Ostomy appliance with liquid sensor with perforated membrane

Abstract

An ostomy appliance including an adhesive layer with a proximal side configured for attachment to the skin surface of a user is disclosed. The ostomy appliance includes a first and a second electrode forming a sensor and arranged on a distal side of the adhesive layer; and a membrane arranged between the adhesive layer and the plurality of electrodes is disclosed. The membrane has a first surface facing the plurality of electrodes and a second opposite surface facing the adhesive layer, wherein the membrane comprises at least one perforation being a channel having an inner surface. The channel has a surface with a surface structure such that the contact angle between a first liquid having a first characteristic and the surface is less than 90° and such that the contact angle between a second liquid having a second characteristic and the surface of the channel is greater than 90°.

Description

[0001] OSTOMY APPLIANCE WITH LIQUID SENSOR WITH PERFORATED MEMBRANE The present disclosure relates to sensing of liquids, more specifically a sensor for detecting whether a liquid with a specific characteristic is present at a sensor interface when the sensor is exposed to multiple liquids including the liquid with the specific characteristic. The sensor may be used in a leakage detection system for an ostomy appliance.

[0002] Brief description of the drawings

[0003] 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.

[0004] Fig. 1A illustrates the capillary effect in a micro channel for a liquid with a contact angle smaller than 90°;

[0005] Fig. IB illustrates the capillary effect in a micro channel for a liquid with a contact angle larger than 90°;

[0006] Fig. 2A illustrates a top view of a membrane according to an embodiment of the invention;

[0007] Fig. 2B illustrates a top view of a sensor surface according to an embodiment of the invention; Fig. 2C illustrates a cross-sectional view of a sensor according to an embodiment of the invention; Fig. 3A illustrates a cross-sectional view of a sensor comprising a membrane and a spacer element according to an embodiment of the invention;

[0008] Fig. 3B illustrates a cross-sectional view of a sensor comprising a membrane with two different surface structures in two different subsections of the channels according to an embodiment of the invention;

[0009] Fig. 3C illustrates a cross-sectional view of a sensor comprising a membrane with two layers and a permeable layer on top of the membrane according to an embodiment of the invention;

[0010] Fig. 4A illustrates a perforated circular membrane, the perforation pattern being hexagonal;

[0011] Fig. 4B illustrates a perforated membrane shaped as a rectangle, the perforation pattern being a square lattice; Fig. 4C illustrates a perforated membrane shaped as an annulus, the perforation pattern being a hexagonal lattice;

[0012] Fig. 4D illustrates a perforated membrane shaped as a rectangle with an opening in the centre, the perforation pattern being a square lattice;

[0013] Fig. 5A illustrates an exemplary sensor surface comprising electrodes;

[0014] Fig. 5B illustrates an exemplary sensor surface comprising electrodes;

[0015] Fig. 6A illustrates a sensor sensing the presence of a liquid connecting two electrodes according to an embodiment of the invention;

[0016] Fig. 6B illustrates a sensor partly covered by a liquid that will not penetrate the membrane according to an embodiment of the invention;

[0017] Fig. 7 A illustrates a top view of an exemplary ostomy appliance incorporating a sensor according to embodiments of the invention;

[0018] Fig. 7B illustrates an exemplary cross-sectional view of a part of the ostomy appliance incorporating a sensor according to embodiments of the invention;

[0019] Fig. 8 illustrates a method of manufacturing a sensor according to embodiments of the invention; Fig. 9A illustrates a measurement of contact angle of water on a PU film;

[0020] Fig. 9B illustrates a measurement of contact angle of a liquid solution comprising water and SDS on a PU film;

[0021] Fig. 9C illustrates a measurement of contact angle of a liquid solution comprising water and SDS on a PU film;

[0022] Fig. 9D illustrates a measurement of contact angle of a liquid solution comprising water and SDS on a PU film; and

[0023] Fig. 9E illustrates a measurement of contact angle of a liquid solution comprising water and SDS on a PU film.

[0024] Summary of the invention

[0025] 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.

[0026] 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 wound dressing. 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 wound dressing. In other words, the proximal side or surface is the side or surface closest to the user, when the wound dressing 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.

[0027] The present disclosure provides a sensor for determining the presence of a first liquid, and in particular, the present disclosure provides an ostomy appliance having such a sensor. Further a related system having such sensor, such as an ostomy system, is disclosed. A medical appliance and related medical system are also disclosed.

[0028] Below, the sensor is described broadly, and it is appreciated that such sensor may be applied to a range of applications. Next, the sensor is described in the context of an ostomy system, and in particular in the context of an ostomy appliance. The sensor as such may be considered a passive component that can cooperate with an electronic device to form an active component, and in this regard, the present disclosure differentiates between a sensor (or ostomy appliance with features of the sensor described below) and a system (e.g., an ostomy system) including the sensor and the electronic device.

[0029] In a first aspect of the present disclosure, a sensor for determining the presence of a first liquid having a first characteristic when the sensor is exposed to multiple liquids comprising both the first liquid and at least a second liquid having a second characteristic different from the first characteristic is disclosed. The sensor comprises:

[0030] a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface; and

[0031] a membrane covering the sensor surface, the membrane having a first surface facing the sensor surface and a second opposite surface, wherein the membrane comprises at least one perforation being a channel having an inner surface, the channel providing access from the opposite surface of the membrane, through the membrane and to the sensor surface; wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between the first liquid and the surface of the subsection of the channel is less than 90° and such that the contact angle between the second liquid and the surface of the subsection of the channel is greater than 90°.

[0032] Thereby is provided a sensor capable (when coupled with an electronic device) of sensing the presence of a specific, filtered, liquid when multiple liquids are present at an exposed sensor interface, said multiple liquids having respectively different contact angles, via their respectively different characteristics, with the surface of the subsection of the channel. This effect is provided by the sensor being engineered such that the specific liquid (the first liquid), which is desired to be sensed in a certain use situation / environment, has a contact angle of less than 90°, whereby capillary forces drive permeability of the first liquid through the at least one perforation of the membrane, whereas the other liquids in the use situation / environment, including at least the second liquid, may be impermeable due to these having a contact angle equal to or greater than 90° (causing impermeability). Thus, whereas the sensor may only determine whether a liquid is present at the sensor interface (e.g., the sensor may provide a binary output signal in accordance with the detection of liquid), it may be derived that the sensed liquid is the first liquid, given this is the only liquid with permeability through the membrane in a certain use situation / environment. In other words, liquids with characteristics providing a contact angle above 90° (thus, impermeable through the membrane) will not trigger the sensor. The underlying theory will be discussed further below. The membrane disclosed above may also be considered and / or denoted a filter, namely a filter configured to filter certain liquids.

[0033] The words sensing and detecting will be used interchangeably throughout the description and are devoted to the same meaning.

[0034] For example, in the context of ostomy appliances, different characteristics may be due to different amounts or contents of electrolytes and surfactants such as bile salts and phospholipids. For example, a first characteristic may be that of a high amount of electrolytes and / or surfactants (thus indicative of stomal output), whereas a second characteristic may be that of a low amount of electrolytes and / or surfactants (thus indicative of sweat or water).

[0035] Theory

[0036] In the following, the underlying theory is introduced with reference to features of the present invention. Thus, whereas parts of the following discussion relate to fundamental physics, the discussion may comprise or relate to features of the present invention.

[0037] Capillary flow of a liquid in a channel formed in a material can be modelled according to the physics discussed in Ichikawa et al. (Journal of colloid and interface science, 162, 350-355 (1994)). A summary sufficient to understand the underlying theory of the present invention is provided in the following.

[0038] In the following, permeability is defined as the ability for a liquid to be pulled / flow through a channel formed in a material, also denoted forward flow. For example, the channel may be a tube, or the channel may be a perforation resembling a channel. In the following, impermeability is defined as the inability for a liquid to be pulled / flow through the channel (or a plurality of like channels) formed in a material. Impermeability may include both the situation of the liquid experiencing backward flow and the situation of the liquid neither experiencing forward flow nor backward flow (i.e., is at a standstill). Further, the terms may particularly relate to permeability in a channel having a size wherein capillary actions are dominating / prevailing.

[0039] The permeability of a liquid through the channel may be found to depend on a few parameters, including material properties of the material of the channel and the surface tension of the liquid, which in turn affects the contact angle between the liquid and the material of the channel.

[0040] For this theory to be an adequate approximation for liquid flow in a channel, the width of the channels must be within the range where capillary forces are dominating. In a simplified format, the capillary flow of a liquid through a channel may be expressed as (see Ichikawa et al. for a complete derivation):

[0041] s2− s02= Df(t* − 1 + e−t*)

[0042] where s is the time-dependent position of the liquid surface in the channel, so is the starting position of the liquid surface, t*is a dimensionless time parameter, and Df is expressed as:

[0043] Df= σ / σ0cos θ + ρgz0 / (4σ0) D

[0044] where a is the dynamic surface tension, ao is the static surface tension, 0 is the contact angle between the liquid and the wall of the channel, p is the density of the liquid, g is the gravity of Earth, zo is the height of a water column and D is the diameter of the channel. The product pgzo represents the hydrostatic pressure. It should be noted that hydrostatic pressure may be replaced by a similar contribution from another source of pressure, such that the liquid is exposed to a driving force. However, for simplicity, the hydrostatic pressure is considered here. In certain situations, the hydrostatic pressure may even be neglected, e.g., where the height of the water column is small.

[0045] Since the position of the liquid surface s is time-dependent, permeability (forward flow) is realized if the left-hand side (LHS) of the equation is positive (LHS > 0), whereas impermeability (none or backward flow) is realized if the left-hand side of the equation is zero or negative (LHS < 0). The right-hand side (RHS) of the equation is a product of the parameter Df and time, the latter of which being positive by nature. Thus, the sign of the LHS may be engineered by means of careful consideration of Df:

[0046] Df= σ / σ0cos θ + ρgz0 / (4σ0) D

[0047] It may be realized that the following is true:

[0048] if Df > 0 -> forward flow / permeability

[0049] if Df < 0 -> backward flow or standstill / impermeability

[0050] The sign of the first term of Df is governed by the trigonometric function cos(0), which is positive when the contact angle 0 is below 90° and negative for values of 0 above 90°. In the context of hydrodynamics and capillary effects, the contact angle 0 is between 0° and 180°, and thereby, it is sufficient to consider these boundaries.

[0051] The second term of Df may be neglected if zo is very small as may be assumed within scopes of the present invention, e.g., where the sensor operates in an environment where there is no contribution from a (hydrostatic) pressure. In other words, the product pgzo represents the hydrostatic pressure, and for use situations discussed herein, such hydrostatic pressure may be assumed to be small and thus neglectable. For example, the sensor as described herein may experience minimal or no contribution from a liquid column exerting a driving force. Thus, in the case of no hydrostatic pressure (or similar contribution), the permeability is governed by the sign of the trigonometric function, and this situation is assumed throughout the present disclosure as it represents a boundary condition for permeability. Accordingly, the sign of Df, and thus the direction of flow in the channel, may be engineered by considering the first term of Df. In embodiments, the hole size D may be considered and engineered as well, as it contributes to the magnitude of the second term and may function to amplify the permeability in certain situations where there is a contribution from a pressure.

