Patent Publication Number: US-2023160771-A1

Title: Ostomy leakage detection system

Description:
BACKGROUND 
     The following description relates generally to a leakage detection system for medical devices, and more particularly to leakage detection system for ostomy appliances. 
     An ostomy pouch system typically includes a pouch formed from opposing walls defining an internal collection area, an inlet opening for receiving a stoma, and an ostomy appliance for attaching the pouch to a user. The ostomy appliance may include, for example, an ostomy barrier of a one-piece pouch system, which is attached to a body-side pouch wall proximate an inlet opening, a baseplate for a two-piece pouch system configured to releasably engage a pouch, and a barrier ring. The ostomy appliance may include a skin barrier material for adhering to and sealing against user&#39;s peristomal skin surrounding the stoma. 
     The ostomy appliance may be susceptible to ostomy effluent leakage, and the seal formed between the skin barrier material and the user may weaken. Often times, the user may be unaware of or cannot easily assess an extent of weakening in the seal. Thus, the user may not become aware of a weakened seal, and consequently, the ostomy effluent may leak through to an exterior of the ostomy appliance. 
     Accordingly, it is desirable to provide a leakage detection system for ostomy appliances. 
     BRIEF SUMMARY 
     In one aspect, a sensing accessory for detecting leakage in a medical device is provided. The sensing accessory may include a sensor region, a connector region, and an elongated tail region extending therebetween. The sensor region may comprise a center opening and a plurality of sensors arranged around the center opening. The plurality of sensors may include at least two substantially elliptical conductive traces substantially surrounding the center opening and at least two arc-shaped conductive traces. The at least two substantially elliptical conductive traces may include a first trace and a second trace, and the at least two arc-shaped conductive traces may include a first arc trace and a second arc trace. Each of the two substantially elliptical conductive traces may be arranged at a different radial distance from the center opening, and each of the at least two arc-shaped conductive traces may be arranged in a different sector in the sensor region. The connector region may include a plurality of connection points provided at terminal ends of the plurality of sensors for electrical connection to an external device. 
     In an embodiment, the first trace may be arranged at a first radial distance from the center opening, the second trace may be arranged at a second radial distance from the center opening, the first arc trace may be arranged at a third radial distance from the center opening, and the second arc trace may be arranged at a fourth radial distance from the center opening, wherein the third and fourth radial distances are greater than the second radial distance and the second radial distance is greater than the first radial distance. In such an embodiment, the first trace, the second trace, and the first and second arc traces may be arranged in three substantially concentric layers substantially surrounding the center opening. The sensing accessory may be configured to measure a resistance of the medical device between the first trace and the second trace and between the second trace and each of the at least two arc-shaped conductive traces. 
     In an embodiment, the first trace may be a first level trace and the second trace may be a first ground trace, and the at least two substantially elliptical conductive traces may further include a second level trace, a fourth level trace, a fifth level trace, a second ground trace, and a third ground trace, and the at least two arc-shaped conductive traces may further include a third arc trace and a fourth arc trace. The first level trace may be arranged at a first radial distance from the center opening, the first ground trace may be arranged at a second radial distance from the center opening, a second level trace may be arranged at a third radial distance from the center opening, the second ground trace may be arranged at a fifth radial distance from the center opening, the fourth level trace may be arranged at a sixth radial distance from the center opening, the fifth level trace may be arranged at a seventh radial distance from the center opening, the third ground trace may be arranged at an eighth radial distance from the center opening, and the first, second, third, and fourth arc traces may be arranged at a fourth radial distance from the center opening, wherein a radial distance may increase from the first radial distance to the eighth radial distance, wherein first radial distance&lt;second radial distance&lt;third radial distance&lt;fourth radial distance&lt;fifth radial distance&lt;sixth radial distance&lt;seventh radial distance&lt;eighth radial distance. In such an embodiment, the level traces, the ground traces, and the arc traces may be arranged in eight substantially concentric layers substantially surrounding the center opening. The sensing accessory may be configured to measure a resistance of the medical device between the first level trace and the first ground trace, between the first ground trace and the second level trace, between each of the first, second, third, and fourth arc traces and the second ground trace, between the second ground trace and the fourth level trace, and between the fifth level trace and the third ground trace. 
     Each of the first, second, third, and fourth arc traces may be arranged in a different quadrant in the sensor region. For example, the first, second, third, and fourth arc traces may be arranged in intercardinal directions of the sensor region with the tail region being arranged at south. In such an embodiment, the first arc trace may extend along a southeast (SE) quadrant of the sensor region. The second arc trace may be formed from an exposed portion of a curved conductive trace extending along an east half of the sensor region, wherein a lower portion of the curved conductive trace may be covered with a masking layer to provide the second arc trace extending along a northeast (NE) quadrant of the sensor region. The third arc trace may be formed from an exposed portion of a curved conductive trace extending along an west half of the sensor region, wherein a lower portion of the curved conductive trace may be covered with a masking layer to provide the third arc trace extending along a northwest (NW) quadrant of the sensor region. The fourth arc trace may extend along a southwest (SW) quadrant of the sensor region. 
