# Patent

## Title
Sensor device with OLED

## Abstract

A sensor device configured to be attached to a drug delivery device and configured to illuminate the drug delivery device when attached, the sensor device having an OLED having a transparent first electrode, a transparent second electrode and a central layer disposed between the first and second electrodes, the central layer comprising at least one organic layer, the at least one organic layer configured to emit light through the transparent first electrode, and an optical sensor arranged to receive light reflected from a surface of the drug delivery device, wherein the central layer of the OLED has a region without the at least one organic layer and wherein the optical sensor is arranged, when the sensor device is attached to the drug delivery device, to view a predetermined area of the surface of the drug delivery device through the region without the at least one organic layer.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a U.S. National Phase Application pursuant to 35 U.S.C. §371 of International Application No. PCT/EP2014/057785 filed Apr. 16, 2014, which claims priority to European Patent Application No. 13164752.1 filed Apr. 22, 2013. The entire disclosure contents of these applications are herewith incorporated by reference into the present application.
TECHNICAL FIELD
The present invention relates to a sensor device for attachment to a drug delivery device, where the sensor device contains an OLED.
BACKGROUND
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-1 and type-2 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 a dosage knob and observing the actual dose from a dose window, dose number indicator, 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.
SUMMARY
A first aspect of the invention provides a sensor device configured to be attached to a drug delivery device and configured to illuminate the drug delivery device when attached, the sensor device comprising:

    
    
        an OLED having a transparent first electrode, a transparent second electrode and a central layer disposed between the first and second electrodes, the central layer comprising at least one organic layer, the at least one organic layer configured to emit light through the transparent first electrode; and
        an optical sensor arranged to receive light reflected from a surface of the drug delivery device, wherein the central layer of the OLED has a region without the at least one organic layer and wherein the optical sensor is arranged, when the sensor device is attached to the drug delivery device, to view a predetermined area of the surface of the drug delivery device through the region without the at least one organic layer.
    
    


The use of an OLED to produce diffuse light is advantageous as the diffuse light which is emitted from the first electrode provides even illumination of the surface of the drug delivery device which is to be imaged by the optical sensor. Reflections, bright spots and distortions which may hamper the image taking process are reduced or eliminated by the use of the OLED.
The first electrode may be an anode and the second electrode may be a cathode. Alternatively, the OLED may have a top emitting structure in which the positions of the anode and cathode are reversed.
The sensor device may further comprise a reflective backing layer adjacent the second electrode configured to reflect any light which escapes the OLED through the second electrode back into the OLED. This increases the illumination efficiency of the OLED and consequently the power efficiency of the sensor device.
The region without the at least one organic layer may comprise a transparent material. This allows the shape of the light emitting part of the OLED to be controlled. The optical sensor is also able to clearly view the surface of the drug delivery device through the transparent material while light within the OLED can pass through the material and be reflected internally.
The region without the at least one organic layer may comprise a hole in the central layer and the OLED may comprise corresponding holes in the first and second electrodes such that a hole is formed through the body of the OLED. No visual distortion of the capture images results when the optical sensor views the drug delivery device through this hole.
The sensor device may further comprise a lens assembly configured to focus light reflected from a surface of the drug delivery device onto the optical sensor. This may reduce the technical requirement of the optical sensor and allow a cheaper sensor to be used. The lens assembly may be disposed in the hole in the OLED such that a first end of the lens assembly is the same or a smaller distance from the surface of the drug delivery device than the first electrode. This may result in a space saving within the sensor device and/or reduce the cost and complexity of the optical elements in the lens assembly. This arrangement may also allow a lower level of illumination to be used as the lens assembly and optical sensor are closer to the surface of the drug delivery device. Unwanted distortion and reflection effects may also be mitigated by placing the lens assembly closer to the drug delivery device.
The sensor device may further comprise a processor configured to receive light intensity signals from the sensor and to perform an optical character recognition process on the received signals to determine a number present on the surface of the drug delivery device. The processor may be further configured to determine an amount of medicament programmed into the drug delivery device and to cause the amount of medicament to be displayed on a display device of the drug delivery device.
The OLED may be curved. The OLED may be substantially concentric with the surface of the drug delivery device. The curvature of the OLED may be such that when the sensor device is attached to the drug delivery device, the light emitting surface (first electrode) of the OLED and the surface of the drug delivery device are concentric or substantially concentric. The second electrode of the OLED may also be concentric or substantially concentric with the surface of the drug delivery device. Thus, the distance between the light emitting surface and the light reflecting surface is approximately constant across the field of view of the optical sensor. This results in a more homogeneous illumination of the drug delivery device.
The OLED may further comprise one or more brightness enhancing layers. These act to increase the illumination efficiency of the OLED and consequently increase the power efficiency of the sensor device.
The drug delivery device may be a pen type injection device and the surface of the drug delivery device may be a cylindrical surface.
A second aspect of the invention provides a system comprising the sensor device of the first aspect and a drug delivery device configured to be attached to the sensor device.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings.