[0052] Accordingly, within the assumptions laid out above and neglecting contributions from the second term of Df, it may be realized that the following is true:

[0053] if Df > 0 => cos0 > 0 => 9 < 90° -> forward flow / permeability if Df≤ 0 ⇒ cosθ ≤ 0 ⇒ θ ≥ 90° → backward flow / impermeability In other words, if the contact angle 0 between the liquid and the material is less than 90°, the liquid experiences forward flow (permeability) through the channel. On the contrary, if the contact angle 0 between the liquid and the material is greater than 90°, the liquid experiences a backward flow (impermeability) through the channel. If the contact angle is 90°, the liquid neither flows forward nor backward, which then corresponds to impermeability.

[0054] According to the above derivation, permeability may thus be engineered by means of considering the contact angle 0 of the material in which the channel is formed and may further be fine-tuned by the hole size (diameter) D: the permeability of liquids through the channel may be optimized by considering the diameter D of the channel. The size of D is further bound by the theory, as capillary forces are required to be the driving force. The inventors have found that an upper limit of the diameter D is at least 500 pm. A lower limit of the diameter D is at least greater than 0. Considering further observations, including ease of manufacturing and the nature of liquids desired to be sensed, the diameter D may be at least 100 pm. The present disclosure comprises a further discussion of a preferred range of the diameter D.

[0055] Whereas the sign of Df is governed by two terms, the inventors have found, and in line with the discussion above, that the effective permeability of a membrane comprising perforations as disclosed herein is indeed governed by the first term and thus the contact angle. Therefore, in the following, the invention is described in terms of the contact angle between a first or second liquid and a surface of a channel, at least because this represents a boundary condition for the theory of permeability as discussed above. However, it is appreciated that finetuning the Df parameter is possible, such that, under appropriate conditions, the contact angle may be above 90° and yet permeability may occur. For example, this may be the situation where the second term of Df is significant and thus cannot be neglected. It should be noted that increasing D will eventually render the capillary effect neglectable. As such, a hole size (diameter) of less than 1 mm is preferred, such as less than 500 pm. Further appropriate ranges are included in the following discussions. Hole sizes / channels, or membranes comprising channels, having a diameter wherein capillary forces are dominated, may be denoted microchannels. Thus, the membrane may comprise microchannels, whereby it is meant that the channels of the membrane are of a size / diameter wherein capillary forces are the driving force of permeability.

[0056] Whereas the surface tension of the liquid is not considered in the determination of permeability (the sign of Df), it should be noted that the surface tension of the liquid and the contact angle between the liquid and the surface of the channel are related.

[0057] As the above theory reveals, different liquids may be separated according to their respective contact angles with the material of the channel. The material or surface structure (giving rise to a certain contact angle) of the channel may thus be engineered accordingly. The contact angle, as referred to through-out the present disclosure, is the angle at which the liquid-vapor interface meets the solid-liquid interface. The contact angle is determined by the balance between adhesive and cohesive forces. As the tendency of a drop to spread out over a flat, solid surface increases, the contact angle decreases. For simplicity, an ideal surface, wherein only one thermodynamically stable contact angle exists, may be considered. In such a system, the contact angle 0 may be expressed by Young's equation:

[0058]

[0059] where γSG, γSL, and γLGare the solid-gas interfacial energy, solid-liquid interfacial energy, and liquid-gas interfacial energy, respectively. The interfacial energies may also be denoted surface tensions, and as such, the contact angle is influenced by the respective surface tensions of liquids in the system.

[0060] In the above, the material of the channel is considered a parameter affecting the contact angle between a liquid and a solid material, namely via the respective surface tension. However, the contact angle may also depend on the surface structure of the material as such, and in particular the surface roughness of the material. Thereby, the contact angle may be altered merely by altering the surface roughness of the same material. This is theorized by the Wenzel correlation:

[0061] cos(θm) = r cos(θY)

[0062] where Qm is the measured contact angle, GY is the contact angle, and r is the roughness ratio. The roughness ratio is defined as the ratio between the actual and projected solid surface area. Thus, in the following, when referring to the material, or to a change of the material, with the purpose of affecting the contact angle with a liquid, said reference may be a reference to changing the surface structure, such as the surface roughness, of the same material. Thereby, the channel may be formed in the same material and the contact angle may be adapted by means of considering the surface structure of the material, cf. the Wenzel correlation.

[0063] In the present disclosure, aspects of the above theory will be discussed in greater detail in relation to the use in a sensor. In particular, with reference to embodiments of the present invention, by choosing the material, or the surface structure thereof, of the channel of the membrane wisely in accordance with the liquids to be sensed in a given use situation / environment, the specific surface tensions of such liquids may be disregarded and permeability through the membrane / channels therein is driven by the contact angle between the liquid and the material / surface structure of the channel.

[0064] Sensor The sensor according to the first aspect of the invention may comprise a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface. This may be any liquid that is in contact with the sensor surface. The sensor surface may be part of any liquid sensor that is capable of sensing or detecting whether a liquid is in contact with the sensor surface. The liquid sensor may be an electronic, mechanical, optical liquid sensor, or any standard liquid sensor for determining whether a liquid is present at a sensor surface. The liquid sensor may be configured to provide a binary signal indicative of the presence of liquid. For example, the liquid sensor may provide a first signal indicative of the presence of liquid at the sensor surface and a second signal indicative of the absence of liquid at the sensor surface. In embodiments, the second signal is a default signal, such that the liquid sensor is only configured to provide the first signal in case liquid is sensed at the sensor surface.

[0065] In embodiments, the sensor comprises a liquid sensor arranged such that the surface of the liquid sensor is the sensor surface.

[0066] The sensor surface is defined as the surface of the liquid sensor that is covered by the membrane. Thus, a liquid that permeates through the membrane will get in contact with the sensor surface. In embodiments, the sensor may comprise a sensor interface. The sensor interface is the side / interface of the sensor where the membrane is exposed to the surroundings, thus the side of the membrane facing away from the sensor surface. In other words, the sensor interface is the interface between the exposed membrane surface and the surroundings. Thus, the sensor may be considered a layered device where the sensor surface is shielded (except where perforations / channels are present) from the environment by the perforated membrane, and the sensor interface is the exposed face of the sensor.

[0067] In embodiments, the liquid sensor is configured to detect a liquid that is inside the channel, but not necessarily in contact with the sensor surface, e.g., by having (laser) light passing through the channel, e.g., transverse to a channel direction defined by the extent of the channel.

[0068] The sensor according to the first aspect of the invention comprises a membrane covering the sensor surface, the membrane having a first surface facing the sensor surface and a second opposite surface facing away from the sensor surface. The second opposite surface of the membrane may also be denoted the second surface. The membrane may comprise at least one perforation being a channel having an inner surface. The channel may provide access from the second opposite surface of the membrane, through the membrane and to the sensor surface. A membrane is a selective barrier or filter with the property of being permeable to certain substances (e.g., molecules / ions / particles, liquids, etc.) and impermeable to other substances. The membrane according to embodiments of the present invention is a film or layer that is permeable to a liquid having a certain characteristic (e.g., a certain surface tension, a surface tension below a certain threshold, or where the surface tension causes the contact angle between the liquid and at least a subsection of the channel formed in the membrane to be less than 90°) and impermeable to liquids having another (different) characteristic (e.g., a certain surface tension, a surface tension equal to or above a certain threshold, or where the surface tension causes the contact angle between the liquid and at least a subsection of the channel formed in the membrane to be equal to or above 90°). Thus, a membrane can be made of a porous material, a thin film, a perforated film, or other structures that can filter liquids. The membrane may comprise multiple layers or films with multiple properties.

[0069] The membrane covers the sensor surface such that only liquids desired to be sensed / detected will permeate through the membrane and contact the sensor surface. Thus, by covering is meant that the membrane encloses or coats the sensor surface, but the membrane does not have to be in direct / physical contact with the sensor surface. Enclosing the sensor surface may mean that the only access for a liquid to the sensor surface is through the membrane. The membrane may be in contact with the sensor surface and by this enclose the sensor surface.

[0070] The membrane may be made of a material selected from one or more of a polymer, fibres, ceramic, or other materials suitable for the disclosed use. in a preferred embodiment, the membrane is made of a flexible and / or stretchable material, in a preferred embodiment, the surface structure of a material forming (part of) the membrane is engineerable by means of plasma treatment.

[0071] In embodiments, the membrane comprises a first polymeric film, and wherein the at least one perforation is formed in the first polymeric film.

[0072] The polymeric film may have any dimensions fitting the sensor. The polymeric film may be made of (thermoplastic) polyurethane, polypropylene, polyvinylchloride, cellophane, or other well-known polymers suitable for the use described herein.

[0073] In embodiments, the first polymeric film has a thickness between 20 μm and 1000 μm, such as between 40 pm and 500 pm, such as between 50 pm and 400 pm, such as between 100 pm and 300 pm, such as between 150 pm and 250 pm.

[0074] In embodiments, the thickness is 30 pm, 42 pm, 60 pm, 100 pm, 150 pm, 200 pm, 250 pm, 300 pm, 350 pm, 450 pm, or 500 pm.

[0075] By having a polymeric film with a thickness between 20 μm and 1000 μm gives a membrane that is flexible and stretchable. Stretchable within the scope of the present disclosure may be defined as being stretchable by a minimum 10 % in length (i.e., the length when exposed to a stretch may be at least 10% greater than the length at rest). The flexibility may ensure that the membrane, or even the sensor, can conform to non-flat surfaces.

[0076] In embodiments the first polymeric film is a polyurethane film.

[0077] Using polyurethane as the first polymeric film the membrane may be fabricated simple and with well-known techniques. Furthermore, polyurethane is flexible and stretchable.

[0078] In embodiments, the membrane comprises a plurality of polymeric films including the first polymeric film and a second polymeric film.

[0079] By having at least two polymeric films in the membrane, at least two different surface structures can be fabricated in the subsections of the channel. Thus, a liquid may have a different contact angle at the surface of each subsection in the channel. By having different contact angles, liquids may be able to pass the first subsection of the channel and not the second. Thus, it might be a more consistent way of detecting whether a specific liquid is present on the interface when a plurality of liquids may be present at the interface. This could, e.g., be used in wound care where there might be more than two liquids present at the sensor interface, e.g., sweat, exudate, and blood.

[0080] By providing the at least one perforation in a polymeric film, the surface of the channel in the polymeric film, and thus the membrane, may be structured by surface treatment and thereby controlled in order to fabricate a membrane with a specific surface structure of the surface of the channel or at least a subsection of the channel.

[0081] At least a subsection of the channel of the membrane has a surface with a surface structure. The surface structure is engineered or chosen / selected such that the contact angle between the first liquid and the surface of the channel, such as the surface of the subsection of the channel, is less than 90° and such that the contact angle between the second liquid and the surface of the channel, such as the surface of the subsection of the channel, is greater than 90°. The requirement of the contact angle being greater than 90° may, in embodiments and for simplicity in the following discussion, also comprise being equal 90°, such that the contact angle between the second liquid and the surface of the channel, such as the surface of the subsection of the channel, is greater than or equal to 90°.

