desirable to measure information related to a condition and/or use of the injection device, such as for instance information on the injected insulin type and dose.

It has been described, for instance in <CIT>, to provide a supplementary device comprising a mating unit for releasably attaching the device to an injection/drug delivery device. The device includes a camera and is configured to perform optical character recognition (OCR) on captured images visible through a dosage window of the injection pen, thereby to determine a dose of medicament that has been dialled into the injection device. In order for such a supplementary device to successfully determine the dose, the dosage window must remain stationary. However not all drug delivery devices operate in this way.

<CIT> relates to a supplemental device that is configured to be used with an injection device. In this supplemental device, the currently dialled dose is visible through a window. <CIT> relates to a drug delivery device having first and second windows and an indicator which indicates whether or not the device is in standby mode.

According to a first aspect of the invention there is provided a sensor device removably attachable to a drug delivery device, the sensor device comprising:.

The sensing arrangement may be is an optical sensor arrangement, for instance a single camera.

The sensing arrangement may comprise a light source arrangement configured to project light towards the aperture or window in the drug delivery device when the sensor device is attached to the drug delivery device.

The sensor device may further comprise a second sensing arrangement arranged within the sensor device and configured to detect an amount of axial movement of a gauge element of the drug delivery device, and wherein the circuitry is configured to calculate a set dose using the encoded information and using outputs from the second sensing arrangement. The second sensing arrangement may comprise an array of optical sensors, each optical sensor being operable to detect light received at different locations along the linear path and to output a signal indicative of an amount of detected light.

The second sensing arrangement may be configured to determine an angular position of a mark on the gauge element.

The sensor arrangement may be configured to determine a drug for which the drug delivery device is being used to dispense using the encoded information or using outputs from the second sensing arrangement.

A second aspect of the invention provides a drug delivery system comprising:.

The part of the drive mechanism may be of a contrasting colour to the rotatable component.

The drug delivery device may comprise the gauge element that is moveable axially along an underlying element and is configured such that movement of the first movable element in a particular direction causes the underlying element to become visible at successive locations along the externally visible path, wherein at least part of the gauge element has a first reflectance and the underlying element has a second, different reflectance.

The first moveable element may be movable relative to the underlying element such that movement in a first direction along the externally visible path causes an increasing length of the underlying element to become visible in the externally visible path.

The drug delivery device may comprise the gauge element that is moveable axially along the device, wherein the gauge element has formed thereon marks that are at different angular positions at different axial positions.

A third aspect of the invention provides a drug delivery device comprising:.

wherein at least a part of the drive mechanism is coincident with the window and is visible through the window when the injection device is in the dose delivery mode and is not visible through the window when the injection device is in the dose setting mode.

The part of the drive mechanism may be a drive sleeve.

For a more complete understanding of example embodiments of the present invention, reference is now made to the following description taken in connection with the following Figures, in which:.

In brief, the specification describes a drug delivery device, for instance an injection device, including a number sleeve having markings (e.g. a code) thereon. A dose setting or dialling mechanism of the device is configured to rotate the number sleeve without axially moving the number sleeve as a dose dialled is increased or decreased in a dose setting/dialling mode. The device includes a drive mechanism that causes expulsion of a dialled dose upon application of a driving force in a dose delivery mode. In addition to a first window, through which a user can read numbers indicating a currently set dose, a second window is provided. The second window is located at a fixed axial position on the main body and is coincident with the markings on the number sleeve.

An add-on device (or clip on device, or supplementary device) is a sensor device and includes an optical sensor that can view the markings through the second window and thus determine the rotational position of the number sleeve, to determine the dialled dose with a high resolution. The number of rotations of the number sleeve is determined through use of a separate sensor, to allow the dialled dose when this corresponds to more than one revolution of the number sleeve. The optical sensor that views the markings through the second window is used to detect whether a part of a drive mechanism, in particular, an end of a drive sleeve, is coincident with the window and thus is visible through the window. The presence, absence or location of the drive sleeve is used to determine whether the injection device is in dose setting mode or dose delivery mode. In the main embodiment, the drive sleeve is visible only when the injection device is in the dose delivery mode, so the detection of the absence of the drive sleeve through the second window is used to determine that the injection device is in dose setting mode and the detection of its presence is used to determine that the injection device is in dose delivery mode. The sensor device is operable to record and manage dose history information.

A drug delivery device, as described herein, may be configured to inject a medicament into a patient. For example, delivery could be sub-cutaneous, intra-muscular, or intravenous. Such a device could be operated by a patient or care-giver, such as a nurse or physician, and can include various types of safety syringe, pen-injector, or auto-injector. The device can include a cartridge-based system that requires piercing a sealed ampule before use. Volumes of medicament delivered with these various devices can range from about <NUM> to about <NUM>. Yet another device can include a large volume device ("LVD") or patch pump, configured to adhere to a patient's skin for a period of time (e.g., about <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> minutes) to deliver a "large" volume of medicament (typically about <NUM> to about <NUM>).

The delivery devices described herein can also include one or more automated functions. For example, one or more of needle insertion, medicament injection, and needle retraction can be automated. Energy for one or more automation steps can be provided by one or more energy sources. Energy sources can include, for example, mechanical, pneumatic, chemical, or electrical energy. For example, mechanical energy sources can include springs, levers, elastomers, or other mechanical mechanisms to store or release energy. One or more energy sources can be combined into a single device. Devices can further include gears, valves, or other mechanisms to convert energy into movement of one or more components of a device.

The one or more automated functions of an auto-injector may each be activated via an activation mechanism. Such an activation mechanism can include one or more of a button, a lever, a needle sleeve, or other activation component. Activation of an automated function may be a one-step or multi-step process. That is, a user may need to activate one or more activation components in order to cause the automated function. For example, in a one-step process, a user may depress a needle sleeve against their body in order to cause injection of a medicament. Other devices may require a multi-step activation of an automated function. For example, a user may be required to depress a button and retract a needle shield in order to cause injection.

<FIG> show views of a drug delivery device <NUM>, in this example an injection device, with which a sensor device (also referred to as a supplementary device - not shown) according to various embodiments of the invention may be used.

The drug delivery device <NUM> of <FIG> is configured such that a user is able to adjust the drug dosage (or number of drug doses) that is to be delivered (or dispensed) using the device <NUM>. In the example of <FIG>, this is achieved by rotating (or dialling) a dose selector <NUM> which causes an internal dialling mechanism (not shown) to adjust an amount of the drug that is to be dispensed once a drug delivery mechanism (not shown) is actuated. In this example, the drug delivery mechanism is actuated by pressing a button <NUM> on the proximal end of the device <NUM>.