BRIEF DESCRIPTION OF THE FIGURES
The figures show:
FIG. 1a: an exploded view of an drug delivery device;
FIG. 1b shows a perspective view of some detail of the drug delivery device of FIG. 1;
FIG. 2a: a schematic illustration of a sensor device to be releasably attached to the drug delivery device of FIG. 1 according to an aspect of the present invention;
FIG. 2b: a perspective view of a sensor device to be releasably attached to the drug delivery device of FIG. 1 according to various aspects of the present invention;
FIG. 2c: a perspective view of a sensor device to be releasably attached to the drug delivery device of FIG. 1 according to other aspects of the present invention;
FIG. 3: a schematic view of a sensor device attached to a drug delivery device showing components of the sensor device;
FIG. 4: an exploded view of some components of the sensor device according to embodiments of the invention;
FIG. 5a: a schematic cross-sectional view of parts of the sensor device and drug delivery device according to embodiments of the invention;
FIG. 5b: a schematic cross-sectional view of parts of the sensor device and drug delivery device according to further embodiments of the invention;
FIG. 6: a plan view of an organic LED suitable for use in embodiments of the present invention
FIG. 7: an exploded view of some components of the sensor device according to embodiments of the invention;
FIG. 8: a schematic cross-sectional view of parts of the sensor device and drug delivery device according to further embodiments of the invention;
FIG. 9: a flowchart of a method used in various aspects.



