WO2020115240A1

WO2020115240A1 - Device for measuring fluid and method of use

Info

Publication number: WO2020115240A1
Application number: PCT/EP2019/083884
Authority: WO
Inventors: Liam MCMORROW; Peter Laitenberger
Original assignee: Adelie Health Limited
Priority date: 2018-12-05
Filing date: 2019-12-05
Publication date: 2020-06-11
Also published as: GB201819828D0

Abstract

A device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof. The device comprises a proximity sensor comprising one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus. The proximity sensor is operable to receive one or more signals from the, or each, electrode.

Description

l

Device for measuring fluid and method of use

Field of the invention The present invention relates to a device for measuring fluid and particularly, but not exclusively, a device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof. The present invention also relates to a system for measuring fluid, and a method of measuring fluid.

Background to the invention

Fluid transfer apparatuses, such as insulin pens, can be used by persons with health conditions, such as diabetes, to self-administer a dose of a drug, such as insulin. Such fluid transfer apparatuses are often provided with a protective cap to protect the applicator or injector of the pen, and to obviate the risk of injury to the user.

Because a user of the insulin pen is self-administering the drug or substance, often at different times of the day, it can be difficult for the user of the pen to accurately know when a dose was applied and what the applied dose was. This makes it difficult for a user to regulate the health condition effectively and efficiently. Furthermore, it is often difficult for the user to know how much fluid remains in the pen and thus how many doses, or units, remain therein. This increases the risk of the pen being devoid of fluid when the user intends to self-administer a dose of a drug or substance. It would be desirable to provide a device for tracking applied doses or units of a drug or substance, and for determining the remaining doses, within a fluid transfer apparatus. The inventor has appreciated the shortcomings in known apparatuses and devices.

According to a first aspect of the present invention there is provided a device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus; and

wherein the proximity sensor is operable to receive one or more signals from the, or each, electrode.

The device may comprise one or more proximity sensors.

The device may comprise a control device operable to control the proximity sensor.

The device may be a cap, lid, cover, or the like, configured to fit on, within, or around at least a part of the fluid transfer apparatus. The device may be configured to accommodate at least a part of the fluid transfer apparatus therein. The device may be configured to accommodate at least a part of the fluid reservoir therein. The device may be a partially cylindrical member. The device may be a substantially hollow member. The device may include an open end and a closed end. The device may comprise attachment means arranged to releasably attach the device to the fluid transfer apparatus. The attachment means may be a snap-fit connector, or the like. The device may be lockable to the fluid transfer apparatus. The device may be releasably attachable to the fluid transfer apparatus.

The fluid transfer apparatus may be a drug, or substance, delivery apparatus. The fluid transfer apparatus may be a drug, or substance, delivery pen, or the like.

The fluid transfer apparatus may be operable to apply, and/or inject, a fluid to a person. The fluid transfer apparatus may comprise applicator and/or injector means for applying and/or injecting fluid to a person. The injector means may include one or more needles, microneedles, or the like. The applicator and/or injector means may be arranged to be in fluid

communication with the fluid reservoir. The fluid transfer apparatus may be operable to transfer fluid from the fluid reservoir to the applicator means and/or injector means.

The fluid reservoir may comprise one or more chambers, compartments, conduits, vessels, containers, or the like. The fluid reservoir may be a substantially cylindrical member. The fluid reservoir may have a substantially circular cross section throughout its longitudinal axis. The fluid reservoir may comprise one or more curved wall portions. The fluid reservoir may be located at an end region of the fluid transfer apparatus. The fluid reservoir may be configured to receive fluid from a source of fluid. The fluid reservoir may be arranged to store fluid. The fluid transfer apparatus may be a portable apparatus. The fluid transfer apparatus may be a hand-operated fluid transfer apparatus. The device may be a portable device. The fluid transfer apparatus may be connectable to a source of fluid. The fluid transfer apparatus may comprise one or more fluids. The fluid may comprise one or more drugs, or substances. The fluid may comprise insulin. The fluid transfer apparatus may be an insulin delivery device, an insulin pen, or the like.

The fluid transfer apparatus may be configured to be pre-filled with the fluid. The fluid reservoir may comprise the fluid. The fluid reservoir may comprise an insulin solution. The fluid reservoir may be connectable to a source of insulin solution.

The device may be configured to at least partially shield the proximity sensor and/or the fluid reservoir from electromagnetic (EM) radiation or interference. The device may comprise one or more EM radiation or interference blocking elements. The device may be configured to at least partially shield the proximity sensor from extraneous electromagnetic fields. The device may be configured to at least partially shield the proximity sensor from electrostatic discharges. In this arrangement, the device is configured to at least partially shield the proximity sensor from electrostatic discharges caused by the user touching, or handling, the device and/or the fluid transfer apparatus. Furthermore, in this

arrangement, the device is configured to at least partially shield the proximity sensor from interference, such as parasitic capacitance (and other electrical parasitic effects) in the device. The proximity sensor may be operable to control the operation of the electrodes. The control device may be operable to control the operation of the electrodes. The device may be configured to apply an alternating, or alternating current (a.c.) electric field to the fluid reservoir. The device may be configured to apply an alternating, or alternating current (a.c.) electric field to the fluid reservoir or a part, or parts, thereof. The device may be configured to apply a static, or direct current (d.c.) electric field to the fluid reservoir. The device may be configured to apply an alternating, or a.c. electric field to the fluid reservoir and to simultaneously apply a static, or d.c. electric field to the fluid reservoir.

The proximity sensor may be arranged to be operable to detect the presence of fluid in the fluid reservoir. The proximity sensor may be an electronic sensor. The proximity sensor may be an electric field sensor. The one or more electrodes may be arranged to form a capacitive sensor element. The, or each, electrode may be arranged to be operable to apply a substantially non-uniform electric field to at least a part of the fluid reservoir.

The proximity sensor may be configured to detect changes in the capacitance of the, or each, electrode. The proximity sensor may be configured to detect changes in the capacitance between at least two electrodes.

The proximity sensor may be arranged, or located, on one or more substrates. The proximity sensor may be arranged, or located on one or more substantially planar substrates. The proximity sensor may be arranged, or located on one or more flexible substrates. The proximity sensor may be arranged, or located on one or more rigid substrates. The substrate may be a plastic substrate.

The, or each electrode may be located on one or more substrates and a part of the proximity sensor may be located on a different substrate or substrates. The proximity sensor may be arranged, or located on an inner surface of a wall portion of the device. The proximity sensor may be arranged, or located on a substantially planar wall portion of the device. The proximity sensor may be arranged, or located on a curved wall portion of the device. The proximity sensor and the device may be integrally formed. The proximity sensor and its substrate may be integrally formed. The proximity sensor may be formed on one or more printed circuit boards (PCBs). The proximity sensor may be formed on a PCB beatable on a wall portion of the device. The PCB may be attached to the wall portion of the device. The PCB may be attached to the wall portion of the device by way of an adhesive. The adhesive may be a glue, or the like. The PCB may be mountable to the device. The PCB may be mountable to a wall portion of the device. The PCB may be a flexible PCB. The PCB may be a rigid PCB. The, or each, electrode may be formed on one or more substrates using an additive manufacturing technique. The, or each, electrode may be formed on one or more substrates using a printing technique. The, or each, electrode may be a printed electrode. The, or each electrode, may be made from a metal material. The, or each, electrode, may be made from copper, or aluminium. The, or each, electrode may be formed, at least in part, by a plating process. The plating process may be electroplating, or the like.

The device may be formed, at least in part, by a moulding process. The device and the, or each, electrode may be integrally formed using a moulding process, or a co-moulding process. The device and the, or each, electrode may be integrally formed, at least in part, by using a plating process to form the, or each electrode on the device.

The, or each electrode may be a substantially planar element. The, or each, electrode may be arranged, or located, on one or more substrates. The, or each, electrode may be arranged on one or more substantially planar substrates. The, or each, electrode may be arranged, or located on one or more flexible substrates. The, or each, electrode may be arranged, or located on one or more rigid substrates. The substrate may be a plastic substrate. One or more of the electrodes may be located on a first substrate. One or more of the electrodes of the proximity sensor may be located on the first substrate and a part of the proximity sensor may be located on a second substrate. One or more of the electrodes of the proximity sensor may be located on the first substrate and the control device may be located on the second substrate.

The first and second substrates may be connected to each other. The first and second substrates may be connected to each other by a connecting member. The connecting member may be a flexible member. The connecting member may comprise electrical connections between one or more of the electrodes and a part of the proximity sensor. The first substrate may be an at least partially flexible substrate. The second substrate may be a rigid substrate. One or more of the electrodes of the proximity sensor may be located on a flexible substrate and a part of the proximity sensor may be located on a rigid substrate.

The, or each, electrode may be configured to be a flexible electrode. The, or each, electrode and the substrate on which it is located may be configured to be flexible.

The first substrate may be configurable between a planar configuration and an at least partially rolled configuration. In the planar configuration, the first substrate is substantially planar. In the at least partially rolled configuration, the shape of the first substrate may be substantially cylindrical, or at least partially cylindrical. In the at least partially rolled configuration, the shape of the first substrate may be configured to substantially match the shape of at least a part of the fluid transfer apparatus and/or the fluid reservoir of the fluid transfer apparatus.

The first substrate may be configured to have an at least partially cylindrical shape. The first substrate may include one or more alignment members configured to align the first substrate to the device. The device may comprise one or more alignment members configured to engage with the one or more alignment members of the first substrate. The alignment members may be one or more notches, cut-out portions, slots, or the like and one or more corresponding protrusions, tabs, raised portions, or the like.

The, or each, electrode may be located on an inner surface of a wall portion of the device. The, or each, electrode may be arranged on a substantially planar wall portion of the device. The, or each, electrode may be arranged on a curved wall portion of the device. The, or each, electrode and the device may be integrally formed. The, or each electrode and its substrate may be integrally formed. The, or each, electrode may be formed on a PCB. The, or each, electrode may be formed on a PCB beatable on a wall portion of the device. The PCB may be attached to the wall portion of the device. The PCB may be attached to the wall portion of the device by way of an adhesive. The adhesive may be a glue, or the like. The PCB may be mountable to the device. The PCB may be mountable to a wall portion of the device.

