Leakage state determination

Abstract

A computer-implemented method for determining a leakage state associated with an ostomy appliance, the method includes: determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period; determining values of one or more characteristics of the electrical signal based on the sensor data; and determining the leakage state associated with the ostomy appliance based on analysis of the values of the one or more characteristics.

Description

[0001] LEAKAGE STATE DETERMINATION

[0002] Technical Field and

[0003] [1] The present techniques relate to determining a leakage state associated with an ostomy appliance, and devices and systems for the same.

[0004] [2] Ostomy appliances are medical devices often used following a surgical ostomy procedure (such as a colostomy, ileostomy, urostomy, or gastrostomy) to collect stomal waste (e.g. faeces and / or urine, also known as stomal output) from a surgically created stoma (i.e. an artificial opening made in the body). Ostomy appliances can include a pouch or bag for collecting the waste and a baseplate for connecting the pouch or bag to the skin surrounding a stoma.

[0005] [3] An ostomy appliance can take a variety of forms, for example a one-piece form where the baseplate and bag or pouch are provided as one, or a two-piece form where the baseplate and bag or pouch are provided as separate connectable elements. Ostomy appliances can be secured to a user of the ostomy appliance, i.e. an ostomate, via an adhesive provided on the baseplate, for example.

[0006] [4] Stomal waste may build-up in a seal or adhesive layer between the ostomy appliance and the user, which can lead to the waste collected in the ostomy appliance or waste from the stoma leaking out from the ostomy appliance to a location external to the ostomy appliance. Such stomal waste leakage is undesirable for a number of reasons, including user comfort, user psychological health, user cleanliness and hygiene, peristomal skin health, and ostomy appliance longevity.

[0007] [5] Aspects of the invention are set out in the accompanying claims.

[0008] [6] Viewed from a first aspect, there is provided a computer-implemented method for determining a leakage state associated with an ostomy appliance, the method comprising: determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period; determining values of one or more characteristics of the electrical signal based on the sensor data; and determining the leakage state associated with the ostomy appliance based on analysis of the values of the one or more characteristics.

[0009] [7] The present inventors have identified that an electrical signal from a sensor device associated with an ostomy appliance can be analysed during a sampling period to provide information relating to a leakage state associated with the ostomy appliance. In particular, the electrical signal can be used to determine one or more characteristics of the electrical signal, and these one or more characteristics can then be used to determine the leakage state. By considering the electrical signal during a sampling period, rather than only taking a single measurement for example, the present approach is able to determine a greater amount of information from the electrical signal. This can then be used to provide an improved determination of the leakage state.

[0010] [8] Indeed, because the present approach determines values of one or more characteristics of the electrical signal based on the sensor data that has been determined during a sampling time period, more information can be determined from the electrical signal and thus more information can be determined from the sensor device associated with the ostomy appliance. As a result, the likelihood that a stomal waste leak is determined when a stomal waste leak is not present is reduced, and the likelihood that a stomal waste leak is detected when a stomal waste leak is present is increased. Thus, a leakage state can be more reliably and accurately determined. A user of the ostomy appliance may thus be more reliably and accurately informed of the leakage state of their ostomy appliance. This can prevent unnecessary discarding or reconfiguring of ostomy appliances when an ostomy appliance is not actually leaking. Further, a confidence of a user of the ostomy appliance in the leakage state determination is increased.

[0011] [9] By supporting an increase in the information that can be determined from the electrical signal and thus the ostomy appliance, a leakage state can also be determined more quickly. The present inventors have identified that the one or more characteristics can be used to provide a fast and early indication of the leakage state and thus by determining values of the one or more characteristics of the electrical signal, the leakage state can be determined more quickly. A user of the ostomy appliance may thus be informed of the leakage state of their ostomy appliance more quickly.

[0012]

[0010] Further, as more information regarding the electrical signal and thus the ostomy appliance can be determined, the present approach supports a more detailed leakage state determination and use of more advanced signal processing techniques. For example, because the present approach determines values of one or more characteristics of the electrical signal, the present approach can support the determining of a variety of different leakage states, such as to differentiate between different types of liquids (e.g. sweat or stomal waste) and also liquids having different properties (e.g. liquid location, spreading or movement direction of a liquid, a rate of liquid egress, etc.). Further, a variety of different signal processing techniques may be used to determine the values of the one or more characteristics, providing a more detailed and flexible leakage state determination. A user of the ostomy appliance may thus be informed of a more detailed leakage state of their ostomy appliance.

[0011] Existing approaches are unable to differentiate between sweat and stomal waste and instead are only able to determine the presence of liquid. However, with the present approach, sweat and stomal waste can be differentiated and identified. Such differentiation of liquid types and properties is particularly advantageous, as sweat typically does not compromise the integrity of an adhesive seal and is a natural consequence of ostomy appliance usage. Thus, although sweat may be present in an adhesive layer of an ostomy appliance (or sensor device of the ostomy appliance), this does not necessarily mean that an external stomal waste leak where stomal waste progresses to a location external from the ostomy appliance is imminent. Whereas, if stomal waste is detected in the adhesive layer, this is a reliable indicator that an external waste leak is imminent. Accordingly, the user can be notified in the case of stomal waste being detected in advance of stomal waste actually leaking externally from the ostomy appliance, and unnecessary changing of an ostomy appliance in the event that sweat is present rather than stomal waste can be avoided. This can result in increased user comfort and ostomy wear time.

[0013]

[0012] Thus, the present approach results in faster leakage state determination, more accurate and reliable leakage state determination, earlier leakage state detection, and supports determination of more informative leakage states. For a user of an ostomy appliance, the present approach therefore results in improved user comfort, improved user cleanliness and hygiene, and improved ostomy appliance lifetime.

[0014]

[0013] In normal operation, stomal waste exits the stoma and passes directly to the ostomy bag without being located between a skin-engageable surface of an adhesive layer associated with the ostomy appliance and the skin-surface of the user. However, in some cases, stomal waste may leak either from the stoma itself or from the ostomy pouch to a location between the skin-engageable surface of the adhesive layer associated with an ostomy appliance and a skin-surface of a user / ostomate. In this regard, a “stomal waste leak” is where, in use, stomal waste is located between the skin-engageable surface of an adhesive layer and skin around the stoma of an ostomate and has not progressed to an external location. An “external stomal waste leak” (or external waste leak) is where, in use, stomal waste is located between the skin-engageable surface of an adhesive layer and skin around the stoma of an ostomate and has progressed to an external location. In this context, the adhesive layer is part of a sensor device or ostomy appliance, as applicable. In this context, the sensor device or ostomy appliance, as applicable, is adhered to the skin by the adhesive layer. The “external location” is external from the sensor device or the ostomy appliance, as applicable. Thus, a stomal waste leak can be considered as a precursor to an external stomal waste leak, where the stomal waste actually leaks outside of the ostomy appliance and onto clothes or surrounding skin, for example. Hence, it will be appreciated that detecting stomal waste in a portion of the adhesive layer is indicative of the presence of a stomal waste leak, which itself is indicative that an external waste leak is likely to occur. Thus, by detecting the presence of stomal waste in the adhesive layer, a stomal waste leak can be determined.

[0015]

[0014] In some examples, the electrical signal corresponds to an electrical parameter associated with an electrode arrangement of the sensor device. Thus, the present approach may be used to determine a leakage state based on an electrical signal from a sensor device having an electrode arrangement, where the electrical signal corresponds to an electrical parameter associated with the electrode arrangement. Thus, the present approach may be used with such sensor devices to determine a leakage state of the ostomy appliance.

[0016]

[0015] In some examples, a value of the electrical parameter is dependent on application of an alternating electrical signal by the electrode arrangement to a portion of an adhesive layer of the sensor device. By applying an alternating electrical signal and determining sensor data indicative of the electrical signal in response, greater information can be determined from the sensor device that can be used to determine the leakage state. For example, properties of a liquid can be determined and the liquid can be classified into sweat or stomal waste, for example.

[0017]

[0016] Indeed, with an alternating electrical signal, an impedance of the adhesive layer can be determined. Unlike resistance, which can be measured in a non-alternating signal arrangement (such as DC), the impedance of the adhesive in an alternating electrical signal arrangement gradually decreases before a short-circuit occurs in the presence of liquid. Indeed, dry adhesive behaves as an insulator with high resistance. However, the dielectric properties of the adhesive change as the adhesive absorbs liquid (such as water), which results in a decreasing impedance even though the liquid has not penetrated across the full thickness of the adhesive between electrodes of an electrode pair. Thus, an output signal can be determined during a time period when the electrical properties of the adhesive (i.e. its impedance) are changing, and this can be used to determine various properties of the liquid, such as classifying the liquid into sweat or stomal waste, which would not otherwise be possible in a DC implementation.

[0018]

[0017] A sensor device having an electrode arrangement (for example including an electrode pair) can be used to receive an alternating electrical signal and provide an output signal in response to applying the alternating electrical signal to the portion of the adhesive layer of the sensor device, the output signal indicative of an electrical property of the portion of the adhesive layer. Such sensor devices can thus use an alternating electrical signal to determine an electrical property of the portion of the adhesive, which may vary and depend on whether liquid is present in the portion of the adhesive. This can be used for leakage detection. When such sensor devices are used with an ostomy appliance, the sensor device may therefore provide an output signal indicative of a leakage state of the ostomy appliance. Thus, a sensor device can output an electrical signal that can be used by the present techniques to determine a leakage state of an ostomy appliance.

[0019]

[0018] It will be appreciated that in use the ostomy appliance may be considered as comprising an ostomy bag, a baseplate and a sensor device, and therefore by using output from the sensor device to detect liquid / determine a leakage state, the leakage state may be associated with the ostomy device. In some examples, the sensor device may be integral with a baseplate of the ostomy appliance. For example, the sensor device may output a signal indicative of an electrical property of a portion of an adhesive layer of the baseplate. In other examples, the sensor device may be provided separately from the baseplate of the ostomy appliance and connectable to the baseplate of the ostomy appliance, and so may output a signal indicative of an electrical property of an adhesive layer of the sensor device.

[0020]

[0019] In some examples, the method comprises receiving, from a control device associated with the sensor device, the sensor data. In this way, the sensor device and control device (which may be configured to provide the alternating signal to the sensor device and determine the output signal) can report the sensor data, and the determining of the leakage state can be based on this received sensor data. Accordingly, the present techniques can be used in combination with a sensor device and control device arrangement. Indeed, the present approach may therefore be performed by a monitor device, for example a user device (such as a user of the ostomy appliance), and therefore support efficient notification of the leakage state to the user.

[0021]

[0020] In some examples, the electrical signal is indicative of an impedance of an adhesive portion of the sensor device. The present inventors have identified that the impedance of an adhesive portion can change depending on whether liquid is present in the adhesive portion and also depending on the type of liquid (such as sweat, stomal waste, etc.) and its properties (amount of liquid, speed of spread, etc.). Thus, by determining the one or more characteristics, information indicative of the impedance change in the adhesive portion can be determined and thus the presence of liquid, and in some examples, the type of liquid and its properties, can be determined. For example, the present inventors have identified that sweat and stomal waste presence in the adhesive result in different output signal responses, and so the output electrical signal can be used to classify a detected liquid into sweat or stomal waste.

[0022]

[0021] In some examples, the one or more characteristics comprise one or more of a signal amplitude, signal phase, waveform, and spatial distribution. As discussed herein, the present inventors have identified that characteristics of the signal can be used to determine a leakage state of the ostomy appliance. In particular, the present inventors have recognised that the presence of liquid in the adhesive can take various forms and have various properties which are identifiable based on analysis of the signal. For example, the presence of sweat in an adhesive layer causes a different change to the electrical signal to the presence of stomal waste (i.e. faeces and / or urine), for example in terms of an effect on the signal amplitude and a signal phase (such as a change of the signal phase with respect to an input alternating electrical signal) during a signal sampling time period. Sweat may cause a slower reduction in signal amplitude compared to stomal waste, for example. Stomal waste or waste as used herein are used interchangeably and refer to waste (liquid waste or waste having a certain amount of moisture or liquid) that has exited from a stoma of the user, and thus refers to waste collected in the ostomy bag and waste that exits the stoma of the user before it has been collected in the ostomy bag.

[0023]

[0022] Further, a fast stomal waste build-up in the adhesive layer causes a different change to the electrical signal compared to a slow stomal waste build-up, and similarly a large stomal waste build-up causes a different change to the electrical signal compared to a small stomal waste build-up. Thus, by determining various characteristics of the signal, for example over a sampling time period, various properties of a liquid detected in the adhesive can be determined. Further, an absence of a stomal waste leak or absence of sweat can be determined based on the one or more characteristics of the electrical signal.

[0024]

[0023] In examples, the leakage state is indicative of a risk of stomal waste leaking externally from the ostomy appliance. In some examples, the leakage state is indicative of whether liquid is present in an adhesive layer of the sensor device. Hence, the leakage state can be indicative of whether a stomal waste leak has occurred and / or whether sweat is present, allowing the user to take action in advance of an external waste leak (i.e. waste actually leaking from the ostomy appliance to a location external to the ostomy appliance).

[0025]

[0024] In examples, the leakage state comprises one or more of: a state indicative of liquid presence in an adhesive layer associated with the ostomy appliance; a state indicative of liquid absence in an adhesive layer associated with the ostomy appliance; a state indicative of stomal waste presence in an adhesive layer associated with the ostomy appliance; a state indicative of sweat presence in an adhesive layer associated with the ostomy appliance; a state indicative of a predicted stomal waste leak associated with the ostomy appliance; and a state indicative of a degradation of an adhesive layer associated with the ostomy appliance.

[0026]

[0025] In some examples, determining the leakage state based on the values of the one or more characteristics comprises determining whether the values of the one or more characteristics satisfy a leakage state condition. In this way, the leakage state may be determined in an efficient manner that supports a fast leakage state determination.

[0027]

[0026] In some examples, the one or more characteristics comprise a signal amplitude and a signal phase of the electrical signal. Thus, the leakage state may be determined on the basis of signal characteristics of the output electrical signal in an efficient manner.

[0028]

[0027] In some examples, determining whether the values of the one or more characteristics satisfy a leakage state condition comprises comparing the values of the one or more characteristics to one or more predetermined thresholds or previously determined values for the one or more characteristics. Predetermined thresholds for determining a given leakage state may be identified based on experiment and testing, for example by supplying liquid to a portion of the adhesive and measuring the response from the electrical signal, and determining thresholds that characterise the presence of the liquid. As a result, predetermined thresholds can be used to efficiently determine a leakage state in use. Additionally, or alternatively, the one or more characteristics may be compared to previously determined values, and thus a change over time of a given characteristic can be determined to indicate the leakage state. For example, a change in a signal amplitude or signal phase may indicate the presence of liquid in the adhesive layer, and also whether the liquid is stomal waste or sweat, and thus may be used to determine the leakage state.

[0029]

[0028] In some examples, determining whether the values of the one or more characteristics satisfy a leakage state condition comprises comparing a rate of change of the values of the one or more characteristics during the sampling time period to a rate of change of previously determined values of the one or more characteristics during a previous sampling time period or one or more predetermined rate of change thresholds.