The drug delivery device <NUM> comprises an external housing <NUM> in which is formed at least one aperture or window 13A, 13B. As will be appreciated, an aperture may simply be a cut-away area of the external housing <NUM>, whereas a window may be a transparent portion of the housing through which components of the device may be seen. For convenience, the at least one aperture or window 13A, 13B, will hereafter simply be referred to as the at least one window.

The at least one window 13A, 13B allows a movable gauge element <NUM> to be visible from the exterior of the housing <NUM>. The drug delivery device is configured such that as the dose selector <NUM> is dialled, the movable gauge element <NUM> is caused to be moved thereby to indicate a selected dose to the user. More specifically, as the dose selector <NUM> is dialled, the gauge element <NUM> moves axially along an underlying surface 15A, 15B thereby to indicate the selected dose. In the example of <FIG>, a surface 15A underlying at least part of the gauge element <NUM> comprises a number sleeve 15A. The number sleeve 15A has numbers indicative of drug doses provided on its outer surface, with the number indicating the currently selected dose being visible through the at least one window 13A, 13B. In this example, the number sleeve 15A is visible through a gauge window (or aperture) <NUM>-<NUM> formed in the movable gauge element. Other parts of the movable gauge element <NUM> are discussed below.

The view of the drug delivery device <NUM> shown in <FIG> illustrates the situation before any dialling has been performed. Consequently, the movable gauge element <NUM> is at its first (or initial) position at a first end of the path along which it is able to move. In this example, when the movable gauge element <NUM> is at the first end of its path, the portion of the number sleeve 15A that is visible through the gauge window <NUM>-<NUM> shows the number zero (i.e. a zero dose).

The view of the drug delivery device <NUM> shown in <FIG> illustrates the situation after dialling has been performed. Consequently, the movable gauge element <NUM> has moved axially along the path that is visible through the first window 13A away from its first position. In this example, the device <NUM> has been dialled to its maximum dose and as such, the movable gauge element <NUM> has moved to the second end of its path. The maximum dose in this example is "<NUM>" and so the portion of the number sleeve 15A that is visible through the gauge window <NUM>-<NUM> shows the number "<NUM>".

The delivery mechanism actuated by the button <NUM> may be injection. Injection is the process by which a bung or piston (not shown) is moved from a proximal location within a syringe (not shown) to a more distal location within the syringe in order to force a medicament from the syringe through a needle (not shown). In some embodiments, a drive spring (not shown) is under compression before the drug delivery device <NUM> is activated. A proximal end of the drive spring can be fixed within a proximal region of the housing <NUM>, and a distal end of the drive spring can be configured to apply a compressive force to a proximal surface of the piston. Following activation, at least part of the energy stored in the drive spring can be applied to the proximal surface of the piston. This compressive force can act on the piston to move it in a distal direction. Such distal movement acts to compress the liquid medicament within the syringe, forcing it out of the needle.

In this example, the device <NUM> comprises first and second windows 13A, 13B (and a further window <NUM>, as will be described below). The number sleeve 15A underlies and is visible through the first window 13A, whereas a further underlying element 15B underlies and is sometimes visible through the second window 13B. The further underlying element 15B may or may not include any numbers. The further underlying surface 15B is visually distinguishable from a second part <NUM>-<NUM> of the movable gauge element <NUM> which overlies it and which is configured to move axially along it. For instance, the second part <NUM>-<NUM> of the movable gauge element <NUM> may be of a different reflectance to the further underlying surface 15B. For example, one of the gauge element <NUM> and the underlying surface 15B may be of a light colour (e.g. may be made of a light coloured polymer) and the other may be of dark colour (e.g. may be made of a dark coloured polymer). The user may, therefore, be able to determine the selected dose by determining the proportion of the second window 13A in which the gauge element <NUM> (specifically, the second part <NUM>-<NUM>) is visible compared to the proportion in which the further underlying surface 15B is visible. This can be seen from <FIG>, in which, when the device <NUM> is dialled to its zero dose, the gauge element <NUM> covers the entire length of the path that is visible through the second window 13B. In contrast, when the device <NUM> is dialled to its maximum dose, none of the gauge element <NUM> is visible through the second window. Instead, the further underlying surface 15B is visible along the entire length of the path defined by the second window 13B.

The number sleeve 15A (which is also surface underlying the gauge element <NUM>) is also visually distinguishable from the movable gauge element <NUM> which overlies it and which is configured to move axially along it. For instance, gauge element <NUM> may be of a different reflectance to the number sleeve 15A. For example, one of the gauge element <NUM> and the underlying surface 15A may be of a light colour (e.g. may be made of a light coloured polymer) and the other may be of dark colour (e.g. may be made of a dark coloured polymer). In the examples shown in the Figures, the number sleeve 15A and underlying surface 15B are of a higher reflectance than the movable gauge element <NUM>.

<FIG> are simplified schematics of components of a drug delivery device such as that of <FIG>. The purpose of <FIG> is to illustrate the operation of a drug delivery device <NUM> such as that of <FIG>; they are not intended to be accurate representations of the exact design of the components.

<FIG> is a simplified schematic of the number sleeve 15A. The sleeve 15A has numbers provided on its surface. In some examples, the numbers, ranging from the minimum dose to the maximum dose, may be provided helically around the surface of the number sleeve.

<FIG> is a simplified schematic of a movable gauge element <NUM>. The gauge element <NUM> comprises a first section <NUM>-<NUM> in which the gauge window <NUM>-<NUM> is provided. In this example, the first section is <NUM>-<NUM> a collar which is configured to encircle the number sleeve 15A (as can be seen in <FIG>). Extending in opposite directions from the first section <NUM>-<NUM> are the second part <NUM>-<NUM> and a third part <NUM>-<NUM>. The second and third parts <NUM>-<NUM>, <NUM>-<NUM> extend generally parallel to the longitudinal axis of the number sleeve.

The second part <NUM>-<NUM> of the movable gauge element is configured to extend from the first part <NUM>-<NUM> by a length sufficient to fill the entire second window 13B when the movable gauge is in its first position. The second part <NUM>-<NUM> may also serve to obscure a portion of the exterior surface of the number sleeve15A, when the gauge element moves away from its first position. The third part of the movable gauge element <NUM>-<NUM> is configured to obscure a portion of the exterior surface of the number sleeve 15A, when the gauge elements moves between its first and second positions. In this way, only the portion of the number sleeve that underlies the gauge window <NUM>-<NUM> is visible through the first window 13A of the device housing <NUM>.