[0082] A subsection of the channel may be defined as the part of the channel that forms a ring or other shape around an axis of the channel, the subsection having a surface area and enclosing the axis of the channel. The axis may be parallel to and coinciding with the channel direction. At least the subsection of the channel may resemble a hollow cylinder with open ends. The subsection may be a cylindrically shaped channel shorter than the extent of the channel as such. The membrane according to the present disclosure relies on at least one perforation and the properties of this at least one perforation, or parts / subsections of said perforation. Preferably, the least one perforation is a through-going opening / hole providing access from the sensor surface, through the membrane, and to the sensor interface exposed to the surroundings / environment. The at least one perforation ensures that liquid has access to the sensor surface through the membrane, given that the liquid has a contact angle of less than 90° as discussed above.

[0083] Aspects of the invention as disclosed herein relies on capillary forces and effects. Accordingly, the size (e.g., diameter) of the perforations needs to be of size ensuring that the driving / primary forces are the capillary forces.

[0084] In embodiments, the at least one perforation has a diameter between 200 μm and 500 μm, such as between 250 μm and 450 μm, such as between 300 μm and 400 μm.

[0085] By having a diameter of the at least one perforation of the membrane within the indicated ranges, the forces acting on the liquid will be dominated by the capillary forces. Other forces, including the gravitational force, may be present but not contribute by a significant amount. There may be external forces acting on the liquid, such as external pressure on the second surface of the membrane. This pressure could be a significant force compared to the capillary forces but will not always be present and will in this disclosure be assumed to be insignificant and is thus ignored. Therefore, the driving force is assumed to be the capillary force.

[0086] The diameter of the at least one perforation may be smaller than 200 μm, or smaller than 100 μm. However, a perforation having a diameter less than 100 μm, or even 200 μm, may prevent desired permeability of liquids having a high viscosity, or solid contents of the liquid may cause the perforations to be blocked. For perforations with a larger diameter than 1000 μm, the contribution from other forces, such as the gravitational force, will increase and thus at some point the capillary forces will not be dominating and all liquids will be able to penetrate the membrane through the perforation. The range for which the capillary forces are dominating may be higher than 1000 μm depending on external forces, material choice, or other considerations. However, it is appreciated that the permeability of the membrane is defined / controlled by the capillary forces, such that the underlying physics may be used to describe and predict the permeability through the membrane. The at least one perforation in the membrane is a channel that provides access from one surface of the membrane and to the opposite surface of the membrane through the membrane. In embodiments, the membrane comprises multiple layers, and thus the channel may comprise multiple subsections each having a surface with a surface structure. In embodiments, the surface structure of two or more, such as each, of the multiple subsections are identical. In an alternative embodiment, the surface structure of each of the multiple subsections are different. At least a subsection of the channel has a surface, such as an inner surface, with a surface structure configured to have a specific characteristic with a certain liquid. In particular, the specific characteristic may be a contact angle between the liquid and the surface of the at least one subsection. The surface structure may be a surface roughness. The surface structure can be modified mechanically or chemically.

[0087] In a preferred embodiment, the surface structure is formed by plasma surface treatment.

[0088] Plasma surface treatment is a well-known and controlled process that modify the surface structure, in particular the surface roughness, of some materials. Plasma treatment will normally modify the surface structure of all free surfaces of a treated item, and thereby it is ensured that the surface of the channel in the membrane will change surface structure when the membrane or part of the membrane is plasma treated. By plasma treatment, the contact angle between a liquid and the surface of the subsection of the channel can be engineered / modified. Parameters including time, temperature, and plasma intensity may influence how fast the surface structure is modified. The plasma may be an oxygen plasma, but other plasmas are foreseen within the scope of the invention.

[0089] Thus, the contact angle between a certain (e.g., expected) liquid and a solid (here, the material of at least the subsection of the channel) can be engineered to have a specific value depending on the surface structure. The contact angle is the angle between the interface between a solid and a liquid and the interface between the liquid and a gas. The contact angle between a liquid and a solid can be modelled according to Youngs equation and / or the Wenzel correlation and thus depends on the surface structure of the solid.

[0090] The sensor surface may comprise, such as consist of, one or more electrodes, such that liquid having propagated through the channel may contact the one or more electrodes, wherein the one or more electrodes are adapted to sense / detect the presence of a liquid. For example, the one or more electrodes may be coupled to a power module and / or a processor, such as a power module and / or a processor of an electronic device couplable to the sensor.

[0091] In embodiments, the sensor comprises at least a first electrode, wherein the sensor surface forms part of the first electrode. Thereby, the sensor can, such as when coupled with an electronic device, detect a liquid at the sensor surface or in the vicinity of the sensor surface electronically.

[0092] The first electrode may be configured to change electronic properties when a liquid is wetting the surface of the electrode. For example, the electronic properties may be measured by means of an applied voltage by an external or internal power source, such as by means of an electronic device coupled to the sensor. By this, the electrode acts as the liquid sensor in the sensor. In embodiments, the electrode is configured to change electrical properties, such as resistance or impedance, when the surface of the electrode is in contact with a liquid. A change in resistance may be due to the electrode absorbing at least part of the liquid. In embodiments, the electrode is configured to dissolve at least partly, such as to break a circuit, when liquid get in contact with the electrode.

[0093] In embodiments, the sensor comprises a first electrode and a second electrode, and wherein the sensor surface is formed by parts of the first electrode and parts of the second electrode.

[0094] In embodiments, the sensor is adapted to sense the presence of a liquid by means of a shortcircuiting event between the first electrode and the second electrode.

[0095] By having two electrodes including the first electrode and the second electrode, it is possible to detect a liquid being in contact with the two electrodes by detecting a short circuit between the electrodes. In one example, the current will run from the first electrode, through liquid in the membrane, and into the second electrode. Thus, in embodiments, a liquid that penetrates / has permeated through the membrane may be sensed by the sensor and the sensor may send a signal to an electronic device. In other words, liquid having permeated through the membrane may cause a short-circuiting event across the first and the second electrode, which may yield a signal indicative of the presence of liquid.

[0096] Liquids suitable for sensing using the sensor as disclosed herein can exhibit different characteristics including, but not limited to, viscosity, density, surface tension, ions, ion concentration, index of refraction, boiling point, and / or vapor pressure. In preferred embodiments, the sensor is capable of sensing liquids based on the surface tension of the liquid as the characteristic of the liquid. It is appreciated that the surface tension of a liquid may be affected by the contents in the liquid, such as the content of surfactants, which in turn may be affected by ions or the ion concentration. The sensor may be able to detect liquids with a specific characteristic. In a preferred embodiment, the specific characteristic is a characteristic affecting the surface tension of the liquid such that the liquid may exhibit a contact angle with at least the subsection of the channel which promotes permeability through the membrane. Thus, if a liquid has a surface tension within a specific range, or higher or lower than a specified threshold, the sensor will detect whether the liquid is present at the sensor interface, and if the liquid has a surface tension outside the specific range or is in non-compliance with the specified threshold, the sensor will not detect the presence of the liquid.

[0097] The surface tension is a result of how the energy of the system is minimized.

[0098] Surfactants present in a liquid may decrease or increase the surface tension of the liquid. Thus, when having two liquids with different characteristics, such as being different in terms of type or concentration of surfactants, the two liquids may have different surface tensions and thus exhibit different contact angles with the channel of the membrane as disclosed herein.

[0099] The sensor may be exposed to a plurality of different liquids, including, but not limited to, bioliquids such as sweat, blood, stomal output, faeces, urine, and (wound) exudate. The sensor may be exposed to water, including water comprising varying amounts of ions or surfactants.

[0100] The sensor may be exposed to a liquid mixture comprising a mixture of such different liquids. A liquid mixture may have characteristics different from the constituent liquids combined to form the liquid mixture. However, when the sensor is appropriately engineered (e.g., having a suitable surface structure of at least the subsection of the surface of the channel), said sensor may be able to differentiate such liquid mixture from another liquid or liquid mixture having different characteristics, such as different surface tension.

[0101] In a preferred embodiment, the sensor is adapted for use in a certain environment comprising at least two liquids. In other words, the sensor may be engineered according to the environment in which the sensor is to be used. Thereby, the sensor does not need to be able to determine the type of liquid in contact with the sensor surface, but rather, the sensor may merely be configured to detect the presence of a liquid, and via knowledge of the environment in which the sensor is operating, it may (e.g., in a processor coupled to the sensor) be derived what liquid has permeated through the membrane, as the sensor, and in particular the membrane, is engineered such that only a certain liquid (or mix of liquids) of the environment may permeate through the membrane. Thereby, it may be derived that the liquid sensed by the sensor at the sensor surface is the liquid of the environment having the capability to permeate through the membrane.

[0102] The contact angle between a first liquid, expected to be sensed by the sensor in a given use situation / environment, and the subsection of the channel can be designed / engineered by manipulating (e.g., surface treating) the surface to be less than 90° while at the same time ensure that the contact angle between a second liquid, expected in a given use situation / environment but not desired to be sensed by the sensor, and the subsection of the channel is equal to or higher than 90°. If the contact angle is equal to 90° the liquid will be in a steady state and not move. Thus, the liquid would not be able to permeate through the membrane.

[0103] For example, where the environment is an ostomy appliance, the environment may be expected to comprise (liquid) stomal output and sweat. Thereby, the sensor may be adapted to be able to be permeable for stomal output and impermeable to sweat. Thereby, it may be derived that liquid sensed by the sensor at the sensor surface is stomal output. Other exemplary environments are discussed below. Thus, the surface structure of at least a subsection of the channel of the membrane of the sensor according to embodiments of the invention may be engineered according to the situation, system, or environment in which the sensor is operating / is to be used. For example, if the environment is expected to comprise two liquids (e.g., where the sensor forms part of an ostomy appliance, the first liquid may be stomal output from an ostomy and a second liquid may be sweat), the surface structure of the subsection may be engineered such that the contact angle between the stomal output and the surface of the subsection is less than 90°, and the contact angle between the sweat and the surface of the subsection is equal to or greater than 90°. Thereby, only the stomal output will be permeable through the membrane, and thereby, the sensing of a liquid at the sensor may be attributed to the presence of stomal output, which may cause a signal indicative of stomal output to be generated. On the contrary, the presence of sweat is not detected by the sensor, which may be an acceptable situation, in particular where the sweat may be absorbed by a feature of the ostomy appliance (e.g., a base plate comprising an adhesive layer comprising moisture-absorbing hydrocolloids).

[0104] When two liquids are present in the environment (e.g., stomal output and sweat), the liquid with the lowest surface tension will be the liquid having the lowest contact angle with a given surface, and thus be the liquid that the sensor can detect by proper engineering of the surface structure of the surface facilitating permeability through the channel.

[0105] The inventors have found that it is indeed possible to fabricate a membrane, having the properties as disclosed herein, suitable for use in an environment comprising stomal output and sweat (i.e., an environment being the vicinity of an ostomy, e.g., as part of an ostomy appliance attached to a peristomal area of the ostomy).

[0106] By preparing / fabricating the surface structure such that the contact angle is below 90° for a first liquid and equal to or above 90° for a second liquid, the membrane will be permeable to the first liquid and impermeable to the second liquid as the capillary forces will pull the first liquid through the channel of the membrane and will prevent the second liquid from entering the channel. Thus, the membrane will act as a filter where only the first liquid can pass the filter and the second liquid cannot. Thereby, the membrane will be permeable to the first liquid and impermeable to the second liquid. This is also known as a hydrophobic valve.