[0030]

[0029] The present inventors have identified that a rate of change of signal characteristics, such as signal amplitude, signal phase (and change thereof), waveform etc., can be used to provide an indication of the presence of liquid in the adhesive layer and whether the liquid is stomal waste (thus indicating the presence of a stomal waste leak), and thus can be used as a precursor to notify the user before an external waste leak occurs. Further, the rate of change of the one or more characteristics can be used to differentiate a type of liquid, such as sweat or stomal waste, from one another. Indeed, a rate of change of phase or signal amplitude for the presence of sweat and the presence of stomal waste is different, and this can be used to provide valuable information regarding the type of liquid present in the adhesive, and thus the risk of an external waste leak in the future.

[0031]

[0030] In some examples, determining the leakage state comprises determining whether liquid is present in an adhesive layer of the sensor device based on analysis of values of the one or more characteristics. In this way, the leakage state can indicate the presence of liquid in the adhesive layer, which can indicate that an external stomal waste leak is imminent or likely in future. It will be appreciated that the adhesive layer may be an adhesive layer of the sensor device (which itself is associated with the ostomy appliance).

[0032]

[0031] In some examples, determining whether liquid is present in an adhesive layer based on analysis of values of the one or more characteristics comprises determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of liquid presence. The present inventors have identified that a rate of change of values of the characteristics (such as signal amplitude and signal phase) can be used to determine that liquid is present in the adhesive layer. For example, a signal amplitude attenuation of around 3dB or more in a time period of approximately 5 minutes may correspond to a condition indicative of liquid presence. In this way, liquid presence can be efficiently and accurately determined.

[0033]

[0032] In some examples, the leakage state comprises one or more of: a state indicative of liquid presence in an adhesive layer associated with the ostomy appliance; a state indicative of liquid absence in an adhesive layer associated with the ostomy appliance; a state indicative of stomal waste presence in an adhesive layer associated with the ostomy appliance; a state indicative of sweat presence in an adhesive layer associated with the ostomy appliance; a state indicative of a predicted external stomal waste leak associated with the ostomy appliance; and a state indicative of a degradation of an adhesive layer associated with the ostomy appliance.

[0034]

[0033] In some examples, the method further comprises determining the leakage state as the state indicative of liquid presence in an adhesive layer associated with the ostomy appliance in response to determining that the values of the one or more characteristics of the output signal satisfy a condition indicative of liquid presence. In some examples, the method further comprises determining the leakage state as the state indicative of liquid absence in an adhesive layer associated with the ostomy appliance in response to determining that the values of one or more characteristics of the output signal satisfy a condition indicative of an absence of liquid. In some examples, the method further comprises determining the leakage state as the state indicative of stomal waste presence in the adhesive layer associated with the ostomy appliance in response to determining that values of the one or more characteristics of the output signal satisfy a condition indicative of stomal waste presence. In some examples, the method further comprises determining the leakage state as the state indicative of a sweat presence in an adhesive layer associated with the ostomy appliance in response to determining that the values of one or more characteristics of the output signal satisfy a condition indicative of sweat presence. In some examples, the method further comprises determining the leakage state as the state indicative of a predicted external stomal waste leak associated with the ostomy appliance in response to determining that the values of the one or more characteristics of the output signal satisfy a condition indicative of an external stomal waste leak. In some examples, the method further comprises determining the leakage state as the leakage state indicative of a degradation of the adhesive layer associated with the ostomy appliance in response to determining that the values of the one or more characteristics satisfy a condition indicative of adhesive degradation.

[0035]

[0034] In some examples, the method further comprises determining the leakage state as a state indicative of stomal waste presence in the adhesive layer associated with the ostomy appliance based on determining that a change in signal amplitude and a change in signal phase of the electrical signal satisfy a condition indicative of stomal waste presence. In some examples, the method further comprises determining the leakage state as a state indicative of sweat presence in the adhesive layer associated with the ostomy appliance based on determining that a change in signal amplitude and a change in signal phase of the electrical signal satisfy a condition indicative of sweat presence.

[0036]

[0035] Thus, the present approach determines the various leakage states based on analysis of the values of the one or more characteristics. In this way, the present approach is able to efficiently identify various leakage states based on analysis of the electrical signal.

[0037]

[0036] In some examples, the method further comprises in response to determining that liquid is present in the adhesive layer of the sensor device, determining one or more properties associated with the liquid based on analysis of the values of the one or more characteristics. In some examples, the one or more properties comprise: a classification of the liquid, for example into one of sweat or stomal waste; a location of the liquid in the sensor device; an area of presence of the liquid; a spreading direction of the liquid; and a rate of movement of the liquid.

[0038]

[0037] As discussed herein, the present inventors have identified that analysis of the one or more characteristics (such as amplitude, phase, waveform, etc.) can be used to determine properties of the liquid. For example, how the amplitude of the electrical signal changes over the sampling time period can be used to identify the type of liquid, and its rate of movement of spread. Similarly, the phase change of the electrical signal can be used to provide an indication of the type of liquid and to classify the liquid, for example into sweat or stomal waste or another liquid.

[0039]

[0038] In some examples, determining the leakage state comprises, in response to determining that liquid is present in the adhesive layer, classifying the liquid into one of sweat or stomal waste. In this way, the present approach can be used to actually classify the type of liquid. While sweat may not be problematic as sweat typically does not affect the integrity of the seal associated with the ostomy appliance and may build-up more slowly as a natural consequence of use, a stomal waste leak can be a reliable precursor to an external stomal waste leak, where stomal waste actually leaks externally from the ostomy appliance.

[0040]

[0039] In some examples, classifying the liquid into one of sweat or stomal waste is based on determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of stomal waste presence. Thus, the type of liquid can be differentiated. As discussed, sweat may not typically affect an integrity of an adhesive seal, whereas stomal waste typically will. By being able to differentiate between these two liquids, the likelihood that a user is caused to unnecessarily change their ostomy appliance or the adhesive is reduced. The condition indicative of stomal waste presence may correspond to whether changes to a signal amplitude and signal phase in a predetermined time period both satisfy predetermined thresholds. For example, whether the signal amplitude has changed by about 3dB and the phase has changed by about 45 degrees in 5 minutes.

[0041]

[0040] In some examples, classifying the liquid into one of sweat or stomal waste is based on determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of sweat presence. As before, specific thresholds can be set for triggering an identification of sweat. Sweat typically attenuates a signal more slowly than a leak of stomal waste and thus a change in signal amplitude of about 3dB in a time period greater than 5 minutes but less than 30 minutes may correspond to the condition indicative of sweat presence.

[0042]

[0041] In some examples, the method further comprises signalling a notification to a user device of the user or causing the user device to generate a notification based on the determined leakage state. In some examples, the method comprises signalling a notification indicating a risk of stomal waste leaking externally from the ostomy appliance in response to classifying the liquid as stomal waste. Thus, a user or healthcare professional can be informed of the leakage state of the ostomy appliance. Accordingly, a user or user device may be signalled depending on the leakage state. This can provide a user of the ostomy appliance, or a healthcare professional, with information that can then be used to provide a response based on the leakage state, such as replacing the ostomy appliance or repairing the adhesive seal in advance of an external waste leak actually occurring.

[0043]

[0042] In some examples, the method further comprises in response to classifying the liquid as sweat, suppressing signalling a notification indicating a risk of stomal waste leaking externally from the ostomy appliance or signalling a notification indicating that sweat is present in the adhesive layer. As mentioned, the presence of sweat may be a natural consequence of wear, particularly during physical activity and thus rather than triggering a false-alarm of a likely external waste leak (which would happen if sweat and stomal waste build-up in the adhesive layer could not be differentiated), the present approach instead suppresses signalling a notification indicating a risk of an external waste leak, or signals a notification indicating the presence of sweat in the adhesive layer. Either way, a false-alarm of an external waste leak is not triggered and so the user is not notified that a change in ostomy appliance or repair of the adhesive seal is required.

[0044]

[0043] In some examples, the method further comprises in response to determining that the leakage state indicates a leak associated with an adhesive layer of the sensor device, generating a notification indicating the presence of a leak. Thus, the user may be notified of the presence of a leak and may take action in response, such as the repair of an adhesive seal, emptying of the ostomy bag, etc.

[0045]

[0044] In some examples, the method further comprises in response to determining the leakage state, sending a notification to a user device of the user or causing the user device to generate an alert based on the notification. Hence, the user is notified based on the determined leakage state.

[0046]

[0045] In some examples, determining the leakage state comprises determining whether an adhesive layer of the sensor device has degraded based on analysis of values of the one or more characteristics. In some examples, determining whether the adhesive layer of the sensor device has degraded based on analysis of values of the one or more characteristics comprises determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of adhesive degradation. Over time, properties of the adhesive may degrade and thus by determining whether the adhesive layer has degraded, a likelihood of the adhesive layer failing and causing stomal waste to leak externally from the ostomy appliance can be reduced.

[0047]

[0046] In some examples, the method further comprises changing the leakage state condition in response to a change condition being satisfied. Thus, the present approach supports dynamic and configurable adjustment of leakage state detection based on user requirements.

[0048]

[0047] In some examples, the change condition comprises one or more of: a user input condition, a time of day condition, a health condition, a physical activity condition, a location condition, and a historical ostomy appliance usage condition. This allows a more flexible and customisable approach to leakage detection. For example, at certain points, the leakage state thresholds may be adjusted to provide more or less sensitive triggering of a given leakage state.

[0048] In some examples, determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period comprises receiving the sensor data from a control device associated with the sensor device. Accordingly, the present method may be performed within a system comprising a sensor device and a control device associated with the sensor device. This allows advantageous distribution of functionality, and supports a lightweight sensor device / control device arrangement as the processing may be offloaded to a device that isn’t situated with the ostomy appliance, for example.

[0049]

[0049] In some examples, a value of the electrical parameter is dependent on application of an alternating electrical signal by the electrode arrangement to a portion of an adhesive layer of the sensor device, and wherein the electrical signal is indicative of an impedance of an adhesive portion of the sensor device.

[0050]

[0050] In some examples, the method further comprises determining a predicted failure time indicative of a predicted future time when stomal waste is predicted to egress from the ostomy appliance based on the values of the one more characteristics.

[0051]

[0051] Viewed from a second aspect, there is provided a computer-readable medium comprising instructions which, when executed by one or more processors, cause the one or more processors to carry out the method described herein.

[0052]

[0052] Viewed from a third aspect, there is provided a monitor device for an ostomy appliance, the monitor device comprising one or more processors configured to perform the method as described herein.

[0053]

[0053] Viewed from a fourth aspect, there is provided a leakage state determining system for an ostomy appliance, the system comprising: a sensor device comprising: an electrode arrangement comprising an electrode pair; and an adhesive layer having a skin-engageable surface arranged in use to adhere the sensor device to a skin surface of a user of the ostomy appliance, wherein the electrode pair is arranged in use to receive an alternating electrical signal and provide an output signal in response to applying the alternating electrical signal to a portion of the adhesive layer, the output signal indicative of an electrical property of the portion of the adhesive layer; a control device configured to provide the alternating electrical signal to the electrode arrangement and determine the output signal from the electrode arrangement; and the monitor device as described above.

[0054] Other aspects will also become apparent upon review of the present disclosure, in particular upon review of the Brief Description of the Drawings, Detailed Description and Claims sections.

[0054] Brief Description of the Drawings

[0055]

[0055] Examples of the disclosure will now be described, byway of example only, with reference to the accompanying drawings in which:

[0056]

[0056] Figure 1A: schematically illustrates an example ostomy appliance in exploded view with which the present techniques and devices may be implemented.

[0057]

[0057] Figure 1 B: schematically illustrates the example ostomy appliance of figure 1A in crosssection and in-situ on a skin-surface of a user.

[0058]

[0058] Figure 2A: schematically illustrates an example sensor device in cross-section as described herein.

[0059]

[0059] Figure 2B: schematically illustrates the example sensor device of figure 2A in crosssection and in-situ on a skin-surface of a user.

[0060]

[0060] Figure 3A: schematically illustrates operation of an example sensor device as described herein.

[0061]

[0061] Figure 3B: schematically illustrates operation of an example sensor device as described herein.

[0062]

[0062] Figure 4: schematically illustrates an example electrical circuit diagram representation of operation of an example sensor device as described herein.

[0063]

[0063] Figure 5A: schematically illustrates an example sensor device in plan view as described herein.

[0064]

[0064] Figure 5B: schematically illustrates an example sensor device in exploded view with an ostomy appliance as described herein.

[0065]

[0065] Figure 6A: schematically illustrates an example sensor device in plan view as described herein.

[0066]

[0066] Figure 6B: schematically illustrates an example sensor device in plan view as described herein.

[0067]

[0067] Figure 7A: schematically illustrates an example sensor device and baseplate in crosssection as described herein.

[0068] Figure 7B: schematically illustrates an example sensor device and baseplate in crosssection as described herein.

[0068]

[0069] Figure 7C: schematically illustrates an example sensor device and baseplate in crosssection and in-situ on a skin surface of a user as described herein.

[0069]

[0070] Figure 8A: schematically illustrates an example system as described herein.

[0070]

[0071] Figure 8B: schematically illustrates an example system as described herein.

[0071]

[0072] Figure 8C: schematically illustrates an example system as described herein.

[0072]

[0073] Figure 9: schematically illustrates steps for performing leakage state determination as described herein.

[0073]

[0074] Figure 10A: shows an example relationship between signal characteristics and time as described herein.

[0074]

[0075] Figure 10B: shows an example relationship between signal amplitude and time for three different liquid amounts as described herein.

[0075]

[0076] Figure 10C: shows an example relationship between signal amplitude and phase and time for sweat and a waste leak.

[0076]

[0077] Figure 11 A: schematically illustrates steps for determining a given leakage state as described herein.

[0077]

[0078] Figure 11 B: schematically illustrates steps for determining leakage states as described herein.

[0078]

[0079] Figure 12: schematically illustrates steps for triggering a signal or notification based on a given leakage state as described herein.

[0079]

[0080] Figure 13: schematically illustrates steps for changing a leakage state condition as described herein.

[0080]

[0081] Figure 14: schematically illustrates an example device that may perform leakage state determination as described herein.

[0081]

[0082] While the disclosure is susceptible to various modifications and alternative forms, specific example approaches are shown by way of example in the drawings and are herein described in detail. It should be understood however that the drawings and detailed description attached hereto are not intended to limit the disclosure to the particular form disclosed but rather the disclosure is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claimed invention.

[0083] It will be recognised that the features of the above-described examples of the disclosure can conveniently and interchangeably be used in any suitable combination.

[0082] Detailed Description

[0083] Discussion of examples will now be provided with reference to the attached figures.

[0084] Example ostomy appliance arrangement and sensor device

[0085]

[0084] Figure 1A shows an example ostomy appliance 100 with which the present techniques and devices may be implemented. Ostomy appliance 100 includes a baseplate 101 for attaching the ostomy appliance 100 to a skin-surface 103 of a user in use. The baseplate 101 may have an adhesive for attaching the ostomy appliance 100 to the skin-surface 103. The skin-surface 103 has a stoma 104 which has been created by a surgical procedure, for example, and from which waste / effluent may exit the user. The ostomy appliance 100 also includes an ostomy bag (or pouch) 102 for collecting the waste or effluent from the stoma 104.