The number sleeve 15A is rotatable about its longitudinal axis within the device housing <NUM>. As such, the number sleeve 15A may be referred to as a movable (or rotatable) element. Rotation of the number sleeve 15A is in some embodiments caused by rotation of the dose selector <NUM>.

The rotational movement NSR of the number sleeve 15A and axial movement GE of the gauge element <NUM> are interdependent. Put another way, the dialling mechanism of the device <NUM> is configured such that when number sleeve 15A is caused to rotate, the gauge element <NUM> is caused to move or translate axially along its path. Moreover, the degree of rotation of the number sleeve 15A corresponds proportionally to the extent of axial movement of the gauge element <NUM>.

<FIG> shows the gauge element <NUM> in its initial position in which, in this example, it indicates a zero dose. <FIG> shows the number sleeve 15A and gauge element <NUM> following rotation of the number sleeve 15A and translation of the gauge element <NUM> from its first position. <FIG> shows this arrangement of <FIG> within a simplified version of the device housing <NUM>.

Various dialling mechanisms for adjusting a dose to be delivered to a user which transform rotation of a dose selector <NUM> into rotational movement of a number sleeve <NUM> A and axial movement of a gauge element <NUM> (as described above) are known in the art. Two such mechanisms are described in <CIT> and <CIT>. As such mechanisms (and also drug delivery mechanisms which cause delivery of the drug once the dose has been dialled) are known in the art, they will not be described herein in any detail.

Rotation of the dose selector <NUM> causes a corresponding rotation in the number sleeve 15A. The rotation of the number sleeve 15A is controlled by ratchet teeth (not shown) in a clutch plate (not shown), so that it can only stop in discrete detented rotational positions, corresponding to each drug unit.

According to embodiments, a sensor device includes one or more sensor arrangements configured to read information from the windows 13A and 13B, and a sensor arrangement configured to read information from a window at a different location on the device <NUM>, as is described below.

<FIG> shows an extremely simplified cut-away view of the components of the delivery device <NUM> as depicted in <FIG> and a simplified schematic illustration of a sensor device <NUM> for use with a delivery device <NUM> such as that described with reference to <FIG>.

The sensor device <NUM> is configured to determine a number of complete rotations of the number sleeve 15A from an initial position to the current position, which provides one component of the set or dialled dose (the other component is the amount of rotation within a complete rotation). One mechanism for making the determination will now be described with reference to <FIG> and <FIG>, and another mechanism is described below with reference to <FIG>.

Referring to <FIG>, the sensor device <NUM> comprises an array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM> arranged such that, when the sensor device <NUM> is in place on the drug delivery device <NUM>, each optical sensor <NUM>-<NUM> to <NUM>-<NUM> in the array <NUM> is operable to detect light received from a different location along an externally visible path defined by one of the at least one window 13A, 13B. Each optical sensor <NUM>-<NUM> to <NUM>-<NUM> then outputs a signal indicative of an amount of detected light. The sensor device <NUM> further comprises circuitry <NUM> configured to receive the signals output from the optical sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> and, based on the received signals, to determine information associated with a location along the path defined by the window 13A, 13B of the movable gauge element <NUM>. The circuitry <NUM> may be further configured to control operation of the array <NUM>.

When the sensor device <NUM> is in place adjacent an externally visible path of the drug delivery device <NUM>, the optical sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> are spaced along the path. The optical sensors <NUM>-<NUM> to <NUM>-<NUM> may be substantially equidistantly spaced from one another along a length generally corresponding to the length of the visible path. The length over which the optical sensors <NUM>-<NUM> to <NUM>-<NUM> are spaced may not be exactly the same as the length of the visible path along which the gauge element <NUM> moves but may be dependent on the length of the visible path with which the sensor device <NUM> is designed to be used.

In some embodiments, the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM> extends generally along an axis which, when the sensor device <NUM> is coupled to the delivery device <NUM>, is generally parallel with the axis along which the moveable gauge element <NUM> is configured to move. The axis along which the array <NUM> of optical sensors extends is therefore also generally parallel with the longitudinal axis of the window 13A, 13B that it overlies. The axis along which the array <NUM> extends is also generally parallel to the longitudinal axis of the drug delivery device <NUM>. The optical sensors <NUM>-<NUM> to <NUM>-<NUM> may be equidistantly spaced from one another along the axis.

Each of the optical sensors <NUM>-<NUM> to <NUM>-<NUM> has a corresponding light source (not shown) arranged to emit light towards the externally visible path (defined by the window 13A, 13B) when the sensor device <NUM> is attached to the drug delivery device <NUM>. The light emitted by each light source is then reflected off the visible path back to the corresponding optical sensor <NUM>-<NUM> to <NUM>-<NUM>. Each optical sensor <NUM>-<NUM> to <NUM>-<NUM> may be provided in a single package with its corresponding light source. Each of the optical sensors <NUM>-<NUM> to <NUM>-<NUM> may comprise a PIN photodiode, for example. Each of the light sources may, for instance, comprise an LED.

Because the visible path towards which the array <NUM> is oriented is formed by the gauge element <NUM> and/or the underlying element 15A, 15B, which are visually distinguishable from one another (e.g. because they are different colours), the amount of light reflected back to each of the optical sensors <NUM>-<NUM> to <NUM>-<NUM> will vary in dependence on the position of the movable gauge element <NUM> along its path.

The optical sensors of the array <NUM> may be configured such that, when the amount of detected light is one-side of a threshold, an output signal having a first value is provided to the circuitry <NUM> and, when the amount of detected light is on the other side of the threshold, an output signal having a second value is provided to the circuitry. In examples in which the optical sensors <NUM> are PIN photodiodes, when the amount of detected light is below a threshold, the output signal is LOW and when the detected light is above the threshold, the output is HIGH. As will be appreciated the exact threshold of the optical sensors and the values of the signals output by the sensors may be dependent on a number of factors including, for example, the bias applied to the sensors.