[0107] If the first liquid passes the membrane it may contact the sensor surface and the sensor surface can detect that a liquid has penetrated / permeated through the membrane. Thereby, the sensor may detect whether a specific first liquid of a certain environment comprising the first liquid and a second liquid is present at the sensor interface or not: if the first liquid is present at the sensor interface, it will penetrate / permeate through the membrane and be detected by the liquid sensor. In embodiments, the membrane is perforated according to a first perforation pattern having a plurality of perforations including the at least one perforation.

[0108] By having a perforation pattern with a plurality of perforations, the sensor will be able to detect whether the first liquid is present in the area comprising perforations.

[0109] The perforation pattern may comprise the plurality of perforations arranged in an arbitrary (random) pattern, in a square lattice, in a triangular lattice, or in a hexagonal lattice. The distance between the perforations may vary. Preferably, the distance between the perforations is in the range of 100 μm to 2000 μm, such as 200 μm to 1000 μm, or such as 200 μm to 500 μm.

[0110] In embodiments, the plurality of perforations includes at least 10 perforations, or at least 20 perforations, or at least 30 perforations, or at least 40 perforations, or at least 50 perforations, or at least 100 perforations, or at least 200 perforations, or at least 300 perforations, or at least 400 perforations, or at least 500 perforations, or at least 1000 perforations.

[0111] In embodiments, the membrane comprises at least two regions each including a plurality of perforations. In embodiments, the at least two regions are separated by a distance greater than a distance between individual perforations of each plurality of perforations. In embodiments, a first plurality of perforations, such as a plurality of perforations of a first region, are aligned with a first sensor surface, and a second plurality of perforations, such as a plurality of perforations of a second region, are aligned with a second sensor surface. In embodiments, the first sensor surface and the second sensor surface are connected in series, such that the detection of a liquid is indistinguishable between the two regions. In embodiments, the first sensor surface and the second sensor surface are connected in parallel, such that the detection of liquid is distinguishable between the two regions.

[0112] In embodiments, the sensor comprises a permeable spacer element arranged between the sensor surface and the membrane.

[0113] Having a spacer element placed between the membrane and the sensor surface gives a possibility of reducing the thickness of the first polymer or strengthening the sensor as such.

[0114] The spacer element may have perforations matching the perforations in the membrane or have larger perforations such that multiple perforations of the membrane align with one perforation of the spacer element. The spacer element may be configured such that all liquids, irrespective of characteristics as previously defined, will be able to permeate through the spacer element. For example, a surface structure of the spacer element is configured in a way that all liquids have a contact angle below 90 degrees for this surface. The spacer element may be a porous material permeable by all liquids. The spacer element may be sponge-like material, such as a sponge. In a second aspect of the present disclosure, a sensing system comprising the sensor according to the first aspect of the invention and an electronic device couplable to the sensor is disclosed. The electronic device comprises:

[0115] a processor; and

[0116] a first interface connectable / couplable (such as mechanically and / or electrically) to the processor and the sensor;

[0117] wherein the first interface is configured to collect sensor data from the sensor, when connected to the sensor, and wherein the processor is configured to sense the presence of a liquid in contact with the sensor surface based on the sensor data.

[0118] It is appreciated that embodiments and advantages as disclosed above in relation to the first aspect of the present disclosure are applicable to the second aspect as disclosed herein.

[0119] A sensing system comprising a sensor and an electronic device will be able to collect sensor data from the sensor through the first interface connected to the processor and the sensor. The processor may be capable of collecting data from the sensor and analyse the data. The processor may send a signal to a device if a liquid is sensed by the sensor. The signal may be an electrical, optical, audio, or haptic signal, and the device may in examples be an optical device or an electrical device such as a portable personal device like a phone, computer, smart device, or a smartwatch. The device may be the electronic device as such, such that said electronic device may give off a signal in response to detecting liquid. Thereby, a user can be alerted if the sensor detects a liquid. The electronic device may comprise a memory connected to the processor. The memory may comprise information related to the environment in which the sensor is used, such as what liquids are expected in the environment. Based on this information, the processor may be configured to determine the type of liquid, i.e., by being configured to derive that the detection of a liquid is the liquid expected to be detected in the given environment.

[0120] The first interface connected to the processor and the sensor may be wired or wireless via Bluetooth, Wi-Fi, or another protocol for wireless connection and data transfer. Thus, the signal might be a wireless signal. Optionally, the sensing system may comprise a module for powering the processor and the sensor, such as a battery. The sensing system may also comprise a memory as disclosed above.

[0121] In embodiments, the sensing system further comprises a medical appliance, wherein the sensor is embedded in the medical appliance. For example, the medical appliance comprises a sensing system according to the second aspect of the invention. The medical appliance may comprise a sensor according to the first aspect of the invention. A medical appliance is disclosed, the medical appliance comprising a sensor according to the first aspect of the invention, or a sensing system according to the second aspect of the invention. The medical appliance may be an ostomy appliance or a wound care appliance. Thereby, the sensor may be used to detect liquids associated with an ostomy appliance and a wound care appliance, respectively.

[0122] Ostomy appliance and ostomy system

[0123] In embodiments, the medical appliance is an ostomy appliance. In particular, the medical appliance may be a base plate or a sensor patch adapted for attachment to the adhesive surface of a base plate, for an ostomy appliance. Thus, the ostomy appliance, and in particular a base plate thereof, may comprise a sensor according to the first aspect of the invention.

[0124] 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.

[0125] The sensing system may form part of an ostomy system.

[0126] Disclosed is an ostomy system and devices thereof, such as an ostomy appliance, a base plate for an ostomy appliance, a sensor patch for application / attachment to a base plate, an electronic device (e.g., the electronic device as disclosed in relation to the sensing system), and optionally one or more accessory devices. Further, methods related to the ostomy system and devices thereof are disclosed. 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. An accessory device can be a docking station. In embodiments, the docking station is configured to electrically and / or mechanically couple the monitor device to the docking station. In embodiments, the docking station is configured for charging a battery of the electronic device and / or configured for transferring data between the monitor device and the docking station. The ostomy system can comprise a server device. In embodiments, the server device is operated and / or controlled by the ostomy appliance manufacturer and / or a service centre. Embodiments of the present disclosure provide an ostomy system and devices thereof, such as an ostomy appliance, a base plate for an ostomy appliance, a sensor patch for application / attachment to a base plate, an electronic device, and optionally one or more accessory devices which either alone or together facilitate reliable determination of the nature, severity, and rapidness of moisture propagation in the adhesive material provided for attaching the base plate and / or sensor patch to the skin surface of a user, and / or the presence, including nature and / or severity, of liquid in the interface between the skin surface and the adhesive material. In particular, the nature, severity, and rapidness may be determined by means of a sensor as disclosed herein. Depending on the nature of the pattern of moisture propagation in the adhesive and / or liquid in the interface, the ostomy system and devices thereof enable providing information to the user about the type of failure, such as adhesive failure patterns, and in turn enable providing an indication to the user of the severity and thus the remaining time frame for replacing the ostomy appliance without experiencing severe leakage and / or skin damage.

[0127] In embodiments, the ostomy appliance includes a base plate, such as a monolithic, one-piece base plate, e.g., integrated with a sensor assembly part, or a separate sensor assembly part, such as a sensor assembly part to be subsequently applied to a base plate. In embodiments, the sensor assembly part is a sensor patch for application to the base plate, such as the proximal surface of the base plate. Thereby, an arbitrary base plate, such as a conventional base plate provided with the sensor patch, can achieve the features as described herein. Features as described with respect to sensing / monitoring capabilities of the base plate herein can be provided by a sensor assembly of a sensor patch to be applied to a base plate, e.g., by the user, and vice versa. In embodiments, the sensor patch is adapted to adhere to a base plate. In embodiments, the sensor patch comprises a first adhesive layer adapted to adhere to the skin surface of a user.

[0128] In embodiments, the ostomy appliance comprises a base plate and an ostomy pouch (also referred to as an ostomy bag). The ostomy appliance can be a colostomy appliance or an ileostomy appliance. In embodiments, the ostomy appliance is a two-part ostomy appliance, i.e., the base plate and the ostomy pouch are 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. Further, a two-part ostomy appliance can facilitate correct application of the base plate to skin, e.g., to an improved user sight of the stomal region. In embodiments, the ostomy appliance is a one-part ostomy appliance, i.e., the base plate and the ostomy pouch are 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.

[0129] The ostomy appliance may comprise a first adhesive layer with a proximal surface configured for attachment to the skin surface of a user and a distal surface. In embodiments, the first adhesive layer of the ostomy appliance is provided as part of a base plate or a sensor patch. In embodiments, the base plate and / or the sensor patch comprises the first adhesive layer and the sensing system according to the second aspect of the invention. The first adhesive layer may comprise a stomal opening, such as a first adhesive stomal opening, with a centre point, or is at least prepared for forming a stomal opening with a centre point. The first adhesive layer may comprise hydrocolloids configured to absorb moisture and / or liquid.

[0130] During use, the first adhesive layer adheres to the user's skin (peristomal area) and / or to additional seals, such as sealing paste, sealing tape, and / or sealing ring. Thus, in embodiments, the first adhesive layer is configured for attachment to the skin surface of a user, e.g., for attachment of a base plate and / or the sensor patch to the skin surface of a user.

[0131] Disclosed is an ostomy system comprising an ostomy appliance, a sensor for determining the presence of a liquid in the ostomy appliance, and an electronic device couplable to the sensor, the ostomy appliance having a proximal surface for attachment of the ostomy appliance to the skin surface of a user (e.g., via a first adhesive layer as disclosed above). The sensor is a sensor according to previously disclosed aspects and embodiments. The sensor may be associated with the ostomy appliance such as by being embedded in, or layered with, features of the ostomy appliance. For example, where the ostomy appliance is a base plate or a sensor patch, the sensor may be arranged on a distal surface of an adhesive layer of the base plate or sensor patch, and the sensor may be exposed to the surroundings via openings in the adhesive layer of the base plate or sensor patch. In particular, the sensor comprises a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface (e.g., the sensor surface is exposed via the openings in the adhesive layer); and a membrane covering the sensor surface, the membrane having a first surface facing the sensor surface and a second opposite surface, wherein the membrane comprises at least one perforation being a channel having an inner surface, the channel providing access from the opposite surface of the membrane, through the membrane and to the sensor surface; wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between the first liquid and the surface of the subsection of the channel is less than 90° and such that the contact angle between the second liquid and the surface of the subsection of the channel is greater than 90°. The ostomy system comprises an electronic device comprising a processor; and a first interface connected to the processor and the sensor; wherein the first interface is configured to collect sensor data from the sensor, and wherein the processor is configured to sense the presence of a liquid in contact with the sensor surface based on the sensor data. In embodiments, the processor is configured to transmit a signal indicative of the presence of stomal output. In embodiments, the signal indicative of the presence of liquid (as previously disclosed) is indicative of the presence of stomal output.