[0086]

[0085] In use, the baseplate 101 is attached to the skin-surface 103 around the stoma 104 by the adhesive of the baseplate 101. In a one-piece construction, the ostomy bag 102 may be provided integrally with the baseplate 101 and thus by attaching the baseplate 101 to the skinsurface 103, the ostomy bag 102 is also attached to the skin-surface 103 and may collect waste from the stoma 104. In a two-piece construction, the ostomy bag 102 may be secured to the baseplate 101 once the baseplate 101 is attached to the skin-surface 103, for example.

[0087]

[0086] Figure 1 B shows the ostomy appliance 100 of figure 1A in cross-section and when attached to the skin-surface 103 of a user. The baseplate 101 includes an adhesive layer 105. As shown, the baseplate 101 surrounds the stoma 104 and is attached to the skin-surface 103 by the adhesive layer 105. This adhesive layer 105 seals the ostomy appliance 100 to the skin-surface 103 of the user.

[0088]

[0087] When waste exits the stoma 104, the waste can be collected in the ostomy bag 102. In some implementations, a further element may be provided with the baseplate 101 that in use extends from the baseplate 101 towards the stoma 104 and that guides waste away from the adhesive layer 105 and towards the ostomy bag 102. In normal operation, waste does not contact the skin-surface 103. Indeed, waste contacting the skin-surface 103 can have detrimental effects on the peristomal skin-surface.

[0089]

[0088] However, in some cases, waste may move towards skin-surface 103 (and thus the adhesive layer 105), as shown in figure 1 B by the arrows labelled W. For example, waste exiting from the stoma 104 or waste that has been collected in the ostomy bag 102 may move towards the skin-surface 103 (and the adhesive layer 105). In this regard, a “stomal waste leak” is where, in use, stomal waste is located between the skin-engageable surface of an adhesive layer and skin around the stoma of an ostomate and has not progressed to an external location. Over time, this waste may build-up in the adhesive seal provided by the adhesive layer 105 and may collect under the baseplate 105 (which would be invisible to the user of the ostomy appliance), resulting in full or partial detachment of the ostomy appliance and spillage of the stomal waste contents. An “external stomal waste leak” (or external waste leak) is where, in use, stomal waste is located between the skin-engageable surface of an adhesive layer and skin around the stoma of an ostomate and has progressed to an external location. In this context, the adhesive layer is part of a sensor device or ostomy appliance, as applicable. In this context, the sensor device or ostomy appliance, as applicable, is adhered to the skin by the adhesive layer. The “external location” is external from the sensor device or the ostomy appliance, as applicable. A stomal waste leak can be considered as a precursor to an external stomal waste leak.

[0090]

[0089] It will be appreciated that the ostomy appliance 100 and arrangement shown in figures 1A and 1 B is only an example, and the shape and arrangement of ostomy appliance 100 may vary depending on implementation and use-case.

[0091]

[0090] As discussed herein, waste leakage associated with the ostomy appliance is undesirable for various reasons, including user comfort, user psychological health, user cleanliness and hygiene, peristomal skin health, and ostomy appliance longevity. In particular, surprise external waste leaks are particularly undesirable for a user of an ostomy appliance and can result in significant user embarrassment.

[0092]

[0091] A sensor device according to the present teachings will now be described with reference to figure 2A.

[0093]

[0092] Figure 2A shows an example sensor device 200. Sensor device 200 includes an electrode arrangement 201 comprising an electrode pair 205. The electrode arrangement may be provided in a variety of ways. For example, the electrode arrangement may comprise a plurality of wires or conducting electrode traces. In some examples, the electrode arrangement may be formed from metallic ink.

[0094]

[0093] The sensor device also includes an adhesive layer 202. Advantageous features relating to the adhesive, such as its composition and arrangement, is discussed further below in the ‘Adhesive composition and arrangement’ section. The adhesive layer 202 has a skin- engageable surface 203 which, in use, adheres the sensor device 200 to a skin surface of a user of an ostomy appliance, for example the skin surface 103 of figures 1A and 1 B.

[0094] It will be appreciated that electrode arrangement 201 may comprise a plurality of electrode pairs 205 each configured to sense an electrical property associated with a respective portion of adhesive layer 202.

[0095]

[0095] The electrode pair 205 may be provided within or partially within the adhesive layer 201 , or may be formed on top of the adhesive layer 201. The electrode pair 205 of the electrode arrangement 201 is arranged in use to receive an alternating electrical signal and provide an output signal in response to applying the alternating electrical signal to a portion 204 of the adhesive layer 202. This output signal is indicative of an electrical property of the portion 204 of the adhesive layer 202. In an example, the output signal corresponds to an electrical parameter associated with the electrode arrangement 201 (such as with the electrode pair 205). For example, the electrical parameter may be selected from current, voltage, resistivity, impedance, capacitance, conductance, and inductance.

[0096]

[0096] The present inventors have identified that an alternating electrical signal (such as an alternating current, AC or an alternating voltage) can be used to determine whether an electrical property of a portion of an adhesive layer has changed in response to the presence of liquid and can thus be used to determine a leakage state of an ostomy appliance. Thus, by measuring the output signal from the electrode pair 205 of the electrode arrangement 201 , the electrode pair 205 can sense the presence of liquid in the portion 204 of the adhesive layer 202. Furthermore, various characteristics of the output signal can be determined, which can be used to identify various properties associated with the liquid, such as a liquid type, position, spread speed etc.

[0097]

[0097] In one example, the alternating electrical signal is an alternating current, which is used by the sensor device to determine an impedance of the portion of the adhesive by applying the alternating current to the portion of the adhesive and measuring the response with the electrode pair. As discussed herein, impedance of the adhesive may vary based on whether liquid is present in the adhesive, and the amount of liquid present (and other properties of the liquid), and thus can be used to detect liquid in the adhesive layer and in some examples determine a leakage state associated with the ostomy appliance.

[0098]

[0098] The sensor device 200 may be formed as part of a baseplate, for example the baseplate 101 of figures 1A and 1 B. In this case, the adhesive layer 202 corresponds to the adhesive layer 105. Thus, the electrode arrangement 201 may be formed in or with the baseplate. As a result, a baseplate with integrated sensing capabilities is provided.

[0099]

[0099] Advantageously, the sensor device 200 may be provided separately from a baseplate, such as separately from the baseplate 101. This allows separate and independent re-use of the sensor device. Figure 2B illustrates an example arrangement of a sensor device provided separately from a baseplate.

[0100]

[0100] Figure 2B corresponds to figure 1 B, except sensor device 200 is provided under the baseplate 101 in use such that the sensor device 200 connects the baseplate 101 to the skinsurface 103 of a user. Although not explicitly shown in figure 2B, sensor device 200 includes the electrode pair 205, portion 204 and skin-engageable surface 203 of figure 2A.

[0101]

[0101] During use, as discussed in relation to figure 1 B, waste exits the stoma 104 and is collected in the ostomy bag 102. However, a waste leak may develop when waste contacts the skin-surface 103 of the user around the stoma and starts to accumulate between the skin- engageable or skin-engageable surface 203 of the adhesive layer 202 (before an external waste leak occurs). Over time, this waste leak may affect the seal provided by the adhesive layer 202, which would be invisible to a user of the device. This can result in an external waste leak, where stomal waste leaks to a location external to the ostomy appliance, resulting in soilage of clothes for example.

[0102]

[0102] For example, waste may move towards the adhesive layer 202 of the sensor device or the adhesive layer 105 of the baseplate and enter between a skin-engageable surface of the adhesive layer and the skin of the user. This is shown by arrows labelled ‘W. Over time, this waste leak may result in waste leaking through the adhesive layer 105 or adhesive layer 202 to a location external to the ostomy appliance 100 (i.e. an external stomal waste leak). In some cases, this may result in compromise of the adhesion provided by the adhesive layer 202 causing detachment of the ostomy appliance from the skin-surface 103 and spillage of its waste contents.

[0103]

[0103] Further, during use, sweat from the skin-surface of the user may affect the adhesive layer (105 or 202), or there may be liquid ingress from external to the ostomy appliance (for example as a result of getting the ostomy appliance wet). While detecting a liquid as described herein refers to liquid ingress to the adhesive more generally, and thus includes waste from a stoma, sweat from a user of the ostomy appliance, and other liquids, a waste leak refers to when stomal waste is located between a skin-engageable surface of an adhesive layer associated with the ostomy appliance and a skin-surface of the user and has not progressed to a location external from the ostomy appliance, whereas an external waste leak refers to when the stomal waste has progressed to a location external from the ostomy appliance as discussed herein.

[0104]

[0104] In some cases, the waste leakage may compromise the adhesive to a point where the adhesive fails and the ostomy appliance detaches from the skin-surface. Such leakage is therefore undesirable for various reasons, including user comfort, user cleanliness and hygiene, and ostomy appliance longevity. In particular, surprise external waste leaks are particularly undesirable for a user of an ostomy appliance.

[0105]

[0105] It will therefore be appreciated that a waste leak can be a reliable predictor or precursor for an external waste leak. Thus, an improved detection of a waste leak (i.e. by detecting stomal waste presence in the adhesive layer) can allow identification of an imminent or future external waste leak before the external waste leak actually occurs. Thus, as described herein, the present sensor device supports an improved approach to leakage detection that results in faster leakage detection, earlier leakage detection, and more informative leakage detection.

[0106] Determining an electrical property with the sensor device

[0107]

[0106] Determining an electrical property of the adhesive of the sensor device during use will now be described in more detail with reference to figures 3A, 3B, and 4.

[0108]

[0107] Figure 3A shows an example sensor device 300, which may correspond to sensor device 200 in the absence of a leak / liquid. Sensor device 300 includes electrodes 301 , 302, forming an electrode pair, an adhesive layer 303, and a portion 304 of the adhesive layer 303. The electrode pair formed by electrodes 301 , 302 may correspond to the electrode pair 205 of the electrode arrangement 201 , adhesive layer 303 may correspond to adhesive layer 202, and portion 304 may correspond to portion 204.

[0109]

[0108] As shown in figure 3A, an alternating electrical signal is received by electrode 301 of the electrode pair. Electrode 301 then applies this alternating electrical signal to the portion 304 of the adhesive layer 303. Electrode 302 then provides an output signal in response to the applied alternating electrical signal. The output signal is thus indicative of an electrical property of the portion 304 of the adhesive layer 303.

[0110]

[0109] In the presence of liquid (which may indicate a waste leak, which in turn can be a precursor to an external waste leak), such as sweat, waste, or another liquid or combination of liquids, the electrical property of the portion 304 of the adhesive layer 303 changes. For example, an impedance of the portion 304 of the adhesive may change in the presence of liquid. Further, a characteristic of the change (such as an amount of change, a speed of change, etc.) may depend on a type of the liquid, an amount of the liquid, a location of the liquid, etc. Thus, by measuring the output signal, the electrode pair is able to sense the presence of liquid in the portion 304 and determine information about the liquid.

[0111]

[0110] This is shown in figure 3B. Figure 3B is the same as figure 3A except liquid 305 (e.g. water) is present in the adhesive layer 303. The liquid 305 may be from sweat from a user, from waste from a stoma or the ostomy bag, or a liquid external from the ostomy appliance (such as the user getting wet, or a spillage). As mentioned, the output signal from electrode 302 in figure 3B is different from the output signal from electrode 302 in figure 3A because the liquid 305 affects an electrical property (such as impedance) of the portion 304 of the adhesive layer 303. Accordingly, the sensor device is able to detect the presence of liquid in the adhesive layer which may indicate a leak.

[0112]

[0111] Indeed, based on the output signal from the sensor device, it can be determined whether the detected liquid is indicative of a stomal waste leak. In some cases, the presence of liquid does not necessarily imply the presence of a stomal waste leak. For example, sweat may be detected in the adhesive layer (i.e. a liquid), but typically sweat transits through the adhesive layer and dissipates over time without necessarily compromising the seal of the adhesive layer and causing waste to exit the ostomy appliance. Thus, it would be advantageous to be able to differentiate the detected liquid between sweat and stomal waste so as to prevent unnecessary indications that an external waste leak is likely to develop (the waste leak being a precursor to an external waste leak).

[0113]

[0112] In some cases, the output signal may be sampled during a signal sampling period. Advantageously, this allows further characterisation of the liquid because signal processing techniques can be performed to extract valuable information relating to the liquid that would not have otherwise been possible had a non-alternating electrical signal been used (such as phase change, waveform, characteristics at different applied signal frequencies).

[0114]

[0113] An example representation of an electrical circuit for measuring the electrical property of the adhesive will now be described with reference to figure 4. Figure 4 schematically represents how the sensor device measures an electrical property of the adhesive (in this example impedance). The ‘in’ as shown in figure 4 corresponds to the electrode 301 of figures 3A and 3B receiving the alternating electrical signal, and the ‘out’ of figure 4 corresponds to the electrode 302 of figures 3A and 4 providing the output signal.

[0115]

[0114] As shown, a measurement can be performed using a 10kHz sinusoidal input signal. This input signal can be provided to electrode 301 and electrode 301 applies this signal to the portion 304 of the adhesive layer 305. A balanced resistor R_SRC (1MQ) is shown, which represents an example ohmage of a dry adhesive across 1mm to support the measurement of the impedance of the adhesive. The ohmage of R_SRC may depend on implementation, such as the specific adhesive being used (its composition, thickness, etc.). As shown, Adhesive_Z corresponds to the impedance of the adhesive, which depends on and varies based on the moisture level in the portion of the adhesive to which the input signal has been applied. In the absence of moisture, the resistance of the portion of adhesive is 1MQ as shown (i.e. this resistance and the resistance R_SRC match). The signal can then be observed at ‘out’ to measure attenuation (signal strength compared to input), and phase changes (and waveform, spatial distribution, etc. over time). Measurement of the ‘out’ signal can be performed using conventional techniques.

[0116]

[0115] When a large amount of moisture is present, it will traverse through the adhesive and the signal attenuation will rapidly increase to short circuit. The phase change will also give an early warning of a large amount of moisture. In contrast, when a small amount of moisture is present, it will cause a slower signal attenuation and the phase change will occur only if the moisture totally saturates the electrodes. Thus, by measuring the output signal, various characteristics of the liquid can be determined. Further, the way the signal amplitude and phase change changes can be used to differentiate the detected liquid between sweat and waste. These determinations would not be possible in a DC arrangement.

[0117]

[0116] It will be appreciated that figure 4 shows only an example configuration and may be varied depending on implementation. For example, a different frequency signal may be used (e.g. 5Hz to 500kHz), and a different signal waveform shape may be used (square, triangle, etc.). Further, difference resistances may be used depending on the type and arrangement of the adhesive, as discussed above.

[0118]

[0117] In some implementations, the electrode arrangement is an electrode array, and an AC input signal is distributed among all electrode pairs of the electrode array, and the signal characteristic analysis is localised to one specific geometric location on the surface of the sensor device. In other words, the input alternating electrical current may be supplied to the sensor device, and then the output signal may be determined at a plurality of different points of the electrode arrangement (for example at different points around a substantially concentric electrode arrangement).

[0119]

[0118] In use, with the sensor device adhering to a skin-surface of a user, the sensor device can be used to determine whether liquid is in the adhesive, and also whether this is indicative of a waste leak, which in turn is indicative of an external waste leak. Using the output signal from the sensor device as described herein sampled over a sampling time period, various characteristics of the output signal can be determined. For example, the output signal may be sampled every minute to monitor the signal for changes of one or more signal characteristics. Using this, liquid can be detected in the adhesive layer and a leakage state associated with the ostomy appliance can be determined.