The fluid transfer apparatus may comprise one or more further electrodes. In this arrangement, the electrodes of the device and the fluid transfer apparatus may be arranged to provide the electric field to the fluid reservoir. In this arrangement, there may be at least one electrical connection point between the device and the fluid transfer apparatus.

The proximity sensor may comprise one or more discrete sensing elements formed from one or more electrodes. At least one electrode may be a common electrode.

The, or each, electrode may comprise one or more optically transparent portions. The, or each, electrode may comprise one or more apertures, holes, gaps, slots, slits, or the like. The electrodes of the proximity sensor may be at least partially located on an optically transparent substrate. The first substrate may comprise one or more optically transparent portions. The optically transparent portion(s) may be located at the common electrode of the proximity sensor. The device may comprise a power supply. The power supply may be a battery. The device may be configured to apply a potential of 0V to at least one of the electrodes. The device may be configured to apply a potential of 0V to the common electrode. Each discrete sensing element may be formed from at least one electrode and the common electrode. In this arrangement, each discrete sensing element is operable to apply an electric field between at least one electrode and the common electrode. The, or each, electrode may be substantially planar. The, or each, electrode may have a substantially rectangular, square, rounded rectangular, or circular, cross section. At least one electrode may be an elongated electrode. At least one electrode may be an elongated electrode, wherein the at least one elongated electrode is arranged to be elongated in the same direction as a longitudinal axis of the fluid reservoir. At least one electrode may be an elongated planar electrode. The common electrode may be an elongated electrode. At least one electrode may have a substantially larger surface area than the other electrode, or electrodes.

The common electrode may be arranged to at least partially surround the other electrodes.

The electrodes may be arranged to be co-planar. The common electrode and the other electrodes may be arranged to be co-planar. The one or more electrodes may be located substantially adjacent to at least one other electrode. At least a part of the proximity sensor may be located on an at least partially cylindrical substrate. The substrate may be a flexible substrate.

The, or each discrete sensing element may comprise one or more first electrodes and one or more second electrodes. The first and/or second electrodes may be common to two or more of the discrete sensing elements. The first and/or second electrodes may be common to all of the discrete sensing elements.

The proximity sensor may comprise five discrete sensing elements.

Each discrete sensing element may comprise a first electrode and a second electrode. Each discrete sensing element may comprise a first electrode and a second electrode, the second electrode being common to each discrete sensing element.

At least one of the electrode(s) of the proximity sensor may be located at or on an at least partially cylindrical wall portion of the device. One or more, or all of the electrode(s) of the proximity sensor may be located at or on one or more at least partially cylindrical wall portions of the device.

The first and second electrodes of the, or each, discrete sensing element may be configured to be adjacent to each other. The first and second electrodes of the, or each, discrete sensing element may be configured to be opposite to each other. The first and second electrodes of the, or each, discrete sensing element may be configured to be adjacent to each other and configured to be opposite each other. At least a portion of the first and second electrodes may be configured to be located at substantially opposing regions of the fluid reservoir of the fluid transfer apparatus when located in the device. At least a portion of the first and second electrodes may be arranged to be adjacent to each other and arranged to be located at substantially opposing regions of the fluid reservoir of the fluid transfer apparatus when the fluid transfer apparatus is located in the device.

The, or each, first electrode may be arranged to be located at a

substantially opposing region of the fluid reservoir to at least one of the second electrode(s) when the fluid transfer apparatus is attached to the device.

The first electrode(s) may be arranged at or on a first, at least partially cylindrical wall portion of the first substrate, and the second electrode(s) may be arranged at or on a second, at least partially cylindrical portion of the first substrate. The first electrode(s) may be arranged at or on a first, at least partially cylindrical portion of the first substrate, and the second electrode(s) may be arranged at or on a second, at least partially cylindrical portion of the first substrate and at least a portion of the first and second electrodes may be configured to be adjacent to each other.

The proximity sensor may comprise one or more first discrete sensing elements and one or more second discrete sensing elements.

The first and second discrete sensing elements may be arranged to be adjacent to each other.

The proximity sensor may comprise a third discrete sensing element. The third discrete sensing element may be arranged adjacent to the second discrete sensing element. The second discrete sensing element may be arranged between the first and third discrete sensing elements.

The proximity sensor may comprise a fourth discrete sensing element. The fourth discrete sensing element may be arranged adjacent to the third discrete sensing element. The third discrete sensing element may be arranged between the second and fourth discrete sensing elements.

The proximity sensor may comprise a fifth discrete sensing element. The fifth discrete sensing element may be arranged adjacent to the fourth discrete sensing element. The fourth discrete sensing element may be arranged between the third and fifth discrete sensing elements.

The, or each electrode may be located on a substrate having a

longitudinal, lateral and vertical axis.

The, or each, electrode may have a V-shaped cross section, or a pentagon shaped cross section, or an irregular shaped pentagon cross section substantially on a plane defined by the longitudinal and lateral axes of the substrate of the, or each, electrode.

The, or each, electrode may have a V-shaped shaped cross section, a pentagon shaped cross section, or an irregular pentagon shaped cross section, on a plane that is coplanar with its substrate. The, or each, electrode may have a V-shaped, a pentagon shaped cross section, or an irregular pentagon shaped cross section on an at least partially curved plane, or an at least partially cylindrical plane, that is coplanar with its substrate. The first discrete sensing element may include an electrode having a pentagon-shaped cross section, or an irregular pentagon shaped cross section. The second discrete sensing element may include an electrode having a V-shaped shaped cross section. The third discrete sensing element may include an electrode having a V-shaped cross section. The fourth discrete sensing element may include an electrode having a V- shaped cross section. The fifth discrete sensing element may include an electrode having a pentagon shaped cross section, or an irregular pentagon shaped cross section.

The, or each, discrete sensing element may include one or more electrode zones defined by the maximum length and maximum width of an electrode of the discrete sensing element. One or more of the discrete sensing elements may include at least one electrode zone that is configured to substantially overlap with at least one electrode zone of one or more of the other discrete sensing elements.

All of the discrete sensing elements may include at least one electrode zone that is configured to substantially overlap with at least one electrode zone of one or more of the other discrete sensing elements.

The first discrete sensing element may include one or more electrode zones configured to substantially overlap with one or more electrode zones of the second discrete sensing element.

The second discrete sensing element may include one or more electrode zones configured to substantially overlap with one or more electrode zones of the third discrete sensing element. The third discrete sensing element may include one or more electrode zones configured to substantially overlap with one or more electrode zones of the fourth discrete sensing element. The fourth discrete sensing element may include one or more electrode zones configured to substantially overlap with one or more electrode zones of the fifth discrete sensing element.

The overlap of the electrode zones may be configured to be substantially in the direction of the longitudinal axis of the fluid reservoir when the fluid transfer apparatus is located in the device.

At least one of the electrodes may include an overlapping portion arranged to protrude into an electrode zone of a discrete sensing element. At least one of the electrodes may include a non-overlapping portion arranged to be entirely within the electrode zone of that electrode.

The electrodes may be arranged in an electrode slider arrangement. The proximity sensor may comprise one or more shielding electrodes.

The one or more shielding electrodes may be located opposite at least one electrode. Each shielding electrode may be arranged to be co-axial with an electrode. The proximity sensor may comprise two or more electrodes arranged to be co-planar and one or more shielding electrodes arranged to be co-axial with at least one of the electrodes. The one or more shielding electrodes may be co-axial with the electrodes and the two or more electrodes may be co-planar. The one or more shielding electrodes may be located on an opposing layer, region, section or surface of a substrate to the one or more electrodes. The proximity sensor may be configured to apply an excitation voltage to each discrete sensing element. The proximity sensor may be configured to apply the same excitation voltage to the, or each shielding electrode. The proximity sensor may be configured to apply the same excitation voltage to each discrete sensing element. The proximity sensor may be configured to apply the same excitation voltage to the, or each discrete sensing element and the, or each shielding electrode.

The proximity sensor may be configured to apply the excitation voltage between at least one electrode of each discrete sensing element and a return electrode. The proximity sensor may be configured to apply a potential of 0V to the return electrode. The return electrode may be a common electrode, common to each discrete sensing element. The one or more electrodes may be located, or arranged, on the same layer, section, or region of a substrate. The one or more electrodes may be located, or arranged, on the same surface of the substrate.

The one or more electrodes may be located on a first section of the substrate and the one or more shielding electrodes may be located on a second section of the substrate.

The one or more shielding electrodes may be located on the same layer, or section, or region, of the substrate as the one or more electrodes.

The proximity sensor may comprise two or more electrodes, wherein at least one electrode substantially surrounds at least one other electrode. At least two of the electrodes may be arranged to be substantially co- planar. Each discrete sensing element may be formed from opposing electrodes. The proximity sensor may comprise two or more electrodes separated by a gap therebetween. Each electrode may be spaced from the other electrodes by an electrically insulating element.

The, or each, electrode may include a hatched portion, or the like. All of the electrodes may comprise a hatched portion.

The electrodes may be operable to apply the electric field to a part of the fluid reservoir. The electrodes may be operable to apply the electric field to one or more parts, sections, or regions of the fluid reservoir. The electrodes may be arranged to be operable to apply the electric field to at least a part of the inside of the fluid reservoir. The electrodes may be arranged to be operable to apply the electric field to at least a part of an inner surface of the fluid reservoir. The electrodes may be arranged to be only outside of the fluid reservoir. The electrodes may be arranged to be opposite an outer surface of the fluid reservoir. The electrodes may be arranged substantially adjacent to the fluid reservoir, or a wall portion thereof, when the device is connected to the fluid transfer apparatus. The electrodes may be arranged substantially adjacent to at least a part of the fluid reservoir. At least one of the electrodes may be arranged to be in contact with at least a part of the fluid reservoir. The electrodes may be arranged to surround at least a part of the fluid reservoir when the device is connected to the fluid transfer apparatus. The electrodes may be arranged on a plane that is tangential to the wall portion of the fluid reservoir when the device is connected to the fluid transfer apparatus.