The drug delivery device <NUM> may be configured such that either one of the underlying surface 15A, 15B and the movable gauge element <NUM> has a reflectance which is sufficiently low such that the light reflected therefrom falls on one side of the sensor threshold. The other one of the underlying surface 15A, 15B and the movable gauge element <NUM> has a reflectance which is sufficiently high such that the light reflected therefrom falls on the other side of the threshold. In the examples described herein, the underlying surface 15A, 15B has a sufficiently high reflectance to overcome the sensor threshold, whereas the movable gauge element <NUM> has a sufficiently low reflectance so as not to surpass the sensor threshold. Consequently, in examples in which the sensors <NUM>-<NUM> to <NUM>-<NUM> are PIN photodiodes, sensors located above a section of path at which the gauge element <NUM> is externally visible output a LOW signal, whereas sensors located above a section of path at which the underlying element 15A, 15B is visible output a HIGH signal.

<FIG> illustrate the operation of the sensor device <NUM> when the movable element is at different positions along its path. In this example, the array <NUM> comprises first to fifth optical sensors <NUM>-<NUM> to <NUM>-<NUM>, with the first sensor <NUM>-<NUM> being located above a first end of the window 13B at which the movable gauge element <NUM> is present only when the minimum dose is dialled. The fifth sensor <NUM>-<NUM> is located above a second end of the window 13B at which the gauge element <NUM> is visible/present unless the maximum dose is dialled.

In <FIG>, the movable gauge element <NUM> is at its initial position (e.g. when the dose is at its minimum). Consequently, the dark coloured (and low reflectance) gauge element <NUM> covers the entire path underlying the array <NUM>. As such, a sufficient quantity of light to surpass the threshold is not detected by any of the sensors <NUM>-<NUM> to <NUM>-<NUM>. As such, all five sensors <NUM>-<NUM> to <NUM>-<NUM> output a LOW signal.

In <FIG>, the gauge element <NUM> has moved to approximately the <NUM>% dose position. In this situation, the light coloured (and high reflectance) underlying surface 15B is visible to the first sensor <NUM>-<NUM>. Consequently, sufficient light to surpass the threshold is reflected back from the underlying surface 15B to the first sensor <NUM>-<NUM> and so the first sensor outputs a HIGH signal. As the gauge element <NUM>, is below each of the other sensors <NUM>-<NUM> to <NUM>-<NUM>, these output a LOW signal.

In <FIG>, the gauge element <NUM> has moved to approximately the <NUM>% dose position and so the light coloured (and high reflectance) underlying surface 15B is visible to the first and second sensors <NUM>-<NUM>, <NUM>-<NUM>, which therefore output a HIGH signal. The third to fifth sensors <NUM>-<NUM> to <NUM>-<NUM> output a LOW signal.

Finally, in <FIG>, the gauge element <NUM> has moved to approximately the <NUM>% dose position and so the light coloured (and high reflectance) underlying surface 15B is visible to the first to fourth sensors <NUM>-<NUM> to <NUM>-<NUM>, which output a HIGH signal. The fifth sensor element outputs a LOW signal.

From the above, it is clear how the signals output from the optical sensors <NUM>-<NUM> to <NUM>-<NUM> can be used by the circuitry <NUM> to determine the dialled dose. This is illustrated in Table <NUM> below:.

Although the above example describes optical sensors having a threshold and two distinct outputs (HIGH and LOW), it will be appreciated that sensors which do not have such a threshold and which instead output a signal from which the amount of detected light is derivable (e.g. because the output signal is proportional to the amount of light detected) may instead be used. In such examples, the circuitry <NUM> is still configured to determine, based on the received signals, whether the movable gauge element <NUM> or the underlying surface 15A, 15B is visible to a particular optical sensor.

As will be appreciated, the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM> provides information from which the number of rotations of the number sleeve 15A, from the initial position, can be determined. The arrangement for determining the rotational position of the number sleeve 15A within a full rotation will now be discussed with reference to <FIG> and <FIG>.

<FIG> shows that the drug delivery device <NUM> includes a further window or aperture <NUM> formed in the housing <NUM>. The further window <NUM> is at a different location to the first and second windows 13A and 13B. In this example, the further window is located on the back of the device <NUM>, at the <NUM> degree position relative to the first and second windows 13A and 13B. The further window <NUM> is located approximately half way along the housing <NUM>. In particular, the location of the further window <NUM> coincides with the end of the number sleeve 65A such that the number sleeve 65A is visible through the further window <NUM>. Also, part of the interior of the device <NUM> that is distally located compared to the end of the number sleeve is visible through the further window <NUM>. This is most clearly seen from <FIG>.

<FIG> shows an example of a rotatable element 65A, in this instance a number sleeve 65A, which may form part of a drug delivery device <NUM> for use with sensor devices <NUM> according to embodiments of the invention. <FIG> and <FIG> show two different simplified views of a delivery device <NUM> including the rotatable element 65A of <FIG>. The delivery device of <FIG> may be generally the same as that described with reference to the previous Figures except for the differences described below. The number sleeve 15A of the above-described Figures corresponds with the rotatable element 65A of these Figures.

As with the previously described delivery device <NUM>, the rotation of the rotatable element 65A is interdependent with the axial movement of the movable gauge element <NUM>. The degree of rotation may be proportional to the axial movement of the movable gauge element <NUM>. The rotatable element 65A has, provided around its exterior surface, a visually-distinguishable code <NUM> for allowing its rotational orientation to be determined. For instance, the code may enable determination by the sensor device <NUM> as to whether the rotational orientation is zero degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees. A rotation of zero degrees corresponds to the initial orientation of the rotatable element 65A when the dose of the delivery device <NUM> is dialled to its minimum. It also corresponds to the orientation after every complete rotation of the rotatable element 65A. In other examples, the code <NUM> may allow a higher or lower accuracy with regards the rotational orientation of the rotatable element 65A. For instance, the code <NUM> may allow an accuracy of <NUM>, <NUM> or <NUM> degrees or may allow an accuracy of only <NUM> degrees. Advantageously, the code <NUM> allows an accuracy of <NUM> degrees. This corresponds to <NUM> doses per revolution of the rotatable element/number sleeve 65A. Because the number sleeve 65A detents into discrete positions, the rotational position is equivalent to a number of drug units, where the number is between zero and the number of drug units that correspond to a full rotation of the number sleeve 65A.

The code <NUM> may take any suitable form so long as it allows the rotational orientation of rotatable element to be determined by the sensor device <NUM>. In this example, the code <NUM> is provided at an end of the number sleeve 65A. The code <NUM> may be printed in visible ink. Although only on row of code is shown, multiple rows may be provided. Multiple rows can allow more information to be provided.

