Liquid identification in ostomy appliance by means of an electrochemical instrument and an electrochemical method

Abstract

An ostomy system (100) for identification of a liquid in an ostomy appliance (110) of the ostomy system is disclosed. The ostomy system includes the ostomy appliance (110) and a monitor device (120). The ostomy appliance (110) includes a reservoir (111) and at least two electrodes (113, 114) associated with the reservoir (111). The monitor device (120) includes an interface (121) for coupling with the two electrodes (113, 114) of the ostomy appliance (110), an electrochemical instrument (122) configured to apply and control an electrical input signal across the two electrodes (113, 114) according to an electrochemical method, and to measure a resulting electrical output signal, and a processor (123) coupled to the electrochemical instrument (122) and configured to identify, based on the resulting electrical output signal, the liquid. Also disclosed is a corresponding method.

Description

[0001] LIQUID IDENTIFICATION IN OSTOMY APPLIANCE

[0002] The present disclosure relates to systems and methods for identification and differentiation of liquids. In particular, the disclosure relates to identification of liquids in an ostomy appliance by means of an electrochemical instrument and electrochemical method.

[0003] Brief description of the drawings

[0004] The accompanying drawings are included to provide a further understanding of embodiments and are incorporated into and a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.

[0005] Fig. 1 illustrates an ostomy system according to an embodiment of the invention;

[0006] Fig. 2 illustrates a schematic exploded side-view of an embodiment of an ostomy appliance;

[0007] Fig. 3 illustrates an ostomy appliance according to an embodiment of the invention;

[0008] Fig. 4 illustrates an ostomy appliance according to an embodiment of the invention;

[0009] Fig. 5 illustrates data obtained according to differential pulse voltammetry using an experimental setup and parameters according to embodiments of the invention;

[0010] Fig. 6 illustrates data obtained according to cyclic voltammetry using an experimental setup and parameters according to embodiments of the invention;

[0011] Fig. 7 illustrates data obtained according to differential pulse voltammetry using an experimental setup and parameters according to embodiments of the invention; and

[0012] Fig. 8 illustrates a medical system according to an embodiment of the invention.

[0013] Detailed description

[0014] Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0015] Throughout this disclosure, the words "stoma" and "ostomy" are used to denote a surgically created opening bypassing the intestines or urinary tract system of a person. The words are used interchangeably, and no differentiated meaning is intended. The same applies for any words or phrases derived from these, e.g. "stomal", "ostomies" etc. Also, the solid and liquid wastes emanating from the stoma may be referred to as both stomal "output," "waste(s)," "liquids," and "fluids" interchangeably. A subject having undergone ostomy surgery may be referred to as "ostomist" or "ostomate" - moreover, also as "patient" or "user". However, in some cases "user" may also relate or refer to a health care professional (HCP), such as a surgeon or an ostomy care nurse or others. In those cases, it will either be explicitly stated, or be implicit from the context that the "user" is not the "patient" him- or herself.

[0016] In the following, whenever referring to proximal side or surface of a layer, an element, a device or part of a device, the referral is to the skin-facing side or surface, when a user wears the ostomy appliance. Likewise, whenever referring to the distal side or surface of a layer, an element, a device or part of a device, the referral is to the side or surface facing away from the skin, when a user wears the ostomy appliance. In other words, the proximal side or surface is the side or surface closest to the user, when the appliance is fitted on a user and the distal side is the opposite side or surface - the side or surface furthest away from the user in use.

[0017] In the context of an ostomy appliance, the axial direction is defined as the direction of the stoma, when a user wears the appliance. Thus, the axial direction is generally perpendicular to the skin or abdominal surface of the user.

[0018] In the context of an ostomy appliance, a radial direction is defined as perpendicular to the axial direction. In some sentences, the words "inner" and "outer" may be used. These qualifiers should generally be perceived with respect to the radial direction, such that a reference to an "outer" element means that the element is farther away from a centre portion of the ostomy appliance than an element referenced as "inner". In addition, "innermost" should be interpreted as the portion of a component forming a centre of the component and / or being adjacent to the centre of the component. In analogy, "outermost" should be interpreted as a portion of a component forming an outer edge or outer contour of a component and / or being adjacent to that outer edge or outer contour. The use of the word "substantially" as a qualifier to certain features or effects in this disclosure is intended to simply mean that any deviations are within tolerances that would normally be expected by the skilled person in the relevant field.

[0019] The use of the word "generally" as a qualifier to certain features or effects in this disclosure is intended to simply mean - for a structural feature: that a majority or major portion of such feature exhibits the characteristic in question, and - for a functional feature or an effect: that a majority of outcomes involving the characteristic provide the effect, but that exceptionally outcomes do no provide the effect.

[0020] In the following, the wording "based on" intends to describe a relationship between, e.g., a result or output obtained from data (e.g., a data set). For example, a result may be determined as a function of the data, such as determined using an algorithm. Thus, in the following, the wording "based on" is used, but it is appreciated that it may be appropriately replaced by the wording "as a function of" or a similar wording.

[0021] The present disclosure provides an ostomy system and a method for identification of a liquid in an ostomy appliance.

[0022] In a first aspect of the invention, an ostomy system for identification of a liquid in an ostomy appliance of the ostomy system is disclosed. The ostomy system includes the ostomy appliance and a monitor device. The ostomy appliance comprises a reservoir and at least two electrodes associated with the reservoir. The at least two electrodes may include two electrodes denoted a working electrode and a first electrode, as will be used throughout the present disclosure. The monitor device comprises a first interface, an electrochemical instrument, and a processor. The first interface is for coupling with the at least two electrodes of the ostomy appliance. The electrochemical instrument is configured to operate according to an electrochemical method, such as configured to apply and control an electrical input signal across the working electrode and the first electrode (via the first interface) according to such an electrochemical method, and to measure a resulting electrical output signal. In embodiments, the processor is coupled to the electrochemical instrument and configured to identify, based on the resulting electrical output signal, the liquid. In an alternative embodiment, the processor may be configured to transmit, via a wireless transceiver and corresponding interface of the monitor device, data indicative of the resulting electrical output signal to an accessory device having one or more processors, and the one or more processors of the accessory device may be configured to identify the liquid based on the received data indicative of the resulting electrical output signal. Thus, an accessory device may form part of the ostomy system. The accessory device may be configured to receive, from the monitor device, such as the processor of the monitor device, data indicative of the resulting electrical output signal and to identify the liquid based on the resulting electrical output signal. In the following, identification the liquid is described as a feature of the processor of the monitor device, but it is appreciated that the description may be adapted to relate to a feature of a processor of an accessory device configured to receive data from the monitor device.

[0023] In an alternative wording of the first aspect, an ostomy system for identification of liquid in an ostomy appliance is disclosed. The ostomy system comprises (i) the ostomy appliance comprising a reservoir and at least two electrodes in fluid communication with the reservoir, the at least two electrodes including a working electrode and a first electrode; and (ii) a monitor device comprising a first interface configured to removably couple with the at least two electrodes of the ostomy appliance, an electrochemical instrument electrically coupled to the first interface, the electrochemical instrument configured to apply an electrical input signal across the working electrode and the first electrode and measure a resulting electrical output signal; and a processor electrically coupled to the electrochemical instrument and configured to control the electrical input of the electrochemical instrument according to an electrochemical method, thereby generating the electrical output signal; and identify, based on the resulting electrical output signal, the liquid in the ostomy appliance. It is appreciated that the alternative wording of the first aspect may be combined with the wording of the preceding paragraph, such as to clarify actions or functionalities of the system and associated devices.

[0024] By "identification" or "identify" is meant that one or more specific properties or characteristics that are inherent to the liquid are determined. For example, the one or more specific properties or characteristics may be properties or characteristics that sets the liquid apart when compared to other (types of) liquids. For example, the properties may include, but are not limited to, physical properties, chemical properties, or any other unique attributes that may define the liquid. The successful identification of a liquid may allow for the differentiation and distinction of this liquid from other liquids, particularly when multiple liquids are present or expected, such as in the reservoir. In embodiments, by identification is meant to differentiate at least two different liquids from each other. In other words, in embodiments, the system is capable of differentiating at least a first liquid from a second liquid, e.g., based on one or more characteristic properties of the liquids. Thus, by identification is meant an ability to not only detect the presence of a (any) liquid in the system, but an ability to further tell that the liquid is one of at least two different liquids (such as liquids expected in the system, see below). In embodiments, the ostomy system is for differentiation of at least a first liquid from a second liquid.

[0025] To identify a liquid may include further actions, such as to initially detect a liquid, analysing the liquid (e.g., reading pre-defined instructions in a processor), and therefrom identifying the liquid. Pre- defined instructions of the processor may aid in identifying the liquid. In particular, pre-defined instructions may include information pertaining to the intended use of the system and thus, which liquids are expected in such a system. In other words, the processor may be configured to select a liquid from a set of expected liquids, thereby improving / optimizing the identification by allowing for an output indicative of a certain liquid (e.g., because a user of an ostomy appliance will assume that a detection of stomal output, or sweat, in an ostomy system is likely). Additional details pertaining to the action of identifying the liquid is provided in further detail below, following a disclosure of the system and employed techniques. Thus, the identification of the liquid may either be based on the liquid initially being completely unknown to the system, or the identification of the liquid may be based on the liquid being known as being either a first liquid (e.g., stomal output) or a second liquid (e.g., sweat), and potentially even further (but pre-defined) liquids, such that the scope of the identification is to determine whether the liquid is the first liquid or the second liquid. For example, the liquid may be categorized according to pre-defined instructions, the pre-defined instructions limiting the number of different categories or types of liquids.

[0026] In embodiments, the monitor device further includes an analog signal processing device configured to filter out all signals representative of sweat and only allow signals representative of stomal output to pass to the processor. In embodiments, the analog signal processing device is a current sensing op-amp (operational amplifier) circuit with a set threshold. Thereby, the processor performance may be optimized, the required power may be reduced, and / or a simpler build of the monitor device and / or required algorithm of the processor may be realized, as it need only to consider the input, which by means of the analog signal processing device can only be indicative of stomal output. Thus, the processor may identify, based on the resulting electrical output signal, such that when no signals are received, the processor may identify a liquid as harmless (e.g., sweat, or non-existent), whereas when signals are received (have passed the filter of the analog signal processing device), the processor may identify the liquid as stomal output.

[0027] Identification of liquids is important within a wide range of technical fields. Within the field of medical devices, such liquids may be bioliquids originating from the human body. Such bioliquids vary in nature, and depending on their composition, it may be relevant to identify the bioliquid, such as to be able to analyse the bioliquid using appropriate techniques and / or to interpret the results within the correct context, or before the bioliquid causes any harm due to being present in an unfavourable place. One such example is the presence of stomal output for people having undergone stoma surgery. Stomal output can cause severe skin irritation / damage if accidentally exposed to the skin. Such exposure may occur if the ostomy appliance designed to contain the stomal output (e.g., an ostomy bag / pouch associated with the ostomy appliance) is not securely attached to the skin, such as by means of a skin adhesive of a base plate. In other situations, it may be beneficial to analyse the stomal output in the ostomy bag, such as to monitor changes over time. This may provide valuable information pertaining to nutrition, hydration, underlying health issues, or complications in the digestive system.

[0028] The inventors have found that stomal output can be characterized and / or identified by its electrochemical redox activity, which is influenced / affected by the natural presence of redox species occurring from food intake and chemical processes in the digestive system, such as the natural presence of enzymes. Exemplary known redox-active species commonly found in stomal output include skatole, indole, ascorbic acid, bilirubin, and uric acid. Further, since other liquids commonly found in ostomy systems (e.g., sweat and water) do not exhibit any significant redox activity, stomal output may be identified using electrochemical methods when a goal is to differentiate stomal output from sweat. In particular, whereas sweat may exhibit redox activity, it is very low and considerably lower than the activity exhibited by, e.g., the redox-active species found in stomal output.