The electrodes of the, or each, discrete sensing element may be arranged in an at least partially curved or at least partially cylindrical arrangement. The electrodes of the, or each, discrete sensing element may be arranged to substantially completely surround the fluid reservoir of the fluid transfer apparatus when the fluid reservoir is located in the device. The device may be configured such that the, or each, electrode is spaced from the fluid reservoir of the fluid transfer apparatus when the fluid reservoir is located in the device. In this arrangement, the electrodes are not in contact with the fluid in the fluid reservoir, and are not in contact with any wall portions of the fluid reservoir.

The device may be operable to determine the position of the device relative to the fluid transfer apparatus. The device may be operable to determine the position of the device relative to the fluid transfer apparatus using, at least in part, one or more signals received from the proximity sensor.

The device may be operable to detect when it is attached to the fluid transfer apparatus. The device may be operable to detect when it is attached to the fluid transfer apparatus using, at least in part, one or more signals received from the proximity sensor.

The device may comprise one or more position detection means arranged to determine the position of the device relative to the fluid transfer apparatus. The device may comprise one or more position detection means arranged to determine whether the device is attached to the fluid transfer apparatus.

The control device may be operable to receive a signal from the position detection means indicating that the device is attached to the fluid transfer apparatus. The control device may be operable to ignore, delete, or discard data obtained from the proximity sensor when the device is not attached to the fluid transfer apparatus. The position detection means may comprise or more optical sensors. The position detection means may comprise one or more relays, or the like. The position detection means may be a switch, a mechanical switch, an electrical switch, or the like. The optical sensors may comprise one or more optical transmitters and one or more optical receivers. The device may comprise one or more position detection means beatable at the open end thereof. The device may comprise one or more position detection means beatable at the closed end thereof.

The device may be operable to discard, ignore, or modify measurement data obtained when the device is not attached to the fluid transfer apparatus. In this arrangement, the device can“zero” any measurement data obtained when the device is not attached to the fluid transfer apparatus.

The device may be operable to continuously obtain measurement data from the proximity sensor. The device may be operable to continuously obtain measurement data from the proximity sensor when the device is attached to the fluid transfer apparatus.

The control device may be operable to control the operation of the device. The control device may be an electronic control device. The control device may be operable to communicate with a computing device. The control device may be operable to communicate wirelessly with the computing device. The control device may be operable to communicate wirelessly with the computing device by a suitable wireless communication protocol. The wireless communication protocol may be an IEEE 802.15.4 wireless communication protocol, Bluetooth, Zigbee, near-field

communication (NFC), infrared communication, WiFi, and/or LoRa.

The device may comprise one or more displays and/or one or more graphical user interfaces. The display and/or the graphical user interface may be operable to display one or more operating parameters and/or measurement data to the user of the device.

The computing device may be a PC, laptop, mobile phone, smartphone, smartwatch, tablet computer, an iPad, a docking station, or the like. The computing device may comprise one or more application software elements configured to control, at least in part, the operation of the control device. The computing device may be configured to display data associated with the amount of fluid in the fluid reservoir based, at least in part, on data received from the device. The device may be configured to display data associated with the amount of fluid in the fluid reservoir based, at least in part, on data received from the proximity sensor. The computing device may be configured to display data associated with the amount of fluid in the fluid reservoir based, at least in part, on data received from the device and the device may be configured to display data associated with the amount of fluid in the fluid reservoir based, at least in part, on data received from the proximity sensor. The control device may be configured to be operable, at least in part, via the computing device or a user input element thereof.

The computing device may be configured to apply a correction function to data received from the, or each, discrete sensing element. The correction function may be a boundary correction function. The correction function may be a drift correction function.

The computing device may be configured to identify regions of high electrode sensitivity to changes in the amount of fluid in the fluid reservoir, and regions of relatively low electrode sensitivity to changes in the amount of fluid in the fluid reservoir. The computing device may be configured to reduce, or remove, drift from data received from the discrete sensing element(s) in the regions of low electrode sensitivity to produce drift- corrected data.

The computing device may be configured to sum the response from each discrete sensing element using the drift-corrected data, to obtain summed electrode data. In this arrangement, the computing device can reduce or remove drift in regions of low electrode sensitivity, such that the response of the dominant electrodes (for a certain amount of fluid in the reservoir) dominate the overall change in signal. It will be understood that as the amount of fluid in the reservoir changes, some discrete sensing elements will produce a larger change in signal due to the arrangement of the electrodes thereof.

The computing device may be configured to obtain an initial signal response from the proximity sensor. The computing device may be configured to obtain an initial signal response from the, or each, electrode of the proximity sensor. The initial signal response may be obtained when the device is attached to the fluid transfer apparatus. The computing device may be configured to use the initial signal response to alter the data received from the proximity sensor. The computing device may be configured to subtract the initial signal response from the data received from the proximity sensor.

The computing device may be configured to prompt the user to enter an initial fill level of the fluid reservoir. The computing device may be configured to obtain the initial signal response when the user has entered the initial fill level of the fluid reservoir.

The initial signal response may be obtained when the fluid reservoir is at the maximum fill level for a given measurement phase. The computing device may be configured to apply a fit function to fit the summed electrode data to the amount of fluid in the fluid reservoir to create fitted summed electrode data. The fit function may be a linear fit function, or the like. The computing device may be configured to detect the deviation of the fitted summed electrode data from an ideal fit curve. The ideal fit curve may be a linear curve. The computing device may be configured to apply a fit correction function to the fitted summed electrode data. The computing device may be configured to apply a fit correction function to the fitted summed electrode data, to reduce or remove the deviation of the fitted summed electrode data from the ideal fit curve.

The device may comprise one or more user input means. The user input means may be a manual input means. The manual input means may comprise one or more buttons, switches, or the like. The control device may be configured to obtain signals from the proximity sensor, and to use the signals to determine the amount of fluid present in the reservoir.

The control device may be configured to prompt the user to select the type of fluid transfer apparatus. The control device may be configured to display a selection of fluid transfer apparatuses to the user and to prompt the user to select a fluid transfer apparatus. The control device may be configured to prompt the user to select the type of fluid present in the fluid reservoir. The control device may be configured to prompt the user to select the type and/or the concentration of a drug or substance in the fluid reservoir.

The control device may be configured to display the number of doses, or units, of a drug or substance remaining in the fluid reservoir. The control device may be configured to use data input from the user and

measurement data obtained from the proximity sensor to display remaining doses, or units, remaining in the fluid reservoir.

The control device may be operable to set, obtain, record, or allow a user to input calibration data associated with the calibration of the fluid transfer apparatus. The calibration data may comprise the amount of fluid discharged from the fluid reservoir to test, or prime, the fluid transfer apparatus, prior to applying and/or injecting fluid to the user. The calibration data may be expressed as a dose, or number of units, of a drug or substance.

The control device may be configured to record the amount of fluid applied and/or injected to the user from the fluid transfer apparatus. The control device may be configured to use at least part of the calibration data and data associated with the measured fluid in the fluid reservoir to determine the amount of fluid applied and/or injected to the user. The control device may be configured to record the applied, or injected dose, or units, of a substance or drug. The control device may be configured to display the applied or injected dose or units to the user. The control device may be operable to record the time of applying and/or injecting the substance or drug to the user. The control device may be operable to display a suggested time for applying and/or injecting fluid to the user.

The control device may be configured to display the units of insulin remaining in the fluid reservoir. The control device may be configured to record the applied and/or injected units of insulin. The control device may be configured to record the time of applying and/or injecting insulin. The control device may be operable to display and record units of insulin, wherein one unit of insulin is 0.01 ml of insulin.

The device may be operable to use reference data to adjust, modify, correct, amend, erase, and/or discard measurement data from the proximity sensor. The device may be operable to use reference data to calibrate the proximity sensor. The device may comprise one or more reference sensors arranged to provide reference data to the device. The device may comprise one or more reference sensors arranged to provide reference data to the control device. At least one of the reference sensors may be operable to detect changes in at least one of: temperature, and electromagnetic interference. The, or each reference sensor may comprise one or more electrodes.

The, or each, reference sensor may comprise one or more electrodes operable to apply an electric field to the surrounding area, and the device may be configured to substantially prevent the electric field from the reference sensor from being applied to the fluid reservoir. The device may be operable to indicate one or more fill-levels of the fluid reservoir to the user. The device may be operable to indicate the amount of fluid in the fluid reservoir. The device may comprise indicator means operable to indicate one or more fill-levels of the fluid reservoir to the user. The indicator means may be operable to indicate the amount of fluid in the fluid reservoir.

The device may be operable to determine whether a predetermined dose has been dispensed from the fluid reservoir, and to indicate a first signal if the predetermined dose has been dispensed and to indicate a second signal if the predetermined dose has not been dispensed.

The indicator means may be a haptic device. The haptic device may be one or more vibrator devices, or the like.

The device may be configured to display, or indicate, the amount of fluid present in the fluid reservoir in discrete fill levels. The device may be configured to prompt the user to add fluid to the fluid reservoir when the amount of fluid present in the fluid reservoir falls below a discrete fill level.

The, or each electrode, may have a length of between approximately 0.1 mm and approximately 50 mm, optionally between approximately 0.5 mm and approximately 20 mm, optionally between approximately 1 mm and 10 mm. The, or each electrode, may have a width of between approximately 0.1 mm and approximately 50 mm, optionally between approximately 0.5 mm and approximately 20 mm, optionally between approximately 1 mm and 10 mm. According to a second aspect of the present invention there is provided a method of measuring an amount of fluid in a fluid reservoir of a fluid transfer apparatus, the method comprising the steps of:

providing a device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus;

wherein the proximity sensor is operable to receive one or more signals from the, or each, electrode;

attaching the device to the fluid transfer apparatus;

using the one or more electrodes to apply an electric field to at least a part of the fluid reservoir; and

using the proximity sensor to receive one or more signals from the, or each, electrode.