DETAILED DESCRIPTION
In the following, embodiments of the present invention will be described with reference to an insulin injection device. The present invention is however not limited to such application and may equally well be deployed with injection devices that eject other medicaments, or with other types of medical devices as well as with other types of transcutaneous drug delivery devices and methods.
FIG. 1a is an exploded view of a drug delivery device 1, which may for instance represent Sanofi's Solostar (R) insulin injection pen. The drug delivery device 1 of FIG. 1 is a pre-filled, disposable injection pen that comprises a housing 10 and contains an insulin container 14, to which a needle 15 can be affixed. The needle is protected by an inner needle cap 16 and an outer needle cap 17, which in turn can be covered by a cap 18. An insulin dose to be ejected from drug delivery device 1 can be selected by turning the dosage knob 12, and the selected dose is then displayed via dosage window 13, for instance in multiples of so-called International Units (IU), wherein one IU is the biological equivalent of about 45.5 micrograms of pure crystalline insulin (1/22 mg). An example of a selected dose displayed in dosage window 13 may for instance be 30 IUs, as shown in FIG. 1a. It should be noted that the selected dose may equally well be displayed differently, for instance by means of an electronic display or any other type of dose number indicator
FIG. 1b is a perspective view of the dosage knob 12 end of the drug delivery device 1. Turning the dosage knob 12 causes a mechanical click sound to provide acoustical feedback to a user. The numbers displayed in dosage window 13 are printed on a sleeve that is contained in housing 10 and mechanically interacts with a piston in insulin container 14. When needle 15 is stuck into a skin portion of a patient, and then injection button 11 is pushed, the insulin dose displayed in display window 13 will be ejected from drug delivery device 1. When the needle 15 of drug delivery device 1 remains for a certain time in the skin portion after the injection button 11 is pushed, a high percentage of the dose is actually injected into the patient's body. Ejection of the insulin dose also causes a mechanical click sound, which is however different from the sounds produced when using dosage knob 12.
The housing 10 of the drug delivery device 1 may comprise locator features, such as one or more protrusions 70 and/or one or more indentations 52. These locator features allow a sensor device (described below) to be releasably attached to the drug delivery device 1 in an accurate predetermined position.
Drug delivery device 1 may be used for several injection processes until either insulin container 14 is empty or the expiration date of drug delivery device 1 (e.g. 28 days after the first use) is reached. Furthermore, before using drug delivery device 1 for the first time, it may be necessary to perform a so-called “prime shot” to remove air from insulin container 14 and needle 15, for instance by selecting two units of insulin and pressing injection button 11 while holding drug delivery device 1 with the needle 15 upwards.
For simplicity of presentation, in the following, it will be exemplarily assumed that the ejected doses substantially correspond to the injected doses, so that, for instance when making a proposal for a dose to be injected next, this dose equals the dose that has to ejected by the drug delivery device. Nevertheless, differences (e.g. losses) between the ejected doses and the injected doses may of course be taken into account.
FIG. 2a is a schematic illustration of an embodiment of a sensor device 2 to be releasably attached to drug delivery device 1 of FIG. 1. The sensor device 2 may also be referred to herein as a supplementary device 2 as it is provided in addition to the drug delivery device and supplements the features of the drug delivery device. Sensor device 2 comprises a housing 20 with a mating unit configured and embrace the housing 10 of drug delivery device 1 of FIG. 1, so that sensor device 2 sits tightly on housing 10 of drug delivery device 1, but is nevertheless removable from drug delivery device 1, for instance when drug delivery device 1 is empty and has to be replaced. FIG. 2a is highly schematic, and details of the physical arrangement are described below with reference to FIG. 2b. 
Sensor device 2 contains optical and optional acoustical sensors for gathering information from drug delivery device 1. Information is displayed via display unit 21 of sensor device 2. The dosage window 13 of drug delivery device 1 is obstructed by sensor device 2 when attached to drug delivery device 1. Sensor device 2 further comprises at least one input transducer, illustrated schematically as a button 22. These input transducers 22 allow a user to turn on/off sensor device 2, to trigger actions (for instance to cause establishment of a connection to or a pairing with another device, and/or to trigger transmission of information from sensor device 2 to another device), or to confirm something.
FIG. 2b is a schematic illustration of a second embodiment of a sensor device 2 to be releasably attached to drug delivery device 1 of FIG. 1. Sensor device 2 comprises a housing 20 with a mating unit configured and embrace the housing 10 of drug delivery device 1 of FIG. 1, so that sensor device 2 sits tightly on housing 10 of drug delivery device 1, but is nevertheless removable from drug delivery device 1. The mating unit may engage with protrusion 70 and/or with indentations 52.
Information is displayed via display unit 21 of sensor device 2. The dosage window 13 of drug delivery device 1 is obstructed by sensor device 2 when attached to drug delivery device 1. Sensor device 2 further comprises three user input buttons or switches. A first button 22 is a power on/off button, via which the sensor device 2 may for instance be turned on and off. A second button 33 is a communications button. A third button 34 is a confirm or OK button. The buttons 22, 33, 34 may be any suitable form of mechanical switch. These input buttons 22 allow a user to turn on/off sensor device 2, to trigger actions (for instance to cause establishment of a connection to or a pairing with another device, and/or to trigger transmission of information from sensor device 2 to another device), or to confirm something.
FIG. 2c is a schematic illustration of a third embodiment of a sensor device 2 to be releasably attached to drug delivery device 1 of FIG. 1. Sensor device 2 comprises a housing 20 with a mating unit configured and embrace the housing 10 of drug delivery device 1 of FIG. 1, so that sensor device 2 sits tightly on housing 10 of drug delivery device 1, but is nevertheless removable from drug delivery device 1.
Information is displayed via display unit 21 of the sensor device 2. The dosage window 13 of drug delivery device 1 is obstructed by sensor device 2 when attached to drug delivery device 1. Sensor device 2 further comprises a touch-sensitive input transducer 35. It also comprises a single user input button or switch 22. The button 22 is a power on/off button, via which the sensor device 2 may for instance be turned on and off. The touch sensitive input transducer 35 can be used to trigger actions (for instance to cause establishment of a connection to or a pairing with another device, and/or to trigger transmission of information from sensor device 2 to another device), or to confirm something.