The code <NUM> may be provided on a recessed portion of the number sleeve 65A. The recess protects the code <NUM> from abrasion when the number sleeve 65A rotates.

The housing <NUM> of the drug delivery device <NUM> includes the third aperture or window <NUM> through which a portion of the rotatable element 65A, on which part of the code <NUM> is provided, is visible. The further window <NUM> is positioned and oriented relative to the rotatable element 65A such that a portion of the code is externally visible through the further window <NUM> regardless of the rotational orientation of the rotatable element 65A. The further window <NUM> is positioned and oriented relative to the rotatable element 65A such that, as the rotatable element rotates through a single complete rotation, a different section of the code <NUM> is visible at each rotational orientation. The further aperture is, in this example, provided on a different side of the device housing <NUM> (or, if the housing is cylindrical or otherwise rounded, around the exterior surface of the device housing <NUM>) from the at least one window 13A, 13B through which the movable gauge element <NUM> is visible. In this way, the movable gauge element <NUM> does not obstruct the code from view.

As shown schematically in <FIG>, the sensor device <NUM> may, in addition to the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM>, include a further sensing arrangement <NUM>. The sensing arrangement <NUM> is arranged within the sensor device <NUM> such that, when the sensor device <NUM> is attached to the drug delivery device <NUM>, the sensing arrangement <NUM> is operable to read the code <NUM> that is externally visible on the drug delivery device through through the further window <NUM>. The further sensing arrangement <NUM> may be a camera and may include a camera sensor and a lens arrangement.

The sensing arrangement <NUM> may be of any suitable type as long as it enables the code <NUM> to be read. For instance, the sensing arrangement may be an optical sensing arrangement comprising a camera or a small array of sensing elements, a magnetic or inductive sensing arrangement or a conductance/resistance sensing arrangement. Advantageously, the sensing arrangement is an optical sensing arrangement.

The circuitry <NUM> of the sensor device <NUM> of <FIG> is configured to determine, based on the code <NUM>, a current dose to which the device <NUM> is dialled, based on the code <NUM> and the signals output from the optical sensors of the array <NUM>. For instance, the signals output from the array <NUM> may be utilised by the circuitry <NUM> to determine the number of complete rotations of the rotatable element 65A that have occurred and the code <NUM> read by the sensing arrangement <NUM> may be utilised to determine the rotational orientation of the rotatable element 65A. Put another way, the signals output from the array <NUM> may be used to determine roughly the extent of axial translation of the moveable gauge element, with the code <NUM> read by the sensing arrangement being used with the rough determination to more precisely determine the extent of translation of the movable gauge element <NUM> (thereby to determine the currently dialled dose).

The array <NUM> may comprise the same number of optical sensors <NUM>-<NUM> to <NUM>-<NUM> as the number of complete rotations of the rotatable element 65A that are required to move the movable gauge element <NUM> from its initial to final position. The sensors <NUM>-<NUM> to <NUM>-<NUM> may be distributed adjacent the visible path of the movable gauge element such that after every complete rotation of the rotatable element 65A, the output of a successive optical sensor in the array <NUM> changes. For instance, using the example described with reference to <FIG> and Table <NUM>, after the first complete rotation of the rotatable element 65A, the output of the first sensor <NUM>-<NUM> in the array <NUM> changes from LOW to HIGH. After the second rotation, the output of the second sensor <NUM>-<NUM> changes from LOW to HIGH. After the third complete rotation, the output of the third sensor <NUM>-<NUM> changes from LOW to HIGH and so on until the fifth complete rotation at which point the output of the fifth sensor <NUM>-<NUM> changes from LOW to HIGH. It will thus be appreciated that the signals output by the sensors of the array <NUM> can be used to determine the number of complete rotations.

The code <NUM> read by the sensing arrangement <NUM> is then used by the circuitry <NUM> to determine the extent of any partial rotations of the rotatable element 65A. The determined extent of partial rotation of the rotatable element 65A is then combined with the determined number of complete rotations to determine the currently dialled dose of the drug delivery device <NUM>. This determination is illustrated in Table <NUM> below:.

It will be understood that the accuracy of the sensor device <NUM> can be improved by increasing the accuracy with which partial rotations can be determined. For instance, in the above example, if quarter rotations (i.e. every <NUM> degrees) were instead identifiable, the circuitry <NUM> would be able to determine the dialled dose to an accuracy of <NUM>%. In embodiments with greater resolution of rotational position, e.g. to <NUM> degrees, the circuitry is able to determine a dialled or set dose of between zero and <NUM> units, corresponding to five rotations and <NUM> doses per rotation.

The sensor device <NUM> is configured to process signals provided by the further sensing arrangement <NUM> (or a still further sensing arrangement - not shown) to determine from inspection of the drug delivery device <NUM> in the vicinity of the further window <NUM> whether the drug delivery device <NUM> is in a dose setting mode or a dose delivery mode. In particular, the sensor device <NUM> is configured to determine a location, presence or absence of a part of a drive mechanism that is viewable through the further window <NUM>.

In particular, the further sensing arrangement <NUM> is arranged to have a field of view that encompasses all of or almost all of the area of the further window <NUM>. As such, the further sensing arrangement <NUM> views the scene shown in <FIG> when the drug delivery device <NUM> is in the dose setting mode. The scene may be viewed by the sensing arrangement <NUM> from the side, rather than directly as shown in the Figures. As can be seen from <FIG> and <FIG>, in the dose setting mode, the end of the number sleeve 15A, on which is provided the code <NUM>, occupies about half of the area of the further window <NUM>. The other half of the window permits observation of a drive screw <NUM>, which is shown at the top of <FIG>. The further sensing arrangement <NUM> views the scene shown in <FIG> when the drug delivery device <NUM> is in the dose delivery mode. As can be seen from <FIG> and <FIG>, in the dose delivery mode, the end of the number sleeve 15A, on which is provided the code <NUM>, still occupies about half of the area of the further window <NUM>. However, the other half of the window <NUM> permits observation of a drive sleeve <NUM>, which now resides at a location in the radial direction between the drive screw <NUM> and the further window <NUM>. Triggering of the button <NUM> causes the drive mechanism within the drug delivery device <NUM> to be activated. This results in movement of various components in a proximal direction, that is away from the button <NUM>. The drive sleeve <NUM> is one component that is moved in a proximal direction. In particular, the drive sleeve <NUM> has moved from a position in which it was substantially surrounded by the number sleeve 15A, at least in the vicinity of the further window <NUM>, to a position in which a proximal end of the drive sleeve <NUM> extends from the number sleeve 15A. In the extended position, the drive sleeve obstructs the view of the drive screw <NUM>, which is shown at the top of <FIG>, from the further window <NUM>. As such, when in the dose delivery mode, it is the number sleeve 15A and the drive sleeve <NUM>, rather than the drive rod <NUM> or other internal components of the drug delivery device <NUM>, that are viewable through the further window <NUM>. The viewability of the drive sleeve <NUM> is facilitated by a cut-out in a clutch. The drive screw <NUM> is not moved axially, but is rotated during drug delivery.