[0029] Redox species in liquids can be measured using electrochemical techniques / methods. Here, typically, the voltage is scanned (e.g., from -1 to +1 V) and the current is recorded. Current only flows when the ionic charges in the liquid are converted to electronic charges in the electrode via an electrochemical reaction at the interface. These electrochemical reactions involve particular redox species, which can be oxidised / reduced at specific voltages. In stomal output, the wealth of redox species results in large currents in the voltammogram (i.e., the plot of current vs. voltage). In contrast, sweat exhibits only small currents owing to low concentrations of redox species in this bioliquid. This difference can be used for leakage detection and differentiation between bioliquids. Importantly, the voltammograms can be seen as a fingerprint of the liquids under investigation. This will be discussed in more detail in the following.

[0030] Differentiation of stomal output of sweat is important when assessing the urgency of a detected presence of a liquid in the interface between the skin surface and the ostomy appliance (e.g., base plate adhering the ostomy bag to the skin). In particular, knowing whether the liquid is stomal output or sweat is important in order to avoid skin damage; if sweat is present, the urgency is low since it does not cause skin damage and because it may be effectively absorbed by an adhesive layer (e.g., hydrocolloid-based) of the base plate. On the contrary, presence of stomal output may prompt immediate action, such as replacement of the ostomy appliance, in order to avoid prolonged exposure of stomal output to the skin. Thus, a need exists to be able to differentiate stomal output and sweat in an ostomy appliance, in particular in the interface between the skin surface and the ostomy appliance (e.g., base plate). Moreover, the use of electrochemical methods allows for a more robust identification of stomal output even if mixed with sweat or water. In particular, situations may occur wherein sweat and stomal output is present at the same time, and depending on the concentration of stomal output, known techniques to differentiate sweat and stomal output may suffer from blinding and incorrectly assuming the liquid is sweat. However, even low concentrations of stomal output may cause skin damage, and as such, a more robust identification of stomal output is desired.

[0031] Accordingly, identification of a liquid in an ostomy appliance may include assessment of the redox activity of the liquid and identification of the liquid based on such redox activity.

[0032] Redox activity can be probed using appropriate electrochemical methods / techniques. Generally, such methods involve applying and controlling (by means of an electrochemical instrument, see definition below) an external voltage or current and measuring the resulting current or voltage, respectively. In particular, the redox activity can be probed using techniques that are designed to induce redox reactions giving rise to the resulting current. Such techniques involve applying and controlling the voltage (or current) to a working electrode, causing species in the solution / liquid to either gain or lose electrons at the electrode surface, leading to reduction or oxidation reactions (commonly denoted redox reactions), respectively. These redox reactions give rise to a resulting current (or voltage). Thus, by a "resulting current" is meant a current that occurs due to redox reactions (also referred to as faradaic current), and it is to be distinguished from a leakage current or residual current (also referred to as non-faradaic current), which is a small current which may occur in the system due to other processes such as the movement of ions in the solution and the charging of the electrical double layer at the electrode surface. However, such residual current is significantly smaller than a resulting current and thus, the resulting current will be indicative of redox reactions taking place, which in turn is indicative of redox active species being present. The same reasoning applies to the use of a system wherein an external current is applied, and the resulting voltage is measured (i.e., when using a galvanostat).

[0033] Ostomy appliance

[0034] The ostomy system comprises an ostomy appliance which can be, or form part of, a colostomy appliance or an ileostomy appliance. In embodiments, the ostomy appliance is selected from (i) a base plate, (ii) a sensor patch for attachment to a proximal surface of a base plate, and (iii) an ostomy bag. The base plate, and / or parts of the sensor patch, may be for attachment (e.g., via an adhesive as discussed below) to the skin of a mammal, preferably to a stoma or the peristomal skin of a mammal, such as a human / user.

[0035] The ostomy appliance may be a base plate arranged for attachment to the (peristomal) skin surface of a user. The base plate may be a two-part ostomy appliance, i.e., the base plate and the ostomy pouch / bag may be releasably coupled, e.g., with a mechanical and / or an adhesive coupling, e.g., to allow that a plurality of ostomy pouches can be utilized (exchanged) with one base plate. For example, the base plate may comprise a coupling ring for coupling an ostomy pouch to the base plate. Further, a two-part ostomy appliance may facilitate correct application of the base plate to skin, e.g., to an improved user sight of the stomal region. Alternatively, the ostomy appliance may be a one-part ostomy appliance, i.e., the base plate and the ostomy pouch may be fixedly attached to each other. The base plate is configured for coupling to a user's stoma and / or skin surrounding the stoma, such as a peristomal skin area.

[0036] The base plate or sensor patch may comprise one or more adhesive layers. The adhesive layer(s) may surround an opening, e.g., a stomal opening. During use, a proximal surface of the adhesive layer(s) adheres to the user's skin in the peristomal area and / or to additional seals, such as sealing paste, sealing tape, and / or sealing ring. The proximal surface of the adhesive layer(s) of the base plate or sensor patch may be configured to adhere to the user's skin. The distal surface of the adhesive layer(s) may be configured to face away from the skin of the user. The adhesive layer(s) of the base plate or sensor patch may form the adhesive surface of the base plate or sensor patch adapted for attachment of the base plate or sensor patch to the skin surface of the user.

[0037] The base plate or sensor patch may comprise a release liner, which may be peeled off by the user prior to applying the base plate or sensor patch to the skin. The release liner may be configured to protect the adhesive layer(s) prior to applying the base plate or sensor patch to the skin.

[0038] The base plate or sensor patch may comprise a backing layer, also denoted a top film. The backing layer may be a protective layer protecting the adhesive layer(s) from external strains and stress during use. Furthermore, the backing layer may also cover the adhesive layer(s), such that the adhesive layer(s) do not adhere to clothes worn on top of the base plate. The backing layer may comprise a distal surface and a proximal surface. The distal surface of the backing layer may be configured to face away from the skin of the user. Where the ostomy appliance is a sensor patch, the distal surface of the backing layer may be configured to adhere to the proximal surface of a base plate. The proximal surface of the backing layer may be facing the adhesive layer(s).

[0039] The ostomy appliance may be a sensor patch for attachment to a proximal surface of a base plate, or for integration into a base plate. Thus, the sensor patch may be subsequently applied, e.g., adhered, to a base plate. Thereby, an arbitrary base plate, such as a generic / conventional base plate, can achieve the features of the sensor patch as described herein.

[0040] The sensor patch may have a first side and a second side. The sensor patch is adapted for attachment to the base plate. For example, the sensor patch may be configured to be positioned between the skin of the user and the proximal side of the base plate. For example, the sensor patch may be adapted for attachment to the adhesive layer(s) and / or surface(s) of the base plate. For example, electrodes of the sensor patch may be arranged according to an electrode layout, and the sensor patch may provide for a corresponding shape of the adhesive, such that the adhesive is only present in the vicinity of the electrodes of the electrode layout. Thereby, the area of the proximal surface of the base plate that is covered by the sensor patch is reduced, such that the main load is carried by the base plate, and the sensor patch takes up as little space as possible in the interface between the base plate and the skin surface. Thus, the sensor patch may be considered an accessory to the base plate, in particular when the base plate is a generic / arbitrary base plate, but where sensing means, as disclosed herein, are desired.

[0041] The base plate or sensor patch may comprise a stomal opening. Each layer of the base plate or sensor patch may comprise stomal openings for collectively forming the stomal opening of the base plate or sensor patch. The stomal opening may be provided in a centre portion of the base plate or sensor patch. The centre portion of the base plate or sensor patch may be surrounding the stomal opening. The stomal opening may be configured to receive a stoma of the user and / or the stomal opening may be configured to allow output from the stoma to pass through the stomal opening an into an ostomy pouch attached to the base plate. For example, the stomal opening may be configured to allow passage of output from the proximal side of the base plate or sensor patch (attached to a base plate) to a distal side of the base plate and / or sensor patch. The size and / or shape of the stomal opening may typically be adjusted by the user or nurse before application of the base plate to accommodate the user's stoma. The stomal opening of a sensor patch may be significantly larger, such as where the sensor patch is ring shaped and intended for adhesion to only a part of the base plate.

[0042] The ostomy appliance may be an ostomy pouch / bag configured to contain stomal output having exited the stoma.

[0043] Reservoir

[0044] The ostomy appliance includes a reservoir. For example, the reservoir is configured to hold / contain / retain a liquid, such as to absorb or collect a liquid. Thus, the reservoir may contain or retain a liquid. For example, the liquid may be either absorbed (e.g., as moisture) or be present in its liquid phase within the reservoir without departing from the definition of the reservoir. The reservoir may be chosen in view of the liquid to be analysed / identified. For example, the reservoir may be a container configured to hold / store liquid in its liquid phase. Alternatively, or in addition, the reservoir may be a gel, such as a hydrogel, where the liquid is absorbed in said gel. By a hydrogel is meant a mixture of porous, permeable solids (e.g., hydrocolloids) configured to absorb at least 10 % by weight or volume of a liquid. The hydrogel may be prepared using a variety of polymeric materials. In embodiments, the hydrogel comprises hydrocolloids, such as hydroxyethyl cellulose (HEC) and / or carboxymethyl cellulose (CMC). The hydrogel may be configured as an adhesive layer, as is described below.

[0045] In embodiments, the reservoir is an absorbent adhesive layer with a proximal surface adapted for attachment of the ostomy appliance to the skin surface of a user. The adhesive layer may have proximal side including the proximal surface, and a distal side including a distal surface. For example, in embodiments, the ostomy appliance is a base plate or a sensor patch, the sensor patch having a distal surface for attachment to a proximal surface of a base plate, and the reservoir is an absorbent adhesive layer with a proximal surface for attachment of the base plate or the sensor patch to the skin surface of a user. In embodiments, the at least two electrodes of the ostomy appliance are arranged on a distal side of the adhesive layer and at least partly exposed to the adhesive layer. In embodiments, the at least two electrodes of the ostomy appliance are at least partly, such as entirely, embedded in the adhesive layer.

[0046] The adhesive layer may be a skin adhesive layer, i.e., an adhesive layer configured to adhere to the skin surface of a user, such as the peristomal skin surface. Thus, the reservoir may be the adhesive layer as such (e.g., moisture may be absorbed and thus contained / retained in the adhesive layer). The adhesive layer may be a hydrogel. The base plate and the sensor patch may be as introduced above. Thus, the base plate includes a proximal surface for attachment to the skin, and a distal surface facing away from the. The sensor patch includes a proximal surface for attachment to the skin and a distal surface for attachment to a proximal surface of a base plate, i.e., implying that the sensor patch is configured to be arranged in the interface between a base plate and a skin surface.

[0047] In embodiments, the reservoir is a plurality of openings in the adhesive layer of the base plate or the sensor patch. The adhesive layer may be provided with a plurality of openings. The plurality of openings may expose electrodes to liquid entering / present in the openings. For example, the plurality of openings may extend entirely through the adhesive layer, such as when the electrodes are arranged on a distal side of the adhesive layer. Alternatively, the openings may extend into, but not entirely through, the adhesive layer, such as to also rely on an absorption of liquid in the adhesive before being assessed by the electrodes.

[0048] In embodiments, in parts of the adhesive layer, the reservoir is the adhesive layer as such, whereas in other parts of the adhesive layer, the reservoir is a plurality of openings for containing a liquid (i.e., liquid may penetrate the openings and thus be partly contained therein).

[0049] In embodiments, the plurality of openings is aligned with the at least two electrodes arranged distal to the proximal surface so as to expose the at least two electrodes to the liquid via the plurality of openings. Preferably, the plurality of openings is through-going from a proximal side of the adhesive layer to a surface of the at least two electrodes (e.g., where the at least two electrodes are arranged on a distal surface of the adhesive layer, the plurality of openings may be through-going from the proximal surface to the distal surface of the adhesive layer). However, the openings may also be at least partly, such as entirely, filled with a material / composition different from a composition the absorbent adhesive layer (see below), such as a material / composition facilitating a different, such as improved, moisture transport than that of the adhesive layer as such. Thereby, the reservoir may be considered the material of such filling composition provided in the plurality of openings.