FIG. 3 shows a schematic view of the sensor device 2 of FIG. 2a, 2b or 2c in a state where it is attached to drug delivery device 1 of FIG. 1.
A plurality of components are contained within the housing 20 of sensor device 2. The components of the sensor device 2 are controlled by a processor 24, which may for instance be a microprocessor, a Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA) or the like. Processor 24 executes program code (e.g. software or firmware) stored in a program memory 240, and uses a main memory 241, for instance to store intermediate results. Main memory 241 may also be used to store a logbook on performed ejections/injections. Program memory 240 may for instance be a Read-Only Memory (ROM), and main memory may for instance be a Random Access Memory (RAM).
In embodiments such as those shown in FIG. 2b, processor 24 interacts with a first button 22, via which sensor device 2 may for instance be turned on and off. A second button 33 is a communications button. The second button may be used to trigger establishment of a connection to another device, or to trigger a transmission of information to another device. A third button 34 is a confirm or OK button. The third button 34 can be used to acknowledge information presented to a user of sensor device 2. In embodiments such as those shown in FIG. 2c, two of the buttons 33, 34 may be omitted. Instead, one or more capacitive sensors or other touch sensors are provided.
Processor 24 controls a display unit 21, which is presently embodied as a Liquid Crystal Display (LCD). Display unit 21 is used to display information to a user of sensor device 2, for instance on present settings of drug delivery device 1, or on a next injection to be given. Display unit 21 may also be embodied as a touch-screen display, for instance to receive user input.
Processor 24 also controls an optical sensor 25, also referred to herein as an optical sensor assembly 25. In some embodiments the optical sensor is a photosensitive device, such as a camera, for capturing images of the dosage window 13, in which a currently selected dose is displayed (by means of numbers printed on the sleeve 19 contained in drug delivery device 1, which numbers are visible through the dosage window 13) and providing information on the captured images to processor 24. Then processor 24 may then perform an Optical Character Recognition (OCR) process on the captured images. In some other embodiments, the optical sensor 25 is embodied as an OCR reader, that is capable of capturing images and recognizing characters (e.g. numbers) from the captured image and to provide this information to processor 24.
Processor 24 also controls a light-source which is an organic light emitting diode (OLED) 29. The OLED 29 illuminates the dosage window 13 as described in detail below. Furthermore, the sensor device 2 may comprise a lens (e.g. an aspheric lens) arranged in front of the optical sensor 25, leading to a magnification (e.g. a magnification of more than 3:1). The sensor device 2 may also comprise a transparent protection window (not shown) on the underside. The protection window prevents the ingress of dust and dirt into the sensor device 2. The light sources may be configured to illuminate the dosage window 13 through this protection window and the optical sensor 25 views the dosage window 13 through the protection window.
Processor 24 may further control a photometer 26, that is configured to determine an optical property of the housing 10 of drug delivery device 1, for example a colour or a shading. The optical property may only be present in a specific portion of housing 10, for example a colour or colour coding of sleeve 19 or of an insulin container comprised within drug delivery device 1, which colour or colour coding may for instance be visible through a further window in housing 10 (and/or in sleeve 19). Information on this colour is then provided to processor 24, which may then determine the type of drug delivery device 1 or the type of insulin contained in drug delivery device 1 (e.g. SoloStar Lantus with purple colour and SoloStar Apidra with blue colour). Alternatively, a camera unit may be used instead of photometer 26, and an image of the housing, sleeve or insulin container may then be provided to processor 24 to determine the colour of the housing, sleeve or insulin container by means of image processing. Further, one or more light sources may be provided to improve reading of photometer 26. The light source may provide light of a certain wavelength or spectrum to improve colour detection by photometer 26. The light source may be arranged in such a way that unwanted reflections, for example by dosage window 13, are avoided or reduced. In an example embodiment, instead of or in addition to photometer 26, a camera unit may be deployed to detect a code (for instance a bar code, which may for instance be a one- or two-dimensional bar code) related to the drug delivery device and/or the medicament contained therein. This code may for instance be located on the housing 10 or on a medicament container contained in drug delivery device 1, to name but a few examples. This code may for instance indicate a type of the drug delivery device and/or the medicament, and/or further properties (for instance a expiration date). The photometer 26 is an optional feature and may be omitted form the sensor device 2.
Processor 24 may further control (and/or receive signals from) an acoustic sensor 27, which is configured to sense sounds produced by drug delivery device 1. Such sounds may for instance occur when a dose is dialled by turning dosage knob 12 and/or when a dose is ejected/injected by pressing injection button 11, and/or when a prime shot is performed. These actions are mechanically similar but nevertheless sound differently (this may also be the case for electronic sounds that indicate these actions). Either the acoustic sensor 27 and/or processor 24 may be configured to differentiate these different sounds, for instance to be able to safely recognize that an injection has taken place (rather than a prime shot only). The acoustic sensor 27 is an optional feature and may be omitted form the sensor device 2.
Processor 24 may further control an acoustical signal generator 23, which is configured to produce acoustical signals that may for instance be related to the operating status of drug delivery device 1, for instance as feedback to the user. For example, an acoustical signal may be launched by acoustical signal generator 23 as a reminder for the next dose to be injected or as a warning signal, for instance in case of misuse. Acoustical signal generator may for instance be embodied as a buzzer or loudspeaker. In addition to or as an alternative to acoustical signal generator 23, also a haptic signal generator (not shown) may be used to provide haptic feedback, for instance by means of vibration. The acoustical signal generator 23 is an optional feature and may be omitted form the sensor device 2.