[0120]

[0119] In this way, the sensor device supports improved leakage detection in ostomy appliances.

[0121] Sensor device arrangements

[0120] Further advantageous features and arrangements of the sensor device will now be described. These features and arrangements can act to further enhance the sensing ability of the sensor device to support improved leakage and liquid detection as described herein. The sensor device referred to in any of the following figures may correspond to the sensor device 200 or 300 as described in relation to figures 2A, 2B, 3A and 3B.

[0122]

[0121] Figure 5A shows an example sensor device 500 according to the present teachings.

[0123]

[0122] In this example, sensor device 500 includes an electrode arrangement having an electrode pair 501. The electrode pair 501 is a full length pad / trace, allowing detection across a large area without interruption.

[0124]

[0123] The pair of electrodes 501 are arranged substantially concentrically around an opening 502 in the sensor device 500. In use, the opening 502 receives a stoma of a user and thus interfaces with a stoma of the user.

[0125]

[0124] Sensor device 500 also includes an input signal interface 503 for receiving an alternating electrical signal and providing the alternating electrical signal to the electrode pair, and an output signal interface 504 for providing the output signal. The input signal interface 503 is connectable to a control device (not shown) and may receive the alternating electrical signal from the control device. Thus, the control device may include a signal generating arrangement to generate the alternating electrical signal (such as an AC signal) and provide the alternating electrical signal to the sensor device 500.

[0126]

[0125] The output signal interface 504 is connectable to the control device (or a different control device), such that the output signal is measureable by the control device. In this way, the sensor device may be electrically coupled to a control device, and the control device may be configured to use the sensor device (i.e. by providing the alternating electrical signal and measuring the signal output in response) to detect the presence of liquid in the adhesive layer and in some examples determine a leakage state associated with the ostomy appliance.

[0127]

[0126] The output signal interface 504 may be arranged in use to provide an output signal from a plurality of different regions of the sensor device. For example, the AC input signal may be distributed between a plurality of electrode pairs (via the input signal interface), and the output signal interface may be arranged to provide a plurality of output signals, each associated with a different electrode pair and region of the sensor device.

[0128]

[0127] Figure 5B shows a similar arrangement to figure 1A, and discussion of like-labelled features is not repeated below. Figure 5B shows the sensor device 500 (of figure 5A) in place around the stoma 104, and demonstrates how the sensor device 500 may be placed substantially concentrically around the stoma 104 in use, and between the baseplate 101 and the skin-surface 103 of a user. Again, it will be appreciated that while shown separately from the baseplate 101 , the sensor device may be provided as part of the baseplate in some implementations.

[0129]

[0128] In some examples, the electrode arrangement may include a plurality of electrode pairs, arranged substantially concentrically around an opening and at different radial distances from the opening. An example of a sensor device having such an arrangement is shown in figure 6A.

[0130]

[0129] As shown, sensor device 600 includes two electrode pairs, a first electrode pair 601 and a second electrode pair 602. As for figure 5A, the electrode pairs are full length traces / pads, allowing detection across a large area without interruption. Sensor device 600 also includes an input / output signal interface 603 as described herein.

[0131]

[0130] The electrode pair 601 corresponds to an inner electrode pair. This may be configured to detect liquid presence in an inner region of the sensor device, which is close to the stoma. Thus, an indication may be generated warning the user of the ostomy appliance that liquid is accumulating close to the stoma. The electrode pair 602 corresponds to an outer electrode pair (relative to the inner electrode pair). This may be configured to detect liquid presence in an outer region of the sensor device, further from the stoma than the inner region. Thus, an indication may be generated warning the user of the ostomy appliance that an external waste leak outside the baseplate is about to occur. As a result, the electrode pairs 601 and 602 are able to provide the user with increased information relating to the upcoming external waste leak, allowing the user to take appropriate action in response.

[0132]

[0131] Further, with this arrangement, a progression or spreading direction of the liquid can be determined. For example, waste will have to cross the two electrodes of an electrode pair, and thus crossing both electrode pairs in an order from the inner electrode pair and then the outer electrode pair indicates that the liquid is progressing from the inside (proximal to the stoma) to the outside. Further, a time difference may be determined between when the liquid is detected by the inner electrode pair and the outer electrode pair to provide an indication of the speed at which the liquid is progressing. Further, the electrodes may be used to determine that the liquid is progressing from the outer electrode pair to the inner electrode pair (for example as a result of external liquid ingress) and thus may be able to indicate that the liquid may reach the stoma and that the adhesive seal may be compromised.

[0133]

[0132] To increase the granularity of the sensing abilities of the sensor device, additional electrode pairs may be provided. An example of this is shown in figure 6B.

[0133] Figure 6B shows the same sensor device 600 as figure 6A, including the electrode pair 601 and the electrode pair 602, and the input / output signal interface 603. Figure 6B shows sensor device 600 also having additional sensor pairs 605 (referred to collectively as sensor pairs 605). Thus, in this example, the sensor device 600 includes an electrode array formed by the various electrode pairs.

[0134]

[0134] As shown in figure 6B, the electrode pairs form a plurality of sensing regions (shown by the numbers 1 , 2, 3, 4, 5, 6). Thus, the sensor device 600 is able to detect liquid in a plurality of different regions and thus identify a location of the liquid for indicating to the user of the ostomy appliance. The input / output signal interface 603 may thus receive an AC signal and supply the AC signal to each of the electrode pairs, and then provide an output signal from each of the different regions of the sensor device. In this way, the output signal from a plurality of different regions of the sensor device can be determined from the output signal.

[0135]

[0135] Further, as described in relation to figure 6A, a movement or spreading direction of the liquid can be determined based on determining the order in which the electrode pairs detect the presence of liquid. A speed of spreading can also be determined based on time differences between liquid detection. This is illustrated by waste 607, which has started moving through the adhesive layer of the sensor device and thus can be detected by electrode pairs in region 2. As the configuration of the sensor device is known, the location of the waste leak can thus be pinpointed. The presence of the waste leak indicates that an external waste leak where waste leaks to a location external to the ostomy appliance is likely to occur. In examples, this is then indicated to a user of the ostomy appliance, allowing them to take action in response (such as fixing the adhesive seal in that region, emptying the ostomy bag, etc.).

[0136]

[0136] Further, as shown in figure 6B, sensor device 600 includes a removable electrode region 606. This removable electrode region 606 is arranged in use to be removed (for example by scissors, as shown) to provide an opening for receiving a stoma of a user. In this way, the opening can be adjusted and customised based on the size and shape of the stoma of the user. Further, by providing a removable electrode region, it can be ensured that the remaining electrode pairs are provided in close proximity to the stoma once the removable electrode region has been removed. This increases liquid detection speed because the electrode pairs are closer to the stoma and so are able to detect liquid in the adhesive nearer to the stoma (as a result of waste from the stoma, for example).

[0137] Electrode substrate and liquid transfer

[0138]

[0137] The electrode arrangement of the sensor device as described herein may be provided on an electrode substrate. In some examples, the electrode substrate may be formed from plastic, for example a plastic film. In examples, the substrate is formed from stretchable / flexible printed circuit board. However, the present inventors have identified that promoting liquid transfer from the adhesive layer of the sensor device results in increased wear time as a greater adhesive layer thickness can be used without significantly impacting liquid detection response time. Thus, in some examples, the electrode substrate is liquid permeable (i.e. liquid water permeable) and thus enables liquid transfer from the adhesive layer.

[0139]

[0138] Figure 7A shows an example cross-section of a sensor device attached to a baseplate (similar to the arrangement of figure 2B). Figure 7B shows a baseplate backing film 701 and baseplate adhesive layer 702. Collectively, the baseplate backing film 701 and baseplate adhesive layer 702 may form part of a baseplate (such as baseplate 101 of figures 1A and 1 B).

[0140]

[0139] Figure 7A also shows a substrate 703, electrode pairs 704, and an adhesive layer 705. Collectively, the substrate 703, electrode pairs 704, and adhesive layer 705 may form parts of the sensor device described herein. The substrate 703 may adhere to the baseplate adhesive layer 702 in use.

[0141]

[0140] As discussed, the substrate 703 may be liquid permeable to enable liquid transfer from the adhesive layer 705 to the baseplate adhesive layer 702. In examples, the substrate 703 is liquid water permeable to enable liquid water transfer between the adhesive layers 705 and 702. This reduces liquid accumulation in the adhesive layer 705 and thus increases wear time of the sensor device.

[0142]

[0141] Figure 7B shows the same arrangement as figure 7A, except the substrate 703 comprises one or more cut-out regions 706. Thus, in use, the adhesive layer 705 is able to directly contact the baseplate adhesive layer 702, thereby promoting liquid transfer from adhesive layer 705 to the baseplate adhesive layer 702. Further, the size and shape of the hole for receiving the stoma in use can be customized depending on need. This allows the electrodes to be as close to the stoma as possible, resulting in earlier detection of potential leakage. In some examples, the substrate 703 is formed from the electrode arrangement itself, for example from the electrode traces.

[0143]

[0142] Figure 7C further illustrates action of a liquid permeable electrode substrate for the sensor device as described herein. Figure 7C is a cross-sectional view of a stoma 708 and skin-surface 709.

[0144]

[0143] Figure 7C shows the baseplate backing film 701 and the baseplate adhesive layer 702 from figures 7A and 7B. Also shown is a liquid permeable electrode substrate 703 and the adhesive layer 705 (the electrode pairs 704 are not shown). The arrows 707 show the direction of liquid transfer, from the adhesive layer 705 of the sensor device to the baseplate adhesive layer 702. Advantageously, the liquid transfer increases the wear time of the sensor device (i.e. the ostomy appliance).

[0145] Example systems with the sensor device

[0146]

[0144] Example systems comprising the sensor device as described herein will now be discussed.

[0147]

[0145] Figure 8A shows an example system 800 for an ostomy appliance. System 800 includes sensor device 801 and control device 802. Sensor device 801 may correspond to the sensor device described herein. Control device 801 is configured in use to provide an alternating electrical signal to the sensor device 801 and determine the output signal from the sensor device 802. Control device 801 may correspond to the control device discussed further above.

[0148]

[0146] Thus, in some examples, control device 802 includes a signal generating arrangement (such as a transducer arrangement) to generate the alternating electrical signal. The control device may be configured to generate an AC signal, for example at different frequencies, such as 5Hz to 500kHz.

[0149]

[0147] The control device 802 may sample the output signal from the sensor device 801 over a signal sampling period. The sampling rate is variable, but in some examples may correspond to once per minute, twice per minute, etc.

[0150]

[0148] Thus, the control device 802 may generate and provide the alternating electrical signal used by the electrode pair(s) of the sensor device 801 , and then measure the output signal(s) from the sensor device 801 . In this way, the system 800 is able to determine an output signal indicative of an electrical property of the portion of the adhesive layer of the sensor device. This can then be used to detect the presence of liquid, and thus determine a leakage state associated with the ostomy appliance.

[0151]

[0149] In examples where a sensor device has a plurality of electrode pairs, the output signal may be determined from each of these electrode pairs. Comparisons may then be made between the output signals to determine information, such as a location of the waste leak based on the electrode pair that detects liquid.

[0152]

[0150] An example method of operation of the sensor device as described herein will now be described. The method comprises: supplying the alternating electrical signal to the sensor device; and determining the output signal from the sensor device indicative of the electrical property of the portion of the adhesive layer. It will be understood that the control device may be used to supply the alternating electrical signal to the sensor device and determine the output signal from the sensor device.

[0151] Figure 8B shows example system 800 in exploded view which may be attached to a baseplate 803 of an ostomy appliance. System 800 includes sensor device 801 and control device 802. Sensor device 801 includes an electrode arrangement 804 (corresponding to the electrode arrangement described herein) and an adhesive layer 805 (corresponding to the adhesive layer described herein). As shown, the sensor device 801 can adhere to the baseplate 803 of an ostomy appliance, and be connected to a control device 802.

[0153]

[0152] Figure 8C shows an example system 806 comprising the system 800 and a monitor device 807. The monitor device 807 may be a user device, mobile phone, tablet, phablet, computer, smartwatch, etc. As for figures 8A and 8B, system 800 comprises the sensor device 801 and the control device 802.

[0154]

[0153] As shown, control device 802 may comprise a number of components (808 to 813). It will be appreciated that figure 8C is just an example and in some cases the control device will be provided with additional circuitry that is not shown in figure 8C, and in some cases some of the components shown in figure 8C may be omitted. Indeed, it will be appreciated that figure 8C is merely an example of possible hardware that may be provided and other components may also be provided.

[0155]

[0154] Control device 802 includes a battery system 808 for providing power to the control device and in some cases for monitoring a battery status. In examples, a battery status may be reported to the monitor device 807, for example indicating that the battery requires charging or replacement. Control device 802 includes a communication arrangement 811 configured in use to communicate with the monitor device 807 (as indicated by the arrow between the monitor device 807 and control device 802). Various communication protocols may be supported by the communication arrangement 811 , such as WiFi®, Bluetooth®, ZigBee®, etc. Control device 802 includes data storage 809 for storing data and instructions to be processed, and processor 812 for performing data processing in response to program instructions. Controller device 802 also includes a signal generating arrangement 810 to generate the alternating electrical signal (such as AC), and a multiplexer arrangement 813 to route the alternating electrical signal to each electrode pair of the sensor device 801.

[0156]

[0155] The monitor device 807 may be configured in use to determine a leakage state associated with the ostomy appliance based on sensor data indicative of the output signal. For example, the control device 802 may measure the output signal from the sensor device and determine sensor device data. The control device 802 may then send the sensor device data to the monitor device 807, and the monitor device 807 may then perform signal processing techniques as described herein to detect liquid and / or determine a leakage state associated with the ostomy appliance.

[0156] Thus, in the example that the monitor device is a user device of the user of the ostomy appliance (for example their mobile phone), the control device 802 may be in communication with the monitor device 807 and the monitor device 807 may generate an alert or notification for the user when liquid is detected or that indicates the determined leakage state of their ostomy appliance. In this way, the user can be alerted when a stomal waste leak is detected (i.e. liquid is detected that is classified as stomal waste) before an actual external waste leak occurs, where waste progresses to a location external to the ostomy appliance. The user can also be provided with information regarding the waste leak, such as a location, a size, a spreading direction, etc. In some examples, the monitor device 807 may be a monitor device of a healthcare professional, and so the healthcare professional may be alerted of a stomal waste leak detected in the user’s ostomy appliance and may then provide assistance.

[0157]

[0157] In some examples, the control device 802 may be provided with a unique visual identifier (such as a barcode or QR code) that may be scanned a camera of a monitor device 807 to perform pairing between the control device 802 and the monitor device 807. The monitor device 807 may have software running thereon configured to receive sensor data from the control device or alerts from the control device and detect liquid presence or determine a leakage state.

[0158]

[0158] In one example implementation, the processor 812 commands the signal generating arrangement 810 to generate the input alternating signal waves, which are multiplexed by the multiplexer arrangement 813 to measure one electrode pair of the sensor device 801 at a time. Sensor data determined by the control device 802 is then wirelessly sent to the monitor device 807 at regular intervals. In some cases, signal / data analysis will be performed by both the processor 812 and software executing on the monitor device 807.