Embodiments of the second aspect of the present invention may include one or more features of the first aspect of the present invention or its embodiments. Similarly, embodiments of the first aspect of the present invention may include one or more features of the second aspect of the present invention or its embodiments. According to a third aspect of the present invention there is provided a fluid transfer system, the system comprising:

a fluid transfer apparatus comprising a fluid reservoir and operable to transfer fluid from the fluid reservoir to a fluid outlet; a device configured for attachment to the fluid transfer apparatus and operable to measure an amount of fluid in the fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

Embodiments of the third aspect of the present invention may include one or more features of the first and/or second aspects of the present invention or their embodiments. Similarly, embodiments of the first and/or second aspects of the present invention may include one or more features of the third aspect of the present invention or its embodiments.

According to a fourth aspect of the present invention there is provided a method of treating one or more health conditions, the method comprising the steps of:

providing a drug, or substance, delivery apparatus comprising a fluid reservoir and a fluid outlet, the apparatus being operable to transfer a drug or substance from the fluid reservoir to the fluid outlet;

providing a device configured for attachment to the drug, or substance, delivery apparatus and operable to measure an amount of fluid in the fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus; wherein the proximity sensor is operable to receive one or more signals from the, or each, electrode;

(i) attaching the device to the drug, or substance, delivery apparatus;

(ii) using the one or more electrodes to apply an electric field to at least a part of the fluid reservoir;

(iii) using the proximity sensor to receive one or more signals from the, or each, electrode;

(iv) removing the device from the apparatus; and

repeating steps (i) to (iv) and using the device to determine the amount of the drug, or substance, applied and/or injected from the fluid reservoir to the user.

The method may comprise the step of rewarding the user for applying or injecting the drug, or substance.

Embodiments of the fourth aspect of the present invention may include one or more features of the first, second and/or third aspects of the present invention or their embodiments. Similarly, embodiments of the first, second, and/or third aspects of the present invention may include one or more features of the fourth aspect of the present invention or its embodiments.

According to a fifth aspect of the present invention there is provided a device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof, the device comprising:

a sensor comprising:

one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus; and wherein the sensor is operable to receive one or more signals from the, or each, electrode.

The sensor may be a proximity sensor. The sensor may be an electric field sensor.

Embodiments of the fifth aspect of the present invention may include one or more features of the first, second, third and/or fourth aspects of the present invention or their embodiments. Similarly, embodiments of the first, second, third and/or fourth aspects of the present invention may include one or more features of the fifth aspect of the present invention or its embodiments.

According to a sixth aspect of the invention, there is provided a system comprising:

an insulin delivery device, or insulin pen, comprising a fluid reservoir; and

a device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

Embodiments of the sixth aspect of the present invention may include one or more features of the first, second, third, fourth and/or fifth aspects of the present invention or their embodiments. Similarly, embodiments of the first, second, third, fourth and/or fifth aspects of the present invention may include one or more features of the sixth aspect of the present invention or its embodiments. Brief description of the drawings

Embodiments of the invention will now be described, by way of example, with reference to the drawings, in which: Figs. 1 a and 1 b show a perspective view of a device according to an aspect of the present invention;

Fig. 2 shows a schematic illustration of the device of Figs. 1 a and 1 b;

Fig. 3a shows a partial isometric view of an alternative embodiment of the device according to an aspect of the present invention;

Fig. 3b shows a partial isometric view of an alternative embodiment of the device of Fig. 1 a;

Figs. 4a to 4d show an isometric view of the device of Fig. 3a;

Fig. 5a shows a partial top view of another alternative embodiment of the device according to an aspect of the present invention;

Fig. 5b shows a partial top view of a further alternative embodiment of the device according to an aspect of the present invention;

Fig. 6a shows a schematic view of an alternative embodiment of the device according to an aspect of the present invention;

Fig. 6b shows a schematic view of a further alternative embodiment of the device according to an aspect of the present invention;

Fig. 7a shows a partial top view of an alternative embodiment of the device according to an aspect of the present invention;

Fig. 7b shows a partial bottom view of the device of Fig. 7a;

Fig. 7c shows a partially assembled view of the device of Fig. 7a; Fig. 7d shows an assembled view of the device of Fig. 7a;

Fig. 7e shows a schematic view of the device of Fig. 7a;

Figs. 8a to 8e show electrode data received from the device of Fig. 7a;

Figs. 9a to 9e show drift-corrected data of Figs. 8a to 8e;

Fig. 10a shows summed electrode data obtained from Figs. 9a to 9e;

Fig. 10b shows offset correction of the data of Fig. 10a;

Fig. 10c shows fitted summed electrode data obtained from Fig. 10b;

Figs. 11 a to 11 e show the deviation from the fitted summed electrode data, using data obtained from five fluid transfer apparatuses;

Fig. 12 shows a fit correction function obtained using data from the device of Fig. 7a;

Figs. 13a to 13e show data from the five fluid transfer apparatuses, as shown in Figs. 11 a to 11 e, after the fit correction function of Fig. 12 has been applied thereto; and

Fig. 14 shows the result of applying the fit correction function to data obtained from another fluid transfer apparatus (i.e. not used in Figs, 11 a to 11 e).

Description of preferred embodiments

Embodiments of the invention will now be described with reference to Figs. 1 to 14.

With reference to Figs. 1 a to 6b, a device 1 configured for attachment to a fluid transfer apparatus 10 is shown. The device 1 is operable to measure an amount of fluid in a fluid reservoir 12 of the fluid transfer apparatus 10. In the embodiment illustrated and described here, the fluid transfer apparatus 10 is an insulin delivery pen and the device 1 is a protective cap for use with the insulin pen. It will be understood that other types of fluid transfer apparatuses 10 and devices 1 could be used. The fluid transfer apparatus 10 could be a drug, or substance, delivery apparatus, or pen, or the like. As shown in Fig. 1 b, the fluid transfer apparatus 10 is a hand- operated, portable apparatus. Likewise, the device 1 is portable and hand-operated.

In the embodiments illustrated and described here, the fluid transfer apparatus 10 is operable to inject an insulin solution to a person. The fluid transfer apparatus 10 includes injector means for injecting fluid to a person, which in this embodiment is a needle. The fluid transfer apparatus 10 is operable to transfer fluid from the fluid reservoir 12 to the injector means.

As best shown in Fig. 1 b, the device 1 is a partially cylindrical member having an open end 1 a and a closed end 1 b, and is configured to accommodate at least a part of the fluid transfer apparatus 10 therein.

The device 1 is also configured to accommodate at least a part of the fluid reservoir 12 therein.

The device 1 is attachable to the fluid transfer apparatus 10 by way of a snap-fit connector, or the like, which also functions as a releasable locking means.

As shown in Fig. 2, the device 1 comprises a proximity sensor 6, which in this embodiment is a capacitive sensor. As described in more detail below, the proximity sensor 6 is used by the device 1 to measure the amount of fluid in the fluid reservoir 12, which in this embodiment is used by the device 1 to track the amount of insulin injected by the user of the fluid transfer apparatus 10. As described in more detail below, the device 1 could also be used to display information to the user, such as the remaining insulin doses (expressed as units of insulin). It will be

appreciated that the device 1 can be used with other fluid transfer apparatuses 10 and fluids, and the device 1 is not limited for use with insulin delivery apparatuses.

In the embodiment illustrated in Figs. 1 a to 2, the proximity sensor 6 comprises an elongated electrode 2 surrounded by a common electrode 2a, the electrodes 2, 2a, being operable to apply an electric field to at least a part of the fluid reservoir 12 when the device 1 is attached to the fluid transfer apparatus 10. As best shown in Fig. 2, the electrode 2 is aligned to the fluid reservoir 12. That is, the elongated electrode 2 is arranged to be elongated in the same direction as a longitudinal axis 12a of the fluid reservoir 12. In the embodiment illustrated here, the device 1 is

configured to apply the electric field to only a part of the fluid reservoir 12. Flowever, in other embodiments the device 1 could be configured to apply the electric field to at least a part of the fluid reservoir 12. It will be understood that in the embodiments illustrated and described here, due to the arrangement of the electrodes 2, 2a, the electrodes 2, 2a are arranged to be operable to apply a substantially non-uniform electric field to at least a part of the fluid reservoir 12. The proximity sensor 6 is operable to receive one or more signals from the electrode 2 and/or the common electrode 2a. When an electric field is applied to at least a part of the fluid reservoir 12 using the electrodes 2,

2a, the signal(s) received from the electrodes 2, 2a, by the proximity sensor 6 will vary according to the amount of fluid in the fluid reservoir 12. For example, as the amount of fluid in the fluid reservoir 12 changes, the capacitance of the two electrodes 2, 2a changes. The change in capacitance of the two electrodes 2, 2a is detected by the proximity sensor 6 using known means. The device 1 is configured to use the measured changes in capacitance (caused by changes in the amount of fluid within the fluid reservoir 12) to determine the amount of fluid remaining in the fluid reservoir 12.

In the embodiments illustrated and described here, the fluid transfer apparatus 10 includes a plunger for transferring fluid from the fluid reservoir 12 to a fluid outlet 13. The electrodes 2, 2a are operable to detect the presence of fluid at a wall portion 12a of the fluid reservoir 12 by applying an electric field to a part of the fluid reservoir 12. Thus, as the plunger moves through the fluid reservoir 12, fluid is present throughout the region of the fluid reservoir 12 between the plunger and the fluid outlet 13. Therefore, the electrodes 2, 2a, are used to measure the presence or absence of fluid at the wall portion 12a of the fluid reservoir 12, and the device 1 is configured to determine the amount of fluid remaining in the fluid reservoir 12 (as described in more detail below). The fluid reservoir 12 comprises a single chamber for storing fluid, and it is a substantially cylindrical member. In spite of the cylindrical shape of the fluid reservoir 12, and its curved wall portions 12a, the electrodes 2, 2a can be located on a substantially planar substrate 4 and used effectively to apply electric fields to at least a part of the fluid reservoir 12.