[0050] In embodiments, the ostomy appliance is a base plate or a sensor patch, the sensor patch having a distal surface for attachment to a proximal surface of a base plate, and wherein the adhesive layer forms part of the base plate or the sensor patch. In other words, the reservoir may be the adhesive layer of a base plate (with a proximal surface for attachment of the base plate to the peristomal skin surface), or the adhesive layer of a sensor patch (with a proximal surface for attachment of the sensor patch to the peristomal skin surface and a distal surface for attachment of the sensor patch to a proximal surface of a base plate). In embodiments, the reservoir is one of (i) the adhesive layer of a base plate and / or a plurality of openings therein, and (i) the adhesive layer of a sensor patch and / or a plurality of openings therein.

[0051] In embodiments, the adhesive layer comprises, or is made of, a first composition. The first composition can comprise one or more polyisobutenes and / or styrene-isoprene-styrene. The first composition can comprise one or more hydrocolloids. The first composition can comprise one or more water soluble or water swellable hydrocolloids. The first composition can be a pressure sensitive adhesive composition suitable for medical purposes comprising a rubbery elastomeric base and optionally one or more water soluble and / or water swellable hydrocolloids. The first composition can comprise one or more polybutenes, one or more styrene copolymers, one or more hydrocolloids, or any combination thereof. The combination of the adhesive properties of the polybutenes and the absorbing properties of the hydrocolloids renders the first composition suitable for use in sensors including sensors for attachment to the skin of a person. The styrene copolymer can for example be a styrene-butadiene-styrene block copolymer or a styrene-isoprene-styrene block copolymer. Preferably, one or more styrene-isoprene-styrene (SIS) block type copolymers are employed. The amount of styrene block-copolymer can be from 5 % to 20 % of the total polymer composition. The butene component is suitably a conjugated butadiene polymer selected from polybutadiene, polyisoprene. The polybutenes are preferably present in an amount of from 35-50 % of the total polymer composition. Preferably, the polybutene is polyisobutylene (PIB). Suitable hydrocolloids for incorporation in the first composition are selected from naturally occurring hydrocolloids, semisynthetic hydrocolloids, and synthetic hydrocolloids. In one or more examples, the first composition can comprise 20-60 % hydrocolloids. The first composition can optionally contain other components, such as one or more of fillers, tackifiers, plasticizers, and other additives.

[0052] The adhesive layer can have a substantially uniform thickness. The adhesive layer can have a thickness defined as the distance between a proximal surface and an opposite distal surface of the layer. The adhesive layer, if used as the reservoir, should be as thin as possible, so as to promote quick detection of redox activity (i.e., the diffusion of redox active particle through the adhesive may be controlled by the thickness of the layer, and by reducing the thickness, such diffusion may occur quicker). In embodiments, such as where the adhesive layer is the reservoir, the thickness is less than 0.5 mm, such as less than 0.4 mm, or less than 0.3 mm, or less than 0.2 mm. In a preferred embodiment, the thickness is 0.2 mm or less. In particular, the inventors have found that a thickness of 0.2 mm or less provides a desired diffusion speed through the layer giving rise to a quick signal / identification of liquid. The thickness may be in the range from 0.1 mm to 1.5 mm (e.g., thicker in regions where electrodes are not present).

[0053] In embodiments, the reservoir is an ostomy bag (e.g., where the ostomy appliance is or includes an ostomy bag), such as an interior compartment of an ostomy bag. Thereby, stomal output may enter the ostomy bag via a stomal opening of the base plate or sensor patch adhering the base plate or sensor patch to the skin, and the at least two electrodes may be associated with the interior compartment, e.g., exposed to the interior compartment.

[0054] Electrodes

[0055] The ostomy appliance comprises at least two electrodes associated with the reservoir. By associated is meant that the at least two electrodes are arranged such that liquid contained in the reservoir may be exposed to the electrodes such that the electrical properties (including redox properties) of a liquid contained in the reservoir may be assessed / probed via the electrodes. For example, as will explained below, the electrical properties may be assessed according to an electrochemical method using an electrochemical instrument.

[0056] Depending on the build of the device, the time it takes for a bioliquid to be identified may vary. Thus, it is appreciated that the present invention both includes embodiments wherein a (near-) instant identification of liquid in the interface between the skin and the adhesive (such as where the electrodes are exposed to the interface via openings in the adhesive layer), and wherein a delayed identification takes place (such as where the electrodes are exposed to the adhesive, and where the bioliquid needs to be absorbed and diffuse through the adhesive to be assessed by electrodes on a distal side of the adhesive layer). However, it is appreciated that the composition of the adhesive may be optimised so as to find a balance between providing a planar adhesive (i.e., an adhesive layer without a plurality of openings in the proximal surface and potentially extending entirely through the layer) and providing a quick identification of stomal output so as to avoid the stomal output spreading further between action can be taken by the user (e.g., replacing the appliance). A planar adhesive may be preferred for manufacturing reasons, while a quick identification of the liquid in the interface between the skin and the adhesive layer may be preferred to avoid prolonged exposure of stomal output to the skin (causing skin irritation) or to avoid the stomal output to spread further and leak onto the clothes of the user (causing a mental burden).

[0057] For example, the electrodes may be arranged, such as printed, on a flexible support film. The support film may be the backing layer / top film introduced above, or the support film may be a separate layer. The electrodes may include, such as consist of, conductive traces of a conductive ink, e.g., silver ink or carbon ink suitable for printing. Thus, in embodiments the electrodes include, such as consist of, a (hardened / cured) conductive ink. In embodiments, conductive ink is created by infusing graphite, silver, or other conductive materials, into ink. In embodiments, the support film is stretchable, flexible and / or elastic. In embodiments, the support layer is flexible and elastic. In embodiments, the support film is made of a polymeric material. In embodiments, the support layer is made of polyurethane (PU), e.g., thermoplastic polyurethane (TPU). In alternative embodiments, the support layer material can be made of or comprise one or more of PTFE, PVDF, polyester (e.g., PET), a thermoplastic elastomer (TPE), polyamide, polyimide, Ethylene-vinyl acetate (EVA), polyurea, and / or silicones. Exemplary thermoplastic elastomers (TPEs) of the support film include styrenic block copolymers (TPS, TPE-s), thermoplastic polyolefin elastomers (TPO, TPE-o), thermoplastic Vulcanizates (TPV, TPE-v), thermoplastic polyurethanes (TPU), thermoplastic copolyester (TPC, TPE-E), and thermoplastic polyamides (TPA, TPE-A). In embodiments, the support film is permeable, such as by means of material choice or perforations. In embodiments, the support film is a textile layer. In embodiments, the support film is impermeable.

[0058] In embodiments, where the reservoir is an adhesive layer of the ostomy appliance, the at least two electrodes are at least partly exposed to the adhesive layer. For example, the electrodes may be partly or entirely embedded in the adhesive layer. In embodiments, the at least two electrodes are arranged on a distal side of the adhesive layer and at least partly exposed to the adhesive layer. Thereby, at least parts of the electrodes may contact the distal surface of the adhesive layer so as to allow assessment of the electrical properties of the adhesive layer and thus the liquid absorbed therein.

[0059] In embodiments, where the reservoir is a plurality of openings in the adhesive layer, the at least two electrodes are aligned with the openings so as to expose parts of the electrodes to the surroundings via the openings (or expose the electrodes to a filling composition, as explained above). In embodiments, wherein the reservoir is an ostomy bag, the at least two electrodes are arranged inside the ostomy bag such that they may come into contact with contents of the ostomy bag or an interior compartment thereof. For example, the at least two electrodes may be arranged in a sidewall of the ostomy bag and exposed to the interior of the bag. For example, the at least two electrodes may be arranged on a strip arranged inside the ostomy bag, or the strip may be configured to be arranged inside the bag, such as by being inserted into the bag prior to use, such as via a stomal opening configured to receive the stoma.

[0060] The at least two electrodes include a working electrode and a first electrode.

[0061] Preferably, the at least two electrodes are made of an inert material, such as carbon (C) (e.g., graphite or graphene) or platinum (Pt). However, depending on the range of the applied voltage by the electrochemical instrument, the material choice may be negligible / of minor importance due to only minor oxidation of, e.g., silver (Ag), at smaller voltages.

[0062] Preferably, the at least two electrodes are made of the same conductive material, such as to avoid any interaction which could affect the results of the electrochemical method.

[0063] Parts of the electrodes not associated with the reservoir may comprise another conductive material, such as chosen for cost considerations. For example, such material may comprise one or more of metallic (e.g., silver, copper, gold, titanium, aluminium, stainless steel), ceramic (e.g., ITO), polymeric (e.g., PEDOT, PANI, PPy), and carbonaceous (e.g., carbon black, carbon nanotube, carbon fibre, graphene, graphite) materials. In particular, for parts of the conductors outside the reservoir, any electrically conductive material commonly used in electronics may be used, as the purpose of the conductors outside the reservoir is merely to connect to the monitor device. In other words, the parts of the conductors outside the reservoir are not intended to take part in the electrochemical reaction described in more detail below.

[0064] Thus, the system may comprise at least two electrodes, both arranged to be exposed to liquid in the reservoir. These electrodes may be connected to an interface of a monitor device via conductors of a different material (cf. the discussion above).

[0065] Electrochemistry commonly employs a three-electrode setup using a working electrode, a counter electrode, and a reference electrode.

[0066] Within the field of electrochemistry, the working electrode is the electrode where the electrochemical reaction of interest occurs. The counter electrode completes the electrical circuit: if an electron is consumed at the working electrode, an electron needs to be released at the counter electrode and vice versa. The reference electrode ensures that the voltage at the working electrode is well-defined. In other words, the voltage of the working electrode is defined against the reference electrode. The reference electrode acts as a reference in measuring and controlling the working electrode voltage without passing any current.

[0067] A three-electrode setup allows for a well-defined voltage at the working electrode. However, the setup may be reduced to a two-electrode setup as disclosed herein according to embodiments of the first aspect. In such a setup, the "first electrode" as denoted herein will act / function as both the reference electrode and the counter electrode, meaning that the voltage is applied against the counter electrode instead of a separate reference electrode. Whereas this might render the voltage at the working electrode less well-known due to drift (e.g., consumption or release of electrons at the counter electrode to counter the redox activity at the working electrode can influence the voltage), and the current might depend on the counter electrode as well, such simplification is within the scope of embodiments of the present invention because the scope thereof is to identify differences between (different) liquids. In other words, while a more well-defined voltage provided by a three-electrode setup allows for a more detailed study of, e.g., identification of specific redox species or concentrations, the two-electrode setup still allows for differentiating liquids based on redox activity as such. Namely, since both setups reveal redox activity, the two-electrode setup provides sufficient information when the scope is that of using redox activity as a proxy for liquid identification. The two-electrode setup may thus be considered a simplification or optimization in view of the problem to be solved. However, using a three-electrode setup (see below) is also within the scope of embodiments disclosed herein.

[0068] In embodiments, the ostomy appliance comprises at least three electrodes associated with the reservoir, the at least three electrodes including a working electrode, a counter electrode (e.g., the first electrode), and a reference electrode (e.g., a second electrode). In other words, in embodiments, the ostomy appliance comprises at least three electrodes, including the working electrode, the first electrode, and a second electrode, wherein the first electrode is configured as a counter electrode, and the second electrode is configured as a reference electrode. The three electrodes may form a single sensor. Such setup is described above and provides for a more detailed study of the redox activity, such as identification of redox species and / or concentrations.

[0069] In embodiments, the ostomy appliance comprises at least three electrodes associated with the reservoir. The three electrodes may form two sensors, each configured according to the two- electrode setup discussed above. Namely, the at least three electrodes may include one electrode configured as a counter electrode, and two electrodes configured as working electrodes (or vice versa), and an electrochemical instrument coupled to the electrodes may be configured to run two separate (but not necessarily different) electrochemical methods across the two sensors, such as separate in time. Thereby, a larger physical coverage of the ostomy appliance may be obtained. For example, one of the working electrodes may be arranged at a larger radial distance from a centre point of a stomal opening of the ostomy appliance than the other working electrode. The same may be obtained using a plurality of electrodes, such as a plurality of working and / or counter electrodes and using a single (or fewer) reference electrodes as reference to each of the plurality of working electrodes. Such setup is discussed in more detail with reference to Fig. 3 below.