[0132] By having the sensing system as disclosed herein arranged in a base plate or sensor patch of an ostomy appliance (e.g., the ostomy system disclosed above), the sensing system is capable of detecting whether stomal output is present at the sensor interface. For example, the sensor may be embedded in, or arranged adjacent to, such as in contact with, an adhesive layer of the base plate or sensor patch. In particular, the sensor interface may be exposed towards the skin surface, such that stomal output in the interface between the base plate / sensor patch and the skin surface may be detected by means of the sensor adapted such that stomal output is permeable through the membrane, whereas sweat, which is also expected in said interface, is engineered (by considering the contact angles as explained above) to be impermeable due to its comparatively lower severity or need for urgent action, and because it may more easily be absorbed by the adhesive layer. The first liquid in this situation is stomal output, which may naturally comprise surfactants lowering the surface tension compared to water and sweat. The second liquid in this situation may be sweat. For example, it may be desired to detect presence of stomal output as this constitutes an urgent situation and may require immediate attention by the user / wearer (e.g., to avoid skin irritation and / or leakage of stomal output onto clothes). On the contrary, the presence of sweat does not require immediate attention and it may be absorbed by the adhesive of the ostomy appliance base plate. Thus, due to the different levels of concern raised by stomal output and sweat, respectively, the detection of sweat may be considered redundant, whereas the detection of stomal output is important.

[0133] Disclosed is an ostomy appliance comprising an adhesive layer with a proximal side configured for attachment of the base plate to the skin surface of a user, the adhesive layer having a stomal opening with a centre point; a plurality of electrodes arranged on a distal side of the adhesive layer, such as between the adhesive layer and a top layer, the plurality of electrodes including a first electrode and a second electrode forming a sensor; and a membrane arranged between the adhesive layer and the plurality of electrodes, the membrane having a first surface facing the plurality of electrodes and a second opposite surface facing the adhesive layer, wherein the membrane comprises at least one perforation being a channel having an inner surface, the channel providing access from the opposite surface of the membrane, through the membrane and to the plurality of electrodes; wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between a first liquid having a first characteristic and the surface of the subsection of the channel is less than 90° and such that the contact angle between a second liquid having a second characteristic different from the first characteristic and the surface of the subsection of the channel is greater than 90°.

[0134] The ostomy appliance comprises features introduced previously in relation to the first aspect of the invention, and it is appreciated that definitions and variations of these features, and related embodiments, are also applicable to the ostomy appliance comprising such features. Embodiments of the ostomy appliance are summarized below, and reference is made to previous discussions relating to these embodiments in the context of the sensor as such.

[0135] In embodiments, the membrane is perforated according to a first perforation pattern having a plurality of perforations including the at least one perforation. In embodiments, the at least one perforation has a diameter between 200 μm and 500 μm.

[0136] In embodiments, the surface structure is formed by plasma surface treatment.

[0137] In embodiments, the membrane comprises a first polymeric film, and wherein the at least one perforation is formed in the first polymeric film. In embodiments, the first polymeric film has a thickness between 20 μm and 1000 μm. In embodiments, the first polymeric film is a polyurethane film. In embodiments, the membrane comprises a plurality of polymeric films including the first polymeric film and a second polymeric film.

[0138] In embodiments, a permeable spacer element is arranged between the plurality of electrodes and the membrane.

[0139] In embodiments, the ostomy appliance is a base plate. In embodiments, the ostomy appliance is a sensor patch for attachment to a proximal surface of a base plate. In embodiments, the first liquid is stomal output, and the second liquid is sweat.

[0140] In embodiments, the first adhesive layer comprises at least one opening extending entirely through the adhesive layer, and wherein the at least one opening is aligned with the at least one perforation of the membrane. Depending on the composition of the first adhesive layer, the thickness of the membrane, and / or other parameters, it may be desirable to completely exposure the at least one perforation to a proximal side of the adhesive layer, such that liquids (stomal output or sweat) may propagate through the opening in the adhesive layer, through the membrane (if the characteristics of the liquid allows) and reach the sensor formed by the electrodes. In embodiments, a plurality of openings is provided in the adhesive layer, the plurality of openings aligned with a plurality of perforations in the membrane. For example, the plurality of openings in the adhesive layer may be more than 10 openings, such as individual openings arranged circularly around a stomal opening of the adhesive layer. The membrane may thus comprise a plurality of perforations, and these may be at least partly aligned with the openings of the adhesive layer so as to expose the electrodes via both the perforations of the membrane and the openings of the adhesive layer. Depending on the size / diameter of the perforations and the openings, they need not necessarily to be aligned fully (e.g., one opening of the adhesive layer may expose a plurality of perforations of the membrane if a diameter of the opening is larger than a diameter of each individual perforation). In the contrary, a build may exist wherein openings of the adhesive are not necessary, such as wherein the moisture absorbed by the adhesive (a normal property of an adhesive for an ostomy appliance) is sufficient for detection at the sensor.

[0141] When incorporated in an ostomy appliance, such as in a base plate or in a sensor patch for attachment to a base plate of an ostomy appliance, the sensor may be ring-shaped to enclose a stomal opening of the base plate. For example, the sensor may comprise one or more electrodes adapted to encircle the stomal opening, where said one or more electrodes are thus embedded in, or in contact with, the first adhesive layer. Thereby, the sensor may detect the presence of stomal output annularly about the stoma. The sensor may be configured to detect the presence of stomal output in separate radial and / or angular sensing zones about the stoma.

[0142] Wound dressing and wound dressing system

[0143] In embodiments, the medical appliance is a wound dressing, or a wound dressing appliance. Thus, the wound dressing may comprise a sensor according to the first aspect of the invention.

[0144] The sensing system may form part of a wound dressing system. Disclosed is a wound dressing system and devices thereof, such as a wound dressing, an electronic device (e.g., the electronic device as disclosed in relation to the sensing system), and optionally one or more accessory devices. Further, methods related to the wound dressing system and devices thereof are disclosed. An accessory device (also referred to as an external device) may be a mobile phone or other handheld device. An accessory device may be a personal electronic device, e.g., a wearable, such as a watch or other wrist-worn electronic device. An accessory device may be a docking station. The docking station may be configured to electrically and / or mechanically couple the monitor device to the docking station. The docking station may be configured for charging the monitor device and / or configured for transferring data between the monitor device and the docking station. The wound dressing system may comprise a server device. The server device may be operated and / or controlled by the wound dressing system manufacturer and / or a service centre.

[0145] Embodiments of the present disclosure provide a wound dressing system and devices thereof, such as a wound dressing, an electronic device, and optionally one or more accessory devices which either alone or together facilitate reliable monitoring of the wound dressing and operating state thereof. In particular, the monitoring may be determined by means of a sensor as disclosed herein. Accordingly, the wound dressing system and devices thereof enable providing information to the user about the operating state of the wound dressing, and in turn optionally enable providing an indication to the user or a caretaker of the remaining time frame for replacing the wound dressing without experiencing leakage and / or to provide optimum wound healing conditions.

[0146] A wound dressing is disclosed, the wound dressing comprising a first adhesive layer with a proximal surface configured for attachment of the wound dressing to the skin surface of a user; an absorbent core layer; and optionally a top layer on a distal side of the absorbent core layer. The wound dressing may comprise an electronic device interface. The first adhesive layer may comprise or be made of a first composition. The first composition may comprise silicone. The first adhesive layer may comprise a support layer with an adhesive material made of a first composition moulded onto or otherwise attached to the support layer. The first composition may be a thermoset, curable adhesive material. An example of such adhesive material may be a silicone based adhesive material. The first composition may be a two-component system. Preferably, the first composition contains no solvent. Preferred first compositions include polyurethane, acrylic, silicone or polyethylene or polypropylene oxide based cross-linking types. The first composition may be a hotmelt type, which initially is heated to flow and subsequently cooled to gel or crosslink. Instead of curing upon cooling, the first composition may in some embodiments cure upon application of thermal energy. The absorbent core layer may be a uniform material, or it may be a composite, for example in the form of a layered construction comprising layers of different texture and properties. The absorbent core layer may comprise foam, cellulose, super absorbent particles and / or fibres. The absorbent core layer may comprise a layer of foam facing the wound. The absorbent core layer may comprise a polyurethane foam. The absorbent core layer may comprise a super absorbing layer.

[0147] It is an advantage of the present disclosure, including a sensing system as disclosed herein and a wound dressing, that an optimum or improved use of the wound dressing is enabled and facilitated. In particular, the present disclosure facilitates that a wound dressing is not changed too early (leading to increased costs and / or material waste) nor too late (leading to adhesive failure, leakage and / or unsatisfactory wound healing conditions). Accordingly, the user or a health care professional is able to monitor and plan the use of the wound dressing.

[0148] In embodiments, the sensor is embedded in, or arranged adjacent to, such as in contact with, the adhesive layer of the wound dressing. For example, the sensor may be arranged on a distal side of the adhesive layer. In embodiments, the sensor may be embedded in, or arranged adjacent to, such as in contact with, the absorbent core layer of the wound dressing. For example, the sensor may be arranged on a distal side of the absorbent core layer. In particular, the sensor interface may be exposed towards the absorbent core layer and / or the skin surface, such that moisture, such as wound exudate, blood, or sweat, may be detected by means of the sensor adapted such that stomal output is permeable through the membrane, whereas other liquids, which is also expected in the system, is engineered (by considering the contact angles as explained above) to be impermeable due to its comparatively lower severity or need for urgent action. Depending on the need or intended use of the wound dressing, the first liquid in this situation may be one of wound exudate, blood, and sweat. The second liquid may be one or wound exudate, blood, and sweat, where said second liquid is not the first liquid.

[0149] For example, it may be desired to detect presence of blood if blood is not expected in the specific wound, as this would constitute an urgent situation and may require immediate attention by the user / wearer or health care professional. On the contrary, the presence of wound exudate may be expected and note constitute a risk to the wound healing and / or the wearer. Thus, due to the different levels of concern raised by blood and wound exudate, respectively, the detection of exudate may be considered redundant, whereas the detection of blood is important. Similar situations may occur where blood is expected in a wound dressing, whereas exudate is not, or sweat may be expected and exudate and / or blood is not. Thus, the sensor of the sensing system incorporated in the wound dressing may be engineered according to the intended use of the specific wound dressing.

[0150] In embodiments, the signal indicative of the presence of liquid is indicative of the presence of one of wound exudate, blood, and sweat.

[0151] Method of manufacturing sensor

[0152] In a third aspect of the present disclosure, a method of manufacturing a sensor for determining the presence of a first liquid having a first characteristic when the sensor is exposed to multiple liquids comprising both the first liquid and at least a second liquid having a second characteristic different from the first characteristic is disclosed. The method comprises the steps of:

[0153] providing a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface; and

[0154] providing a membrane having a first surface and a second opposite surface, the membrane comprising at least one perforation being a channel having an inner surface, wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between the first liquid and the surface of the subsection of the channel is less than 90° and such that the contact angle between the second liquid and the surface of the subsection of the channel is greater than 90°; arranging the first surface of the membrane to face the sensor surface, such that the channel provides access from the opposite surface of the membrane to the sensor surface, to form the sensor.