Processor 24 may control a wireless unit 28, which is configured to transmit and/or receive information to/from another device in a wireless fashion. Such transmission may for instance be based on radio transmission or optical transmission. In some embodiments, the wireless unit 28 is a Bluetooth transceiver. Alternatively, wireless unit 28 may be substituted or complemented by a wired unit configured to transmit and/or receive information to/from another device in a wire-bound fashion, for instance via a cable or fibre connection. When data is transmitted, the units of the data (values) transferred may be explicitly or implicitly defined. For instance, in case of an insulin dose, always International Units (IU) may be used, or otherwise, the used unit may be transferred explicitly, for instance in coded form. In some other embodiments, no means for removing data from the sensor device 2 are provided.
Processor 24 receives an input from a pen detection switch 30, which is operable to detect whether the pen 1 is present, i.e. to detect whether the sensor device 2 is coupled to the drug delivery device 1. The pen detection switch 30 is an optional feature. A battery 32 powers the processor 24 and other components by way of a power supply 31.
The sensor device 2 of FIG. 3 is thus capable of determining information related to a condition and/or use of drug delivery device 1. This information is displayed on the display 21 for use by the user of the device. The information may be either processed by sensor device 2 itself, or may at least partially be provided to another device (e.g. a blood glucose monitoring system).
The processor 24 constitutes a processor arrangement. The optical sensor/OCR reader 25 and the processor 24 together constitute a dose dialled detector operable to detect a dose of medicament dialled and may also constitutes a dose delivery determiner for determining that a dose of medicament has been delivered and the quantity of the delivered dose. The processor 24 provides a function of a clock configured to determine a current time.
FIG. 4 is an exploded view of some components of the sensor device 2 according to embodiments of the invention, including the optical sensor 25 and OLED 29 parts. The optical sensor 25 may be a matrix sensor comprising an array of light sensitive elements each capable of measuring the intensity of incident light. The matrix sensor may be a monochrome sensor. The optical sensor 25 is mounted on a printed circuit board (PCB) 401.
A lens assembly 400 may be mounted in front of the optical sensor 25. The focus of the lens assembly 400 may be adjustable. For example, the lens assembly 400 may be provided in two parts which are threadably engaged such that rotation of one part causes movement of an optical element along an optical axis. Both the lens assembly 400 and optical sensor 25 may be mounted on the same PCB 401. The lens assembly 400 may provide magnification of incident light onto the optical sensor 25. In some embodiments a lens assembly 400 is not needed and can be omitted.
FIG. 4 also shows an internal carrier member 402 located between the optical sensor 25 and the OLED 29. The internal carrier member 402 may serve several purposes, such as to protect and support the PCB 401, optical sensor 25, lens assembly 400 and other hardware components of the sensor device 2. The internal carrier member 402 may also ensure correct separation distance between the optical sensor 25 and external housing 20 of the sensor device 2 and block any light from reaching the optical sensor 25 directly from the OLED 29. The internal carrier member 402 has a hole arranged to receive the lens assembly 400 (if present) and to allow light reflected from the surface of the drug delivery device 1 to enter the sensor device 2 and be received by the optical sensor 25.
The OLED 29 is constructed from a transparent material. The OLED 29 comprises a first electrode 405, a second electrode 406 and a central layer 408 located between the first and second electrodes 405, 406. All of these layers are transparent to visible light. The OLED 29 may also comprise a substrate (not shown). In some embodiments, the first electrode 405 is the anode and the second electrode 406 is the cathode. The central layer 408 is comprised of one or more layers of organic semiconductor. In some embodiments, the central layer 408 comprises a conductive layer and an emissive layer. In some other embodiments, one or more additional organic semiconductor layers may be interposed between the conductive and emissive layers. This may be done to alter the electronic profile of the central layer 408. In yet further embodiments, the central layer 408 may comprise a single organic layer which is a graded heterojunction. In any case, the central layer 408 is so arranged that when a voltage is applied across the electrodes 405, 406, recombination in the central layer 408 causes light to be emitted from the central layer.
When the sensor device 2 is attached to the drug delivery device 1 and is in use, light is emitted from the central layer 408, through the transparent first electrode 405 and out towards the surface of the drug delivery device. As the second electrode 406 is also transparent, light is also emitted out through the second electrode towards the internal carrier member 402. In some embodiments, a reflective layer 404 may be disposed between the second electrode 406 and the internal carrier member 402. The reflective layer 404 may be a mirror foil. This reflective layer 404 ensures that light which escapes the OLED 29 through the second electrode 406 is reflected back into the OLED so that it can be emitted through the first electrode 405. In some embodiments, the reflective layer 404 may be the substrate onto which the OLED 29 is formed. The reflective layer 404 has a hole aligned with the hole in the internal carrier member 402 in order to allow light reflected from the surface of the drug delivery device 1 to enter the sensor device 2 and be received by the optical sensor 25. In some other embodiments, the reflective layer 404 may be adhered to the internal carrier member 402 or the internal carrier member 402 may be coated with a reflective layer. The reflective layer 404 is an optional feature which may be omitted.
The central layer 408 of the OLED 29 comprises a region 37 without any organic semiconductor layers. This region 37 is arranged underneath the holes in the internal carrier member 402 and reflective layer 404 (if present) so as to be aligned with the lens assembly 400 (if present) and optical sensor 25. As this region 37 does not have any organic semiconductor layers, no light is emitted from this region. The region 37 may be made of any transparent material, such as a plastic, which is preferably an insulator (non-conducting). In some other embodiments, the region 37 without any organic semiconductor layers comprises a hole extending through the body of the OLED 29, i.e. through the first electrode 405, second electrode 406, and central layer 408. Although the OLED 29 is transparent, providing a region 37 which does not emit light and through which the optical sensor 25 views the drug delivery device 1 avoids the sensor 25 being saturated by the emitted light, which would prevent the sensor from obtaining a high contrast image of the surface of the drug delivery device. The region 37 without any organic semiconductor layers may be any suitable shape, such as square, rectangular (as shown in FIGS. 4 and 6), any other regular polygon, circular, oval or a mixture of straight and curved edges.