[0070] Each of the electrodes disclosed herein may comprise a terminal element for connection with a corresponding terminal element of a first interface of a monitor device of the ostomy system. The terminal elements may be arranged in a monitor interface of the ostomy appliance. Thus, in embodiments, the at least two electrodes are coupled to a monitor interface. In embodiments, the monitor interface is configured for at least electrically, but preferably also mechanically, connecting the electrodes to the monitor device. Thus, the monitor interface can be configured to electrically and / or mechanically couple the electrodes, and thus the sensors formed therefrom, and the monitor device.

[0071] In embodiments, the monitor interface comprises, e.g., as part of a first connector of the monitor interface, a coupling part for forming a mechanical connection, such as a releasable coupling between the monitor device and the ostomy appliance and the electrodes thereof. In embodiments, the coupling part is configured to engage with a coupling part of the monitor device for releasably coupling the monitor device to the sensor assembly, base plate, and / or the sensor patch.

[0072] Monitor device

[0073] The ostomy system includes a monitor device. A monitor device may be considered a device with electronic processing capabilities that is couplable to the ostomy appliance, so as to probe the electrical properties of the liquid via the electrodes. The monitor device may also be denoted an electronic device. The monitor device may include one or more of a housing, a processor, a power unit (e.g., a (rechargeable) battery), a memory connected to the processor, a first interface, and a second interface, the first interface being configured for connecting the monitor device to the at least two electrodes, and the second interface comprising a transceiver module configured for connecting the monitor device to an accessory device or external device.

[0074] The monitor device comprises a first interface for coupling with the at least two electrodes of the ostomy appliance, such as terminal elements of the at least two electrodes. In embodiments, the monitor device comprises at least two terminal elements configured for electrical connection with corresponding terminal elements of the at least two electrodes. In embodiments, the monitor device and the ostomy appliance comprise corresponding releasable coupling mechanisms for mechanical releasable coupling between the monitor device and the ostomy appliance (e.g., the monitor interface discussed above). The coupling mechanisms may secure the monitor device in a coupled configuration with the ostomy appliance, so as to provide a fixed electrical connection between the at least two terminal elements of the monitor device and the at least two electrodes / terminal elements of the at least two electrodes. The first interface may comprise a plurality of terminals, such as two, three, four, five, six, seven, eight, or more terminals, for forming electrical connections with respective terminals / electrodes of the ostomy appliance. One or more terminals of the first interface may be configured for forming electrical connections with another device, e.g., with respective terminals of a docking station provided for charging of the monitor device and / or data transfer.

[0075] The monitor device may comprise a power unit for powering the monitor device. The power unit may comprise a battery. The power unit may comprise charging circuitry connected to the battery and terminals of the first interface for charging the battery via the first interface or via an auxiliary interface having dedicated charging terminals for charging the battery, separate from the first interface.

[0076] Electrochemical instrument

[0077] The monitor device includes an electrochemical instrument. The electrochemical instrument is configured / programmed to operate according to an electrochemical method. For example, the electrochemical instrument is configured to apply and control an electrical input signal across the working electrode and the first electrode (when coupled to the electrodes, such as via the first interface) according to an electrochemical method, and to measure a resulting electrical output signal. The resulting electrical output signal may be considered the results of the applied / employed electrochemical method.

[0078] In embodiments, the electrochemical instrument is a potentiostat. Thereby, the electrical input signal is a voltage, and the electrical output signal is a resulting current flowing between the working electrode and the first electrode.

[0079] In embodiments, the electrochemical instrument is a galvanostat. Thereby, the electrical input signal is a current, and the electrical output signal is a resulting voltage across the working electrode and the first electrode. A galvanostat is also known as an amperostat.

[0080] In embodiments, the electrochemical instrument is selected from a potentiostat and a galvanostat.

[0081] The electrochemical method referred to above is employed using the electrochemical instrument selected from a potentiostat and a galvanostat. The electrochemical method must be chosen according to the electrochemical method. A potentiostat is configured to apply and control a voltage, and to measure a resulting current. A galvanostat is configured to apply and control a current, and to measure a resulting voltage. When using a two-electrode setup as disclosed above, the voltage (for a potentiostat; or current for a galvanostat) is thus applied across the working electrode and the first electrode, and the resulting current (or resulting voltage for a galvanostat) is thus measured between the same electrodes. If using a three-electrode setup, which is also within scope of embodiments of the present disclosure, the voltage (or current for a galvanostat) is applied across the working electrode and a reference electrode, and the resulting current (or resulting voltage for a galvanostat) is measured at the working electrode (the counter electrode completes the circuit).

[0082] An electrochemical instrument may also be referred to as an electrochemical measurement device, electrochemical cell controller, and electrochemical controller, which all intend to cover the functionality of a potentiostat or a galvanostat. In particular, since the redox reactions expected within the present invention may be induced using either a potentiostat or a galvanostat, the umbrella term "electrochemical instrument" is used. However, for the sake of discussing the reactions and electrochemical techniques, a potentiostat is used in the following, but it is appreciated that corresponding results may be obtained using a galvanostat without deviating from the scope of the invention.

[0083] Accordingly, in embodiments, the ostomy system, in particular the monitor device, comprises an electrochemical instrument selected from a potentiostat and a galvanostat.

[0084] The electrochemical instrument may be embodied as a combination of a hardware processor (e.g., employing the electrochemical method) and a battery (e.g., ensuring the presence of a voltage) of the monitor device. The electrochemical instrument may be considered a physical device / entity of the monitor device. In embodiments, the processor of the electrochemical instrument is configured to also identify the liquid according to embodiments described herein in relation to the processor of the monitor device (i.e., it may be the same or different processors)). In embodiments, the electrochemical instrument is formed by (simple) electronic components, such as components without dedicated integrated circuit capabilities.

[0085] The electrochemical instrument may include a processor / memory with a control software. The software may set the desired voltage and other parameters. The software communicates with the instrument to implement these settings.

[0086] The electrochemical instrument may include a current measurement circuit (where the electrochemical instrument is a potentiostat) that detects the flow of electrons at the working electrode. Further, the signal, such as a current (analog signal), may be converted to a digital signal by an ADC for further processing and analysis. The digital signal may be recorded by a data acquisition system, which captures the current response over time. The data acquisition system may communicate with or form part of the processor of the monitor device.

[0087] Electrochemical method

[0088] The electrochemical instrument is configured to employ an electrochemical method. The electrochemical method may be considered an operational mode of the electrochemical instrument. To employ an electrochemical method is meant that the electrochemical instrument is configured to apply and control an electrical input signal (e.g., voltage) according to pre-defined instructions (such as included in control software), and to measure a resulting electrical output signal (e.g., resulting current) due to redox activity induced by the applied and controlled input signal. The electrochemical method may also be denoted an electrochemical technique.

[0089] An electrochemical method may be defined by the value(s) of one or more parameters relating to how the electrical input signal (e.g., voltage) is applied / controlled. Such parameters may include one or more of, but is not limited to, equilibration time, initial potential, stop potential, step potential, pulse potential, pulse time, scan range, scan rate, temperature, number of cycles, bias potential, amplitude, and frequency. It is appreciated that not all parameters are relevant to all electrochemical methods. In addition, the parameters may vary according to the setup.

[0090] Potentiostatic methods

[0091] In embodiments, where the electrochemical instrument is a potentiostat, the electrochemical method is selected from cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry and differential pulse voltammetry may be collectively referred to as voltammetry. Further exemplary voltammetric methods include linear sweep voltammetry (LSV), square wave voltammetry (SVW), and normal pulse voltammetry (NPV), which may also be employed according to embodiments of the present invention. Likewise, another amperometric method is that of pulsed amperometric detection.

[0092] Below, cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) are briefly discussed and exemplary values for defining parameters of the methods are provided. However, it is appreciated that these values do not intend to limit the invention to these values, at least because a scope of the present invention is to probe redox activity as such and use this to identify the liquid. Accordingly, any electrochemical method suitable for probing the redox activity may be chosen without departing from the scope of the invention. The below electrochemical methods may be considered preferred electrochemical methods of the system, at least because they are well-known in the field of electrochemistry. Cyclic voltammetry (CV)

[0093] One exemplary electrochemical method is cyclic voltammetry (CV). In CV, the voltage of the working electrode is linearly swept between two set values at a constant rate, and then reversed back to the initial potential, forming a cyclic pattern. This process is repeated multiple times. During the voltage sweep, the analyte undergoes oxidation and reduction reactions, generating a current that is measured and plotted as a function of the applied voltage, resulting in a cyclic voltammogram.

[0094] In a specific example, CV may be defined / setup according to the table below, where the method may be defined according to the "specific setup", or the method may be defined by embodiments falling within the "preferred range", which is intended to cover a wider range of values for the parameters. Thus, it is appreciated that one may choose a value from the preferred range when setting up CV according to the methods as described herein. In particular, the values of the preferred range provide a setup known to induce redox activity, provide a resulting current that may be used to identify the liquid providing the analyte of the electrochemical reaction, while at the same time providing stability to the electrodes and the chemical reactions of the system described herein.

[0095] Differential pulse voltammetry (DPV)

[0096] One exemplary electrochemical method is differential pulse voltammetry (DPV). In DPV, a series of potential pulses are superimposed on a linear potential sweep. Each pulse consists of a small potential step followed by a larger pulse, and the current is measured just before and at the end of each pulse. This method enhances the signal-to-noise ratio by focusing on the difference in current, which is less sensitive to non-faradaic (charging) currents. The applied potential induces redox activity by driving the oxidation or reduction of the analyte at the working electrode. The result of the DPV method is referred to as a voltammogram.

[0097] In a specific example, DPV may be defined / setup according to the table below, where the method may be defined according to the "specific setup", or the method may be defined by embodiments falling within the "preferred range", which is intended to cover a wider range of values for the parameters. Thus, it is appreciated that one may choose a value from the preferred range when setting up DPV according to the methods as described herein. In particular, the values of the preferred range provide a setup known to induce redox activity, provide a resulting current that may be used to identify the liquid providing the analyte of the electrochemical reaction, while at the same time providing stability to the electrodes and the chemical reactions of the system described herein.

[0098] A special case of DPV may be square wave voltammetry (SWV), wherein the current response of an analyte as a function of an applied voltage waveform is studied. This waveform may consist of square wave pulses superimposed on a staircase potential.

[0099] Chronoamperometry

[0100] One exemplary electrochemical method is chronoamperometry. In this method, a constant voltage is applied to the working electrode, and the resulting current is measured over time. The applied voltage may be chosen to drive a specific redox reaction of the analyte. When the voltage is applied, the analyte undergoes oxidation or reduction, producing a current that initially spikes and then decays as the concentration of the electroactive species near the electrode surface decreases due to consumption of the species. The current-time response provides valuable information about the reaction kinetics and diffusion kinetics of the analyte.

[0101] In a specific example, chronoamperometry may be defined / setup according to the table below, where the method may be defined according to the "specific setup", or the method may be defined by embodiments falling within the "preferred range", which is intended to cover a wider range of values for the parameters. Thus, it is appreciated that one may choose a value from the preferred range when setting up chronoamperometry according to the methods as described herein. In particular, the values of the preferred range provide a setup known to induce redox activity, provide a resulting current that may be used to identify the liquid providing the analyte of the electrochemical reaction, while at the same time providing stability to the electrodes and the chemical reactions of the system described herein.

[0102] Electrochemical impedance spectroscopy (EIS)

[0103] One exemplary electrochemical method is electrochemical impedance spectroscopy (EIS). In EIS, a small alternating voltage around a bias voltage is applied across the working electrode and the first electrode over a range of frequencies, and the resulting current response is measured. The impedance, which is the ratio of the applied voltage to the measured current, is then calculated as a function of frequency. This impedance data provides insights into various processes occurring at the electrode interface, such as charge transfer, build-up of an electric double-layer, and diffusion. By modeling the impedance data with equivalent electrical circuits, the kinetics and mechanisms of electrochemical reactions may be studied.

[0104] In a specific example, EIS may be defined / setup according to the table below, where the method may be defined according to the "specific setup", or the method may be defined by embodiments falling within the "preferred range", which is intended to cover a wider range of values for the parameters. Thus, it is appreciated that one may choose a value from the preferred range when setting up EIS according to the methods as described herein. In particular, the values of the preferred range provide a setup known to induce redox activity, provide a resulting current that may be used to identify the liquid providing the analyte of the electrochemical reaction, while at the same time providing stability to the electrodes and the chemical reactions of the system described herein.