[0155] Using this method to fabricate a sensor for detecting a liquid with a specific characteristic ensures that the sensor is fabricated by simple and well-known techniques and results in a sensor with the desired properties.

[0156] It is appreciated that embodiments and advantages as disclosed above in relation to the first aspect of the present disclosure are applicable to a method as disclosed herein. In particular, disclosed is a method of manufacturing a sensor according to the first aspect of the invention.

[0157] In embodiments, the step of providing a membrane having a first surface and a second opposite surface comprises the steps of:

[0158] providing a membrane precursor; and

[0159] forming the at least one perforation in the membrane precursor to form the membrane. By a membrane precursor is preferably meant a polymeric film suitable for the formation of at least one perforation therein. Thus, the membrane precursor may be considered the substrate for the formation of the membrane comprising the at least one perforation. Using a membrane precursor to form the membrane by introducing perforations in the membrane precursor ensures that the membrane comprises perforations. The membrane precursor can be made of a polymeric material and may be a film of this polymer with the desired area of the sensor. The perforations may be fabricated by using lithography, laser cutting, or other micro fabrication processes.

[0160] In embodiments, the step of providing a membrane having a first surface and a second opposite surface comprises the step of plasma surface treating at least the surface of the subsection of the channel to form the surface structure.

[0161] Plasma treatment is a known technique for manipulating the surface structure of a materials, and by using this technique, the surface structure can be controlled and thus the contact angle with specific liquids may be manipulated to be over or under 90°.

[0162] In order to plasma treat only a subsection of the membrane, a mask layer and / or multiple layers of the membrane, each having different sensitivity to plasma treatment, may be used.

[0163] In embodiments, the method further comprises the step of plasma surface treating the sensor.

[0164] By plasma treating the sensor, it is ensured that the entirety of exposed parts of the membrane, including the entirety of the perforation(s), are configured to have the surface structure for the sensor to detect if a liquid with the desired characteristics is detected by the liquid sensor when the liquid sensor detects a liquid.

[0165] By plasma treating the entire sensor may yield a simpler fabrication process, as the sensor may be assembled prior to plasma treatment.

[0166] Detailed description of the drawings

[0167] In the following, specific examples according to aspects of the present disclosure will be explained in more detail with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms than depicted and described below, and should not be construed as limited to any examples set forth herein. Rather, any examples are provided so that the disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure.

[0168] The sensor disclosed herein is based on surface tension of liquids and how liquids interact with solids resulting in contact angles between the liquid and the solid. Capillary effects are present when liquids enter microchannels. By microchannels are meant channels of dimensions wherein capillary forces are the driving / dominating force. In the following, for simplicity, by a channel is meant a microchannel wherein capillary forces are the main driving forces. The words "channel" and "perforation" may be used interchangeably and are devoted to the same meaning. Relative dimensions may be highly exaggerated to highlight features of the sensor.

[0169] Fig. 1A illustrates how the capillary effect gives rise to the phenomenon that a first liquid 90 in a channel 97 having a contact angle with the material of the channel 97 of less than 90° will be pulled forward or upwards by surface tension. Thus, the liquid will travel through the channel 97 until other forces, such as the gravitational force, will contribute to balance and / or counteract the movement of the liquid. In Fig. 1B, the same channel 97 is shown with a second liquid 92 having a contact angle with the material of the channel 97 of above 90°. This drawing illustrates that the surface tension will push the liquid in the vertical channel / tube down and towards the end of the channel 97 that is in contact with the liquid. This illustrates that surface tension of a liquid can be used to either having a liquid being pulled through a channel (permeability) or the surface tension restricting the liquid to travel through the channel (impermeability).

[0170] Fig. 2A illustrates a top view of a membrane according to an embodiment of the invention. The sensor according to embodiments of this disclosure comprises the membrane 102 and a sensor surface 107 (see Fig. 2B). The membrane has at least one perforation 104 (illustrated by a black dot). A perforation 104 is a through-going opening through the membrane 102 that provides access from a first surface of the membrane and to a second opposite surface of the membrane. The membrane may have a width and / or length (e.g., a diameter) between 0.5 cm and 50 cm, such as between 0.5 cm and 10 cm. The thickness of the membrane may be between 20 pm and 1000 pm.

[0171] The first surface of the membrane 102 is arranged to face the sensor surface 107 such that when liquid penetrates / permeate through the membrane 102 it can be detected at the sensor surface 107.

[0172] Fig. 2B illustrates a top view of a sensor surface 107 according to an embodiment of the invention. The sensor surface 107 is the surface of a liquid sensor 105 of a sensor 100 (see Fig. 2C), such that the sensor 100 is capable of sensing whether a liquid is present at the sensor surface 107.

[0173] Fig. 2C illustrates a cross-sectional view of the sensor 100 according to an embodiment of the invention. The sensor 100 comprises the membrane 102 arranged on top of the sensor surface 107, thereby providing a barrier between the sensor surface 107 and the surroundings. The perforations 104 in the membrane 102 include at least a subsection 106 where the surface structure 112 is configured such that the contact angle between a first liquid and the surface of the subsection 106 of the channel is less than 90°, and such that the contact angle between a second liquid and the surface of the subsection 106 of the channel is greater than or equal to 90°. Thus, to detect a liquid using this sensor 100, the liquid must have a contact angle less than 90° with the entire surface of the channel in order for the liquid to advance / permeate all the way through the perforation 104 of the membrane 102 and contact the sensor surface 107 and be detected.

[0174] The entire surface of the channel / perforation may be configured to have a specific surface structure 112. The illustration of the sensor 100 shows three perforations 104, but it is appreciated that there may be more or less, depending on the desired use of the sensor 100.

[0175] The membrane 102 may be made of / in a polymeric material including, but not limited to, polyurethane, PDMS, polypropylene, polyethylene. The surface structure 112 of the material can be modified either mechanically or chemically. This modification may change the surface roughness or the atoms or molecules binding to the surface of a material.

[0176] Another method for modifying the surface structure 112 of a material is by using plasma treatment. By plasma treatment, the surface structure 112 may be modified to have a desired contact angle as discussed herein.

[0177] Fig. 3A illustrates a cross-sectional view of a sensor 100 comprising a membrane 102 and a spacer element 108 according to an embodiment of the invention. The sensor 100 includes a membrane 102, a liquid sensor 105 with a sensor surface 107, and a sensor interface 101 exposed to the surroundings. The sensor, such as the membrane, comprises a polymeric film 114 treated by a plasma, the plasma treatment forming the surface structure 112.

[0178] The membrane 102 may comprise multiple layers in order to change the properties of the membrane 102. As illustrated in Fig. 3A, the membrane 102 may comprise the polymeric layer 114 with the modified surface structure 112 and a spacer element 108 or layer. Examples of properties obtained by adding the spacer element 108 include to provide the membrane 102 with more or less flexibility or to strengthen the membrane 102. The spacer element 108 may also be a material that binds well to both the sensor surface 107 and the rest of the membrane 102, such as to the polymeric film 114. The spacer element 108 may be a porous layer where liquids can penetrate the layer, but solid material cannot. The spacer element 108 may be permeable to all liquids, and thus not provide the aforementioned selectivity, which may be governed by the polymeric film 114 of the membrane 102. Fig. 3B illustrates a cross-sectional side view of a sensor 100 comprising a membrane 102 with two different surface structures in two different subsections of the channels according to an embodiment of the invention. In the embodiment, the membrane 102 comprises multiple polymeric films 114, 116 and the surface of the channels in these films may exhibit different properties, such that the contact angle is different between a liquid and the first polymeric film 114 and between the liquid and the second polymeric film 116. Thus, the surface of the second polymeric film 116 has a second surface structure 113 different from the first surface structure 112 of the first polymeric film 114.

[0179] Fig. 3C illustrates a cross-sectional side view of a sensor 100 comprising a membrane 102 with two layers and a permeable layer on top of the membrane according to an embodiment of the invention. The membrane 102 comprises one or more liquid permeable elements 118 or layers on top of the polymeric film 114 and the spacer element 108 of the membrane. In embodiments, the spacer element 108 may be omitted. The liquid permeable element 118 is porous such that the element is impermeable to solid particles and permeable to (all) liquids. By having a porous layer allowing liquids to penetrate, the risk of channels in the membrane 102 being blocked by solid particles is reduced. Here, the aforementioned selectivity of the liquids is governed by the properties of, at least, the polymeric film 114 of the membrane.

[0180] The sensor 100 may have different thicknesses depending on the layers and / or elements of the sensor 100 as described in the present embodiments.

[0181] Figs. 4A-4D illustrate top views of the sensor 100, thus illustrating the exposed surface of the membrane 102. The exposed surface of the membrane 102 is also denoted the interface of the sensor 100, i.e., the sensor interface. Fig. 4A illustrates a perforated circular membrane with evenly distributed perforations 104. Fig. 4B illustrates a perforated membrane shaped as a rectangle, the perforation pattern being a square lattice. Fig. 4C illustrates a perforated membrane shaped as an annulus, the perforation pattern being a hexagonal lattice. The circular membrane (and sensor) has a central circular opening, the central opening, e.g., being configured to receive a (potentially) liquid emanating container or a stoma. The sensor comprises evenly distributed perforations 104. Fig. 4D illustrates a perforated membrane shaped as a rectangle with an opening in the centre, the perforation pattern being a square lattice. The membrane comprises evenly distributed perforations 104 in a square lattice.

[0182] Fig. 5A and Fig. 5B illustrate exemplary sensor surfaces comprising electrodes for a liquid sensor according to embodiments of the invention.

[0183] The liquid sensor comprising the sensor surface 107 may be an optical or electronic sensor. For an electronic sensor, the liquid sensor may comprise one or more electrodes 110 distributed on and / or forming the sensor surface 107. A sensor 100 with one or more electrodes 110 may work by measuring a short circuit between two electrodes of the one or more electrodes 110, as liquid that penetrates the membrane 102 in multiple perforations 104 (see Figs. 4A-4D) may contact two electrodes 110 and thus make a short circuit. The electrodes 110 may be arranged such that they are able to make a short circuit when areas of the membrane 102 is covered by a liquid that the membrane 102 is permeable to. In another example, the electrode 110 may change properties when wetted by a liquid. For example, the electrode may be soluble in the liquid and thus, the resistance of the electrode 110 may increase as the electrode 110 is dissolved.

[0184] The size and shape of the electrodes 110 may be designed for the purpose of the sensor 100. Fig. 6A illustrates a liquid droplet 90 of a first liquid placed on a sensor 100 according to an embodiment of the invention. The liquid surface 96 has a contact angle lower than 90° to the surface of the entirety of the membrane 102. The contact angle affects the shape of the droplet. Liquids with a contact angle lower than 90° are somewhat wetting the surface of a solid. According to theory presented herein, liquids with a contact angle lower than 90° will enter, via the opening(s) 103, and move through the perforations 104. Thereby, the liquid will fill up the channels of the membrane 102. Some of the channels may terminate at a sensor surface, here in the form of electrodes 110. Thereby, the liquid contacts these electrodes 110. Other channels may terminate at an insulating material 109. If the liquid covers perforations 104 covering two or more electrodes 110, the liquid will act as a conductor and connect / form a bridge between the electrodes 110 and thus make a short circuit. This can be measured electronically and sent to a processor. In this way, the detection of the liquid can be processed, and the processor may generate a signal indicative of the presence of liquid. The signal may be sent to a device, such as a personal device, such that a user of the sensor is alerted of the presence of liquid. Fig. 6B illustrates the situation where a second liquid with a contact angle greater than 90° between the liquid and the membrane surface. Here, a liquid droplet 92 of the second liquid is illustrated on top of the membrane 102 and the sensor 100. As the contact angle is greater than 90°, the membrane 102 is impermeable for the liquid and the liquid will thus not enter the channels in the membrane 102. This will result in that no liquid will contact the sensor surface 107, and the sensor surface 107 will not detect any liquid. Not to detect a liquid is useful when multiple liquids may be present, but where it is only important to have information if one of the liquids is present at the sensor interface 101.