[0159]

[0159] It will be appreciated that the data / signal analysis of the output signal from the sensor device 801 may be performed by the control device 802 (for example by one or more processors 812 of the control device) only, by the monitor device 807 only, by a combination of the control device 802 and the monitor device 807, and by an external network connected server.

[0160]

[0160] In this way, the control device 802 may send sensor data indicative of the output signal to the monitor device 807 to perform liquid detection and leakage state determination. Alternatively, the control device 807 may perform liquid detection and leakage state determination and report the result to the monitor device 807. Control device 807 may perform some initial processing of the output signal to determine the sensor data, and then send the sensor data to the monitor device 807.

[0161] Signal processing: leakage state determination and liquid detection

[0161] A method 900 for determining a leakage state associated with an ostomy appliance will now be described with reference to figure 9.

[0162]

[0162] It will be appreciated that the methods described below may be applied generally and are not limited to the sensor devices described herein. Instead, these are examples that may be used with the method. Indeed, a sensor device which outputs an electrical signal indicative of an electrical property of an adhesive portion of an adhesive layer, either of the sensor device itself or of a baseplate, may be used with the methods described below. The specific arrangement of the sensor device is not particularly limited in this respect. In this way, the methods described below may be used with a sensor device that is provided integrally with a baseplate of an ostomy appliance and with a sensor device provided separately from a baseplate.

[0163]

[0163] That being said, a combination of the methods described below with the sensor devices described herein can be particularly advantageous, as these may synergistically combine to create an improved leakage state detection approach. For example, aspects of the sensor devices described herein are particularly well-suited to the methods described below, such that stomal waste leaks may be detected more reliably, more quickly, and with increased information relating to the waste leak such that an external stomal waste leak where waste leaks from the ostomy appliance is less likely to occur.

[0164]

[0164] Thus, the methods described below are not limited to the sensor devices described herein, and neither are the sensor devices described herein limited to the methods described below. However, when used together, their existing advantages can be further enhanced.

[0165]

[0165] Method 900 may be performed by a monitor device such as monitor device 807, by control device 802, or by a combination of the control device 802 and monitor device 807.

[0166]

[0166] At 901 , method 900 includes determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period. For example, the electrical signal of the sensor device may correspond to the output signal from the sensor device as described above.

[0167]

[0167] For example, the determining the sensor data may include receiving the sensor data (for example from the control device 802). In some cases, determining the sensor data may include determining the sensor data based on measuring an output signal from a sensor device, such as sensor device 801.

[0168]

[0168] The electrical signal may correspond to an electrical parameter associated with an electrode arrangement of the sensor device. For example, the electrical parameter may be one of impedance, resistivity, and conductance. In this way, a value of the electrical parameter may be dependent on application of an alternating electrical signal by the electrode arrangement to a portion of an adhesive layer of the sensor device. In some cases, the electrical signal may be indicative of an impedance of an adhesive portion of the sensor device.

[0169]

[0169] As discussed herein, the adhesive layer of the sensor device may be an adhesive layer used to adhere the sensor device to a skin-surface of a user and thus the sensor device sits between the skin-surface and a baseplate of an ostomy appliance, or the adhesive layer of the sensor device may refer to an adhesive layer of the baseplate when the baseplate is provided with a sensor device.

[0170]

[0170] At 902, the method includes determining values of the one or more characteristics of the electrical signal based on the sensor data. As discussed herein, values of signal characteristics such as signal amplitude / attenuation, signal phase, phase change / signal offset, waveform, spatial distribution, and rates of changes of values of these characteristics can be determined. The present inventors have identified that values of these characteristics and how values of these characteristics change over time can be used to determine a leakage state associated with the ostomy appliance (such as whether liquid is present in an adhesive layer, and also provide information relating to properties of the liquid). Indeed, these characteristics provide a valuable insight into whether liquid is present in an adhesive layer, and if so, properties associated with the liquid.

[0171]

[0171] At 903, the method includes determining the leakage state associated with the ostomy appliance based on analysis of the values of the one or more characteristics.

[0172]

[0172] As discussed herein, the present inventors have identified that, by using characteristics of the electrical signal, a leakage state of the ostomy appliance can be determined.

[0173]

[0173] The leakage state may be indicative of a risk of stomal waste leaking externally from the ostomy appliance (i.e. an external waste leak). For example, the leakage state may be indicative of whether liquid is present in an adhesive layer associated with the ostomy appliance (such as the adhesive layer of the sensor device). In this way, the leakage state may indicate that no liquid (sweat or stomal waste) is present and as such the risk of external stomal waste leakage may be low, that liquid is present (sweat or stomal waste) in an adhesive layer associated with the ostomy appliance (such as the adhesive layer of the sensor device) and as such that there is a risk of external stomal waste leakage from the ostomy appliance, and that there is stomal waste leakage present in the adhesive layer associated with the ostomy appliance and as such the risk of an external stomal waste leak is high.

[0174] Indeed, the present approach is able to determine and distinguish between a variety of leakage states, such as a state indicative of liquid presence in an adhesive layer associated with the ostomy appliance; a state indicative of liquid absence in an adhesive layer associated with the ostomy appliance; a state indicative of stomal waste presence in an adhesive layer associated with the ostomy appliance; a state indicative of sweat presence in an adhesive layer associated with the ostomy appliance; a state indicative of a predicted external stomal waste leak associated with the ostomy appliance; and a state indicative of a degradation of an adhesive layer associated with the ostomy appliance.

[0174]

[0175] The present inventors have characterised, through experimental observation, signal profiles and signal characteristic thresholds that are indicative of the various leakage states. Indeed, each leakage state may be associated with its own leakage state condition, which corresponds to criteria or conditions that, when satisfied, trigger the determination of that leakage state.

[0175]

[0176] In other words, the present inventors have determined what liquid (i.e. stomal waste leakage, sweat), a fast moving waste leak, a slow moving waste leak, external liquid ingress, etc. ‘looks like’ in terms of the output signal associated with the adhesive layer when analysing the sensor data indicative of the electrical signal of the sensor device during a signal sampling period. Thus, by determining one or more characteristics of the sensor data (which is indicative of the electrical signal, i.e. in some cases the output signal described herein), a leakage state associated with the ostomy appliance can be determined.

[0176]

[0177] The determination in step 903 may be based on determining whether values of the one or more characteristics satisfy a leakage state condition. Indeed, by determining values of the one or more characteristics of the electrical signal, and comparing the values of the one or more characteristics (absolute value, rate of change, etc.) to predetermined thresholds and signal profiles during a sampling period, liquid can be detected and a leakage state can be determined. This result can then be used to inform a user of the ostomy appliance and so the user is able to more quickly understand whether a stomal waste leak is present in the adhesive layer and thus that an external waste leak is going to occur, and better understand the nature of the stomal waste leak if present.

[0177]

[0178] The leakage state condition may correspond to whether the values of the one or more characteristics satisfy one or more predetermined thresholds or previously determined values for the one or more characteristics. Additionally, or alternatively, a rate of change of the values of the one or more characteristics may be compared during the sampling time period to a rate of change of the one or more characteristics during a previous sampling period or a rate of change threshold.

[0179] In some cases, the leakage state condition corresponds to whether a plurality of different conditions associated with different signal characteristics are satisfied. For example, a given leakage state condition may correspond to whether a signal amplitude changes by X and a signal phase changes by Y in a time period Z (the same or different time periods). If it is determined that these conditions are all true, the leakage state is determined as the given leakage state.

[0178]

[0180] In some examples, the method comprises determining a predicted failure time indicative of a predicted future time when stomal waste is predicted to egress from the ostomy appliance based on the values of the one more characteristics. In this way, the values of the characteristics may be used to determine a time in the future or a time period after which waste is expected to leak out from the ostomy appliance. This can be particularly beneficial for a user, as it provides the user with the flexibility to address the potential leak, or wait until a later more convenient time to address the potential leak. For example, a user may be travelling, such as in a car or aeroplane, and thus it may not be simple at that time to take action to address the potential leak of the ostomy appliance. However, because the user may be informed that, while there is liquid in the adhesive region, it is not expected to cause waste egress from the ostomy appliance for another period of time, such as an hour. This allows the user the flexibility to choose to take action at a later, more convenient time.

[0179]

[0181] Determining the signal characteristics and determining the leakage state based on the determined characteristics will now be discussed in more detail with reference to figures 10A, 10B, and 10C.

[0180]

[0182] The present inventors have identified that signal characteristics (such as amplitude, phase, waveform, spatial distribution, and rates of change of these characteristics) can be used to determine the presence of liquid in an adhesive layer, but also to determine various properties of the liquid in the adhesive layer and can thus be used to provide improved liquid detection and the determination of a more detailed leakage state. Indeed, as a result, rather than simply indicating whether liquid is detected, the leakage state can provide a significantly more detailed view. For example, by analysing the sensor data / electrical signal from the sensor device, an amount of the liquid, a type of the liquid, a speed of spreading or movement of the liquid, etc. can be determined.

[0181]

[0183] In particular, the present inventors have identified that signal characteristic value thresholds can be determined that, when satisfied, for example in certain combinations, indicative the presence of liquid, and various properties of the liquid. In other words, the present inventors have determined what waste leakage, sweat, a fast moving leak, a slow moving leak, external liquid ingress, slow degradation of the adhesive over time etc. ‘looks like’ in terms of the output signal when analysing the output signal of the sensor device described herein during a signal sampling period.

[0182]

[0184] Thus, by determining values of one or more characteristics of the output signal, and comparing the values of the one or more characteristics (absolute value, rate of change, etc.) to predetermined thresholds and signal profiles during a sampling period, liquid can be detected and a leakage state can be determined and characterised when the sensor device is part of or associated with the ostomy appliance. This result can then be used to inform a user of the ostomy appliance and so the user is able to more quickly understand whether a leak is present, and better understand the nature of the leak.

[0183]

[0185] For example, the present inventors have recognised through experimental observation that a signal caused by waste presence in an adhesive layer (i.e. a waste leak) during a sampling time period (i.e. when a large amount of liquid is present in the adhesive) is significantly different from a signal where the sensor device is exposed to normal sweating. Also, in the case of sweat, it would be expected that the signal amplitude would recover to its original amplitude once the moisture moves away from the electrodes of the sensor device (as sweat typically transits relatively quickly through the adhesive).

[0184]

[0186] Figure 10A illustrates an example relationship between example signal characteristics and time for an output signal of the sensor device described herein. In this example, the output signal from a sensor device has been sampled during a sampling time period to generate sensor data, and signal amplitude and phase change (relative to the input electrical signal) have been determined from the sensor data.

[0185]

[0187] In the example of figure 10A, liquid enters the adhesive layer at t1. As shown, at times before t1 , the signal amplitude and the signal phase are substantially constant, indicating that an electrical property of the adhesive layer (i.e. impedance) has not changed and thus there is no liquid present in the adhesive layer.

[0186]

[0188] At t1 , the determined signal amplitude starts to reduce. Depending on how the threshold for detecting liquid is set, liquid could be detected when the signal amplitude changes by a predetermined amount or percentage. In some examples, the rate of change of the signal amplitude can indicate a size of the leak, and thus indication may be determined based on the rate of change of the signal amplitude satisfying one or more predetermined thresholds.

[0187]

[0189] Thus, in this case, once the signal amplitude changes by a predetermined amount, a leakage state corresponding to the presence of liquid in the adhesive layer may be determined. It will be appreciated that this is just an example, and that instead a number of conditions may be evaluated to determine the leakage state as a state indicating the presence of liquid in the adhesive layer. For example, a predetermined signal amplitude change in a predetermined time period may trigger this leakage state, or also combined with a predetermined change in signal phase.

[0188]

[0190] Furthermore, how the signal amplitude and / or phase changes can be used to predict an external waste leak in advance of the ostomy appliance actually leaking. For example, once a waste leak has been detected, by comparing how the characteristics change over a time period to predetermined profiles, a waste leak that will cause the adhesive seal to fail can be predicted and notified in advance of the adhesive seal failure. In other examples, the presence of a waste leak is by itself enough to cause an external waste leak to be predicted.

[0189]

[0191] As shown, the signal amplitude reacts faster to the presence of the liquid than the signal phase change (i.e. the signal phase takes longer to respond to the change in the electrical property of the adhesive). However, valuable information can be determined from the signal phase over time. For example, the length of time after the signal amplitude starts to reduce before the signal phase changes can be characteristic for certain types of liquid. Further, the rate of change of the signal phase once the signal phase starts changing (approximately at 1200s) can also be characteristic for different liquid and waste leak properties and types. Accordingly, by determining signal characteristics of the output signal and performing various analysis on the characteristics over time (such as comparison to thresholds and profiles), significant detail relating to the liquid can be determined. This would not have otherwise been possible in a non-alternating electrical signal arrangement.

[0190]

[0192] Figure 10B further illustrates how determining a signal characteristic of the output signal during an output signal sampling time period can be used to determine information about the detected liquid in the adhesive. Figure 10B shows example relationships of signal amplitude against time for three different amounts of liquid in the adhesive of the sensor device described herein. Liquid amount 3 is greater than liquid amount 2, and liquid amount 2 is greater than liquid amount 1. The liquid is introduced to the adhesive layer at t = 0. The greatest liquid amount shown in figure 10B is significantly less than the liquid amount shown in figure 10A (hence the difference in how long the characteristics take to respond to the liquid presence).

[0191]

[0193] As shown, the three different liquid amounts produce different profiles for signal amplitude over time. For example, the initial response of the signal amplitude depends on the relative amount of liquid, with the signal amplitude corresponding to liquid amount 3 reducing more rapidly compared to liquid amounts 2 and 1. While the exact response will depend on various characteristics of the sensor device (such as size, adhesive composition, electrode arrangement and size, etc.), the present inventors have identified that thresholds and profiles can be established that are able to differentiate liquid amounts based on observation of the output signal over time.

[0192]

[0194] In general, presence of liquid in the adhesive causes changes to the output signal such as a change of -dB (damping) of amplitude and a change of phase of n degrees within a time period (such as within 3 to 5 minutes). The amount of time for the signal characteristics (like the amplitude and phase) are indicative of the external factors that can be detected - a fast change may indicate a waste leak, a slow change may indicate sweat (as well as signal recovery), and very slow change may indicate degradation of the adhesive.

[0193]

[0195] As an example of possible thresholds, a change of -3dB of voltage amplitude in less than 5 minutes may be used to indicate the presence of liquid in the adhesive layer. This combined with a change of phase larger than 45 degrees would then confirm the presence of a waste leak (and thus that an external waste leak may be likely). A change of -3db in less than 30 minutes may indicate the presence of sweat (and in examples this is combined with a phase change less than 25 degrees). It will be appreciated that these are example thresholds and the exact values and time periods will vary depending on implementation.

[0194]

[0196] Other signal characteristics may be determined and used to determine information regarding the presence of liquid and to determine properties of the liquid. For example, a waveform or spatial distribution of the signal over time may be compared to predetermined profiles that are characteristics of certain properties and certain liquids, in a similar way to that described above.

[0195]

[0197] Figure 10C shows an example relationship between signal amplitude and phase and time for an output signal of the sensor device described herein, for both sweat and a waste leak. In this example, the output signal from a sensor device has been sampled during a sampling time period to generate sensor data, and signal amplitude and phase change (relative to the input electrical signal) have been determined from the sensor data.