[0105] Galvanostatic methods

[0106] In embodiments, where the electrochemical instrument is a galvanostat, the electrochemical method is selected from chronopotentiometry (CP) and galvanostatic electrochemical impedance spectroscopy (GEIS). Further exemplary potentiometric methods include open circuit potentiometry (OCP), and linear sweep potentiometry (ESP), which may also be employed according to embodiments of the present invention

[0107] Below, chronopotentiometry (CP) and galvanostatic electrochemical impedance spectroscopy (GEIS) are briefly discussed and exemplary values for defining parameters of the methods are provided. However, it is appreciated that these values do not intend to limit the invention to these values, at least because a scope of the present invention is to probe redox activity as such and use this to identify the liquid. Accordingly, any electrochemical method suitable for probing the redox activity may be chosen without departing from the scope of the invention. The below electrochemical methods may be considered preferred electrochemical methods of the system, at least because they are well-known in the field of electrochemistry.

[0108] Chronopotentiometry (CP) Chronopotentiometry is an electrochemical technique where a constant current is applied across the working electrode and the first electrode, and the resulting voltage is measured over time. The constant current forces the electroactive species in the solution to undergo oxidation or reduction. As the reaction progresses, the voltage changes, reflecting the kinetics and mechanisms of the redox processes.

[0109] In a specific example, CP may be defined / setup according to the table below, where the method may be defined according to the "specific setup", or the method may be defined by embodiments falling within the "preferred range", which is intended to cover a wider range of values for the parameters. Thus, it is appreciated that one may choose a value from the preferred range when setting up CP according to the methods as described herein. In particular, the values of the preferred range provide a setup known to induce redox activity, provide a resulting current that may be used to identify the liquid providing the analyte of the electrochemical reaction, while at the same time providing stability to the electrodes and the chemical reactions of the system described herein.

[0110] Galvanostatic electrochemical impedance spectroscopy (GEIS)

[0111] GEIS involves applying a constant current to the working electrode and the first electrode while measuring the resulting voltage response over a range of frequencies.

[0112] In a specific example, GEIS may be defined / setup according to the table below, where the method may be defined according to the "specific setup", or the method may be defined by embodiments falling within the "preferred range", which is intended to cover a wider range of values for the parameters. Thus, it is appreciated that one may choose a value from the preferred range when setting up GEIS according to the methods as described herein. In particular, the values of the preferred range provide a setup known to induce redox activity, provide a resulting current that may be used to identify the liquid providing the analyte of the electrochemical reaction, while at the same time providing stability to the electrodes and the chemical reactions of the system described herein. All of the above electrochemical methods are known to induce redox activity when employed to an electrode setup as described herein. Accordingly, the combination of a suitable electrode setup and the electrochemical method allows for the probing of redox activity of a liquid in the ostomy system.

[0113] Identifying liquid

[0114] The monitor device comprises a processor coupled to the electrochemical instrument and may be configured to identify, based on the electrical output signal, the liquid. Where the electrochemical instrument is embodied as a processor and a battery (see above), the processor may be the same, or a different, processor.

[0115] The processor is configured to identify the liquid based on / as a function of the electrical output signal. In embodiments, the electrical output signal includes a value of the resulting current at one or more applied voltages. The processor may be configured to collect data over a period of time, so as to form graphs of the resulting current as a function of applied voltage (known as a voltammogram), or to form a graph of the resulting current as a function of time at a fixed voltage. The electrical output signal may vary depending on the electrochemical method employed, and it is appreciated that the processor may be configured to identify the liquid according to different analyses of the electrical output signal, depending on the employed electrochemical method. In the detailed description of the drawings below (e.g., in relation to Fig. 5), a more detailed example of the electrical output signal is provided, which also shows how the processor may be configured to identify the liquid.

[0116] In embodiments, to identify the liquid comprises to compare the resulting electrical output signal with one or more thresholds. In other words, the processor may be configured to identify the liquid by comparing the resulting electrical output signal with one or more thresholds / threshold values. For example, the electrical output signal may be a value (e.g., a value of current / at an applied voltage E, 1(E)'), and to compare the resulting electrical output signal with a threshold value, e.g., a specific value of current / at the same specified voltage E: if the value of the electrical output signal is above the threshold value, the liquid may be identified as being a liquid having a first (e.g., high) redox activity, and if the value of the electrical output signal is below the threshold value, the liquid may be identified as being a liquid having a second (e.g., low) redox activity. By applying a plurality of threshold values the identification may be further improved. In the context of an ostomy system, a high redox activity will be associated with the presence of stomal output, and as such, such high redox activity will correspond to the identification of stomal output. Similarly, a low redox activity will be associated with the presence of sweat, and as such, such low redox activity will correspond to the identification of sweat. In embodiments, to identify the liquid comprises to compare the resulting electrical output signal with a threshold, and in accordance with the resulting electrical output signal being above the threshold, determine that the liquid is stomal output, and in accordance with the resulting electrical output signal being below the threshold, determine that the liquid is sweat.

[0117] In an alternative embodiment, the monitor device includes an analog signal processing device configured to filter out all signals below a threshold (i.e., signals indicative of sweat according to embodiments disclosed herein), and to allow only (passing of) signals above a threshold (i.e., signals indicative of stomal output according to certain embodiments disclosed herein). Thereby, the processor performance may be optimized, the required power may be reduced, and / or a simpler build of the monitor device and / or required algorithm of the processor may be realized, as it need only to consider the input, which by means of the analog signal processing device can only be indicative of stomal output. Thus, the processor may identify, based on the resulting electrical output signal, such that when no signals are received, the processor may identify a liquid as harmless (e.g., sweat, or non-existent), whereas when signals are received (have passed the filter of the analog signal processing device), the processor may identify the liquid as stomal output. Thus, in embodiments, to identify the liquid comprises to (at an analog signal processing device) compare the resulting electrical output signal with a threshold, and (in the processor) to identify the liquid in accordance with the signal passed through the analog signal processing device.

[0118] In embodiments, to identify the liquid comprises to input the electrical output signal to a function, look-up table, a neural network, or a model, such as a machine-learning model. In other words, to identify the liquid may be based on a function, look-up table, a neural network, or a model, such as a machine-learning model. For example, a neural network or (machine-learning) model may be trained using empirical data, wherein the electrochemical method is performed on a known liquid (e.g., on stomal output, and on sweat), and where the output data may be represented as a graph. The neural network or model may thus be trained on such graphs known to be representative of a specific liquid (e.g., stomal output or sweat). Thereby, when a similar-looking graph is obtained / observed in a use-case (where the liquid is then unknown, but using pre-defined instructions, may be expected as either one of, e.g., two liquids), the neural network or model may be able to determine that the liquid is one or the other based on similarity with the training data.

[0119] An output of the function, look-up table, neural network, or model may be an indication of whether the liquid is stomal output or sweat.

[0120] In embodiments, where the electrochemical instrument is a potentiostat, the processor is configured to generate a voltammogram or an impedance spectrum based on a plurality of applied voltages and the resulting currents, and to identify the liquid based on the voltammogram or the impedance spectrum. A voltammogram or an impedance spectrum are commonly employed visualizations of the results of an electrochemical measurement using a potentiostat, e.g., varying the voltage and measuring the resulting current, such that the voltammogram may express resulting current / as a function of voltage E, 1(E).

[0121] In embodiments, the processor is configured to determine one or more characteristic features (e.g., distinct peaks, ratio between peaks, size of peaks, etc.) of the voltammogram or impedance spectrum, and to identify the liquid based on the one or more characteristic features. The processor may also be configured to generate a chronoamperogram.

[0122] In embodiments, the processor is configured to generate a chronopotentiogram or an impedance spectrum based on a plurality of applied currents and the resulting voltages, and to identify the liquid based on the chronopotentiogram or an impedance spectrum. A chronopotentiogram or or an impedance spectrum are commonly employed visualizations of the results of an electrochemical measurement using a galvanostat, e.g., varying the current and measuring the resulting voltage, such that the chronopotentiogram may express resulting voltage E as a function of current / , E(l).

[0123] In embodiments, the processor is configured to determine one or more characteristic features (e.g., distinct peaks, ratio between peaks, size of peaks, etc.) of the chronopotentiogram or impedance spectrum, and to identify the liquid based on the one or more characteristic features.

[0124] The output / visualization may depend on the applied electrochemical method.

[0125] In embodiments, the processor is configured to detect, based on the resulting electrical output signal, a liquid in contact with the at least two electrodes. In an alternative wording, the processor is configured to detect the liquid in contact with the at least two electrodes; and the controlling and the identifying are performed in response to detecting the liquid. This may be considered a preceding action prior to identifying the liquid. Namely, detecting a liquid may involve affirming that a liquid is present at the at least two electrodes, without identification of the liquid as such. In embodiments, to identify a liquid comprises to detect a liquid and to determine (identify) the type / nature of the liquid. Thus, to identify a liquid may be a two-step process depending on the implementation. In embodiments, to detect a liquid includes to determine that the resulting electrical output signal is non-zero. For example, even in the absence of redox active species in the liquid present in the reservoir, a leakage current or residual current may be present, as is discussed above.

[0126] In embodiments, the processor is adapted for use with the ostomy system by being configured to associate a detected liquid with being either stomal output or sweat. In the case of an ostomy system, the processor may be programmed (e.g., via pre-defined instructions) to assume that a detected liquid is either stomal output or sweat, and therefrom, in combination with / based on the measured resulting electrical output signal, identify the liquid more precisely. For example, the processor may be configured to map / associate the resulting electrical output signal to be / with either stomal output or sweat, such as in accordance with compliance with one or more thresholds.

[0127] In embodiments, to associate a detected liquid with being either stomal output or sweat comprises to read pre-defined instructions defining that a detection of a liquid is a detection of either stomal output or sweat. And therefrom, in embodiments, to identify the liquid comprises to determine, based on the resulting electrical output signal and the pre-defined instructions, that the liquid is either stomal output or sweat. More specifically, in embodiments, to determine that the liquid is either stomal output or sweat comprises to select the liquid as being either stomal output or sweat based on the resulting electrical output signal and the pre-defined instructions.

[0128] In embodiments, to determine that the liquid is either stomal output or sweat comprises to determine, in accordance with the resulting electrical output signal being above a first threshold at one or more electric voltages (for a potentiostat) or electric currents (for a galvanostat), that the liquid is stomal output (i.e., high redox activity), and in accordance with the resulting electrical output signal being below the first threshold at one or more electric voltages, that the liquid is sweat (i.e., low redox activity).

[0129] In embodiments, the monitor device is configured to output (e.g., transmit and / or display) a signal indicative of the identified liquid. For example, the monitor device may comprise a second interface comprising a transceiver module configured for connecting the monitor device to an accessory device or external device. Thus, the transceiver module may be connected to the processor and configured for connecting the monitor device to an accessory device of the ostomy system. The monitor device may be configured to transmit a signal via the transceiver module. The second interface may be configured as an accessory interface for connecting, e.g., wirelessly connecting, the monitor device to one or more accessory devices. The second interface may comprise an antenna and a wireless transceiver, e.g., configured for wireless communication at frequencies in the range from 2.4 to 2.5 GHz. The wireless transceiver may be a Bluetooth transceiver, i.e., the wireless transceiver may be configured for wireless communication according to Bluetooth protocol, e.g., Bluetooth Low Energy, Bluetooth 4.0, Bluetooth 5. The second interface optionally comprises a loudspeaker and / or a haptic feedback element for provision of an audio signal and / or haptic feedback to the user, respectively. The second interface may comprise a display configured to indicate / display the signal, such as by means of a graphical user interface object. In embodiments, the monitor device is configured to, in accordance with a determination that the liquid is stomal output, output a first signal indicative of the presence of stomal output, and in accordance with a determination that the liquid is sweat, output a second signal indicative of the presence of sweat.