The drive sleeve <NUM> is configured so as to facilitate fast and reliable detection of its presence or absence in the window <NUM>. In particular, the drive sleeve <NUM> is provided with an appearance that contrasts in colour with surrounding parts, in particular the number sleeve 15A and any other parts that are visible through the further window <NUM>. For instance, the drive sleeve may be dark colour, for instance black, dark grey or dark blue, and the number sleeve (apart from the code <NUM>) and the other visible components may be a light colour, such as white or yellow. The other visible components may instead be substantially transparent. The internal components that are viewed through the window when the drive sleeve <NUM> is not present are a similar colour to the number sleeve 15A are a similar colour to and any components that are visible in both of the dose selecting and dose delivery modes. The contrast may be in the non-visible spectrum, for instance ultra-violet or infra-red. Contrast may be provided by providing different luminescence or reflectivity to different components. Different colours may be provided by material selection or by coating, such as printing, of either or both components <NUM>, 15A.

The circuitry <NUM> is configured to process signals provided by the further sensing arrangement <NUM> to determine the presence, absence or location of the drive sleeve <NUM> in the further window <NUM>. From this, the circuitry <NUM> determines that the drug delivery device is in the dose setting mode (if the drive sleeve <NUM> is absent) or is in the dose delivery mode (if the drive sleeve <NUM> is present). If the circuitry <NUM> determines that the drive sleeve <NUM> is partly present, the circuitry <NUM> may determine that the drug delivery device is transitioning between the dose delivery mode and the dose setting mode.

By providing the drive sleeve <NUM> in a colour that contrasts with the number sleeve 15A and other viewable components, the presence or absence of the drive sleeve <NUM> in the further window <NUM> can readily be determined by processing of the signals from the further sensing arrangement <NUM>.

Using knowledge of the mode of operation of the drug delivery device <NUM> and the set dose at different times, the circuitry <NUM> can determine the delivered dose. In a drug delivery device in which all of the set dose is delivered when the drive mechanism is activated, the dose is calculated as the set dose that was present at the time that the drug delivery device transitioned from the dose setting mode to the dose delivery mode. In a drug delivery device in which it is possible to deliver some (but not all) of a set dose, the dose is calculated as the set dose that was present at the time that the drug delivery device transitioned from the dose setting mode to the dose delivery mode minus the set dose that was present at the time that the drug delivery device subsequently transitioned from the dose delivery mode back to the dose setting mode.

<FIG> shows the profile of the further window <NUM>. An internal surface 63A of the further window <NUM> has a first profile. An external surface 63B of the further window <NUM> has a different profile.

The profiles of the surfaces 63A and 63B may be chosen to provide magnification, i.e. to provide the further window <NUM> with an optical power. This can improve effectiveness of the further sensing arrangement <NUM> and the circuitry <NUM> in determining the mode of operation of the drug delivery device <NUM> and the rotational position of the number sleeve 15A.

The profiles of the surfaces 63A and 63B may be chosen in addition or alternatively to divert the field of view of the sensing arrangement <NUM>, in particular in a longitudinal direction relative to the housing <NUM>, a lateral direction, or both.

The profiles of the surfaces 63A and 63B may be chosen in addition or alternatively to support parts internal to the drug delivery device <NUM>.

The profile of the internal surface 63A is rounded and further advantageously is circular, which provides better mechanical support for the number sleeve 15A.

The profile of the external surface 63B is flat, and is recessed from the outside of the housing <NUM>. This provides protection of the external surface 63B from abrasion.

Alternatively or additionally, the edges of the window <NUM> may be angled or roughened. This can allow illumination of the code <NUM> without reflecting light from an illuminating light source (not shown) to the further sensing arrangement <NUM>.

Because of geometric tolerances and free play between parts, the location of the code <NUM> relative to the further sensing arrangement <NUM> may vary between different devices produced by a manufacturing process. Where there is variation, it may be difficult to determine a difference between an image sensed by the sensing arrangement <NUM> for n units of drug on one device and an image for n+<NUM> units of drug on another device. This problem is ameliorated by the use of a reference mark <NUM>, as is shown in <FIG>. The reference mark <NUM> is located at the edge of the further window <NUM>. The reference mark <NUM> may be a protrusion which extends from the housing <NUM>. The reference mark <NUM> may be hidden from view in that it is not visible when the drug delivery device <NUM> is viewed side on. However, the reference mark <NUM> is visible to the sensing arrangement <NUM>, which views the scene in the further window <NUM> from the side of the window <NUM>.

An alternative arrangement for allowing the sensor device <NUM> to determine the number of rotations of the number sleeve from the initial position to the currently set dose will now be described with reference to <FIG>. Here, the gauge element <NUM> includes a number of marks, which are shown in this example on the exterior surface of the second part <NUM>-<NUM> of the gauge element <NUM>. The marks each extend generally parallel to the longitudinal axis of the drug delivery device <NUM>. However, the angular position varies for different marks. In particular, each mark is at a different angular position. The marks are spaced in the axial direction. The marks are at different angular positions at different axial positions.

The marks may be provided in visible ink. They may alternatively be provided in ink which is invisible, for instance ink which is visible only in infra-red or ultra-violet. This can allow the sensing arrangement <NUM> to detect the marks but without potentially confusing a user of the device <NUM>.

The sensing arrangement <NUM> is located so as to view the mark that is present at a certain axial position. By operating the circuitry <NUM> to determine the angular position of the mark, the axial position of the gauge element <NUM> can be determined to within the resolution of the length of the marks. By providing each of the the marks with a length that corresponds to one full rotation of the number sleeve 15A, the circuitry <NUM> can determine the number of rotations of the number sleeve from the initial position by detecting the angular position of the mark that is viewed by the sensing arrangement <NUM>.