[0196]

[0198] As shown by figure 10C, the waste leak signal amplitude reduces more rapidly and earlier compared to the sweat signal amplitude. Further, the waste leak signal phase reduces more rapidly than the sweat signal phase. Thus, as explained above, detected liquid can be classified into sweat or a waste leak based on characteristics of the output signal.

[0197]

[0199] An example leakage state determination process 1100 will now be described with reference to figure 11 A.

[0198]

[0200] At 1101 , sensor data indicative of the electrical signal from the sensor device is determined over a sampling period. In some cases, the sensor data corresponds to the value of the electrical signal at successive time points during the sampling time period.

[0201] At 1102, values of a characteristic of the electrical signal is determined, for example an amplitude or phase change, for the sampling period. The output electrical signal may be sampled at a sampling rate (such as once a minute, twice per minute, etc.) and from this the signal amplitude and phase may be determined for each sampling data point. Thus, over time, the signal amplitude and signal phase and how it varies during the time period can be determined. An example of this is shown in figures 10A and 10B, which show how signal amplitude and phase change over a sampling time period. The phase change can be determined at a given point by determining the phase of output electrical signal and comparing this to the phase of the input alternating electrical signal.

[0199]

[0202] At 1103, it is determined whether the values of the characteristic satisfy a given leakage state condition. This may comprise comparison to one or more thresholds defined for the values of the characteristic (and change thereof) and each leakage state, or one or more known profiles. Each leakage state may be associated with a different leakage state condition which, if satisfied by the one or more characteristics (or combinations thereof), results in the determination of that leakage state. It will be appreciated that the leakage state condition may actually be a combination of conditions (i.e. a combination of thresholds or criteria being satisfied).

[0200]

[0203] For example, as discussed above, a change of -3dB of signal amplitude in less than 5 minutes may be used to indicate the presence of liquid in the adhesive and thus trigger a leakage state indicative of liquid presence in the adhesive layer.

[0201]

[0204] A change of signal amplitude of -3dB in less than 5 minutes combined with a change of phase larger than 45 degrees may be used to indicate the presence of a waste leak and thus trigger a leakage sate indicative of a waste leak in the adhesive layer.

[0202]

[0205] A change of -3db of signal amplitude in less than 30 minutes may indicate the presence of sweat (and in examples this may be combined with a phase change less than 25 degrees).

[0203]

[0206] An attenuation of the signal amplitude to near zero (i.e. less than 0.05V) over a predetermined time period (such as 10 hours) may indicate that the adhesive properties have started to degrade over time, and thus trigger a leakage state indicative of adhesive properties degradation. As a further example, the condition indicative of adhesive degradation may correspond to whether a predetermined amount of liquid is detected. When the adhesive becomes very wet, its adhesive abilities may be compromised. This may be notified to the user, such that the user is then able to apply new adhesive in a timely manner and before an external waste leak occurs, for example before waste leaking to a location external from the base plate occurs.

[0207] It will be appreciated that the values of these thresholds may vary depending on implementation, adhesive composition, thickness, etc.

[0204]

[0208] At 1104, when values of a characteristic satisfy a given leakage state condition, the leakage state is determined as the given leakage state. It will be appreciated that the absence of a waste leak corresponds to a leakage state, and so in some cases if the one or more characteristics do not satisfy any other leakage state conditions associated with other leakage states or satisfy a condition indicative of no waste leak, the leakage state may be determined as a leakage state corresponding to the absence of a waste leak.

[0205]

[0209] As described above, various leakage states may be determined. In particular, the method may comprise determining the leakage state as one of the leakage states described herein.

[0206]

[0210] It will be appreciated that detecting a waste leak does not necessarily mean that an external waste leak associated with the ostomy appliance is present at that point. For example, waste may have started moving from the stoma towards a first electrode pair arranged closer to the stoma than other electrode pairs. Thus, while a waste leak is detected in the adhesive layer, an external waste leak of stomal waste progressing to a location external from the ostomy appliance is not yet present.

[0207]

[0211] Accordingly, a first leakage state may indicate the presence of liquid in the adhesive layer of the sensor device, and a second leakage state may indicate that a waste leak is present. A further leakage state may indicate that, based on the detected waste leak, an external waste leak from the ostomy appliance is likely. This can provide the user with advanced warning.

[0208]

[0212] The present approach may also differentiate between different leakage states based on determining one or more characteristics from sensor data associated with different electrode arrangements of the sensor device. For example, the sensor data may be associated with electrode pairs located in different regions of the sensor device, and thus the present approach can compare the sensor data from different sensor devices to differentiate between different leakage states.

[0209]

[0213] Thus, the present approach is able to determine a variety of different leakage states based on the determined one or more characteristics of the electrical signal in response to determining that the one or more characteristics satisfy a condition indicative of adhesive degradation.

[0210]

[0214] Figure 11 B shows an example process 1110 for determining leakage states as described herein.

[0215] At 1111 , sensor data is determined as previously described. At 1112, signal amplitude and phase change of the electrical signal are determined throughout a sampling period (i.e. values of these signal characteristics are determined). At 1113, the amplitude change during a time period T1 is compared to a threshold, A. When the amplitude change during T1 is less than or equal to A, no liquid is detected at 1115 (i.e. a leakage state corresponding to liquid absence in the adhesive layer is determined). When the amplitude change during T1 is greater than A, liquid is detected at 1114 (i.e. a leakage state corresponding to liquid presence in the adhesive layer is determined).

[0211]

[0216] At 1116, the amplitude change during a time period T2 is compared to a threshold, 8, where T2<T 1 . When the amplitude change during T2 is less than or equal to B, sweat is detected at 1117 (i.e. a leakage state corresponding to the presence of sweat in the adhesive layer is determined). When the amplitude change during T2 is greater than B, the process continues to step 1118. At 1118, it is determined whether the phase change during a time period T3 is greater than a threshold C. When it is, a waste leak is detected at 1119 (i.e. a leakage state corresponding to a waste leak in the adhesive layer is determined). In other words, the detected liquid is classified as a waste leak rather than sweat.

[0212]

[0217] As discussed herein, in response to detecting the leakage state as the leakage state corresponding to a waste leak, the method may include determining that an external waste leak is to occur and generating a notification informing a user of the ostomy appliance.

[0213]

[0218] It will be appreciated that thresholds A, B, and C and time periods T1 and T2 may vary and depend on implementation. It will also be appreciated that steps 113 onwards need not be processed in the order shown.

[0214]

[0219] Figure 12 shows an example notification / signalling process for when a given leakage state has been determined. As discussed herein, once the leakage state has been determined, a notification indicating the leakage state may be signalled. For example, the monitor device 807 may signal a notification to the user to alert the user to the leakage state. The user is then able to take action based on the leakage state, such as prepare for external waste leakage, find privacy, repair a seal of the adhesive, replace the adhesive, etc.

[0215]

[0220] At 1201 , a given leakage state is determined. The leakage state then determines how a user may be notified of the leakage state.

[0216]

[0221] At 1202, it is determined whether the given leakage state indicates that liquid is absent in an adhesive layer associated with the ostomy appliance (such as the adhesive layer of the sensor device). When the given leakage state indicates that liquid is absent, at 1203, a signal or notification may be suppressed, or a signal may be generated that indicates that liquid is absent. When the given leakage state does not indicate that liquid is absent, the process moves to 1204.

[0217]

[0222] At 1204, it is determined whether the given leakage state indicates that sweat is present. When the given leakage state indicates that sweat is present, at 1205, a signal or notification may be suppressed, or a signal may be generated that indicates that sweat is present. When the given leakage state does not indicate that sweat is present, the process moves to 1206.

[0218]

[0223] At 1206, it is determined whether the given leakage state indicates that a waste leak is present. When the given leakage state indicates that a waste leak is present, at 1208, a signal or notification may be generated that indicates that a waste leak is present (and thus that an external waste leak is imminent). It will be appreciated that this signal may include information indicating that waste is building up under the adhesive and / or that an external waste leak is likely to occur shortly. When the given leakage state does not indicate that a waste leak is present, the process moves to 1207. At 1207, a signal or notification is suppressed or a signal or notification is generated that indicates that no waste leak is present (and optionally that a liquid other than sweat or waste is present).

[0219]

[0224] In this way, a user of the ostomy device (or a healthcare professional) can be informed of the leakage state associated with the ostomy appliance. Unnecessary notifications may be suppressed, and a leakage state can be notified to allow the user to take action in response.

[0220]

[0225] In some cases, it can be advantageous to modify the leakage state condition associated with a given leakage state. In other words, it can be advantageous to support modification to the thresholds at which certain leakage states are determined. This allows a more flexible and customisable approach to leakage detection.

[0221]

[0226] For example, during night-time hours, changing the leakage state condition associated with determining that a leak is present to make the condition more sensitive to smaller changes in signal characteristics may be advantageous. At night, soilage of bedsheets can be a particular concern for a user, and so by changing the thresholds (i.e. the leakage state condition) to require less of a change in signal characteristic, a user may be more likely to be alerted during the night that a leak is happening, at an earlier point, and thus soilage of clothes or bedsheets may be prevented.

[0222]

[0227] Similarly, during physical activity, the user may wish to provide input that they are about to start physical activity and that the threshold should be changed. For some users, they may wish the threshold at which a leak is detected to increase, to prevent false alarms caused by more significant movement. For other users, they may wish to increase the sensitivity as described above so that they are alerted earlier and can take action if needed. In some cases, like with physical activity, the leakage state condition associated with the detection of sweat can also be modified, as sweat build-up will be more likely and so the thresholds can be configurably adjusted to reduce the likelihood that a false alarm of a leak is generated when actually the cause is an increased amount of sweat. This may also apply based on a current weather or temperature, where in warm climates or during warm temperatures, sweat buildup may be more likely.

[0223]

[0228] Thus, the present approach supports dynamic and configurable adjustment of leakage state detection based on user requirements.

[0224]

[0229] This is illustrated in example method 1300, which shows a leakage state condition being changed. At 1301 , it is determined whether a leakage state change condition is satisfied. This may include one or more of: a user input condition, a time of day condition, a health condition, a physical activity condition, a location condition, and a historical ostomy appliance usage condition. Thus, the leakage conditions can be modified when it may be desirable to have more or less sensitive thresholds for determining a leak.

[0225]

[0230] At 1302, the leakage state condition associated with a given leakage state is changed. For example, the threshold for triggering a leak (i.e. an amplitude change threshold) may be reduced or relaxed, such that a potential leak may be triggered earlier. This can be useful for situations where early leak detection is desirable, for example at night time and during physical activity. In some cases, a certain user may be particularly prone to experiencing leaks and so it may be advantageous to alter the thresholds accordingly. In this way, the approach can be customised based on user need.

[0226]

[0231] Art 1303, the changed leakage state condition is used to determine whether a value of a characteristic (such as signal amplitude, phase change, etc.) satisfies the changed leakage state condition and thus that a given leakage state is determined.

[0227]

[0232] Figure 14 schematically illustrates an example of an electronic device 1400 which can be used to implement teachings described above, including methods 900, 1100, 1200, and 1300.

[0228]

[0233] The electronic device 1400 has processing circuitry 1401 for performing data processing in response to program instructions and data storage 1402 for storing data and instructions to be processed by the processing circuitry 1401. In some examples, the processing circuitry

[0229] 1401 includes one or more caches for caching recent data or instructions. The data storage

[0230] 1402 may have a database 1403 which can, for example, store sensor data and / or the determined electrical output signal. The device further includes a communication interface 1404 which can be used, for example, to obtain / receive sensor data indicative of the electrical signal of a sensor device and / or output a notification based on the determined leakage state. It will be appreciated that Figure 14 is merely an example of possible hardware that may be provided in the device and other components may also be provided. The device 1400 may additionally or alternatively be provided with one or more user input / output device(s) 1405 to receive input from a user device (e.g. to enter information relating to the change condition, to enter user health information, to enter that a new ostomy appliance has been attached, etc.) or to output information (e.g. the signalled or generated notification based on the leakage state) to a user device. For example, one or more input / output device(s) 1405 may include one or more of a sound generator device, a display output device, a haptic output device, which may be configured to generate an alarm or alert based on the determined leakage state.

[0231] Adhesive layer composition and arrangement

[0232]

[0234] The adhesive layer as described herein will now be described in further detail. The present inventors have identified that the composition and arrangement (such as thickness) of the adhesive layer can be tuned to synergistically complement the use of alternating current in the electrode arrangement. Indeed, the present inventors have identified that certain adhesive compositions and adhesive thicknesses are particularly beneficial for use with electrodes that apply an alternating electrical signal to a portion of the adhesive layer.

[0233]

[0235] The adhesive layer may comprise a continuous portion having a skin-engageable surface and a distal surface. The first portion of the adhesive layer may be located in the continuous portion (and thus the alternating electrical signal may be applied to a portion of continuous portion). The continuous portion may be made of an adhesive composition comprising a blend of one or more pressure sensitive adhesive polymers and one or more hydrocolloids. The term “hydrocolloid” is known in the art of the present disclosure, and typically refers to a hydrophilic material (e.g. particle) that forms a colloid (typically a gel) when contacted with water. The one or more hydrocolloids in the present disclosure may be in the form of particles. In some examples, the one or more pressure sensitive adhesive polymers may be in the form of a matrix and the one or more hydrocolloids (e.g. in the form of particles) may be dispersed in said matrix.

[0234]

[0236] The continuous portion may have a thickness of at least about 200 pm. The adhesive composition may have a water absorption at 30 minutes of at least about 0.05 g / cm2, and / or the hydrocolloids may be present in an amount of at least about 30 wt.% based on the weight of the adhesive composition.

[0235]

[0237] The adhesive layer may include, but not be limited to the continuous portion. Thus, the adhesive layer may include the adhesive layer and at least one further portion. It is to be understood that the continuous portion is substantially absent any apertures (e.g. holes). In the present disclosure, this is what is meant by the term “continuous”. Thus, a fluid traversing though the continuous portion is absorbed by the adhesive composition from which the continuous portion is made. It will further be appreciated that the portion of the adhesive layer that the electrical signal is applied to, as discussed herein, may correspond to a portion within the continuous portion.

[0236]

[0238] As discussed herein, the present inventors have identified that existing approaches may be ineffective at detecting a leak of stomal waste, which enters between the ostomy appliance and the skin of a user in use. The present inventors have found that existing ostomy appliances may be unable to distinguish between moisture from perspiration and stomal waste, such that the ostomy appliance may falsely identify the former as the latter and thereby prompt replacement of the ostomy appliance before this is in fact required. Thereby, materials are wasted and additional time is spent replacing ostomy appliances, which increase costs and reduce efficiency.

[0237]

[0239] The present techniques address this problem. In this regard, the properties and arrangement of the continuous portion provides for a sensor device that can effectively and reliably detect a leak of stomal waste, which enters between the skin-engageable surface and the skin during use, and has a reduced likelihood of false detection.