[0130] Also disclosed is an accessory device. An accessory device (also referred to as an external device) can be a mobile phone or other handheld device, such as a smart device including a smartphone or a smartwatch. In embodiments, an accessory device is a personal electronic device, e.g., a wearable, such as a watch or other wrist-worn electronic device. The user of the ostomy appliance / system as disclosed herein may thus be notified of the presence of stomal output or sweat by means of his / her accessory device, such as in a graphical user interface of the accessory device. The accessory device may form part of the ostomy system.

[0131] Method for identification of a liquid

[0132] In a second aspect of the invention, a method for identification of a liquid in an ostomy appliance of an ostomy system (such as the ostomy system according to the first aspect) is disclosed. The ostomy system includes the ostomy appliance and a monitor device, the ostomy appliance including a reservoir and at least two electrodes associated with the reservoir, the at least two electrodes including a working electrode and a first electrode; and the monitor device including a first interface for coupling with the at least two electrodes of the ostomy appliance, an electrochemical instrument, and a processor coupled to the electrochemical instrument. The method, performed in the monitor device, includes the steps of: applying and controlling, by means of the electrochemical instrument, an electrical input signal across the working electrode and the first electrode according to an electrochemical method; measuring, by means of the electrochemical instrument, a resulting electrical output signal; and identifying, by means of the processor, the liquid based on the resulting electrical output signal.

[0133] In an alternative wording of the second aspect, a method for identification of a liquid in an ostomy appliance of an ostomy system, the method comprising (i) applying, via an electrochemical instrument and according to an electrochemical method, an electrical input signal across a working electrode and a first electrode of the ostomy appliance, wherein the working electrode and the first electrode are each in fluid communication with a reservoir of the ostomy appliance; (ii) measuring, via the electrochemical instrument, a resulting electrical output signal; and (iii) processing the resulting electrical output signal to classify the liquid as a liquid type of a predetermined set of liquid types, the predetermined set of liquid types comprising stomal output and sweat. It is appreciated that the alternative wording of the second aspect may be combined with the wording of the preceding paragraph, such as to clarify actions or functionalities of the system and associated devices.

[0134] It is appreciated that definitions, features, and functionalities of the ostomy system (such as of the monitor device) as described above in relation to the first aspect of the invention are applicable to the method as described with respect to the second aspect of the invention and vice versa. In particular, features and functionalities of the monitor device may be converted into method steps of such respective monitor device according to the second aspect of the invention. For example, embodiments of the method may be for identification of a liquid in an ostomy appliance of an ostomy system according to the first aspect of the invention.

[0135] In embodiments, the electrical input signal is provided to the working electrode and the first electrode via a monitor interface that is configured to removably couple with the ostomy appliance; and the electrical output signal is measured via the monitor interface.ln embodiments, the step of identifying by means of the processor, the liquid based on the resulting electrical output signal includes comparing the resulting electrical output signal with one or more thresholds.

[0136] In embodiments, the method includes generating a voltammogram or an impedance spectrum based on a plurality of applied voltages and the resulting currents, and identifying the liquid based on the voltammogram or the impedance spectrum.

[0137] In embodiments, the method includes generating a chronopotentiogram based on a plurality of applied currents and the resulting voltages, and identifying the liquid based on the chronopotentiogram.

[0138] In embodiments, the method includes detecting, based on the resulting electrical output signal, a liquid in contact with the at least two electrodes. In embodiments, the method further includes associating a detected liquid with being either stomal output or sweat.

[0139] In embodiments, the method includes outputting a signal indicative of the identified liquid, such as via a second interface of the monitor device, the second interface comprising a transceiver module configured for connecting the monitor device to an accessory device or external device.

[0140] For example, the method may further include transmitting an indication of the classified liquid type to an accessory device of a user, thereby causing the accessory device to present a notification based thereon to the user. Absorption kinetics

[0141] In an ostomy appliance, such as a base plate or sensor patch described in relation to the first aspect of the invention, it may be favourable to incorporate the electrodes inside the adhesive layer instead of having them exposed, such as via sensor point openings extending through the adhesive layer and aligned with at least parts of the electrodes. Both of these embodiments are covered in preceding paragraphs of the present disclosure. To incorporate the electrodes may ensure proper adhesion in the entire area of the product and the adhesive layer may be substantially planar and free of openings (except the stomal opening). Crucially, however, the redox species need to reach the electrode surface to undergo the desired electrochemical reaction and thus cause a resulting current / voltage as described herein. Naturally, the response time of such a sensor will be limited by the absorption kinetics of the adhesive and its thickness.

[0142] In order to study the absorption kinetics of the adhesive, the inventors have conducted experiments with the goal of establishing that the relevant redox species, giving rise to the resulting current, can indeed diffuse through the adhesive. For this purpose, a Franz diffusion cell was used. The donor chamber contained stomal output from a single user, and a model adhesive containing approx. 33 wt.% HEC in a polymer matrix with a thickness of 1 mm was used as a membrane, and the receptor chamber was filled with saline solution (150 mM NaCl). The resulting voltammograms (obtained using DPV with parameters disclosed herein) of the liquid in the receptor chamber, showed the development of two oxidation peaks around approx. 0.3 and 0.7 V, respectively, as well as one reduction peak around approx. 0.1 V with increasing exposure time. The peaks occur at potentials where native stomal output (without diffusion through an adhesive) also shows redox peaks (see, e.g., Fig. 5), indicating that the same redox species are present in the receptor chamber after diffusion through the adhesive. This shows that the relevant redox species are indeed absorbed by the adhesive and transported to the electrodes, where they can be oxidised / reduced.

[0143] Next, the inventors conducted an experiment with the goal of determining whether the diffusion time is relevant for use in an ostomy appliance (e.g., base plate or sensor patch as described herein) where it is important to avoid prolonged exposure of stomal output to the peristomal skin (i.e., the diffusion time must be within a range where a signal indicative of stomal output may be generated / issued before skin damage or further spreading of the stomal output occur). Here, the same model adhesive containing approx. 33 wt.% HEC in a polymer matrix was used, but now with a thickness of approximately 180 pm. The model adhesive was placed on a screen-printed carbon electrode (DRP-110, DropSens) and the upper surface of the adhesive was exposed to stomal output and sweat, respectively. Initial results reveal that the redox species of stomal output reached the electrodes after approximately 30 minutes (i.e., after 30 minutes, the voltammogram showed peaks indicative of the redox species of stomal output). In certain cases of using an ostomy appliance, this time frame may be sufficient. Accordingly, the results of the experiments reveal that the invention works for electrodes covered with an adhesive. In other words, electrodes arranged to assess the electrical properties of the adhesive layer (which in this case then includes the redox species of stomal output having diffused through the layer) are indeed capable of identifying a liquid (by means of electrochemical methods described herein) absorbed in the adhesive (i.e., when the adhesive is the reservoir according to embodiments of the present invention).

[0144] Medical system

[0145] Also disclosed is a medical system for identification of a bioliquid in a medical appliance of the medical system. The medical system includes the medical appliance and a monitor device. The medical appliance comprises a reservoir and at least two electrodes associated with the reservoir. The reservoir may be an absorbent article, such as an absorbent adhesive layer as disclosed in relation to the first aspect of the invention, such that the bioliquid may be contained as absorbed moisture in the absorbent article, or the reservoir may be a contained in its liquid phase in a container. The at least two electrodes may include two electrodes denoted a working electrode and a first electrode. The at least two electrodes are associated with the reservoir, such as according to definitions provided in relation to the first aspect of the invention. The medical system includes a monitor device. The monitor device has an interface for coupling with the at least two electrodes of the medical appliance, an electrochemical instrument coupled to the interface and configured to operate according to an electrochemical method, and a processor coupled to the electrochemical instrument and configured to identify, based on results of the electrochemical method, the bioliquid.

[0146] Also disclosed is a method, performed in a monitor device, for identification of a liquid in a medical appliance of a medical system, the medical system including the medical appliance and the monitor device, the medical appliance comprising a reservoir and at least two electrodes associated with the reservoir, the at least two electrodes including a working electrode and a first electrode; and the monitor device comprising a first interface for coupling with the at least two electrodes of the ostomy appliance, an electrochemical instrument, and a processor coupled to the electrochemical instrument, the method comprising the steps of: applying and controlling, by means of the electrochemical instrument, an electrical input signal across the working electrode and the first electrode according to an electrochemical method; measuring, by means of the electrochemical instrument, a resulting electrical output signal; and identifying, by means of the processor, the liquid based on the resulting electrical output signal.

[0147] It is appreciated that definitions, considerations, and / or embodiments discussed in relation to the first aspect of the invention are applicable to the medical system disclosed herein. For example, the medical system disclosed above may be an ostomy system including an ostomy appliance and a monitor device. Correspondingly, it is envisioned that embodiments relating to an ostomy system / appliance of the first aspect may be generalized to that of the disclosed medical system / appliance. In particular, it is envisioned that such medical system may be relevant in all settings wherein it is relevant to identify and / or distinguish bioliquids, such as, but not limited to urine, sweat, stomal output, faeces, blood, mucus, saliva, and exudate, such as wound exudate.

[0148] In embodiments, identifying the liquid comprises classifying the liquid as a liquid type of a predetermined set of liquid types, the predetermined set of liquid types comprising stomal output and sweat. In embodiments, the predetermined set of liquid types comprises two or more of urine, sweat, stomal output, faeces, blood, mucus, saliva, and exudate, such as wound exudate.

[0149] In embodiments, the medical system is an ostomy system, and the medical appliance is an ostomy appliance.

[0150] In embodiments, the medical system is a wound dressing system, and the medical appliance is a wound dressing.

[0151] In embodiments, the medical system is a catheter system, and the medical appliance is a catheter, such as an (intermittent) urinary catheter or a bowel catheter.

[0152] In embodiments, the medical system is a sweat dressing system, and the medical appliance is a sweat dressing for application to the skin of a user.

[0153] In embodiments, the medical system is a personal care system, and the medical appliance is a personal care appliance, such as an ostomy appliance, a wound dressing, a catheter, or a sweat sensor dressing. In embodiments, the personal care appliance includes a skin adhesive for sweat analysis.

[0154] Detailed description of the drawings

[0155] Fig. 1 illustrates an ostomy system 100 according to an embodiment of the invention. The ostomy system is for identification of a liquid in an ostomy appliance of the ostomy system. The ostomy system 100 includes an ostomy appliance 110 and a monitor device 120. The ostomy appliance 110 may be a base plate with a proximal surface for attachment to the skin surface (e.g., peristomal skin area) of a user and a distal surface coupled to an ostomy bag (one-piece device) or comprising means for coupling with an ostomy bag (two-piece device), or a sensor patch with a proximal surface for attachment to the skin surface (e.g., peristomal skin area) of a user and a distal surface for attachment to an adhesive proximal surface of a base plate, such that the sensor patch may be layered between the skin and a conventional / generic base plate. The ostomy appliance may be an ostomy bag. The ostomy appliance 110 has a stomal opening 119 with a centre point, the stomal opening 119 being configured to receive / encircle a stoma. Thus, the stoma may extend through the stomal opening 119 and, e.g., enter a stomal bag (not shown) coupled to the ostomy appliance 119.

[0156] The illustrated embodiment may be considered a view of a distal surface of a base plate or sensor patch, where the electrodes 113,114 are illustrated as lines, but it is appreciated that the electrodes may be embedded in an adhesive layer or generally not visible (i.e., the illustration may represent a see-through view of the device to highlight embedded or layered features).

[0157] The ostomy appliance 110 includes a reservoir 111 and at least two electrodes 113,114 associated with the reservoir. The at least two electrodes include a working electrode 113 and a first electrode 114. The reservoir 111 may be embodied as the absorbent adhesive layer of a base plate or a sensor patch, the adhesive layer forming a proximal surface for attachment to the skin surface. The reservoir is configured to absorb liquid. The at least two electrodes 113,114 are associated with the reservoir, such as by being exposed to the adhesive layer. Thereby, changes in electrical properties of the adhesive layer may be assessed by the electrodes via their direct contact with / exposure to the adhesive layer. The electrodes may be masked in some areas, such as to only collect data from zones of the reservoir.