It should be understood that the proximity sensor 6 can be arranged, or located on one or more flexible substrates. Alternatively, the proximity sensor 6 may be arranged, or located on one or more rigid substrates, although it will be apparent that the proximity sensor 6 could be located on a rigid and/or flexible substrate. For example, it may be desirable for the electrodes 2 to be arranged, or located on one or more flexible substrates and for the remaining parts of the proximity sensor 6 to be located on a different substrate or substrates, such as a rigid substrate. It will be appreciated that the fluid reservoir 12 is located at an end region of the fluid transfer apparatus 10. However, the device 1 could be modified to measure fluid in a fluid reservoir 12 that is located at other regions of the fluid transfer apparatus 10, such as a central region. It will be appreciated that in some embodiments, the fluid reservoir 12 is configured to receive fluid from a source of fluid, and in other

embodiments the fluid transfer apparatus 10 could be a disposable, or prefilled, apparatus 10 in which the fluid reservoir 12 already contains a predetermined amount of fluid prior to use by the end-user. The device 1 is configured for use with both types of fluid transfer apparatus 1 , and is capable of being transferred from one fluid transfer apparatus 10 to another (such as when a disposable pen is empty of fluid).

With reference to Fig. 1 a and 1 b, the device 1 comprises one or more electromagnetic (EM) radiation or interference blocking elements configured to at least partially shield the proximity sensor 6 and/or the fluid reservoir 12 from EM radiation or interference. The device 1 is configured to at least partially shield the proximity sensor 6 from extraneous electromagnetic fields, electrostatic discharges, including electrostatic discharges caused by the user touching, or handling, the device 1 and/or the fluid transfer apparatus 10. Furthermore, in this embodiment, the device 1 is configured to at least partially shield the proximity sensor 6 from other sources of interference, such as parasitic capacitance (and other electrical parasitic effects) in the device 1. As shown in the alternative embodiment of fig. 5b, a shielding electrode 2b (e.g. a ground plane) is arranged opposite the electrodes 2 and the common electrode 2a, to at least partially shield the electrodes 2, 2a from EM radiation or interference.

In the embodiments illustrated and described here, the proximity sensor 6 is operable to control the operation of the electrodes 2, 2a. However, it will be apparent that in other arrangements the proximity sensor 6 could be used to receive one or more signals from the electrodes 2, 2a, and another component could be used to control the operation of the electrodes 2, 2a.

In the embodiments illustrated here, the device 1 is configured to apply an alternating, or alternating current (a.c.) electric field to the fluid reservoir 12.

In the embodiments illustrated and described here, the device 1 includes a control device 8 operable to control the proximity sensor 6 and the operation of the device 1. The proximity sensor 6 is configured to detect changes in the capacitance of the electrodes 2, 2a, and the proximity sensor 6 is configured to provide signal(s) to the control device 8 indicative of the change in capacitance. The signal(s) sent to the control device 8 are then used to determine the amount of fluid present in the fluid reservoir 12.

The device 1 is operable to continuously obtain measurement data from the proximity sensor 6, particularly when the device is attached to the fluid transfer apparatus 10. Although, when the device 1 is not attached to the fluid transfer apparatus 10, in some embodiments the device 1 will continue to obtain measurement data from the proximity sensor 6, which can be used to determine that the device 1 has been removed from the fluid transfer apparatus 10.

The device 1 is operable to perform a calibration routine, in which one or more measurement data are obtained from the proximity sensor 6 when the device 1 is not attached to the fluid transfer apparatus 10, and one or more measurement data is obtained from the proximity sensor 6 when the device 1 is attached to the fluid transfer apparatus 10. In this

arrangement, the device 1 is operable to use one or more measurement data obtained when the device 1 is not attached to the fluid transfer apparatus 10 as a reference measurement.

Figs. 3a and 3b show an alternative electrode arrangement of the device 1 , comprising an elongated electrode 2 and seven substantially square electrodes 2. In this embodiment, the common electrodes are not shown. The electrodes 2 are covered by an insulating member and are all located on the same substrate 4 as the proximity sensor (not visible in this embodiment). However, as shown in Fig. 5a, in some embodiments the electrodes 2 are not covered by an insulating member.

In the embodiment illustrated in Fig. 3b, the fluid transfer apparatus 10 is a syringe and the device 1 is a substantially planar member.

The proximity sensor 6 is typically arranged, or located, on the same substrate as the electrodes 2, 2a. However, it will be appreciated that different arrangements are envisaged, and the control device 8, at least part of the proximity sensor 6 and the electrodes 2, 2a, could be located, or arranged, on different substrates. In the embodiment illustrated in Fig. 1 a, the proximity sensor 6 and the electrodes 2, 2a are located on an inner surface of a wall portion 1e of the device 1. In the alternative embodiment shown in Fig. 5a, and the further

embodiment shown in Fig. 5b, the electrodes 2, 2a are formed on a plastic substrate 4. It should be appreciated that the electrodes 2, 2a, proximity sensor 6 and/or the control device 8 could be formed on a printed circuit board (PCB). The control device 8 and the proximity sensor 6 (including the electrodes 2, 2a) can be manufactured using mass-manufacturing techniques. For example, in the embodiments illustrated and described here, each electrode 2, 2a is a substantially planar element located on a substantially planar substrate 4. In the embodiments illustrated in Figs. 3a to 6b, the proximity sensor 6 includes one or more discrete sensing elements 14 formed from a single electrode 2 and a common electrode 2a. The device 1 is configured to apply a potential of 0V to the common electrode 2a, and thus the common electrode 2a is a ground electrode. Flowever, it will be appreciated that other electrode arrangements are possible, and the common electrode 2a need not be connected to 0V.

The device 1 includes a battery (an example power supply). In the embodiments illustrated here, each discrete sensing element 14 is operable to apply an electric field between a single electrode 2 and the common electrode 2a.

Figs. 4a and 4b illustrate the fluid reservoir 12 of the fluid transfer apparatus 10 being inserted into the device 1 , and the elongated electrode 2 is then used to apply an electric field to the fluid reservoir 12 and thus the device 1 is then able to determine the amount of fluid present in the fluid reservoir 12. Similarly, the same operation is depicted in Figs. 4c and 4d, with the difference being that the substantially square electrodes 2 are used in conjunction with the elongated electrode 2 to determine the amount of fluid present in the fluid reservoir 12.

As shown in the embodiments of Fig. 5a and 5b, the common electrode 2a is arranged to at least partially surround the other electrodes 2, and the electrodes 2 and the common electrode 2a are arranged to be co-planar. As shown in fig. 5b, a shielding electrode 2b is located opposite the electrodes 2, and is a ground plane. It will be appreciated that other arrangements are envisaged, such as one or more shielding electrodes 2b located coaxially from each electrode 2. It should be appreciated that in some embodiments, the device 1 could be configured to apply the electric field using at least one electrode and at least one shielding electrode.

In the embodiments shown in Figs. 3a to 5b, the electrodes 2, 2a are each located substantially adjacent to at least one other electrode 2, 2a. It will be appreciated that in some embodiments, the electrodes 2, 2a could be located closer together or further apart, depending on a number of factors, such as the required accuracy of the device 1 , the size of the electrodes, and the size of the device 1 and the fluid reservoir 12. As described above, and with reference to Fig. 5b, the proximity sensor 6 includes a shielding electrode 2b. In the arrangement depicted in Fig. 5b, it will be appreciated that an electric field can be applied between each electrode 2 and the common electrode 2a, and an electric field can be applied between each electrode 2 and the shielding electrode 2b. It will be apparent that the shielding electrode 2b is primarily used to shield each electrode 2 from EM radiation or interference and other external influences, such as an electrostatic discharge from a user of the device 1 , and that the detection of fluid in the fluid reservoir 12 is primarily achieved through variations in the capacitance between the electrode 2 and the common electrode 2a. It will also be apparent that the common electrode 2a and/or the shielding electrode 2b could be implemented using one or more electrodes (e.g. each electrode 2 could be“paired” with an opposing common electrode 2a and/or a shielding electrode 2b to form discrete sensing elements 14).

As shown in Fig. 5b, the proximity sensor 6 comprises six electrodes 2 arranged to be co-planar with each other, and to be co-planar with the common electrode 2a, and a shielding electrode 2b arranged to be opposite the electrodes 2 and the common electrode 2a. The shielding electrode 2b is located on an opposing region of the substrate 4 to the electrodes 2.

In the embodiments illustrated and described here, each discrete sensing element 14 is formed from opposing electrodes 2, 2a.

Each electrode 2 is spaced from the other electrodes 2 by an electrically insulating element.

In the embodiments illustrated and described here, the electrodes 2 are arranged to be operable to apply the electric field to at least a part of the inside of the fluid reservoir 12.

In the embodiments illustrated and described here, the electrodes are arranged to be only outside of the fluid reservoir 12, and are opposite an outer surface of the fluid reservoir 12. As best shown in Figs. 3a to 4d, the electrodes 2 are arranged substantially adjacent to the wall portion 12a of the fluid reservoir 12 when the device is connected to the fluid transfer apparatus 10. However, in other embodiments, at least one of the electrodes 2 could be arranged to be in contact with at least a part of the fluid reservoir 12.

As shown in Figs. 3a to 4d, the electrodes 2 are arranged to surround at least a part of the fluid reservoir 12 when the device 1 is connected to the fluid transfer apparatus 10. In the embodiments depicted here, the electrodes 2 are arranged on a plane that is tangential to the wall portion 12a of the fluid reservoir 12 when the device 1 is connected to the fluid transfer apparatus 10.