[0238]

[0240] Without wishing to be bound by a particular theory, it is believed that in use, moisture from perspiration (and other liquid in trace amounts) is absorbed by and distributed through the continuous portion, particularly via the hydrocolloids therein. As a result of the moisture being distributed through the continuous portion (e.g. rather than collecting adjacent to the electrodes), the moisture is unlikely to cause the electrodes to detect a change in an electrical property (e.g. impedance) that falsely indicates a waste leak. By contrast, it is believed that liquid from leak of stomal waste, which presents in far greater amounts than moisture from perspiration, will penetrate through the continuous portion and result in a liquid concentration adjacent to the electrodes that causes the electrodes to detect a change in an electrical property (e.g. impedance) that correctly indicates a waste leak.

[0239]

[0241] The present inventors have found that in existing ostomy appliances in which the electrodes are directly exposed to the skin, moisture from perspiration may collect adjacent to the electrodes, causing the electrodes to detect a change in an electrical property (e.g. impedance) that falsely indicates a potential leak. Such a problem is avoided in sensor devices of the present disclosure, with the continuous portion not only providing a barrier but also facilitating liquid distribution.

[0240]

[0242] Further, the sensor device can be efficiently manufactured. For example, the electrodes may be provided in contact with the continuous portion, without the need for any structural complexity as to the nature of the contact. By contrast, in existing ostomy appliances having electrodes provided over through-holes in an adhesive layer, it must be ensured that the electrodes are aligned with the holes, otherwise the ostomy appliance may not function as intended. Indeed, in such ostomy appliances the alignment may be disrupted overtime, having a negative impact on performance. The sensor device of the present disclosure thereby has increased robustness and reliability.

[0241]

[0243] Further advantageous aspects of the adhesive layer will now be discussed.

[0242]

[0244] For example, the continuous portion may have a thickness of from about 250 pm to about 550 pm. The continuous portion may have a thickness of from about 250 pm to about 500 pm. Preferably, the continuous portion has a thickness of from about 250 pm to about 450 pm. The thickness of the continuous portion refers to the extent of the continuous portion measured from the skin-engageable surface to the distal surface thereof. The thickness of the continuous portion is measured orthogonally to the plane or lateral extent of the continuous portion.

[0243]

[0245] The adhesive composition may have a water absorption at 30 minutes of at least about 0.10 g / cm2. The adhesive composition may have a water absorption at 30 minutes of at least about 0.12 g / cm2. The adhesive composition may have a water absorption at 30 minutes of at least about 0.14 g / cm2. The adhesive composition may have a water absorption at 30 minutes of from about 0.10 g / cm2to about 0.24 g / cm2. The adhesive composition may have a water absorption at 30 minutes of from about 0.12 g / cm2to about 0.20 g / cm2. Preferably, the adhesive composition has a water absorption at 30 minutes of from about 0.14 g / cm2to about 0.18 g / cm2. Herein, it is to be understood that the water absorption at 30 minutes of the adhesive composition is measured by:

[0244] 1. providing a dry sample of the adhesive composition having a length of 25 mm, a width of 25 mm, and a thickness of 1 mm (the dry sample defining a square outer perimeter);

[0245] 2. attaching one of the two surfaces of the sample to an impermeable (e.g. polystyrene) plate (e.g. using double-sided tape), such that the plate seals said surface from liquid ingress;

[0246] 3. immersing the sample attached to the plate in 300 ml to 400 ml (an excess) of 0.9 wt.% NaCI solution (aq.) held at a temperature of 32 °C (such that the sample is fully submerged);

[0247] 4. weighing the sample, having immersed the sample for 30 minutes, and recording said weight (Ww) in g;

[0248] 5. drying the sample to remove the water from the sample (e.g. using an oven); 6. weighing the dried sample, and recording said weight (WD) in g; and

[0249] 7. calculating the water absorption in g / cm2(e.g. (Ww - WD) / 0.625).

[0250]

[0246] The adhesive composition may comprise the one or more thermoplastic materials in an amount of from about 20 wt.% to about 45 wt.%, based on the total weight of the adhesive composition. The adhesive composition may comprise the one or more thermoplastic materials in an amount of from about 25 wt.% to about 45 wt.%, based on the total weight of the adhesive composition. In some examples, the one or more pressure sensitive adhesive polymers comprise one or more thermoplastic materials. The one or more thermoplastic materials may be selected from the group comprising polyalkenes, polyacrylates, silicones, polyurethanes, ethylene-vinyl acetate, styrene copolymers, butyl rubber, and a combination thereof. Preferably, the one or more thermoplastic materials are selected from polyalkenes, preferably polyisobutylenes. Preferably, the adhesive composition does not comprise styrene copolymers. Preferably, the adhesive composition does not comprise butyl rubber.

[0251]

[0247] The one or more hydrocolloids may be present in an amount of from about 50 wt.% to about 70 wt. % based on the total weight of the adhesive composition. The one or more hydrocolloids may be present in an amount of from about 55 wt.% to about 65 wt. % based on the total weight of the adhesive composition. In some examples, the one or more hydrocolloids are selected from the group comprising polyacrylic acid, polyvinyl alcohol, gelatine, pectin, alginates, starch, modified starch, natural vegetable gum, cellulose, a cellulose derivative, an alkali metal salt of a cellulose derivative, and a combination thereof. It is to be understood that polyacrylic acid and polyvinyl alcohol are sometimes referred to as “hydrophilic polymers”. In some examples, the one or more hydrocolloids are selected from the group comprising an alkali metal salt of a cellulose derivative, pectin, gelatin, and a combination thereof. Preferably, the alkali metal salt of the cellulose derivative is sodium carboxymethyl cellulose.

[0252]

[0248] In preferred examples, the adhesive composition comprises: the one or more thermoplastic materials in an amount of from about 20 wt.% to about 45 wt.%, based on the total weight of the adhesive composition, wherein the one or more thermoplastic materials are selected from the group comprising polyisobutylene, optionally wherein the mass fraction of polyisobutylene based on the total mass of the one or more pressure sensitive adhesive polymers is at least about 99%, optionally wherein the adhesive composition does not comprise a styrene copolymer, optionally wherein the adhesive composition does not comprise butyl rubber; the one or more hydrocolloids in an amount of from about 55 wt.% to about 65 wt.%, based on the total weight of the adhesive composition, wherein the one or more hydrocolloids are selected from the group comprising an alkali metal salt of a cellulose derivative, pectin, gelatin, and a combination thereof, optionally wherein the alkali metal salt of the cellulose derivative is sodium carboxymethyl cellulose, optionally wherein the polyisobutylene has a weight average molecular weight of from about 60 000 g / mol to about 80 000 g / mol, or the polyisobutylene comprises a first polyisobutylene and a second polyisobutylene, the weight average molecular weight of the first polyisobutylene being from about 60 000 g / mol to about 80 000 g / mol and the weight average molecular weight of the second polyisobutylene being from about 1 000 000 g / mol to about 1 100 000 g / mol, optionally wherein the mass ratio of the first polyisobutylene to the second polyisobutylene is from about 1.5:1 to about 2.2:1 , optionally wherein the adhesive composition has a water absorption at 30 minutes of at least about 0.14 g / cm2, optionally from about 0.14 g / cm2to about 0.18 g / cm2, wherein the continuous portion has a thickness of from about 250 pm to about 450 pm.

[0253]

[0249] It is to be understood that weight average molecular weight may be measured by gel permeation chromatography. For example, the weight average molecular weight of a sample may be determined using a Waters Alliance 2695 system and a Styragel HR 5E mixed bed column with a 2K - 4M range. Determining the weight average molecular weight of a sample may include dissolving the sample (5 mg) in tetra hydrofuran (3 mL) at room temperature to provide a sample solution; filtering the sample solution through a 0.1 pm filter; and calculating the weight average molecular weight using a polystyrene standard. In the dissolving step, the sample may be left in tetrahydrofuran overnight (e.g. for at least 12 hours) at room temperature (e.g. approximately 20°C). Each sample may be tested in triplicate.

[0254]

[0250] In preferred examples, the adhesive composition comprises: the one or more thermoplastic materials in an amount of from 20 wt.% to 45 wt.%, based on the total weight of the adhesive composition, wherein the one or more thermoplastic materials are selected from the group comprising polyisobutylene, optionally wherein the mass fraction of polyisobutylene based on the total mass of the one or more pressure sensitive adhesive polymers is at least about 99 %, optionally wherein the adhesive composition does not comprise a styrene copolymer, optionally wherein the adhesive composition does not comprise butyl rubber; the one or more hydrocolloids in an amount of from about 55 wt.% to about 65 wt.%, based on the total weight of the adhesive composition, wherein the one or more hydrocolloids are selected from the group comprising an alkali metal salt of a cellulose derivative, pectin, gelatin, and a combination thereof, wherein the alkali metal salt of the cellulose derivative is sodium carboxymethyl cellulose, wherein the alkali metal salt of a cellulose derivative is present in an amount of from about 15 wt.% to about 25 wt. % based on the total weight of the adhesive composition, optionally wherein pectin is present in an amount of from about 15 wt.% to about 25 wt.% based on the total weight of the adhesive composition, optionally wherein gelatin is present in an amount of from about 15 wt.% to about 25 wt.% based on the total weight of the adhesive composition, optionally wherein the polyisobutylene has a weight average molecular weight of from about 60 000 g / mol to about 80 000 g / mol, or the polyisobutylene comprises a first polyisobutylene and a second polyisobutylene, the weight average molecular weight of the first polyisobutylene being from about 60 000 g / mol to about 80 000 g / mol and the weight average molecular weight of the second polyisobutylene being from about 1 000 000 g / mol to about 1 100 000 g / mol, optionally wherein the mass ratio of the first polyisobutylene to the second polyisobutylene is from about 1.5:1 to about 2.2:1 , optionally wherein the adhesive composition has a water absorption at 30 minutes of at least about 0.14 g / cm2, optionally from about 0.14 g / cm2to about 0.18 g / cm2, wherein the continuous portion has a thickness of from about 250 pm to about 450 pm.

[0255]

[0251] In preferred examples, the adhesive composition comprises: the one or more thermoplastic materials in an amount of from about 35 wt.% to about 45 wt.%, based on the total weight of the adhesive composition, wherein the one or more thermoplastic materials are selected from the group comprising polyisobutylene, optionally wherein the mass fraction of polyisobutylene based on the total mass of the one or more pressure sensitive adhesive polymers is at least about 99 %, optionally wherein the adhesive composition does not comprise a styrene copolymer, optionally wherein the adhesive composition does not comprise butyl rubber; the one or more hydrocolloids in an amount of from about 55 wt.% to about 65 wt.%, based on the total weight of the adhesive composition, wherein the one or more hydrocolloids are selected from the group comprising an alkali metal salt of a cellulose derivative, pectin, gelatin, and a combination thereof, wherein the alkali metal salt of the cellulose derivative is sodium carboxymethyl cellulose, wherein the alkali metal salt of a cellulose derivative is present in an amount of from about 15 wt.% to about 25 wt. % based on the total weight of the adhesive composition, optionally wherein pectin is present in an amount of from about 15 wt.% to about 25 wt.% based on the total weight of the adhesive composition, optionally wherein gelatin is present in an amount of from about 15 wt.% to about 25 wt.% based on the total weight of the adhesive composition, optionally wherein the polyisobutylene has a weight average molecular weight of from about 60 000 g / mol to about 80 000 g / mol, optionally wherein the adhesive composition has a water absorption at 30 minutes of at least about 0.14 g / cm2, optionally from about 0.14 g / cm2to about 0.18 g / cm2, wherein the continuous portion 102 has a thickness of from about 250 pm to about 450 pm.

[0256]

[0252] Herein, it is to be understood that weight average molecular weight may be determined by gel permeation chromatography.

[0257]

[0253] The present inventors have found that such examples facilitate particularly effective and reliable detection of a leak of stomal waste, which enters between the skin-engageable surface and the skin during use, and facilitate a reduced likelihood of false detection due to moisture from perspiration (and other trace amounts of liquid).

[0258]

[0254] The methods discussed above may be performed under control of a computer program executing on a device. Hence a computer program may comprise instructions for controlling a device to perform any of the methods discussed above. The program can be encoded in a computer-readable medium. A computer-readable medium may include non-transitory type media such as physical storage media including storage discs and solid state devices. A computer-readable medium may also or alternatively include transient media such as carrier signals and transmission media. A computer-readable storage medium is defined herein as a non-transitory memory device. A memory device includes memory space within a single physical storage device or memory space spread across multiple physical storage devices.

[0259]

[0255] In the present application, the words “configured to...” are used to mean that an element of an apparatus has a configuration able to carry out the defined operation. In this context, a “configuration” means an arrangement or manner of interconnection of hardware or software. For example, the apparatus may have dedicated hardware which provides the defined operation, or a processor or other processing device may be programmed to perform the function. “Configured to” does not imply that the apparatus element needs to be changed in any way in order to provide the defined operation.

[0260]

[0256] Although illustrative teachings of the disclosure have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise teachings, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope and spirit of the invention as defined by the appended claims.

[0261]

[0257] Some examples are set out in the following clauses and numbered examples:

[0262] Clause 1. A computer-implemented method for determining a leakage state associated with an ostomy appliance, the method comprising: determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period; determining values of one or more characteristics of the electrical signal based on the sensor data; and determining the leakage state associated with the ostomy appliance based on analysis of the values of the one or more characteristics.

[0263] Clause 2. The method of clause 1 , wherein the electrical signal corresponds to an electrical parameter associated with an electrode arrangement of the sensor device.

[0264] Clause 3. The method of clause 2, wherein a value of the electrical parameter is dependent on application of an alternating electrical signal by the electrode arrangement to a portion of an adhesive layer of the sensor device.

[0265] Clause 4. The method of any preceding clause, wherein the electrical signal is indicative of an impedance of an adhesive portion of the sensor device.

[0266] Clause 5. The method of any preceding clause, wherein the one or more characteristics comprise one or more of a signal amplitude, signal phase, waveform, and spatial distribution. Clause 6. The method of any preceding clause, wherein the leakage state is indicative of a risk of stomal waste leaking externally from the ostomy appliance.

[0267] Clause 7. The method of any preceding clause, wherein determining the leakage state based on analysis of the values of the one or more characteristics comprises determining whether the values of the one or more characteristics satisfy a leakage state condition.

[0268] Clause 8. The method of clause 7, wherein determining whether the values of the one or more characteristics satisfy a leakage state condition comprises comparing the values of the one or more characteristics to one or more predetermined thresholds or previously determined values for the one or more characteristics.

[0269] Clause 9. The method of clause 7 or 8, wherein determining whether the values of the one or more characteristics satisfy a leakage state condition comprises comparing a rate of change of the values of the one or more characteristics during the sampling time period to a rate of change of previously determined values of the one or more characteristics during a previous sampling time period or one or more predetermined rate of change thresholds.

[0270] Clause 10. The method of any preceding clause, wherein determining the leakage state comprises determining whether liquid is present in an adhesive layer of the sensor device based on analysis of values of the one or more characteristics.

[0271] Clause 11. The method of clause 10, wherein determining whether liquid is present in an adhesive layer based on analysis of values of the one or more characteristics comprises determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of liquid presence.

[0272] Clause 12. The method of any of clauses 10 or 11 , further comprising in response to determining that liquid is present in the adhesive layer of the sensor device, determining one or more properties associated with the liquid based on analysis of the values of the one or more characteristics.