[0158] The monitor device 120 includes a first interface 121 for coupling with the at least two electrodes 113,114 of the ostomy appliance. For example, the first interface 121 of the monitor device may be configured to couple to a monitor interface 116 of the ostomy appliance, the monitor interface including terminals for each of the electrodes 113,114.

[0159] The monitor device 120 includes an electrochemical instrument 122 (here illustrated schematically as a dashed box) configured to apply and control an electrical input signal across the working electrode 113 and the first electrode 114 according to an electrochemical method, and to measure a resulting electrical output signal. For example, the electrochemical instrument 122 may be a potentiostat or a galvanostat. The electrochemical method may be any of the methods disclosed herein.

[0160] The monitor device 120 includes a processor 123 (here illustrated schematically) coupled to the electrochemical instrument 122. The processor 123 is configured to identify, based on the resulting electrical output signal, the liquid.

[0161] The monitor device 120 may further include a power unit, such as a battery, a housing, and optionally a second interface. The second interface may be configured as an accessory interface for connecting, e.g., wirelessly connecting, the monitor device to one or more accessory devices. The second interface may comprise an antenna and a wireless transceiver, e.g., configured for wireless communication at frequencies in the range from 2.4 to 2.5 GHz. The wireless transceiver may be a Bluetooth transceiver, i.e., the wireless transceiver may be configured for wireless communication according to Bluetooth protocol, e.g., Bluetooth Low Energy, Bluetooth 4.0, Bluetooth 5. The second interface optionally comprises a loudspeaker and / or a haptic feedback element for provision of an audio signal and / or haptic feedback to the user, respectively. The second interface may comprise a display configured to indicate / display the signal, such as by means of a graphical user interface.

[0162] It is appreciated that the order of the electrodes in the radial direction from the centre point of the stomal opening 119 is arbitrary, and that the working electrode 113 may thus instead be the inner electrode (closest to the stomal opening) and the first electrode 114 may be the outer electrode (encircling the working electrode 113) without departing from the scope of the invention.

[0163] Fig. 2 illustrates a schematic exploded side-view of an embodiment of the ostomy appliance of Fig. 1. The side-view may be taken along the line A-A of Fig. 1.

[0164] The reservoir 111 is an adhesive layer 111' with a proximal surface 111A for attachment of the adhesive layer to the skin surface of a user, such as a peristomal skin area, and a distal surface 111B. Two electrodes including a working electrode 113 and a first electrode 114 are arranged on a distal side of the adhesive layer 111'. For example, the electrodes may be arranged on the distal surface 111B of the adhesive layer 111'. The electrodes 113,114 are arranged, such as printed, on a proximal surface of a support layer 115. Thus, the support layer 115 may be layered with the adhesive layer 111', such that the electrodes 113,114 are sandwiched between the support layer and the adhesive layer. Thereby, the electrodes 113,114 are in contact with the adhesive layer being the reservoir according to the embodiment, whereby the electrodes may assess the electrical properties of the adhesive layer, and in particular, may assess the redox activity of any liquid absorbed in the adhesive layer (i.e., contained in the reservoir). According to embodiments described herein, a monitor device electrically connected to the electrodes 113,114 may thus identify the liquid based on the use / application of an electrochemical method via an electrochemical instrument included in the monitor device.

[0165] Fig. 3 illustrates an ostomy appliance 210 according to an embodiment of the invention. The ostomy appliance 210 is similar to the ostomy appliance 110 of Fig. 1, with the addition of a third electrode 214'. The third electrode 214' is shown as being arranged further away from the stomal opening and encircling the first electrode 214' and the working electrode 213. The third electrode 214' may be configured as (and denoted) a secondary first electrode, such that the three electrodes effectively form two sensors, each including a working electrode and a first electrode. In other words, a monitor device coupled to the ostomy appliance (see Fig. 1) may thus, via the electrochemical instrument of the monitor device, be configured to apply and control an electrical input signal across the working electrode 213 and the first electrode 214, and to measure a resulting electrical output signal, and likewise, be configured to apply and control an electrical input signal across the working electrode 213 and the secondary first electrode 214', and to measure a resulting electrical output signal. Thus, two sensors may thus be formed by sharing the working electrode 214. Providing further sensors may be realized by adding further first electrodes and / or working electrodes. For example, a tertiary first electrode (not shown) may encircle the secondary first electrode 214', but via appropriate control of the monitor device, the sensor may thus span a larger radial distance (i.e., spanning over the secondary first electrode). Accordingly, various configurations of a plurality of electrodes are foreseen within the scope of the invention, wherein each of such configurations may provide, for example, increased radial coverage (larger distance between the first electrode and the working electrode), or track of progression of liquid (e.g., an inner sensor may detect stomal output before an outer sensor because stomal output originates from the stoma arranged in the stomal opening, closest to the inner sensor).

[0166] In an alternative build of the ostomy appliance 210, the third electrode 214' may be configured as a dedicated reference electrode, such that the shown embodiment represents a 3-electrode setup for redox measurements (the first electrode 214 may thus be denoted a counter electrode), as is described previously. A 3-electrode setup may provide improved accuracy in the analysis of the redox current.

[0167] Fig. 4 illustrates an ostomy appliance 310 according to an embodiment of the invention. The ostomy appliance 310 is similar to the ostomy appliance 210 of Fig. 2, wherein the first electrode 314 and the third electrode 314' partly encircle the stomal opening, whereas the working electrode 313 fully encircles the stomal opening 319.

[0168] It is appreciated that in the vicinity of the area where the electrodes extend towards the monitor interface 316, the fully encircling nature of the working electrode 313 may be interrupted. However, for the take of simplicity, the working electrode 313 in the embodiments shown in the present set of figures is denoted as fully encircling the stomal opening 319.

[0169] The first electrode 314 partly encircles the stomal opening in a first sector of the ostomy appliance, and the third electrode 314' partly encircles the stomal opening in a second sector of the ostomy appliance, wherein the first sector and second sector are separate, i.e., non-overlapping. For example, the first electrode 314 may encircle 180° of the stomal opening in the first sector, and the third electrode 314' may encircle 180° of the stomal opening in the second sector.

[0170] Thereby, the ostomy appliance 310 provides for directional identification of liquid. Namely, by appropriate control of the monitor device, liquid may be identified in either the first sector (via the working electrode 313 and the first electrode 314 and in accordance with embodiments described herein with relation to the measurement principles of the monitor device / electrochemical instrument) and / or in the second sector (via the working electrode 313 and the third electrode 314' and in accordance with embodiments described herein with relation to the measurement principles of the monitor device / electrochemical instrument).

[0171] Further sensing sectors may be realized. For example, a fourth electrode (not shown) may be included in a third sector, and each of the first / third / fourth electrodes may thus encircle the stomal opening by 120°.

[0172] Fig. 5 illustrates data (voltammogram) obtained according to differential pulse voltammetry (DPV) using an experimental setup and parameters according to embodiments described herein. The resulting current / (y-axis) is plotted as a function of the applied voltage E (x-axis).

[0173] Data from 12 stomal output samples (from 12 different people) is illustrated (all solid lines) along with a representative sample of sweat (dotted line). The data representative of stomal output are covered by the bracket SO at their end point (1.00 V), and the data representative of sweat is covered by the backet SW at the end point (1.00 V).

[0174] The data clearly shows that stomal output may be differentiated from sweat based on the resulting current (y-axis). In particular, for positive voltages > 0.0 V, a clear differentiation occurs due to the redox species of stomal output inducing a resulting current due to redox reactions as discussed extensively previously. Accordingly, stomal output may be identified by (and in particular differentiated from sweat) by the size of the resulting current when applying an electrochemical method, and in particular by the size of the current at positive voltages.

[0175] Thus, a processor may be configured to identify the liquid as being stomal output by comparing the resulting current with one or more thresholds / threshold values, such as with a threshold at a predefined voltage (e.g., a voltage greater than 0.0 V, such as a voltage between 0.0 and 1.0 V). For example, in Fig. 5, the threshold value may be 10 pA at >0.75 V (indicated by the solid horizontal line T): if the value of the resulting current is above the threshold T, the liquid may be identified as being a liquid having a first (e.g., high) redox activity (in the context of an ostomy appliance, this can be assumed / expected (by pre-defined instructions of the processor) to be stomal output), and if the value of the electrical output signal is below the threshold value, the liquid may be identified as being a liquid having a second (e.g., low) redox activity (in the context of an ostomy appliance, this can be assumed / expected (by pre-defined instructions of the processor) to be sweat). By applying a plurality of threshold values (e.g., specific values of the current at specific values of the voltage), the identification may be further improved.

[0176] Alternatively, or additionally, to identify the liquid may comprise to input the electrical output signal (here, the voltammogram) to a function, look-up table, a neural network, or a model, such as a machine-learning model. In other words, to identify the liquid may be based on a function, look-up table, a neural network, or a model, such as a machine-learning model. For example, a neural network or (machine-learning) model may be trained using empirical data (such as the data shown in Fig. 5, or similar data obtained under similar conditions), wherein the electrochemical method is performed on a known liquid (e.g., on stomal output, and on sweat, as is the case of Fig. 5), and where the output data may be represented as a graph (Fig. 5). The neural network or model may thus be trained on such graphs known to be representative of a specific liquid (e.g., stomal output or sweat). Thereby, when a similar-looking graph is obtained / observed in a use-case (where the liquid is then unknown, but using pre-defined instructions, may be expected as either one of, e.g., two liquids), the neural network or model may be able to determine that the liquid is one or the other based on similarity with the training data. An output of the function, look-up table, neural network, or model may thus be an indication of whether the liquid is stomal output or sweat.

[0177] In embodiments, to identify the liquid comprises to compare the resulting electrical output signal with a threshold and in accordance with the resulting electrical output signal being above the threshold, determine that the liquid is stomal output, and in accordance with the resulting electrical output signal being below the threshold, determine that the liquid is sweat.

[0178] The data of Fig. 5 further illustrates that despite interpersonal variations in redox currents of stomal output, it may readily be distinguished from sweat. Namely, a wealth of redox species exists in stomal output, which results in large currents in the voltammogram of Fig. 5. In contrast, sweat exhibits only small currents owing to low concentrations of redox species in this biofluid.

[0179] While interpersonal variations in the redox response of output exist, many similarities can be observed. Generally, all voltammograms show an increasing background current between 0 and 1 V (bracket A), a peak around approximately 0.3 V (bracket B), and a peak around approximately 0.7 V (bracket C). Importantly, all features of the voltammograms are related to the composition of output and hence, may aid in identification of the bioliquid.

[0180] Fig. 6 illustrates data similar to that of Fig. 5 but obtained using cyclic voltammetry (CV) with parameters according to embodiments described herein. Accordingly, the figure illustrates that a similar differentiation of stomal output SO and sweat SW may be obtained using another electrochemical method.

[0181] Similar to the situation in Fig. 5, a threshold T may be applied to differentiate the stomal output and sweat; here illustrated for the range from 0.9 V to 1.00 V at 2.5 pA. However, it is appreciated that other means (e.g., function, look-up table, neural network, or model) for identifying the liquid may be used on data similar to that of Fig. 6 as is explained in more detail previously.

[0182] Fig. 7 illustrates data obtained according to differential pulse voltammetry (DPV) using an experimental setup and parameters according to embodiments described herein. The data includes samples having different ratios of a mix of sweat and stomal output (three sweeps for each of the ratios 0:1 (pure stomal output, solid line), 1:1 (dashed line), 10:1 (dotted line), and 100:1 (dashed- dotted line)), thus highlighting that even for diluted stomal output, the disclosed methods and systems are capable of reliably differentiating the presence of stomal output from that of sweat. In particular, the data reveals that at least for a mixture of 10:1 (sweat:stomal output), the method can be used to differentiate presence of stomal output from sweat. Namely, even the presence of small amounts of stomal output, even if diluted, may cause severe skin irritation and as such, it is important that the method can detect such presence of stomal output.

[0183] Fig. 8 illustrates a medical system 500 according to an embodiment of the invention. The medical system is for identification of a liquid, such as a bioliquid, in a medical appliance 510 of the medical system.