As shown in Fig. 1 a, the device 1 includes position detection means 16 arranged to determine the position of the device 1 relative to the fluid transfer apparatus 10. The control device 8 is operable to receive a signal from the position detection means 16 indicating that the device 1 is attached to the fluid transfer apparatus 10, which in this embodiment is one or more optical sensors. If the device 1 is not in the correct position with respect to the fluid transfer apparatus 10, the control device 8 is operable to ignore, delete, or discard data obtained from the proximity sensor 6 (e.g. if the device 1 is removed from the apparatus 1 ). The one or more optical sensors are typically one or more optical transmitters and one or more optical receivers. It should be understood that in some embodiments, the device 1 could be configured to prompt the user to use a user input means of the device 1 to indicate when the device 1 is attached to the fluid transfer apparatus 10. The user input means could be a button (an example of a manual input means). It should be understood that the position detection means could be a relay, switch, a mechanical switch, an electrical switch, or the like.

In some embodiments, the device 1 is operable to determine the position of the device 1 relative to the fluid transfer apparatus 10 using, at least in part, one or more signals received from the proximity sensor 6. It will be appreciated that in some embodiments, the device 1 is operable to detect when it is attached to the fluid transfer apparatus 10 using, at least in part, one or more signals received from the proximity sensor 6.

In some embodiments, the device 1 is operable to discard, ignore, or modify measurement data obtained when the device 1 is not attached to the fluid transfer apparatus 10. In this arrangement, the device 1 can “zero” any measurement data obtained when the device 1 is not attached to the fluid transfer apparatus 10.

The device 1 is operable to perform a calibration routine, in which one or more measurement data are obtained from the proximity sensor 6 when the device 1 is not attached to the fluid transfer apparatus 10, and wherein one or more measurement data is obtained from the proximity sensor 6 when the device 1 is attached to the fluid transfer apparatus 10. In this arrangement, the device 1 is operable to use one or more measurement data obtained when the device 1 is not attached to the fluid transfer apparatus 10 as a reference measurement.

In some embodiments, the device 1 is operable to obtain a single sample of measurement data from the proximity sensor 6 when the device 1 is connected to the fluid transfer apparatus 10. In other embodiments, measurement data is obtained periodically, or continuously, from the proximity sensor 6. For example, when the device 1 is attached to the fluid transfer apparatus 10, the device 1 could be operable to obtain one or more samples of measurement data from the proximity sensor 6 and could convert the one or more samples of measurement data to an average value.

In the embodiment illustrated in Fig. 1a, the position detection means 16 are located at the open end 1 a of the device 1. However, the device 1 could comprise one or more position detection means 16 beatable at the closed end 1 b thereof and/or the open end 1 a thereof.

The control device 8 is operable to control the operation of the device 1 , including the proximity sensor 6, and thus the operation of the electrodes 2, 2a. The control device 8 is an electronic control device 8 operable to communicate with a computing device, such as a mobile phone, or other computing device (not shown). In the embodiment illustrated in Fig. 1 a, the control device 8 is operable to communicate wirelessly with the computing device by way of Bluetooth (an example of a wireless

communication protocol). However, it should be understood that the control device 8 could be operable to communicate wirelessly with the computing device using other suitable wireless communication protocols, such as an IEEE 802.15.4 wireless communication protocol, Bluetooth, Zigbee, near-field communication (NFC), infrared communication, WiFi, and/or LoRa. In the embodiments illustrated in Figs. 3a to 4d, the control device 8 is operable to communication with a computing device by way of a wired communication channel, such as a universal serial bus (USB) connector. It will be appreciated that other wireless communication protocols, and other wired communication channels could be used. It should be appreciated that the computing device could be a PC, laptop, mobile phone, smartphone, smartwatch, tablet computer, an iPad, a docking station, or the like. The control device 8 is configured to obtain signals from the proximity sensor 6, and to use the signals to determine the amount of fluid present in the reservoir 12.

In some embodiments, the control device 8 is configured to prompt the user to select the type of fluid transfer apparatus 10. For example, the user will be able to select from a list of commercially available insulin pens, which allows the control device 8 to correctly determine the amount of fluid in the fluid reservoir 12, using stored data associated with the type of fluid transfer apparatus 10 selected by the user. Furthermore, the control device 8 is also configured to prompt the user to select the type of fluid present in the fluid reservoir 12, such as the type of insulin solution or the type and/or the concentration of a drug or substance in the fluid in the fluid reservoir 12. This allows the control device 8 to display the number of doses, or units, of a drug or substance remaining in the fluid reservoir 12 (e.g. the remaining doses, or units, of insulin). Thus, the control device 8 is configured to use the data input from the user and the measurement data obtained from the proximity sensor 6 to display the remaining doses, or units, remaining in the fluid reservoir 12. It will be appreciated that, in such embodiments, the device 1 could comprise one or more displays and/or one or more graphical user interfaces operable to display one or more operating parameters and/or measurement data to the user of the device 1.

In the embodiment illustrated in Fig. 1 a, the control device 8 is operable to set, obtain, record, or allow a user to input calibration data associated with the calibration of the fluid transfer apparatus 10, particularly the amount of fluid discharged from the fluid reservoir 12 to test, or prime, the fluid transfer apparatus 10, prior to applying and/or injecting fluid to the user. For example, it is common practice for a user of an insulin pen to configure the insulin pen to dispense a test dose (which could be used to remove air from the fluid reservoir 12). This is known as priming the insulin pen, prior to use. It will be appreciated that, whilst it is

recommended that a user primes the insulin pen before use, it will be understood that sometimes the user will opt not to prime the insulin pen, and thus it will not be necessary for the device 1 to obtain the amount of fluid discharged from the fluid reservoir 12 prior to use. The calibration data can be expressed as a dose, or number of units, of a drug or substance.

The control device 8 is configured to record the amount of fluid applied and/or injected to the user from the fluid transfer apparatus 10, by using at least part of the calibration data and data associated with the measured fluid in the fluid reservoir 12 to determine the amount of fluid applied and/or injected to the user. The control device 8 could be configured to display the applied or injected dose or units to the user, and the time of applying and/or injecting the substance or drug to the user, on an electronic display. The control device 8, or the computing device, could be operable to display a suggested time for applying and/or injecting fluid to the user.

In the embodiment illustrated in Fig. 1 a, the control device 8 is configured to display the units of insulin remaining in the fluid reservoir 12, wherein one unit of insulin is 0.01 ml of insulin.

Figs. 6a and 6b show two further embodiments of the present invention.

As shown in Fig. 6b, the common electrode 2a substantially surrounds the other electrodes 2. In some embodiments, the device 1 comprises one or more reference sensors arranged to provide reference data to the device 1. The device 1 is thus operable to use reference data to adjust, modify, correct, amend, erase, and/or discard measurement data from the proximity sensor 6. The reference sensors are operable to detect changes in at least one of:

temperature, and electromagnetic interference.

The, or each reference sensor typically comprises one or more electrodes arranged in a similar, or substantially identical arrangement to the electrodes of the proximity sensor. In this way, changes in temperature or electromagnetic interference effects common to the proximity sensor 6 and the reference sensor(s) can be eliminated from measurement data.

The, or each, reference sensor is typically configured to substantially prevent the electric field from the reference sensor from being applied to the fluid reservoir 12.

In some embodiments, the device 1 comprises a haptic indicator, such as a vibrator device (example indicator means) operable to indicate one or more fill-levels of the fluid reservoir 12 to the user.

In some embodiments, the device 1 is operable to determine whether a predetermined dose has been dispensed from the fluid reservoir 12, and to indicate a first signal if the predetermined dose has been dispensed and to indicate a second signal if the predetermined dose has not been dispensed. This is useful in alerting the user that an insufficient dose has been applied from the fluid transfer apparatus 10.

Figs. 7a to 14 illustrate another embodiment of the present invention. In the embodiment illustrated in Fig. 7a, five electrodes 2, a common electrode 2a and a shielding electrode 2b are located on a first substrate 20 and the other parts of the proximity sensor 6 are located on a second substrate 22. The control device 8 is also located on the second substrate 22. The proximity sensor 6 includes five discrete sensing elements 14a,

14b, 14c, 14d and 14e formed from five electrodes 2 and the common electrode 2a. In this embodiment, the common electrode 2a is connected to 0V, and is a ground electrode or ground plane, and an excitation voltage is applied to the electrodes 2 and the shielding electrode 2b.

The first and second substrates 20, 22 are connected to each other by a flexible connecting member 24, which includes electrical connections between the electrodes 2 and a part of the proximity sensor 6. In the embodiment shown in Figs. 7a to 7c, the electrodes 2, 2a, 2b of the proximity sensor 6 are located on a flexible substrate (first substrate 20) and the other parts of the proximity sensor 6 are located on a rigid substrate (second substrate 22). The flexible substrate of the electrodes allows the proximity sensor to be adapted to fit with a wide variety of devices 1.

As best shown in Fig. 7c, each electrode 2, 2a, 2b and the substrate on which it is located is configured to be flexible. With reference to Figs. 7a and 7c the first substrate 20 is configurable between a planar configuration and an at least partially rolled

configuration. In the planar configuration, the first substrate 20 is substantially planar. In the at least partially rolled configuration, the shape of the first substrate 20 could be substantially cylindrical, or at least partially cylindrical. In the at least partially rolled configuration, the shape of the first substrate 20 could be configured to substantially match the shape of at least a part of the fluid transfer apparatus 10 and/or the fluid reservoir 12 of the fluid transfer apparatus 10. The first substrate 20 includes one or more alignment members 26 configured to align the first substrate to the device 1 , and the device 1 comprises one or more corresponding alignment members 28 configured to engage with the one or more alignment members of the first substrate. In the embodiment shown in Figs. 7a to 7c the common electrode 2a comprises three optically transparent portions 30, which in this

embodiment are formed from holes in the common electrode 2a, and the first substrate 20 is at least partially transparent, such that the three holes allow for inspection of the location of the fluid reservoir 12 relative to the electrodes 2, 2a, during testing or calibration of the device 1.

Each discrete sensing element 14 comprises a first electrode 2 and a second electrode 2a. In this embodiment, the second electrode 2a is common to all five of the discrete sensing elements 14. However, it should be understood that in other embodiments, separate second electrodes 2a could be used.