One or more brightness enhancing films (not shown) may be provided, for example as a layer deposited on the first electrode 405 or on the second electrode 406. The brightness enhancing films may be, for example prism films or reflective films. These may increase the output brightness of the OLED 29 and/or reduce the power consumption of the sensor device 2 for a given brightness. One or more diffuser foils may also be provided to increase the homogeneity of the output light and therefore the homogeneity of the illumination of the drug delivery device 1. Alternatively a single film which both enhances brightness and causes diffusion of the light may be provided.
A number of different arrangements of the OLED 29 and region 37 without any organic semiconductor layers may be used, as will now be described with reference to FIGS. 5A to 9. In these Figures, like numerals are used for like parts, and these parts are not described again in detail.
FIG. 5A is a schematic cross-section view showing an arrangement similar to that of FIG. 4. The internal carrier member 402, reflective layer 404 and other components are omitted for clarity. FIG. 5A shows the optical sensor 25 and lens assembly 400 positioned above the OLED 29. The OLED 29 of FIG. 5A is constructed of planar layers and has upper and lower surfaces which are flat and parallel to each other. The region 37 without any light out-coupling structure is located directly underneath the lens assembly 400.
Diffuse light is emitted from the regions of the central layer 408 of the OLED 29 having the organic semiconductor layers when a voltage is applied across the electrodes 405, 406. This light passes through the dosage window 13 and illuminates the number sleeve 19 of the drug delivery device 1. Light reflected from the number sleeve 19 passed through the region 37 without any organic semiconductor layers, through the lens assembly 400 and is received by the optical sensor 25. The optical sensor 25 then sends signals to the processor 24.
FIG. 5B shows another embodiment of the sensor device 2 in which the OLED 29 is curved. Unlike other light emitting structures, OLEDs can readily be manufactured to be flexible. Having a curved OLED 29 increases the evenness of the illumination of the number sleeve 19, as the number sleeve has a cylindrical surface. Having a curved OLED 29 also reduces reflections from the dosage window 13 and protection window (if present), therefore increasing the efficiency of the illumination and preventing the occurrence of bright spots which may impair the capturing of a high quality image by the optical sensor 25. Preferably, the curvature of the OLED 29 is such that it is concentric with the number sleeve 19 and/or dosage window 13 when the sensor device 2 is attached to the drug delivery device 1.
FIG. 6 is a plan view of an OLED 29 suitable for use in embodiments of the present invention. The central layer 408 of the OLED 29 comprises one or more organic semiconductor layers, represented by dots. A rectangular region 37 without any organic semiconductor layers is provided approximately centrally in the OLED 29. This region 37 may comprise a transparent material. The optical properties of the region 37, such as the refractive index and opacity may be chosen based on the optical sensor 25, lens assembly 400 and other components so as to allow the optical sensor 25 to capture a high quality, high contrast image of the number sleeve 19. In some other embodiments, this region 37 comprises a hole extending through the whole body of the OLED 29, i.e. the region 37 is comprised of air. Although a rectangular region 37 is shown, any suitable shape may be used, such as square, any other regular polygon, circular, oval or a mixture of straight and curved edges. The OLED 29 of FIG. 6 may be a planar film, or may be curved as shown in FIGS. 5A and 5B respectively.
FIG. 7 is an exploded view of some components of the sensor device 2 according to embodiments of the invention. FIG. 7 comprises the same components as described above with reference to FIG. 4. The OLED 29 shown in FIG. 7 has a region 37 without any light out-coupling structure which is comprised of a hole in the OLED. Providing a hole 37 in the OLED 29 has advantages over the transparent region shown in FIG. 4, in that there is zero distortion of the reflected light which passes through the hole 37. However, using a transparent piece of material for the region 37 may increase the efficiency of the illumination as light can propagate through and undergo total internal reflection within this region 37. Thus the power requirements of the sensor device 2 may be reduced while providing the same illumination brightness relative to a OLED with a hole.
FIG. 8 shows in schematic cross-section a further embodiments of the sensor device 2. In FIG. 8, the hole in the OLED 29 is large enough to accommodate the lens assembly 400. This may result in a space saving within the sensor device 2 and/or reduce the cost and complexity of the optical elements in the lens assembly. This arrangement may also allow a lower level of illumination to be used as the lens assembly 400 and optical sensor 25 are closer to the surface of the number sleeve 19. Unwanted distortion and reflection effects produced by the dosage window 13 and by the protection window (if present) may also be mitigated by placing the lens assembly 400 and optical sensor 25 closer to the window 13.
FIG. 9 is a flowchart 900 of a method in which the present invention is embodied. In step 901, a user attaches the sensor device 2 to the drug delivery device 1. The pen detection switch 30 (if present) detects that the sensor device 2 has been attached to the drug delivery device 1. This may cause the sensor device 2, including the OLED 29, to be powered on. Alternatively, or if the detect switch 30 is not present, the user presses the power button 22 to switch the sensor device on. At this time the OLED 29 and optical sensor 25 are also powered on (step 902).
The processor 24 of sensor device 2 may then execute a program stored in program memory 240 to determine a dose which is dialled into the drug delivery device 1 to which the sensor device is attached.
In a step 903, a sub-image is captured by an optical sensor such as optical sensor 25 of sensor device 2. The captured sub-image is for instance an image of at least a part of the dosage window 13 of drug delivery device 1, in which a currently selected dose is displayed (e.g. by means of numbers and/or a scale printed on the sleeve 19 of drug delivery device 1, which is visible through the dosage window 13). For instance, the captured sub-image may have a low resolution and/or only show a part of the part of sleeve 19 which is visible through dosage window 13. For instance, the captured sub-image either shows the numbers or the scale printed on the part of sleeve 19 of drug delivery device 1 which is visible through dosage window 13. The OLED 29 which causes illumination of the number sleeve 19 may be operated in a dimmer and therefore lower power mode for the purpose of sub-image capture. After capturing an image, it is, for instance, further processed as follows:

    
    
        Division by a previously captured background image;
        Binning of the image(s) to reduce the number of pixels for further evaluations;
        Normalization of the image(s) to reduce intensity variations in the illumination;
        Sheering of the image(s); and/or
        Binarization of the image(s) by comparing to a fixed threshold.
    
    


Several or all of these steps may be omitted if applicable, for instance if a sufficiently large optical sensor (e.g. a sensor with sufficiently large pixels) is used.
In a step 904, it is determined whether or not there is a change in the captured sub-image. For instance, the currently captured sub-image may be compared to the previously captured sub-image(s) in order to determine whether or not there is a change. Therein, the comparison to previously captured sub-images may be limited to the sub-image of the previously captured sub-images that was captured immediately before the current sub-image was captured and/or to the sub-images of the previously captured sub-images that were captured within a specified period of time (e.g. 0.1 seconds) before the current sub-image was captured. The comparison may be based on image analysis techniques such as pattern recognition performed on the currently captured sub-image and on the previously captured sub-image. For instance, it may be analyzed whether the pattern of the scale and/or the numbers visible through the dosage window 13 and shown in the currently captured sub-image and in the previously captured sub-image is changed. For instance, it may be searched for patterns in the image that have a certain size and/or aspect ratio and these patterns may be compared with previously saved patterns. Steps 903 and 904 may correspond to a detection of a change in the captured image.
If it is determined in step 904 that there is a change in the sub-image, step 903 is repeated. Otherwise in a step 905, an image is captured by an optical sensor such as optical sensor 25 of sensor device 2. The captured image is for instance an image of the dosage window 13 of drug delivery device 1, in which a currently selected dose is displayed (e.g. by means of numbers and/or a scale printed on the sleeve 19 of drug delivery device 1, which is visible through the dosage window 13). For instance, the captured image may have a resolution being higher than the resolution of the captured sub-image. The captured image at least shows the numbers printed on the sleeve 19 of drug delivery device 1 which are visible through the dosage window 13.
In a step 906, optical character recognition (OCR) is performed on the image captured in step 905 in order to recognize the numbers printed on the sleeve 19 of drug delivery device 1 and visible through the dosage window 13, because these numbers correspond to the (currently) selected dose. This step may be performed by the optical sensor 25 if it is so programmed, or alternatively the optical sensor 25 may send signals representing light intensity values to the processor 24 and the processor may then perform the OCR process. In accord to the recognized numbers, the selected dose is determined, for instance by setting a value representing the selected dose to the recognized numbers.
In a step 907, it is determined whether or not there is a change in the determined selected dose and, optionally, whether or not the determined selected dose does not equal zero. For instance, the currently determined selected dose may be compared to the previously determined selected dose(s) in order to determine whether or not there is a change. Therein, the comparison to previously determined selected dose(s) may be limited to the previously determined selected dose(s) that were determined within a specified period of time (e.g. 3 seconds) before the current selected dose was determined. If there is no change in the determined selected dose and, optionally, the determined selected dose does not equal zero, the currently determined selected dose is returned/forwarded for further processing (e.g. to processor 24).
Thus, the selected dose is determined if the last turn of the dosage knob 12 is more than 3 seconds ago. If the dosage knob 12 is turned within or after these 3 seconds and the new position remains unchanged for more than 3 seconds, this value is taken as the determined selected dose.
A standard drug delivery device 1, in particular an insulin device, may be connected with a blood glucose monitoring system in a useful and productive way. The sensor device 2 may provide this connection, assuming the blood glucose monitoring system has wireless or other communication capabilities. The benefits from the connection between the blood glucose monitoring and an insulin drug delivery device are inter alia the reduction of mistakes by the user of the drug delivery device and a reduction of handling steps—no more manual transfer of the injected insulin unit to a blood glucose monitoring is required, in particular to a blood glucose monitoring system with functionality of providing guidance for the next dose based on the last dose injected and latest blood glucose values.
As described with reference to exemplary embodiments above, when a user/patient gets a new insulin pen, the user attaches the sensor device 2 to the pen. The sensor device reads out the injected dose. It may also transfer it to a blood glucose monitoring system with insulin titration capabilities. For patients taking multiple insulins, the sensor device 2 recognizes the device structure to the insulin type and may also transmit this piece of information to the blood glucose monitoring system.
In example embodiments, the information shown on a display, for example LCD display 21 of FIGS. 2a-c and 3, may also be converted to a sound signal played to a user through a speaker, for example by a text-to-speech functionality implemented by processor 24 using the acoustical signal generator 23. Thus, a user with impaired vision may have improved access to the information of sensor device 2, such as a dialled dose, a recommended dose, a recommended time for administration and/or the like.
When using embodiments of the present invention, the user inter alia has the following advantages:
The user can use the most convenient disposable insulin injector.
The sensor device is attachable and detachable (reusable).
Injected dose information may be transferred to the blood glucose monitoring system automatically (no more transfer mistakes). Improved dose guidance may result from this as the blood glucose monitoring system calculates the dose to be taken.
Keeping of a manual data logbook may not be needed any more.
Furthermore, when deploying the sensor device proposed by the present invention, patients may also be reminded of injecting their next dose by receiving an alarm signal, for instance, after an appropriate time after a first dose of a medicament (for instance insulin or heparin) has been injected.
Injected dose information may be transferred to any computerized system, for instance as input for any dose calculation or any other applicable therapeutic guidance calculation, or for the creation of an alarm signal, for instance to remind the user of taking the next dose.