Instead of lines, the marks on the gauge element may take the form of optically-readable codes, comprising encoded digital information.

Up until now, the composition of the sensor device <NUM> has been described at a relatively high level. <FIG>, <FIG> and <FIG> depict the sensor device <NUM> in more detail.

<FIG> is a simplified schematic block diagram of a sensor device <NUM> according to various embodiments. As described above, the sensor device <NUM> comprises the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM> which are configured to output signals to the circuitry <NUM>. The device <NUM> also comprises the further sensing arrangement <NUM> which is configured to output signals indicative of the encoded information to the circuitry <NUM>.

The circuitry <NUM> may be of any suitable composition and may comprise any combination of one or more processors and/or microprocessors <NUM> (for simplicity, hereafter referred to as "the at least one processor") suitable for causing the functionality described herein to be performed. The circuitry <NUM> may additionally or alternatively comprise any combination of one or more hardware-only components such as ASICs, FPGAs etc. (which are not shown in <FIG>).

The circuitry <NUM> may further comprise any combination of one or more non-transitory computer readable memory media <NUM>, such as one or both of ROM and RAM, which is coupled to the at least one processor <NUM>. The memory <NUM> may have computer-readable instructions 211A stored thereon. The computer readable instructions <NUM>, when executed by the at least one processor <NUM> may cause the sensor device <NUM> to perform the functionality described in this specification, such as controlling operation of the array <NUM> and sensing arrangement <NUM> and interpreting the signals received therefrom.

The further sensing arrangement <NUM> comprises at least a light source <NUM>-<NUM> and a photosensor <NUM>-<NUM>. The light source <NUM>-<NUM> is for illuminating the code <NUM> that is visible within the further window <NUM> formed in the device housing <NUM>, and for illuminating the drive sleeve <NUM> if it is viewable through the further window (i.e. if not obscured by the number sleeve 15A).

The photosensor <NUM>-<NUM> is configured to process an image (which includes the code <NUM>) which is visible to the photosensor (i.e. which underlies the photosensor). The image is detected by detecting the light reflected back from different parts of the surface(s) on which the image is provided. The image, including an image of the code <NUM>, is then passed to the circuitry <NUM>. The image is then processed by the circuitry <NUM> to determine the presence or absence of the drive sleeve <NUM>, and to determine therefrom whether the drug delivery device <NUM> is in the dose setting mode or the dose delivery mode. The image is processed also to determine the rotational position of the number sleeve 15A.

Instead of one photosensor <NUM>-<NUM>, separate sensors may be used for detecting the code <NUM> and for detecting the presence or absence of the drive sleeve <NUM>.

The sensing arrangement <NUM> may comprise further non-electrical components, which are not shown on <FIG>. These non-electrical components of the sensing arrangement <NUM> are described with reference to <FIG>.

The sensor device <NUM> may further comprise one or both of a display screen <NUM> (such as an LED or LCD screen) and a data port <NUM>. The display screen <NUM> may be operable under the control of the circuitry <NUM> to display information regarding operation of the drug delivery device <NUM> to the user. For instance, the dialled dose determined by the sensor device <NUM> may be displayed to the user. Other information which can be determined by the sensor device <NUM> includes the drug being dispensed, and/or a history of previously-dispensed doses.

The data port <NUM> may be used to transfer stored information relating to the operation of the drug delivery device <NUM> from the memory <NUM> to a remote device such a PC, tablet computer, or smartphone. Similarly, new software/firmware may be transferred to the sensor device via the data port <NUM>. The data port <NUM> may be a physical port such as a USB port or may be a virtual, or wireless, port such as an IR, WiFi or Bluetooth transceiver.

The sensor device <NUM> may further comprise a removable or permanent (preferably rechargeable with e.g. photovoltaic cells) battery <NUM> for powering the other components of the device <NUM>. Instead of the battery <NUM>, a photovoltaic or capacitor power source may be used. Other electrical components which are not shown in <FIG>, but which may nonetheless be included in the sensor device <NUM> include a trigger buffer <NUM>-<NUM>, a regulator <NUM>-<NUM>, a voltage suppressor <NUM>-<NUM> and a charger chip <NUM>-<NUM>, for charging the rechargeable battery if present.

<FIG> shows an example of a physical arrangement of the components of the sensor device of <FIG>. The optical sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> are arranged on a first surface of a PCB <NUM>-<NUM> in a way that is determined by the shape of the visible path of the movable element <NUM> with which the sensor device <NUM> is designed to be used. In the examples described herein, the visible path is linear and, consequently, the optical sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> are linearly arranged on the PCB <NUM>-<NUM>. When the sensor device <NUM> is attached to the drug delivery device <NUM>, the first surface of the PCB <NUM>-<NUM> faces the at least one window 13A, 13B of the drug delivery device <NUM>.

One or more of: the light source <NUM>-<NUM> of the sensor arrangement <NUM>, the at least one processor <NUM>, the memory <NUM>, the charger chip <NUM>-<NUM>, the voltage suppressor <NUM>-<NUM>, the regulator <NUM>-<NUM> and the trigger buffer <NUM>-<NUM> may also be provided on the first surface of the PCB <NUM>-<NUM>.

The screen or display <NUM> is provided on the opposite side of the PCB to the <NUM>-<NUM> to the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM>, such that it is visible to the user when the sensor device <NUM> is attached to the drug delivery device <NUM>. The sensor device <NUM> may be configured so as to extend over the entire area of the at least one window 13A, 13B such that the at least one window 13A, 13B is not visible to the user when the sensor device <NUM> is attached.

The photosensor <NUM>-<NUM> of the sensing arrangement <NUM> may not be provided on the PCB <NUM>-<NUM>. Instead, the photosensor <NUM>-<NUM> may be provided on a support element <NUM>-<NUM> which extends from the PCB <NUM>-<NUM>. In the example of <FIG>, the support element <NUM>-<NUM> extends perpendicularly from the PCB, such that when it is attached to the drug delivery device <NUM>, it wraps around a side of the device <NUM>.

As will be appreciated the exact physical arrangement of the components within the sensor device <NUM> may not be crucial as long as, when the sensor device <NUM> is attached to the drug delivery device <NUM>, the array <NUM> of optical sensors is aligned with and faces the visible path of the movable element <NUM>. In embodiments including the further sensing arrangement <NUM>, it may also be important that the photosensor <NUM>-<NUM> of the sensing arrangement <NUM> is positioned so as to overlie further window <NUM> formed in the housing <NUM> of the drug delivery device <NUM>.