As shown in Fig. 7e, in this embodiment the electrodes 2, 2a, 2b of the proximity sensor 6 are located at or on an at least partially cylindrical wall portion of the device 1.

In this embodiment, the first electrodes 2 and second electrodes 2a of each discrete sensing element are configured to be adjacent to each other and configured to be opposite each other, when assembled in the device 1 (Fig. 7c). Thus, when the fluid reservoir 12 of the fluid transfer apparatus 10 is located in the device 1 (Fig. 7d), at least a portion of the first and second electrodes 2, 2a, are configured to be located at substantially opposing regions of the fluid reservoir 12 of the fluid transfer apparatus 10 when located in the device 1.

The proximity sensor 6 comprises a first discrete sensing element 14a, a second discrete sensing element 14b, a third discrete sensing element 14c, a fourth discrete sensing element 14d and a fifth discrete sensing element 14e.

An electrode 2 of the first and fifth discrete sensing elements 14a, 14e, has an irregular pentagon shape substantially on a plane defined by the longitudinal 20y and lateral axes 20x of the first substrate 20. The second, third and fourth discrete sensing elements 14b, 14c, 14d each include an electrode 2 having a V-shaped cross section.

In this embodiment, each discrete sensing element 14a to 14e includes an electrode zone 32 defined by the maximum length and width of the first electrode 2. As shown in Fig. 7a, each electrode zone is configured to substantially overlap with at least one electrode zone of at least one of the other discrete sensing elements 14. This means that at any given fill level of the fluid reservoir 12, it is likely that the response from at least two discrete sensing elements 14 will dominate, which improves the accuracy of the device 1.

Fig. 7a shows the electrode zones 32, 32’ of two of the electrodes 2 of the first and second discrete sensing elements 14a, 14b. The overlap 33 of the electrode zones 32, 32’ is configured to be substantially in the direction of the longitudinal axis of the fluid reservoir 12 when the fluid transfer apparatus 10 is located in the device 1. As shown in Fig. 7a, each electrode 2 of the discrete sensing elements 14 includes an overlapping portion arranged to protrude into an electrode zone 32 of another discrete sensing element 14. The first and fifth discrete sensing elements 14a, 14e include first electrodes 2 that have a non-overlapping portion arranged to be entirely within the electrode zone of that electrode 2.

In the alternative embodiment shown in Fig. 7a, the electrodes 2 are arranged in an electrode slider arrangement.

In the embodiment shown in Fig. 7a each electrode 2, 2a, 2b includes a hatched portion. In the embodiment illustrated in Fig. 7a to 7e, the electrodes 2 of each discrete sensing element 14 are arranged to substantially completely surround the fluid reservoir 12 of the fluid transfer apparatus 10 when the fluid reservoir 12 is located in the device 1. Flowever, in other

embodiments the electrodes could be arranged to partially surround the fluid reservoir 12.

The device 1 is configured such that each electrode 2, 2a, 2b is spaced from the fluid reservoir 12 of the fluid transfer apparatus 10 when the fluid reservoir 12 is located in the device 1. In this arrangement, the electrodes 2a, 2b, 2c are not in contact with the fluid in the fluid reservoir 12, and are not in contact with any wall portions of the fluid reservoir 12.

As shown in Fig. 7d, the device 1 is operable to communicate with a computing device 18. The computing device 18 comprises one or more application software elements configured to control, at least in part, the operation of the control device 8.

The computing device 18 includes a display 1 d’ configured to display data associated with the amount of fluid in the fluid reservoir 12 based, at least in part, on data received from the device 1 and a user input element 1 c.

As shown in Fig. 7d the device 1 is configured to display data associated with the amount of fluid in the fluid reservoir 12 based, at least in part, on data received from the proximity sensor 6.

In the embodiment illustrated in Fig. 7a to 7e, the control device 8 is configured to be operable at least in part via the computing device 18 and, the computing device 18 is used to obtain measurement data from the device 1.

Figs. 8a to 8e show data received from the first discrete sensing element 14a (Fig. 8a) through to the fifth discrete sensing element 14e (Fig. 8e) of the device 1 of Fig. 7a. As shown in Figs. 9a to 9e, the computing device 18 is configured to apply a drift correction function to data received from each discrete sensing element 14a to 14e. In this embodiment, the computing device 18 is configured to identify regions of high electrode sensitivity to changes in the amount of fluid in the fluid reservoir 12, and regions of relatively low electrode sensitivity to changes in the amount of fluid in the fluid reservoir 12. The computing device 18 is configured to reduce, or remove, drift from data received from the discrete sensing elements 14a to 14e in the regions of low electrode sensitivity to produce drift-corrected data (shown in Figs. 9a to 9e). As shown in Fig. 10a, the computing device 18 is configured to sum the response from each discrete sensing element using the drift-corrected data (shown in Fig. 9a to 9e), to obtain summed electrode data (Fig. 10a). In this arrangement, the computing device 18 can reduce or remove drift in regions of low electrode sensitivity, such that the response of the dominant electrodes (for a certain amount of fluid in the reservoir) dominate the overall change in signal. It will be understood that as the amount of fluid in the reservoir changes, some discrete sensing elements 14 will produce a larger change in signal due to the arrangement of the electrodes.

The computing device 18 is configured to obtain an initial signal response from the proximity sensor 6 when the device 1 is attached to the fluid reservoir 12 and when the fluid reservoir 12 is at its maximum fill level. In this embodiment, the user inputs this information to the computing device 18, such that the initial signal response can then be subtracted from the measurement data. This subtraction is shown in Fig. 10b, although it will be appreciated that other forms of offset correction could be used.

As shown in Fig. 10c, the computing device 18 is configured to apply a fit function (a linear fit) to fit the summed electrode data to the amount of fluid in the fluid reservoir 12 to create fitted summed electrode data (Fig. 10c).

It will be appreciated that other forms of fit function could be used.

As shown in Figs. 11a to 11 e the computing device 18 is configured to detect the deviation of the fitted summed electrode data from an ideal linear fit curve, and is configured to apply a fit correction function to the fitted summed electrode data, to reduce or remove the deviation of the fitted summed electrode data from the ideal fit curve. Figs. 11 a to 11 e were obtained using the device of Fig. 7a and using five different fluid transfer apparatuses 10. The fit correction curve is shown in Fig. 12 and was obtained using the data shown in Figs. 11 a to 11 e. The result of applying the fit correction curve to the data of Figs. 11 a to 11 e is shown in Figs. 13a to 13e.

Fig. 14 shows the effect of the fit correction curve of Fig. 12 on data obtained from a further fluid transfer apparatus 10 (that is, a fluid transfer apparatus that was not used to create the data shown in Figs. 11a to 11 e). Modifications and improvements may be made to the foregoing

embodiments without departing from the scope of the present invention. For example, whilst not shown here, it will be appreciated that the device could comprise one or more sensors and/or one or more proximity sensors, operable to apply an electric field to at least a part of the fluid reservoir.

The, or each electrode, could have a length of between approximately 0.1 mm and approximately 50 mm, optionally between approximately 0.5 mm and approximately 20 mm, optionally between approximately 1 mm and 10 mm. The, or each electrode, could have a width of between approximately 0.1 mm and approximately 50 mm, optionally between approximately 0.5 mm and approximately 20 mm, optionally between approximately 1 mm and 10 mm. Although it will be appreciated that the electrodes could be formed with any suitable dimensions.

The device 1 can be operated by using the elongated electrode to measure changes in capacitance as the amount of fluid in the fluid reservoir 12 changes. The device 1 can also be operated by using changes in capacitance from discrete sensor elements 14, and using the sum of the capacitance changes measured in this way to determine the amount of fluid in the fluid reservoir 12. This could be done using a calibration function. In other arrangements, the changes in capacitance could be split into discrete measurement bands to simplify the

measurement process. For example, in arrangements where there are multiple discrete sensing elements 14, the device 1 could use

measurement data from the closest discrete sensing element 14 to the fill level of the fluid reservoir 12. It should be appreciated that each discrete sensing element could have a threshold capacitance value for determining whether the discrete sensing element has detected the presence of fluid in the fluid reservoir 12 at a location substantially adjacent to it.

The fluid transfer apparatus 10 may be connectable to a source of fluid. The fluid transfer apparatus 10 could comprise one or more fluids, and the fluid may comprise one or more drugs, or substances.

The fluid transfer apparatus 10 could be configured to be pre-filled with the fluid. In this arrangement, the fluid reservoir 12 comprises the fluid, such as an insulin solution. However, it should be appreciated that the fluid reservoir 12 could be connectable to a source of an insulin solution.

Whilst in the embodiments illustrated and described here, the device 1 is configured to apply an alternating electric field to at least a part of the fluid reservoir 12, it should be understood that in other embodiments the device could be configured to apply a static, or d.c. electric field to the fluid reservoir 12. In other embodiments, the device 1 could be configured to apply an alternating, or a.c. electric field to the fluid reservoir and to apply a static, or d.c. electric field to the fluid reservoir.

In some embodiments, the proximity sensor 6 and the device 1 may be integrally formed, and the electrodes 2 and the device 1 could be integrally formed. The proximity sensor 6 and its substrate could be integrally formed. The, or each electrode and its substrate could be integrally formed. The, or each, electrode may be formed on a PCB. The proximity sensor 6 could comprise one or more electrodes, and the fluid transfer apparatus could comprise one or more further electrodes. In this arrangement, the electrodes of the device 1 and the fluid transfer apparatus 10 could be arranged to provide the electric field to the fluid reservoir 12. In this arrangement, there may be at least one electrical connection point between the device 1 and the fluid transfer apparatus 10.

Each discrete sensing element 14 could be formed from at least one electrode and the common electrode. Each discrete sensing element 14 could be formed from one or more electrodes, one or more common electrodes and/or one or more shielding electrodes. That is, many combinations of electrodes, common electrodes, and/or shielding electrodes are envisaged.