[0185] Fig. 7A illustrates a top view of an exemplary ostomy appliance 500 incorporating a sensor according to embodiments disclosed herein. The ostomy appliance includes an adhesive layer 501 with a proximal side configured for attachment to the skin surface of a user. The ostomy appliance 500 includes a plurality of electrodes including a first electrode 511 and a second electrode 512 arranged circularly about a stomal opening 503 configured to receive a stoma. The electrodes 511,512 may be configured to detect moisture absorbed by the adhesive layer 501 of the ostomy appliance and / or presence of liquid in an interface between the skin surface of a user and the adhesive layer. The first and second electrodes 511,512 terminate in a monitor interface 513 configured for coupling a monitor device comprising one or more processors to the plurality of electrodes, such as to detect a short-circuit between the first and second electrodes. The ostomy appliance 500 may be a base plate for an ostomy appliance, the base plate further comprising coupling means for attachment of an ostomy bag or an ostomy bag attached to the base plate. The ostomy appliance 500 may be a sensor patch for attachment to the adhesive (proximal) side of a base plate.

[0186] The ostomy appliance may comprise a membrane arranged between the adhesive layer 501 and the plurality of electrodes 511,512, the membrane having a first surface facing the plurality of electrodes 511,512 and a second opposite surface facing the adhesive layer 501, wherein the membrane comprises at least one perforation being a channel having an inner surface (see Fig. 7B), the channel providing access from the opposite surface of the membrane, through the membrane and to the plurality of electrodes. At least a subsection of the channel has a surface with a surface structure such that the contact angle between a first liquid having a first characteristic and the surface of the subsection of the channel is less than 90° and such that the contact angle between a second liquid having a second characteristic different from the first characteristic and the surface of the subsection of the channel is greater than 90°.

[0187] Fig. 7B illustrates an exemplary cross-sectional view of a part of the ostomy appliance 500 attached to a skin surface 599, the ostomy appliance incorporating a sensor according to embodiments of the invention. The ostomy appliance 500 comprises an adhesive layer 501 having a proximal side 501A facing the skin surface 599 and a distal opposite side 501B facing away from the skin surface 599. I he first electrode 511 and the second electrode 512 are arranged on the distal side 501B of the adhesive layer 501. The first and second electrodes may be configured to detect moisture in the adhesive layer 501 and / or presence of liquid in the interface between the adhesive layer 501 and the skin surface 599. A membrane 502 according to previous embodiments is arranged between the adhesive layer 501 and the first and second electrodes 511, 512.

[0188] Dimensions may be highly exaggerated to highlight the membrane and electrodes.

[0189] The sensor as previously discussed may be formed by the membrane 502 and the electrodes 511,512. The electrodes 511,512 may be shielded on their distal side (not shown), such as by means of a backing film / top layer. Thereby, the membrane 502 may allow for the determination of a first liquid (in particular being stomal output, as this is likely to enter the interface between the skin surface and the adhesive, and therefrom propagate through the adhesive layer, either via absorption or via openings in the adhesive layer aligned with the electrodes), as this will be permeable through the membrane by appropriate engineering of the contact angle of the membrane / perforations as previously discussed. Thereby, the stomal output may reach the electrodes and cause a signal indicative of the presence of liquid in the interface, it may then be derived that the liquid is stomal output. On the contrary, the membrane will hinder the detection of sweat (as the second liquid), which may be of a lower concern, as previously discussed.

[0190] The build illustrated in Fig. 7B may likewise be applicable to a wound dressing, where the electrodes may be arranged on a distal side of an adhesive and / or an absorbent core, and where the membrane is arranged between the electrodes and said adhesive and / or absorbent core, in such a situation, the membrane may be engineered such that it is permeable to blood, but not wound exudate, or vice versa. Alternatively, it may be permeable to wound exudate, but not sweat, or vice versa. Thus, in general, the membrane may be permeable to a first liquid expected in the region of a wound / wound bed, but impermeable to a second liquid expected in the region of a wound / wound bed, where the second liquid is of minor concern in terms of requiring action by the user / wearer.

[0191] Fig. 8 illustrates a method 1000 of manufacturing a sensor according to embodiments of the invention. The method comprises the steps of providing 1002 a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface, providing 1004 a membrane, and arranging 1006 a first surface of the membrane to face the sensor surface, such that channels of the membrane provide access from an opposite surface of the membrane to the sensor surface, to form the sensor.

[0192] A liquid sensor may comprise the sensor surface and thus, the sensor surface can be provided by providing a liquid sensor having a sensor surface. The membrane comprises a first surface and a second opposite surface, and at least one perforation being a channel having an inner surface, wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between a first liquid and the surface of the subsection of the channel is less than 90° and such that the contact angle between a second liquid and the surface of the subsection of the channel is greater than 90°.

[0193] Three optional steps may be comprised in the step of providing 1004 a membrane.

[0194] The first optional step may comprise providing 1004A a membrane precursor and form at least one perforation in the membrane precursor to form the membrane. The membrane precursor may be a polymeric film. In embodiments, forming at least one perforation may be done by lithography or using a laser.

[0195] The second optional step may comprise plasma treating 1004B at least the surface of a subsection of the channel / perforation to form the surface structure on the surface of the channel.

[0196] The third optional step may comprise plasma surface treating 1004C the sensor as a whole.

[0197] Thereby, the entirety of the exposed surface of the membrane in the sensor may be surface structured, including at least a subsection of the perforations / channels.

[0198] The three optional steps may be independent of each other, and the method 1000 may comprise one or more of the three optional steps.

[0199] Figs. 9A-9E illustrate the results from an experimental setup wherein the contact angle of water on a polyurethane (PU) film (Fig. 9A) is compared to liquid solutions (Figs. 9B-9E) comprising increasing concentrations of sodium dodecyl sulfate (SDS).

[0200] SDS is used here to simulate stomal output / feces. SDS is a chemical compound known to reduce the surface tension of a solution (see " A light scattering investigation of the sodium dodecyl sulfate-lysozyme system", Fig. 2, May 1996, The Journal of Chemical Physics 104(20):8112-8117). The surface tension of human feces may vary depending on the composition, hydration, and microbial activity of the stool. However, in general, it can be assumed that the surface tension of feces is lower than that of water, due to the presence of organic matter, electrolytes, and surfactants such as bile salts and phospholipids. These substances may act as wetting agents that reduce the cohesive forces between liquid molecules at the surface and increase the spreading of the liquid over a solid surface. Therefore, the contact angle of feces on a PU film may be expected to be lower than that of water on the same film, indicating a higher degree of wetting and adhesion. Accordingly, the use of SDS to simulate wetting properties of stomal output is considered appropriate. The contact angle may be measured by a drop shape analyzer, such as the DSA100E Drop Shape Analyzer by Kruss Scientific. For example, if the PU film has been corona treated prior to use, the measurement may be done according to ISO 15989.

[0201] Fig. 9A illustrates a drop of water on a PU film according to embodiments herein. The contact angle is measured to be 94.77° (average left / right measurement).

[0202] Figs. 9B-9E illustrate the measurement of the contact angle between the same PU film and a liquid solution comprising water and SDS at concentrations of 0.1 mM, 0.3 mM, 1 mM, and 3 mM, respectively. The measured corresponding contact angles are 81.75°, 78.35°, 65.28°, and 45.80°, respectively (average left / right measurement).

[0203] Accordingly, the experiment illustrates that increasing amounts of surfactants (here, SDS), as may be found in stomal output, reduce the contact angle considerably compared to water.

[0204] An experiment using the various solutions of water and SDS was conducted, wherein the size of the hydrostatic force needed to drive permeability through a membrane according to embodiments herein was determined. In particular, the experiment aims at supporting the theory presented previously in relation to the Df parameter:

[0205]

[0206] In particular, it was argued that the second term of Df may be neglected if zo is very small as may be assumed within scopes of the present invention, e.g., where the sensor operates in an environment where there is no contribution from a (hydrostatic) pressure. To support this assumption, the inventors covered a bottom end of a vertically arranged glass tube (20 mm diameter) with a membrane according to embodiments herein (i.e., a PU film with perforations having a diameter of 200 pm), filled the glass tube with a liquid solution of water and SDS (see table) until permeability was observed, and noted the height of the liquid column (represented by zo in the above second term of Df). The table below summarizes the findings:

[0207] Sample Height of column (mm)

[0208] Water 32

[0209] Water + 0.1 mM SDS 22

[0210] Water + 0.3 mM SDS 10

[0211] Water + 0.1 mM SDS < 5

[0212]

[0213] Water + 3 mM SDS < 1

[0214] The experiment shows that for increasing concentrations of SDS, the height of the column (and thus the hydrostatic force) needed to drive permeability through the membrane is reduced. As was argued earlier, the sensor as discussed herein may experience minimal to no hydrostatic pressure (e.g., due to its arrangement in an ostomy appliance attached to the skin), and this is indeed acceptable, as the experiment illustrates that this is indeed not relevant in order to observe permeability of liquids having higher amounts of surfactants compared to water (e.g., SDS or stomal output).

[0215] The use of the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. does not imply any particular order but are included to identify individual elements. Moreover, the use of the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. does not denote any order or importance, but rather the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. are used to distinguish one element from another. Note that the words "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. are used here and elsewhere for labelling purposes only and are not intended to denote any specific spatial or temporal ordering.

[0216] Furthermore, the labelling of a first element does not imply the presence of a second element and vice versa.

[0217] It may be appreciated that the figures comprise some modules or operations which are illustrated with a solid line and some modules or operations which are illustrated with a dashed line. The modules or operations which are comprised in a solid line are modules or operations which are comprised in the broadest example embodiment. The modules or operations which are comprised in a dashed line are example embodiments which may be comprised in, or a part of, or are further modules or operations which may be taken in addition to the modules or operations of the solid line example embodiments. It should be appreciated that these operations need not be performed in order presented. Furthermore, it should be appreciated that not all of the operations need to be performed. The exemplary operations may be performed in any order and in any combination. It is to be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed.

[0218] It is to be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements.

[0219] It should further be noted that any reference signs do not limit the scope of the claims, that the exemplary embodiments may be implemented at least in part by means of both hardware and software, and that several "means", "units" or "devices" may be represented by the same item of hardware. Although 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 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.

[0220] Exemplary embodiments are set out in the following first set of items. The set of items may be combined with items of other sets.