The sensing arrangement <NUM>, in this example, further comprises a light guide <NUM>-<NUM> for guiding the light from the light source <NUM>-<NUM> to the further window <NUM> of the drug delivery device <NUM>. The sensing arrangement <NUM> also comprises a lens array <NUM>-<NUM> for focussing on the photosensor <NUM>-<NUM> the light reflected back from the surface(s) underlying the photosensor <NUM>-<NUM>. Put another way, the lens array <NUM>-<NUM> is configured to focus the image, which is provided on the surface(s) underlying the photosensor <NUM>-<NUM>, on to the photosensor <NUM>-<NUM>.

<FIG> shows one embodiment of the sensor device <NUM>, without a housing, in position on the drug delivery device <NUM>. Although not shown, the sensor device <NUM> may be configured to be removably attached in position on the drug delivery device <NUM>. For instance, the housing (not shown) of the sensor device <NUM> may include a coupling mechanism for securely affixing the sensor device <NUM> to the drug delivery device <NUM>. Alternatively, any other means for securing the sensor device <NUM> in position on the drug delivery device <NUM> may be used.

As discussed above, the code <NUM> that is read by the sensing arrangement <NUM> may include a portion of a code <NUM> for enabling the circuitry to determine the rotational orientation of the rotatable element 15A, 65A. However, in some embodiments, other operational information may alternatively or additionally be included in the code <NUM> that is read by the sensing arrangement. For instance, the code <NUM> may include a portion (for instance in the form of a bar code - not shown) for indicating the drug that is being delivered, in the sense of indicating the brand name or scientific name of the drug. The drug indication code portion (not shown) may be provided on, for instance, a portion of a drug cartridge that is inserted into the drug delivery device <NUM> and which is visible through the further window <NUM> and so can be read by the sensing arrangement <NUM>. Alternatively, it may be provided on a portion of the exterior of the delivery device housing <NUM> that is adjacent the further window <NUM> and which is also beneath (and so readable by) the photosensor <NUM>-<NUM> of the sensing arrangement <NUM> when the sensor device <NUM> attached to the drug delivery device <NUM>.

In some embodiments, the sensor device <NUM> is configured to store a history of dispensed drug doses. This may be carried out by storing information indicative of the currently dialled dose, when a change from dialling mode to delivery mode is detected based on the mode indicator <NUM>. A timestamp indicative of a time at which the mode change occurred may also be stored in association with the information indicative of the dose. In addition or alternatively, information indicative of the type of the dispensed drug, which is determined based on the drug indication code portion <NUM>, may be stored in association with the dose information. This may be repeated each time a dose of a drug is dispensed.

Information about the type of drug may be determined in any suitable way. The type of drug may be indicated on the drug delivery device <NUM> by printing, etching or moulding. It may instead be indicated on a printed or etched label. Such markings can be read by the sensor device optically, either in the visible spectrum or in infrared or ultra-violet. Alternatively, the type of drug may be indicated electronically, e.g. on an RFID transponder or in some other wired or wireless memory device.

Although the drug delivery devices described herein include two windows 13A, 13B through which the movable gauge element <NUM> is visible, it will be appreciated (particularly from the discussions of <FIG>) that sensor devices <NUM> according to embodiments of the invention may be used with drug delivery devices <NUM> which include only one of these windows 13A, 13B.

Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles of the invention, the scope of which is defined in the claims.

Exemplary insulin derivatives are, for example, B29-N-myristoyl-des(B30) human insulin; B29-N-palmitoyl-des(B30) human insulin; B29-N-myristoyl human insulin; B29-N-palmitoyl human insulin; B28-N-myristoyl LysB28ProB29 human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin; B30-N-myristoyl-ThrB29LysB30 human insulin; B30-N-palmitoyl- ThrB29LysB30 human insulin; B29-N-(N-palmitoyl-gamma-glutamyl)-des(B30) human insulin; B29-N-(N-lithocholyl-gamma-glutamyl)-des(B30) human insulin; B29-N-(ω-carboxyheptadecanoyl)-des(B30) human insulin and B29-N-(ω-carboxyhepta¬decanoyl) human insulin. Exemplary GLP-<NUM>, GLP-<NUM> analogues and GLP-<NUM> receptor agonists are, for example: Lixisenatide / AVE0010 / ZP10 / Lyxumia, Exenatide / Exendin-<NUM> / Byetta / Bydureon / ITCA <NUM> / AC-<NUM> (a <NUM> amino acid peptide which is produced by the salivary glands of the Gila monster), Liraglutide / Victoza, Semaglutide, Taspoglutide, Syncria / Albiglutide, Dulaglutide, rExendin-<NUM>, CJC-<NUM>-PC, PB-<NUM>, TTP-<NUM>, Langlenatide / HM-11260C, CM-<NUM>, GLP-<NUM> Eligen, ORMD-<NUM>, NN-<NUM>, NN-<NUM>, NN-<NUM>, Nodexen, Viador-GLP-<NUM>, CVX-<NUM>, ZYOG-<NUM>, ZYD-<NUM>, GSK-<NUM>, DA-<NUM>, MAR-<NUM>, MAR709, ZP-<NUM>, ZP-<NUM>, TT-<NUM>, BHM-<NUM>. MOD-<NUM>, CAM-<NUM>, DA-<NUM>, ARI-<NUM>, ARI-<NUM>, Exenatide-XTEN and Glucagon-Xten.

Acid addition salts are e.g. HCI or HBr salts.

Claim 1:
A sensor device (<NUM>) removably attachable to a drug delivery device (<NUM>), the sensor device comprising:
a sensing arrangement (<NUM>) arranged within the sensor device; and
circuitry (<NUM>) configured to process signals provided by the sensor arrangement,
wherein the sensing arrangement is configured such that, when the sensor device is attached to the drug delivery device, the sensing arrangement is operable to read encoded information present on a rotatable component (15A) that is internal to the drug delivery device and that is able to be sensed through a window or aperture (<NUM>) of the drug delivery device, and is operable to sense through the window or aperture the presence or absence of at least a part (<NUM>) of a drive mechanism of the drug delivery device, wherein the circuitry is configured:
to determine, based on the encoded information, information relating to a set dose, and
to determine, based on sensing the presence or absence of the part of the drive mechanism, information relating to whether the drug delivery device is in a dose setting mode or whether the device is in a dose delivery mode.