The, or each, electrode could be substantially planar and could have a substantially rectangular, square, rounded rectangular, or circular, cross section. For example, at least one electrode may be an elongated, or elongated planar electrode.

Whilst in the embodiments depicted here, the common electrode 2a is typically substantially larger than the other electrodes 2, the common electrode 2a could be any suitable size and shape. Furthermore, at least one electrode may have a substantially larger surface area than the other electrode, or electrodes. It will be appreciated that a wide variety of arrangements of shielding electrodes 2b are envisaged.

The electrodes 2 could be operable to apply the electric field to one or more parts, sections, or regions of the fluid reservoir 12. For example, a first set of electrodes could be located at a first part of the fluid reservoir 12 and a second set of electrodes could be located a second part of the fluid reservoir 12 (such as at opposing ends of the fluid reservoir 12).

Claims

1. A device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

one or more electrodes operable to apply an

electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus; and wherein the proximity sensor is operable to receive one or more signals from the, or each, electrode.

2. The device of claim 1 , wherein the, or each electrode is a substantially planar electrode.

3. The device of claim 1 or claim 2, wherein at least one electrode has a substantially larger surface area than the other electrode, or other electrodes.

4. The device of any preceding claim, wherein the, or each, electrode is arranged on one or more substantially planar substrates.

5. The device of any preceding claim, wherein the proximity sensor comprises one or more discrete sensing elements each formed from one or more electrodes, each discrete sensing element being operable to apply an electric field to at least a part of the fluid reservoir.

6. The device of claim 5, wherein each discrete sensing element is formed from at least one electrode and at least one common electrode, each discrete sensing element being operable to apply an electric field between its electrode, or electrodes, and its common electrode.

7. The device of claim 6, wherein the common electrode is arranged to at least partially surround the other electrodes.

8. The device of any preceding claim, wherein the device comprises two or more electrodes, and at least two of the electrodes are arranged to be substantially co-planar.

9. The device of any preceding claim, wherein the proximity sensor comprises one or more shielding electrodes arranged to at least partially shield the other electrodes of the proximity sensor from electromagnetic radiation.

10. The device of any preceding claim, wherein the device comprises two or more electrodes, and at least two of the electrodes are located, or arranged, on the same layer, surface, section, or region of a substrate.

11. The device of any preceding claim, wherein the, or each, electrode is arranged to be opposite an outer surface of the fluid reservoir when the device is connected to the fluid transfer apparatus.

12. The device of any preceding claim, wherein the electrodes are arranged to surround at least a part of the fluid reservoir when the device is connected to the fluid transfer apparatus.

13. The device of any preceding claim, wherein the electrodes are arranged on a plane that is tangential to the wall portion of the fluid reservoir when the device is connected to the fluid transfer apparatus.

14. The device of any preceding claim, wherein the fluid transfer apparatus is a drug, or substance, delivery apparatus.

15. The device of any preceding claim, wherein the device and/or the fluid transfer apparatus is portable and/or hand-operable.

16. The device of any preceding claim, wherein the proximity sensor is configured to detect changes in the capacitance of the, or each, electrode.

17. The device of claim 16, wherein the device proximity sensor is configured to detect changes in the capacitance between at least two electrodes.

18. The device of any preceding claim, wherein the device comprises one or more position detection means arranged to determine the position of the device relative to the fluid transfer apparatus.

19. The device of any preceding claim, wherein the device comprises a control device operable to control the operation of the proximity sensor.

20. The device of claim 19, wherein the control device is operable to communicate with a computing device.

21. The device of claim 19 or claim 20, wherein the control device is configured to obtain signals from the proximity sensor, and to use the signals to determine the amount of fluid present in the fluid reservoir.

22. The device of any one of claims 19 to 21 , wherein the control device is configured to display a selection of types of fluid transfer apparatuses to the user and to prompt the user to select a type of fluid transfer apparatus, wherein the control device is configured to prompt the user to select the type of fluid present in the fluid reservoir, wherein the control device is configured to use data input from the user and

measurement data obtained from the proximity sensor to display remaining doses, or units, of a drug or substance remaining in the fluid reservoir.

23. The device of any one of claims 19 to 22, wherein the control device is operable to set, obtain, record, or allow a user to input calibration data associated with the calibration of the fluid transfer apparatus, wherein the calibration data comprises the amount of fluid discharged from the fluid reservoir to test, or prime, the fluid transfer apparatus, prior to applying and/or injecting fluid to the user, the control device being configured to record the amount of fluid applied and/or injected to the user from the fluid transfer apparatus and configured to use at least part of the calibration data and data associated with the measured fluid in the fluid reservoir to determine the amount of fluid applied and/or injected to the user.

24. The device of any preceding claim, wherein the one or more electrodes are located on a first substrate and a part of the proximity sensor is located on a second substrate.

25. The device of claim 24, wherein the control device is located on the second substrate.

26. The device of claim 24 or claim 25, wherein the first substrate is an at least partially flexible substrate.

27. The device of any of claims 24 to 26, wherein the second substrate is a rigid substrate.

28. The device of any of claims 24 to 27, wherein the first and second substrates are connected to each other by a flexible connecting member.

29. The device of any preceding claim, wherein the one or more electrodes are configured to be flexible electrodes.

30. The device of any of claims 24 to 29, wherein the first substrate is configurable between a planar configuration and an at least partially rolled configuration.

31. The device of any preceding claim, wherein the one or more electrodes are located at or on an at least partially cylindrical wall portion of the device.

32. The device of any of claims 5 to 31 , wherein the, or each, discrete sensing element comprises one or more first electrodes and one or more second electrodes.

33. The device of claim 32, wherein the, or each, first electrode is located adjacent to at least one second electrode.

34. The device of claim 32 or claim 33, wherein the, or each, first electrode may be arranged to be located at a substantially opposing region of the fluid reservoir to at least one of the second electrodes when the fluid transfer apparatus is attached to the device.

35. The device of any of claims 5 to 34, wherein the, or each, discrete sensing element includes one or more electrode zones defined by the maximum length and maximum width of an electrode of the discrete sensing element, wherein one or more of the discrete sensing elements includes at least one electrode zone that is configured to substantially overlap with at least one electrode zone of one or more of the other discrete sensing elements.

36. The device of any preceding claim, wherein the device comprises two or more electrodes arranged in an electrode slider arrangement.

37. The device of any of claims 20 to 36, wherein the computing device comprises one or more application software elements configured to, at least in part, control the operation of the control device.

38. The device of any of claims 20 to 37, wherein the computing device is configured to display data associated with the amount of fluid in the fluid reservoir based, at least in part, on data received from the device.

39. The device of any of claims 20 to 38, wherein the computing device is configured to apply a correction function to data received from the, or each discrete sensing element.

40. The device of claim 39, wherein the correction function is a drift correction function.

41. The device of any of claims 20 to 40, wherein the computing device is configured to identify regions of high electrode sensitivity to changes in the amount of fluid in the fluid reservoir, and regions of relatively low electrode sensitivity to changes in the amount of fluid in the fluid reservoir.

42. The device of claim 41 , wherein the computing device is configured to reduce, or remove, drift from data received from the discrete sensing element(s) in the regions of low electrode sensitivity to produce drift- corrected data.

43. The device of claim 42, wherein the computing device is configured to sum the response from the discrete sensing elements using the drift- corrected data, to obtain summed electrode data.

44. The device of any of claims 20 to 43, wherein the computing device is configured to obtain an initial signal response from the proximity sensor.

45. The device of claim 44, wherein the initial signal response is obtained when the device is attached to the fluid transfer apparatus.

46. The device of claim 44 or 45, wherein the computing device is configured to use the initial signal response to alter the data received from the proximity sensor.

47. The device of any of claims 44 to 46, wherein the computing device is configured to subtract the initial signal response from the data received from the proximity sensor.

48. The device of any of claims 20 to 47, wherein the computing device is configured to prompt the user to enter an initial fill level of the fluid reservoir.

49. The device of claim 48, wherein the computing device is configured to obtain the initial signal response when the user has entered the initial fill level of the fluid reservoir.

50. The device of any of claims 43 to 49, wherein the computing device is configured to apply a fit function to fit the summed electrode data to the amount of fluid in the fluid reservoir to create fitted summed electrode data.

51. The device of claim 50, wherein the fit function is a linear fit function.

52. The device of claim 50 or claim 51 , wherein the computing device is configured to detect the deviation of the fitted summed electrode data from an ideal fit curve.

53. The device of claim 52, wherein the ideal fit curve is a linear curve.

54. The device of claim 52 or 53, wherein the computing device is configured to apply a fit correction function to the fitted summed electrode data, to reduce or remove the deviation of the fitted summed electrode data from the ideal fit curve.

55. A fluid transfer system, the system comprising:

a fluid transfer apparatus comprising a fluid reservoir and operable to transfer fluid from the fluid reservoir to a fluid outlet;

a device configured for attachment to the fluid transfer apparatus and operable to measure an amount of fluid in the fluid reservoir thereof, the device comprising:

a proximity sensor comprising: one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the fluid transfer apparatus; and

56. A device configured for attachment to a drug or substance delivery apparatus, the device being operable to measure an amount of fluid in a fluid reservoir of the drug or substance delivery apparatus, the device comprising:

a proximity sensor comprising:

one or more electrodes operable to apply an electric field to at least a part of the fluid reservoir when the device is attached to the drug or substance delivery apparatus; and

57. The device of claim 56, wherein the drug or substance delivery apparatus is an insulin delivery device, an insulin pen, or the like.

58. A system comprising:

an insulin delivery device, or insulin pen, comprising a fluid reservoir; and

a device according to any of claims 1 to 57, the device being attachable to the insulin delivery device, or insulin pen.

59. A method of measuring an amount of fluid in a fluid reservoir of a fluid transfer apparatus, the method comprising the steps of: providing a device configured for attachment to a fluid transfer apparatus and operable to measure an amount of fluid in a fluid reservoir thereof, the device comprising:

a proximity sensor comprising:

attaching the device to the fluid transfer apparatus;