[0184] In the illustrated embodiment, the medical appliance may be one of an ostomy appliance 510A, a wound dressing 510B, and a catheter 510C. Other medical appliances are foreseen within the scope of the invention, such as those disclosed previously. The medical system 500 further includes a monitor device 520.

[0185] The medical appliance 510 includes at least two electrodes 513,514. In the figure, these electrodes are illustrated as extending into the medical appliance 510, but no explicit association with the exemplary embodiments 510A, 510B, and 510C is illustrated. It is appreciated that the electrodes may be incorporated into the medical appliance by different means, such as embedded in an adhesive layer, a compartment, a lumen, and / or exposed to surroundings associated with the medical appliance 510. The medical appliance 510 includes a monitor interface 516, the monitor interface including terminals for each of the electrodes 513,514.

[0186] The medical appliance includes a reservoir (which may depend on the implementation of the medical appliance) and the at least two electrodes 513,514 associated with the reservoir. The at least two electrodes include a working electrode 513 and a first electrode 514. The reservoir is configured to contain (e.g., absorb) a liquid. The at least two electrodes 513,514 are associated with the reservoir. Thereby, changes in electrical properties of the liquid in the medical appliance may be assessed by the electrodes. The electrodes may be masked in some areas, such as to only collect data from zones of the reservoir.

[0187] The monitor device 520 includes a first interface 521 for coupling with the at least two electrodes 513,514 of the medical appliance. For example, the first interface 521 of the monitor device may be configured to couple to the monitor interface 516 of the medical appliance, the monitor interface including terminals for each of the electrodes 513,514.

[0188] The monitor device 520 includes an electrochemical instrument 522 (here illustrated schematically as a dashed box) configured to apply and control an electrical input signal across the working electrode 513 and the first electrode 514 according to an electrochemical method, and to measure a resulting electrical output signal. For example, the electrochemical instrument 522 may be a potentiostat or a galvanostat. The electrochemical method may be any of the methods disclosed herein.

[0189] The monitor device 520 includes a processor 523 (here illustrated schematically) coupled to the electrochemical instrument 522. The processor 523 is configured to identify, based on the resulting electrical output signal, the liquid.

[0190] The monitor device 520 may further include a power unit, such as a battery, a housing, and optionally a second interface. The second interface may be configured as an accessory interface for connecting, e.g., wirelessly connecting, the monitor device to one or more accessory devices. The second interface may comprise an antenna and a wireless transceiver, e.g., configured for wireless communication at frequencies in the range from 2.4 to 2.5 GHz. The wireless transceiver may be a Bluetooth transceiver, i.e., the wireless transceiver may be configured for wireless communication according to Bluetooth protocol, e.g., Bluetooth Low Energy, Bluetooth 4.0, Bluetooth 5. The second interface optionally comprises a loudspeaker and / or a haptic feedback element for provision of an audio signal and / or haptic feedback to the user, respectively. The second interface may comprise a display configured to indicate / display the signal, such as by means of a graphical user interface.

[0191] Although particular features have been shown and described, it will be understood that they are not intended to limit the claimed invention, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the claimed invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The claimed invention is intended to cover all alternatives, modifications, and equivalents.

[0192] Embodiments of the present disclosure are set out in the following first set of items.

[0193] 1. A medical system for identification of a bioliquid in a medical appliance of the medical system, the medical system including the medical appliance and a monitor device, the medical appliance comprising:

[0194] - a reservoir; and

[0195] - at least two electrodes associated with the reservoir, the at least two electrodes including a working electrode and a first electrode; and the monitor device comprising:

[0196] - a first interface for coupling with the at least two electrodes of the medical appliance; - an electrochemical instrument configured to apply and control an electrical input signal across the working electrode and the first electrode according to an electrochemical method, and to measure a resulting electrical output signal; and

[0197] - a processor coupled to the electrochemical instrument and configured to identify, based on the resulting electrical output signal, the liquid.

[0198] 2. The medical system according to item 1, wherein the reservoir is an absorbent adhesive layer with a proximal surface for attachment of the medical appliance to the skin surface of a user.

[0199] 3. The medical system according to item 2, wherein the at least two electrodes are arranged on a distal side of the adhesive layer and at least partly exposed to the adhesive layer.

[0200] 4. The medical system according to item 1, wherein the reservoir is a medical bag.

[0201] 5. The medical system according to any of items 1-4, wherein to identify the liquid comprises to compare the resulting electrical output signal with one or more thresholds.

[0202] 6. The medical system according to any of items 1-5, wherein the electrochemical instrument is a potentiostat.

[0203] 7. The medical system according to item 6, wherein the electrochemical method is selected from cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS).

[0204] 8. The medical system according to any of items 6-7, wherein the processor is configured to generate a voltammogram or an impedance spectrum based on a plurality of applied voltages and the resulting currents, and to identify the liquid based on the voltammogram or the impedance spectrum.

[0205] 9. The medical system according to any of items 1-5, wherein the electrochemical instrument is a galvanostat.

[0206] 10. The medical system according to item 9, wherein the electrochemical method is selected from chronopotentiometry (CP) and galvanostatic electrochemical impedance spectroscopy (GEIS).

[0207] 11. The medical system according to any of items 9-10, wherein the processor is configured to generate a chronopotentiogram based on a plurality of applied currents and the resulting voltages, and to identify the liquid based on the chronopotentiogram.

[0208] 12. The medical system according to any of items 1-11, wherein the medical appliance comprises at least three electrodes, including the working electrode, the first electrode, and a second electrode, wherein the first electrode is configured as a counter electrode, and the second electrode is configured as a reference electrode. 13. The medical system according to any of items 1-12, wherein the processor is configured to detect, based on the resulting electrical output signal, a liquid in contact with the at least two electrodes.

[0209] 14. The medical system according to item 13, wherein processor is adapted for use with the medical system by being configured to associate a detected liquid with one or more bioliquids associated with the medical appliance.

[0210] 15. The medical system according to any of items 1-14, wherein the monitor device is configured to output a signal indicative of the identified liquid.

[0211] 16. The medical system according to any of items 1-15, wherein the medical system is selected from an ostomy system, a wound dressing system, a catheter system, and a sweat dressing system, and wherein the medical appliance is selected from an ostomy appliance, a wound dressing, a catheter, and a sweat dressing, respectively.

[0212] 17. A method, performed in a monitor device, for identification of a liquid in a medical appliance of a medical system, the medical system including the medical appliance and the monitor device, the medical appliance comprising a reservoir and at least two electrodes associated with the reservoir, the at least two electrodes including a working electrode and a first electrode; and the monitor device comprising a first interface for coupling with the at least two electrodes of the medical appliance, an electrochemical instrument, and a processor coupled to the electrochemical instrument, the method comprising the steps of:

[0213] - applying and controlling, by means of the electrochemical instrument, an electrical input signal across the working electrode and the first electrode according to an electrochemical method;

[0214] - measuring, by means of the electrochemical instrument, a resulting electrical output signal; and

[0215] - identifying, by means of the processor, the liquid based on the resulting electrical output signal.

[0216] Embodiments of the present disclosure are set out in the following second set of items.

[0217] 1. A medical system for identification of a bioliquid in a medical appliance of the medical system, the medical system including the medical appliance and a monitor device, the medical appliance comprising: a reservoir; and at least two electrodes associated with the reservoir; and the monitor device comprising: an interface for coupling with the at least two electrodes of the medical appliance; an electrochemical instrument coupled to the interface and configured to operate according to an electrochemical method; and a processor coupled to the electrochemical instrument and configured to identify, based on measurement results of the electrochemical method, the bioliquid.

[0218] 2. The medical system according to item 1, wherein the electrochemical instrument is selected from a potentiostat and a galvanostat.

[0219] 3. The medical system according to any of items 1-2, wherein the reservoir is an absorbent adhesive configured to absorb the liquid, or a container, such as configured to store the liquid in a liquid phase.

[0220] 4. The medical system according to any of items 1-3, wherein to identify the liquid comprises to analyse the measurement results of the electrochemical method.

[0221] 5. The medical system according to any of items 1-4, wherein the electrochemical method is selected from cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), chronopotentiometry (CP) and galvanostatic electrochemical impedance spectroscopy (GEIS).

[0222] 6. The medical system according to any of items 1-5, wherein the medical appliance comprises at least three electrodes, including the working electrode, the first electrode, and a second electrode, wherein the first electrode is configured as a counter electrode, and the second electrode is configured as a reference electrode.

[0223] 7. The medical system according to any of items 1-6, wherein the processor is configured to detect a liquid in contact with the at least two electrodes.

[0224] 8. The medical system according to any of items 1-7, wherein processor is adapted for use with the medical system by being configured to associate a detected liquid with being a liquid commonly found in the medical system.

[0225] 9. The medical system according to any of items 1-8, wherein the monitor device is configured to output a signal indicative of the identified liquid.

Claims

Claims1. An ostomy system for identification of a liquid in an ostomy appliance of the ostomy system, the ostomy system including the ostomy appliance and a monitor device, the ostomy appliance comprising:- a reservoir; and- at least two electrodes associated with the reservoir, the at least two electrodes including a working electrode and a first electrode; and the monitor device comprising:- a first interface for coupling with the at least two electrodes of the ostomy appliance;- an electrochemical instrument configured to apply and control an electrical input signal across the working electrode and the first electrode according to an electrochemical method, and to measure a resulting electrical output signal; and- a processor coupled to the electrochemical instrument and configured to identify, based on the resulting electrical output signal, the liquid.

2. The ostomy system according to claim 1, wherein the reservoir is an absorbent adhesive layer with a proximal surface for attachment of the ostomy appliance to the skin surface of a user.

3. The ostomy system according to claim 2, wherein the at least two electrodes are arranged on a distal side of the adhesive layer and at least partly exposed to the adhesive layer.

4. The ostomy system according to claim 1, wherein the reservoir is an ostomy bag.

5. The ostomy system according to any of claims 1-4, wherein to identify the liquid comprises to compare the resulting electrical output signal with one or more thresholds.

6. The ostomy system according to any of claims 1-5, wherein the electrochemical instrument is a potentiostat.

7. The ostomy system according to claim 6, wherein the electrochemical method is selected from cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS).

8. The ostomy system according to any of claims 6-7, wherein the processor is configured to generate a voltammogram or an impedance spectrum based on a plurality of applied voltages and the resulting currents, and to identify the liquid based on the voltammogram or the impedance spectrum.

9. The ostomy system according to any of claims 1-5, wherein the electrochemical instrument is a galvanostat.

10. The ostomy system according to claim 9, wherein the electrochemical method is selected from chronopotentiometry (CP) and galvanostatic electrochemical impedance spectroscopy (GEIS).

11. The ostomy system according to any of claims 9-10, wherein the processor is configured to generate a chronopotentiogram based on a plurality of applied currents and the resulting voltages, and to identify the liquid based on the chronopotentiogram.

12. The ostomy system according to any of claims 1-11, wherein the ostomy appliance comprises at least three electrodes, including the working electrode, the first electrode, and a second electrode, wherein the first electrode is configured as a counter electrode, and the second electrode is configured as a reference electrode.

13. The ostomy system according to any of claims 1-12, wherein the processor is configured to detect, based on the resulting electrical output signal, a liquid in contact with the at least two electrodes.

14. The ostomy system according to claim 13, wherein the processor is adapted for use with the ostomy system by being configured to associate a detected liquid with being either stomal output or sweat.

15. The ostomy system according to any of claims 1-14, wherein the monitor device is configured to output a signal indicative of the identified liquid.

16. A method, performed in a monitor device, for identification of a liquid in an ostomy appliance of an ostomy system, the ostomy system including the ostomy appliance and the monitor device, the ostomy appliance comprising a reservoir and at least two electrodes associated with the reservoir, the at least two electrodes including a workingelectrode and a first electrode; and the monitor device comprising a first interface for coupling with the at least two electrodes of the ostomy appliance, an electrochemical instrument, and a processor coupled to the electrochemical instrument, the method comprising the steps of: - applying and controlling, by means of the electrochemical instrument, an electrical input signal across the working electrode and the first electrode according to an electrochemical method;- measuring, by means of the electrochemical instrument, a resulting electrical output signal; and - identifying, by means of the processor, the liquid based on the resulting electrical output signal.

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