[0273] Clause 13. The method of clause 12, wherein the one or more properties comprise: a classification of the liquid; a location of the liquid in the sensor device; an area of presence of the liquid; a spreading direction of the liquid; and a rate of movement of the liquid.

[0274] Clause 14. The method of any of clauses 10 to 13, wherein determining the leakage state comprises, in response to determining that liquid is present in the adhesive layer, classifying the liquid into one of sweat or stomal waste.

[0275] Clause 15. The method of clause 14, wherein classifying the liquid into one of sweat or stomal waste is based on determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of stomal waste presence.

[0276] Clause 16. The method of clauses 14 or 15, wherein classifying the liquid into one of sweat or stomal waste is based on determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of sweat presence.

[0277] Clause 17. The method of any preceding clause, further comprising signalling a notification to a user device of the user or causing the user device to generate a notification based on the determined leakage state.

[0278] Clause 18. The method of any of clauses 14 to 16, further comprising signalling a notification indicating a risk of stomal waste leaking externally from the ostomy appliance in response to classifying the liquid as stomal waste.

[0279] Clause 19. The method of any of clauses 14 to 17, further comprising in response to classifying the liquid as sweat, suppressing signalling a notification indicating a risk of stomal waste leaking externally from the ostomy appliance or signalling a notification indicating that sweat is present in the adhesive layer. Clause 20. The method of any preceding clause, wherein determining the leakage state comprises determining whether an adhesive layer of the sensor device has degraded based on analysis of the values of the one or more characteristics.

[0280] Clause 21. The method of clause 20, wherein determining whether the adhesive layer of the sensor device has degraded based on analysis of values of the one or more characteristics comprises determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of adhesive degradation.

[0281] Clause 22. The method of any preceding clause, wherein the method further comprises determining a predicted failure time indicative of a predicted future time when stomal waste is predicted to egress from the ostomy appliance based on the values of the one more characteristics.

[0282] Clause 23. The method of any preceding clause, wherein the leakage state comprises one or more of: a state indicative of liquid presence in an adhesive layer associated with the ostomy appliance; a state indicative of liquid absence in an adhesive layer associated with the ostomy appliance; a state indicative of stomal waste presence in an adhesive layer associated with the ostomy appliance; a state indicative of sweat presence in an adhesive layer associated with the ostomy appliance; a state indicative of a predicted external stomal waste leak associated with the ostomy appliance; and a state indicative of a degradation of an adhesive layer associated with the ostomy appliance.

[0283] Clause 24. The method of any of clauses 7 to 23, further comprising changing the leakage state condition in response to a change condition being satisfied.

[0284] Clause 25. The method of clause 24, wherein the change condition comprises one or more of: a user input condition, a time of day condition, a health condition, a physical activity condition, a location condition, and a historical ostomy appliance usage condition.

[0285] Clause 26. The method of any preceding clause, wherein determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period comprises receiving the sensor data from a control device associated with the sensor device.

[0286] Clause 27. A computer-readable medium comprising instructions which, when executed by one or more processors, cause the one or more processors to carry out the method of any preceding clause.

[0287] Clause 28. A monitor device for an ostomy appliance, the monitor device comprising one or more processors configured to perform the method of any of clauses 1 to 26.

[0288] Clause 29. A leakage state determining system for an ostomy appliance, the system comprising: a sensor device comprising: an electrode arrangement comprising an electrode pair; and an adhesive layer having a skin-engageable surface arranged in use to adhere the sensor device to a skin surface of a user of the ostomy appliance, wherein the electrode pair is arranged in use to receive an alternating electrical signal and provide an output signal in response to applying the alternating electrical signal to a portion of the adhesive layer, the output signal indicative of an electrical property of the portion of the adhesive layer; a control device configured to provide the alternating electrical signal to the electrode arrangement and determine the output signal from the electrode arrangement; and the monitor device of clause 28.

[0289] Example 1 . A sensor device for an ostomy appliance, the sensor device comprising: an electrode arrangement comprising an electrode pair; and an adhesive layer having a skin-engageable surface arranged in use to adhere the sensor device to a skin surface of a user of the ostomy appliance, wherein the electrode pair is arranged in use to receive an alternating electrical signal and provide an output signal in response to applying the alternating electrical signal to a portion of the adhesive layer, the output signal indicative of an electrical property of the portion of the adhesive layer.

[0290] Example 2. The device of example 1 , wherein the electrical property comprises an impedance of the portion of the adhesive layer between electrodes of the electrode pair.

[0291] Example 3. The device of any preceding example, wherein the output signal corresponds to an electrical parameter associated with the electrode arrangement.

[0292] Example 4. The device of example 3, wherein the electrical parameter is selected from current, voltage, resistivity, impedance, capacitance, conductance, and inductance.

[0293] Example 5. The device of any preceding example, wherein the electrode arrangement is arranged to provide an output signal indicative of whether liquid is present in the portion of the adhesive layer.

[0294] Example 6. The device of any preceding example, wherein the electrode arrangement comprises a plurality of electrode pairs, each arranged in use to receive an alternating electrical signal and provide an output signal indicative of an electrical property of a portion of the adhesive layer between electrodes of the respective pair of electrodes.

[0295] Example 7. The device of any preceding example, wherein the electrode arrangement comprises a plurality of electrode pairs arranged substantially concentrically around an opening in the adhesive layer, wherein the opening is arranged in use to interface with a stoma of the user.

[0296] Example 8. The device of example 7, wherein at least two electrode pairs are arranged substantially concentrically around the opening at different radial distances from the opening. Example 9. The device of any preceding example, wherein the electrode arrangement comprises a removable electrode region arranged in use to be removed to provide an opening for receiving a stoma of the user. Example 10. The device of any preceding example, wherein the alternating electrical signal comprises an alternating current or alternating voltage.

[0297] Example 11. The device of any preceding example, wherein the alternating electrical signal has a frequency in a range between 5Hz and 500kHz.

[0298] Example 12. The device of any preceding example, wherein the electrode arrangement comprises a plurality of electrode pairs arranged so as to extend across a plurality of distinct regions of the adhesive layer, each region having an electrode pair configured to provide an output signal indicative of an electrical property of a portion of the adhesive layer of the respective region.

[0299] Example 13. The device of any preceding example, wherein the sensor device comprises an input signal interface connectable to a control device for receiving the alternating electrical signal, and an output signal interface connectable to the control device for providing the output signal to the control device such that the output signal is measurable by the control device.

[0300] Example 14. The device of any preceding example, wherein the electrode arrangement is provided on an electrode substrate arranged in use to adhere to an adhesive layer of a baseplate for an ostomy appliance.

[0301] Example 15. The device of example 14, wherein the electrode substrate is arranged in use to allow liquid transfer between the adhesive layer of the sensor device and the adhesive layer of the baseplate.

[0302] Example 16. The device of any of examples 14 or 15, wherein the electrode substrate comprises one or more cut-out regions such that in use the adhesive layer of the sensor device is configured to directly contact the adhesive layer of the baseplate.

[0303] Example 17. The device of any of examples 14 to 16, wherein the electrode substrate is liquid permeable.

[0304] Example 18. The device of any of examples 14 to 16, wherein the electrode substrate is formed from the electrode arrangement.

[0305] Example 19. The device of any preceding example, wherein the adhesive layer comprises a continuous portion having a skin-engageable surface and a distal surface, wherein the continuous portion has a thickness of at least about 200 pm, the continuous portion being made of an adhesive composition comprising a blend of one or more pressure sensitive adhesive polymers and one or more hydrocolloids, wherein: the adhesive composition has a water absorption at 30 minutes of at least about 0.05 g / cm2, and / or the hydrocolloids are present in an amount of at least about 30 wt.% based on the weight of the adhesive composition.

[0306] Example 20. The device of example 19, wherein the electrode arrangement is disposed on the continuous portion such that the continuous portion of the adhesive layer spaces the electrode arrangement from the skin-engageable surface of the adhesive layer. Example 21. The device of any of examples 19 or 20, wherein thickness of the continuous portion is from about 250 pm to about 450 pm.

[0307] Example 22. The device of any of examples 19 to 21 , wherein the water absorption at 30 minutes of the adhesive composition is from about 0.14 g / cm2to about 0.18 g / cm2.

[0308] Example 23. The device of any of examples 19 to 22, wherein the one or more hydrocolloids are present in an amount of from about 55 wt.% to about 65 wt.%, based on the total weight of the adhesive composition.

[0309] Example 24. The device of any preceding example, wherein the electrode arrangement is disposed at least partially within the adhesive layer.

[0310] Example 25. The device of any preceding example, wherein the adhesive layer comprises one or more recess portions proximal to one or more electrodes of the electrode arrangement, the one or more recess portions having a minimum thickness of at least about 200 pm.

[0311] Example 26. A method of operating the sensor device of any preceding example, the method comprising: supplying the alternating electrical signal to the sensor device; and determining the output signal from the sensor device indicative of the electrical property of the portion of the adhesive layer.

[0312] Example 27. A system for an ostomy appliance, the system comprising: the sensor device of any of examples 1 to 25; and a control device configured to provide the alternating electrical signal and determine the output signal from the sensor device.

[0313] Example 28. The system of example 27, wherein the control device is configured to sample the output signal from the sensor device over a time period.

[0314] Example 29. The system of any of examples 27 or 28, further comprising: a monitor device configured in use to determine a leakage state associated with the ostomy appliance based on data indicative of the output signal.

[0315] Example 30. The system of example 29, wherein the monitor device comprises a user device of the user of the ostomy appliance or a server.

[0316] Example 31. The system of any of examples 27 to 30, wherein the control device comprises a transducer arrangement to provide the alternating electrical signal and a battery system configured to signal a battery status.

[0317] Example 32. The system of any of examples 27 to 31 , wherein the control device comprises a multiplexer arrangement configured to route the alternating electrical signal to each electrode pair.

[0318] Example 33. The system of any of examples 27 to 32, wherein the control device comprises a communication arrangement configured to signal data indicative of the output signal.

Claims

Claims1. A computer-implemented method for determining a leakage state associated with an ostomy appliance, the method comprising: determining sensor data indicative of an electrical signal of a sensor device associated with the ostomy appliance during a sampling time period; determining values of one or more characteristics of the electrical signal based on the sensor data; and determining the leakage state associated with the ostomy appliance based on analysis of the values of the one or more characteristics.

2. The method of claim 1 , wherein the electrical signal corresponds to an electrical parameter associated with an electrode arrangement of the sensor device.

3. The method of claim 2, wherein a value of the electrical parameter is dependent on application of an alternating electrical signal by the electrode arrangement to a portion of an adhesive layer of the sensor device.

4. The method of any preceding claim, wherein the electrical signal is indicative of an impedance of an adhesive portion of the sensor device.

5. The method of any preceding claim, wherein the one or more characteristics comprise one or more of a signal amplitude, signal phase, waveform, and spatial distribution.

6. The method of any preceding claim, wherein the leakage state is indicative of a risk of stomal waste leaking externally from the ostomy appliance.

7. The method of any preceding claim, wherein determining the leakage state based on analysis of the values of the one or more characteristics comprises determining whether the values of the one or more characteristics satisfy a leakage state condition.

8. The method of claim 7, wherein determining whether the values of the one or more characteristics satisfy a leakage state condition comprises comparing the values of the one or more characteristics to one or more predetermined thresholds or previously determined values for the one or more characteristics.

9. The method of claim 7 or 8, wherein determining whether the values of the one or more characteristics satisfy a leakage state condition comprises comparing a rate of change of the values of the one or more characteristics during the sampling time period to a rate of change of previously determined values of the one or more characteristics during a previous sampling time period or one or more predetermined rate of change thresholds.

10. The method of any preceding claim, wherein determining the leakage state comprises determining whether liquid is present in an adhesive layer of the sensor device based on analysis of values of the one or more characteristics.11 . The method of claim 10, wherein determining whether liquid is present in an adhesive layer based on analysis of values of the one or more characteristics comprises determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of liquid presence.

12. The method of any of claims 10 or 11 , further comprising in response to determining that liquid is present in the adhesive layer of the sensor device, determining one or more properties associated with the liquid based on analysis of the values of the one or more characteristics.

13. The method of claim 12, wherein the one or more properties comprise: a classification of the liquid; a location of the liquid in the sensor device; an area of presence of the liquid; a spreading direction of the liquid; and a rate of movement of the liquid.

14. The method of any of claims 10 to 13, wherein determining the leakage state comprises, in response to determining that liquid is present in the adhesive layer, classifying the liquid into one of sweat or stomal waste.

15. The method of claim 14, wherein classifying the liquid into one of sweat or stomal waste is based on determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of stomal waste presence.

16. The method of claims 14 or 15, wherein classifying the liquid into one of sweat or stomal waste is based on determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of sweat presence.

17. The method of any preceding claim, further comprising signalling a notification to a user device of the user or causing the user device to generate a notification based on the determined leakage state.

18. The method of any of claims 14 to 16, further comprising signalling a notification indicating a risk of stomal waste leaking externally from the ostomy appliance in response to classifying the liquid as stomal waste.

19. The method of any of claims 14 to 17, further comprising in response to classifying the liquid as sweat, suppressing signalling a notification indicating a risk of stomal waste leaking externally from the ostomy appliance or signalling a notification indicating that sweat is present in the adhesive layer.

20. The method of any preceding claim, wherein determining the leakage state comprises determining whether an adhesive layer of the sensor device has degraded based on analysis of the values of the one or more characteristics.21 . The method of claim 20, wherein determining whether the adhesive layer of the sensor device has degraded based on analysis of values of the one or more characteristics comprises determining whether a rate of change of the values of the one or more characteristics satisfies a condition indicative of adhesive degradation.

22. The method of any preceding claim, wherein determining the leakage state based on analysis of the values of the one or more characteristics comprises determining whether the values of the one or more characteristics satisfy a leakage state condition, the method further comprising changing the leakage state condition in response to a change condition being satisfied.

23. The method of claim 22, wherein the change condition comprises one or more of: a user input condition, a time of day condition, a health condition, a physical activity condition, a location condition, and a historical ostomy appliance usage condition.

24. The method of any preceding claim, wherein a value of the electrical parameter is dependent on application of an alternating electrical signal by the electrode arrangement to a portion of an adhesive layer of the sensor device, and wherein the electrical signal is indicative of an impedance of an adhesive portion of the sensor device.

25. The method of any preceding claim, wherein the method further comprises determining a predicted failure time indicative of a predicted future time when stomal waste is predicted to egress from the ostomy appliance based on the values of the one more characteristics.

26. A computer-readable medium comprising instructions which, when executed by one or more processors, cause the one or more processors to carry out the method of any preceding claim.

27. A monitor device for an ostomy appliance, the monitor device comprising one or more processors configured to perform the method of any of claims 1 to 25.

28. A leakage state determining system for an ostomy appliance, the system comprising: a sensor device comprising: an electrode arrangement comprising an electrode pair; and an adhesive layer having a skin-engageable surface arranged in use to adhere the sensor device to a skin surface of a user of the ostomy appliance, wherein the electrode pair is arranged in use to receive an alternating electrical signal and provide an output signal in response to applying the alternating electrical signal to a portion of the adhesive layer, the output signal indicative of an electrical property of the portion of the adhesive layer; a control device configured to provide the alternating electrical signal to the electrode arrangement and determine the output signal from the electrode arrangement; and the monitor device of claim 27.

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