## Claims

1. A sensor device configured to be attached to a drug delivery device and configured to illuminate the drug delivery device when attached, the sensor device comprising:
an OLED having a transparent first electrode, a transparent second electrode and a central layer disposed between the first and second electrodes, the central layer comprising at least one organic layer, the at least one organic layer configured to emit light through the transparent first electrode; and
an optical sensor arranged to receive light reflected from a surface of the drug delivery device, wherein the central layer of the OLED has a region without the at least one organic layer and wherein the optical sensor is arranged, when the sensor device is attached to the drug delivery device, to view a predetermined area of the surface of the drug delivery device through the region without the at least one organic layer,
wherein the region without the at least one organic layer comprises a hole in the central layer and wherein the OLED comprises corresponding holes in the first and second electrodes such that a hole is formed through the body of the OLED; the sensor device further comprises a lens assembly configured to focus light reflected from a surface of the drug delivery device onto the optical sensor; and the lens assembly is disposed in the hole in the OLED such that a first end of the lens assembly is the same or a smaller distance from the surface of the drug delivery device than the first electrode.

2. A sensor device according to claim 1, wherein the first electrode is an anode and the second electrode is a cathode.

3. A sensor device according to claim 1, wherein the sensor device further comprises a reflective backing layer adjacent the second electrode configured to reflect any light which escapes the OLED through the second electrode back into the OLED.

4. A sensor device according to claim 1, wherein the region without the at least one organic layer comprises a transparent material.

5. A sensor device according to claim 1, wherein the sensor device further comprises a processor configured to receive light intensity signals from the sensor and to perform an optical character recognition process on the received signals to determine a number present on the surface of the drug delivery device.

6. A sensor device according to claim 5, wherein the processor is further configured to determine an amount of medicament programmed into the drug delivery device and to cause the amount of medicament to be displayed on a display device of the drug delivery device.

7. A sensor device according to claim 1, wherein the OLED is curved.

8. A sensor device according to claim 7, wherein the OLED is substantially concentric with the surface of the drug delivery device.

9. A sensor device according to claim 1, wherein the OLED further comprises one or more brightness enhancing layers.

10. A sensor device according to claim 1, wherein the drug delivery device is a pen type injection device and the surface of the drug delivery device is a cylindrical surface.

11. A system comprising the sensor device of claim 1 and a drug delivery device configured to be attached to the sensor device.