[0221] 1. A wound dressing comprising:

[0222] an absorbent core;

[0223] a plurality of electrodes arranged on a distal side of the adhesive layer (e.g., between the absorbent core and a top layer), the plurality of electrodes including a first electrode and a second electrode forming a sensor; and

[0224] a membrane arranged between the absorbent core and the plurality of electrodes, the membrane having a first surface facing the plurality of electrodes and a second opposite surface facing the absorbent core, wherein the membrane comprises at least one perforation being a channel having an inner surface, the channel providing access from the opposite surface of the membrane, through the membrane and to the plurality of electrodes;

[0225] wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between a first liquid having a first characteristic and the surface of the subsection of the channel is less than 90° and such that the contact angle between a second liquid having a second characteristic different from the first characteristic and the surface of the subsection of the channel is greater than 90°.

[0226] 2. The wound dressing according to item 1, wherein the membrane is perforated according to a first perforation pattern having a plurality of perforations including the at least one perforation.

[0227] 3. The wound dressing according to any of items 1-2, wherein the at least one perforation has a diameter between 200 μm and 500 μm.

[0228] 4. The wound dressing according to any of items 1-3, wherein the surface structure is formed by plasma surface treatment.

[0229] 5. The wound dressing according to any of items 1-4, wherein the membrane comprises a first polymeric film, and wherein the at least one perforation is formed in the first polymeric film.

[0230] 6. The wound dressing according to item 5, wherein the first polymeric film has a thickness between 20 μm and 1000 μm. 7. The wound dressing according to any of items 5-6, wherein the first polymeric film is a polyurethane film.

[0231] 8. The wound dressing according to any of items 5-7, wherein the membrane comprises a plurality of polymeric films including the first polymeric film and a second polymeric film. 9. The wound dressing according to any of items 1-8, wherein a permeable spacer element is arranged between the plurality of electrodes and the membrane.

[0232] 10. The wound dressing according to any of items 1-9, wherein the wound dressing comprises an adhesive layer configured to adhere the wound dressing to the skin surface of a user.

[0233] Exemplary embodiments are set out in the following second set of items. The set of items may be combined with items of other sets.

[0234] 1. A sensor for determining the presence of a first liquid having a first characteristic when the sensor is exposed to multiple liquids comprising both the first liquid and at least a second liquid having a second characteristic different from the first characteristic, the sensor comprising:

[0235] a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface; and

[0236] a membrane covering the sensor surface, the membrane having a first surface facing the sensor surface and a second opposite surface, wherein the membrane comprises at least one perforation being a channel having an inner surface, the channel providing access from the opposite surface of the membrane, through the membrane and to the sensor surface;

[0237] wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between the first liquid and the surface of the subsection of the channel is less than 90° and such that the contact angle between the second liquid and the surface of the subsection of the channel is greater than 90°.

[0238] 2. The sensor according to item 1, wherein the membrane is perforated according to a first perforation pattern having a plurality of perforations including the at least one perforation.

[0239] 3. The sensor according to any of items 1-2, wherein the at least one perforation has a diameter between 200 μm and 500 μm.

[0240] 4. The sensor according to any of items 1-3, wherein the surface structure is formed by plasma surface treatment.

[0241] 5. The sensor according to any of items 1-4, wherein the membrane comprises a first polymeric film, and wherein the at least one perforation is formed in the first polymeric film. 6. The sensor according to item 5, wherein the first polymeric film has a thickness between 20 μm and 1000 μm.

[0242] 7. The sensor according to any of items 5-6, wherein the first polymeric film is a polyurethane film.

[0243] 8. The sensor according to any of items 5-7, wherein the membrane comprises a plurality of polymeric films including the first polymeric film and a second polymeric film.

[0244] 9. The sensor according to any of items 1-8, wherein the sensor comprises a liquid sensor arranged such that the surface of the liquid sensor is the sensor surface.

[0245] 10. The sensor according to any of items 1-9, wherein the sensor comprises a permeable spacer element arranged between the sensor surface and the membrane.

[0246] 11. The sensor according to any of items 01-10, wherein the sensor comprises at least a first electrode, and wherein the sensor surface forms part of the first electrode.

[0247] 12. The sensor according to any of items 1-11, wherein the sensor comprises a first electrode and a second electrode, and wherein the sensor surface is formed by parts of the first electrode and parts of the second electrode.

[0248] 13. The sensor according to item 120, wherein the sensor is adapted to sense the presence of a liquid by means of a short-circuiting event between the first electrode and the second electrode.

[0249] 14. A sensing system comprising a sensor according to any of items 1-13 and an electronic device couplable to the sensor, the electronic device comprising:

[0250] - a processor; and

[0251] - a first interface connected to the processor and the sensor;

[0252] wherein the first interface is configured to collect sensor data from the sensor, and wherein the processor is configured to sense the presence of a liquid in contact with the sensor surface based on the sensor data.

[0253] 15. The sensing system according to item 14 further comprising a medical appliance, wherein the sensor is embedded in the medical appliance.

[0254] 16. The sensing system according to item 15, wherein the medical appliance is an ostomy appliance.

[0255] 17. The sensing system according to item 16, wherein the signal indicative of the presence of liquid is indicative of the presence of stomal output.

[0256] 18. The sensing system according to item 15, wherein the medical appliance is a wound

[0257] dressing. Exemplary embodiments are set out in the following third set of items. The set of items may be combined with items of other sets.

[0258] 1. A method of manufacturing a sensor for determining the presence of a first liquid having a first characteristic when the detector sensor is exposed to multiple liquids comprising both the first liquid and at least a second liquid having a second characteristic different from the first characteristic; the method comprising the steps of:

[0259] providing a sensor surface adapted to sense the presence of a liquid in contact with the sensor surface; and

[0260] providing a membrane having a first surface and a second opposite surface, the membrane comprising at least one perforation being a channel having an inner surface, wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between the first liquid and the surface of the subsection of the channel is less than 90° and such that the contact angle between the second liquid and the surface of the subsection of the channel is greater than 90°;

[0261] arranging the first surface of the membrane to face the sensor surface, such that the channel provides access from the opposite surface of the membrane to the sensor surface, to form the sensor.

[0262] 2. The method according to item 19, wherein the step of providing a membrane having a first surface and a second opposite surface, comprises the steps of:

[0263] providing a membrane precursor; and

[0264] forming the at least one perforation in the membrane precursor to form the membrane.

[0265] 3. The method according to any of items 19-20, wherein the step of providing a membrane having a first surface and a second opposite surface comprises the step of:

[0266] plasma surface treating at least the surface of the subsection of the channel to form the surface structure.

[0267] 4. The method according to any of items 19-21, wherein the method further comprises the step of plasma surface treating the sensor.

[0268] List of references:

[0269] 90 first liquid

[0270] 92 second liquid

[0271] 93 blood

[0272] 95 liquid container

[0273] 96 liquid surface

[0274] 97 micro channel 98 skin

[0275] 99 wound

[0276] 100 sensor

[0277] 101 sensor interface

[0278] 102 membrane

[0279] 103 opening of perforation

[0280] 104 perforation

[0281] 105 liquid sensor

[0282] 106 subsection of perforation

[0283] 107 sensor surface

[0284] 108 spacer element

[0285] 109 insulating material

[0286] 110 electrode

[0287] 112 surface structure with configured properties

[0288] 113 Second surface structure

[0289] 114 first polymeric film

[0290] 116 second polymeric film

[0291] 118 permeable layer

[0292] 120 wound dressing

[0293] 121 wound dressing container space

[0294] 122 sticky layer

[0295] 124 surface of an object

[0296] 126 hole in the surface of an object

[0297] 128 space between the sensor and the surface of an object 500 ostomy appliance

[0298] 501 adhesive layer

[0299] 501A proximal side of adhesive layer

[0300] 501 B distal side of adhesive layer

[0301] 502 membrane

[0302] 503 stomal opening

[0303] 511 first electrode

[0304] 512 second electrode

[0305] 513 monitor interface

[0306] 599 skin surface

[0307] 1000 method for fabricating a sensor

[0308] 1002 providing a sensor surface 1004 providing a membrane

[0309] 1004A providing a membrane precursor and form the at least one perforation in the membrane precursor to form the membrane

[0310] 1004B plasma treating at least a subsection of the channel

[0311] 1004C plasma treating the sensor

[0312] 1006 arranging a first surface of the membrane to face the sensor surface

Claims

Claims1. An ostomy appliance comprising:an adhesive layer with a proximal side configured for attachment to the skin surface of a user;a plurality of electrodes arranged on a distal side of the adhesive layer, the plurality of electrodes including a first electrode and a second electrode forming a sensor; and a membrane arranged between the adhesive layer and the plurality of electrodes, the membrane having a first surface facing the plurality of electrodes and a second opposite surface facing the adhesive layer, wherein the membrane comprises at least one perforation being a channel having an inner surface, the channel providing access from the opposite surface of the membrane, through the membrane and to the plurality of electrodes;wherein at least a subsection of the channel has a surface with a surface structure such that the contact angle between a first liquid having a first characteristic and the surface of the subsection of the channel is less than 90° and such that the contact angle between a second liquid having a second characteristic different from the first characteristic and the surface of the subsection of the channel is greater than 90°.

2. The ostomy appliance according to claim 1, wherein the membrane is perforated according to a first perforation pattern having a plurality of perforations including the at least one perforation.

3. The ostomy appliance according to any of claims 1-2, wherein the at least one perforation has a diameter between 200 μm and 500 μm.

4. The ostomy appliance according to any of claims 1-3, wherein the surface structure is formed by plasma surface treatment.

5. The ostomy appliance according to any of claims 1-4, wherein the membrane comprises a first polymeric film, and wherein the at least one perforation is formed in the first polymeric film.

6. The ostomy appliance according to claim 5, wherein the first polymeric film has a thickness between 20 μm and 1000 μm.

7. The ostomy appliance according to any of claims 5-6, wherein the first polymeric film is a polyurethane film.

8. The ostomy appliance according to any of claims 5-7, wherein the membrane comprises a plurality of polymeric films including the first polymeric film and a second polymeric film.

9. The ostomy appliance according to any of claims 1-8, wherein a permeable spacer element is arranged between the plurality of electrodes and the membrane.

10. The ostomy appliance according to any of claims 1-9, wherein the ostomy appliance is a base plate.

11. The ostomy appliance according to any of claims 1-9, wherein the ostomy appliance is a sensor patch for attachment to a proximal surface of a base plate.

12. The ostomy appliance according to any of claims 1-11, wherein the first liquid is stomal output, and wherein the second liquid is sweat.

13. The ostomy appliance according to any of claims 1-12, wherein the first adhesive layer comprises at least one opening extending entirely through the adhesive layer, and wherein the at least one opening is aligned with the at least one perforation of the membrane.

14. An ostomy system comprising an electronic device and an ostomy appliance according to any of claims 1-13, wherein the electronic device comprises a processor and a first interface connected to the processor and the sensor of the ostomy appliance; wherein the first interface is configured to collect sensor data from the sensor, and wherein the processor is configured to sense the presence of a liquid in contact with the sensor surface based on the sensor data.

15. The ostomy system according to claim 14, wherein, in accordance with sensing the presence of a liquid, the processor is configured to transmit a signal indicative of the presence of stomal output.

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