     In such an embodiment, the sensing accessory may be configured to measure a resistance of the medical device between the first level trace and the first ground trace for determination of a level 1 leakage, a resistance between the first ground trace and the second level trace for determination of a level 2 leakage, a resistance between the first arc trace and the second ground trace for determination of a level 3 leakage in the SE quadrant, a resistance between the second arc trace and the second ground trace for determination of a level 3 leakage in the NE quadrant, a resistance between the third arc trace and the second ground trace for determination of a level 3 leakage in the NW quadrant, a resistance between the fourth arc trace and the second ground trace for determination of a level 3 leakage in the SW quadrant, a resistance between the second ground trace and fourth level trace for determination of a level 4 leakage, and a resistance between the fifth level trace and the third ground trace for determination of a level 5 leakage. The severity of a leakage may increase from level 1 leakage to level 5 leakage, wherein level 1 leakage&lt;level 2 leakage&lt;level 3 leakage&lt;level 4 leakage&lt;level 5 leakage, wherein the level 5 leakage may be a critical leakage. 
     In another embodiment, the at least two substantially elliptical conductive traces may include first, second, third, and fourth traces, and the at least two arc-shaped conductive traces may include first, second, third and fourth arc traces. The first trace may be arranged at a first radial distance from the center opening, the second trace may be arranged at a second radial distance from the center opening, a third trace may be arranged at a fourth radial distance from the center opening, the fourth trace may be arranged at a fifth radial distance from the center opening, and the first, second, third, and fourth arc traces are arranged at a third radial distance from the center opening, wherein a radial distance may increase from the first radial distance to the fifth radial distance, wherein first radial distance&lt;second radial distance&lt;third radial distance&lt;fourth radial distance&lt;fifth radial distance. In such an embodiment, the first, second, third, and fourth traces, and the first, second, third, and fourth arc traces may be arranged in five substantially concentric layers substantially surrounding the center opening, wherein the first arc trace extends along a SE quadrant, the second arc trace extends along a NE quadrant, the third arc trace extends along a NW quadrant, and the fourth arc trace extends along a SW quadrant of the sensor region. 
     In such an embodiment, the sensing accessory may be configured to measure a resistance of the medical device between the first trace and the second trace for determination of a level 1 leakage, a resistance between the second trace and the first arc trace for determination of a level 2 leakage in the SE quadrant, a resistance between the second trace and the second arc trace for determination of a level 2 leakage in the NE quadrant, a resistance between the second trace and the third arc trace for determination of a level 2 leakage in the NW quadrant, a resistance between the second trace and the fourth arc trace for determination of a level 2 leakage in the SW quadrant, a resistance between the first arc trace and the third trace for determination of a level 3 leakage in the SE quadrant, a resistance between the second arc trace and the third trace for determination of a level 3 leakage in the NE quadrant, a resistance between the third arc trace and the third trace for determination of a level 3 leakage in the NW quadrant, a resistance between the fourth arc trace and the third trace for determination of a level 3 leakage in the SW quadrant, and a resistance between the third trace and fourth trace to determine a level 4 leakage. The severity of a leakage may increase from level 1 to level 4, wherein level 1 leakage&lt;level 2 leakage&lt;level 3 leakage&lt;level 4 leakage, wherein the level 4 leakage may be a critical leakage. 
     In any of the foregoing embodiments, the medical device may be an ostomy appliance including an adhesive layer configured for attachment to a peristomal skin of a user, wherein the plurality of sensors may be arranged adjacent the adhesive layer to measure a resistance of the adhesive layer. 
     In an embodiment, the sensor region may have a ring-like shape, and the center opening may be configured to receive a stoma. Each of the at least two substantially elliptical conductive traces and the at least two arc-shaped conductive traces may extend from the sensor region through the tail region to the connector region and terminate at the plurality of connection points. 
     The sensing accessory may include a sensor layer having a body-side and a distal side, an adhesive layer arranged on the body-side of the sensor layer, and a backing layer arranged on the distal side of the sensor layer. The sensor layer may include a substrate, wherein the plurality of sensors may be provided on a body-side of the substrate and in contact with the adhesive layer. The sensing accessory may be configured to measure a resistance of the adhesive layer using the plurality of sensors. 
     In an embodiment, the backing layer may be formed from an adhesive. In such an embodiment, the sensing accessory may include a body-side release liner covering the adhesive layer and a distal side release liner covering the backing layer. Each of the release liners may include a tab configured to facilitate removal of the release liners, wherein the tabs may be arranged offset from each other. In some embodiments, the release liners may include indicator labels to guide assembling of the sensing accessory with an ostomy appliance and attachment of the assembled sensing accessory and ostomy appliance to a user. 
     In an embodiment, exposed portions of the tail region of the sensor layer may be covered with a tail cover. The tail cover may also cover a portion of the connector region and include a wing-like extensions in the connector region, wherein an adhesive is provided on the wing-like extensions for attachment to an ostomy pouch or a user. 
     In an embodiment, the sensing accessory may be configured to attach to an ostomy barrier. In such an embodiment, the backing layer may be attached to the ostomy barrier, and the adhesive layer may be attached to a peristomal skin of a user. The adhesive layer may be formed from a hydrocolloid adhesive configured to exhibit a resistance drop from greater than 2 MΩ to about 1 kΩ when exposed to an ostomy effluent. 
     In an embodiment, the sensing accessory may be configured to stretch to conform to a convex ostomy barrier, wherein the substrate and the plurality of sensors may be formed from stretchable materials. 
     In another aspect, a leakage detection system for an ostomy appliance is provided. The leakage detection system may include the sensing accessory according to any of the foregoing embodiments and a wearable subsystem configured to communicate with the sensing accessory and receive signals from the sensing accessory to detect an ostomy effluent leakage. 
     In an embodiment, the wearable subsystem may include a hinged case comprising a bottom housing, a top housing, and a hinge connecting the bottom housing and the top housing. The hinged case may be configured to be closed after the wearable subsystem is connected to the connector region to secure the wearable subsystem to the sensing accessory. 
     In some embodiments, the sensing accessory may include a first alignment member and the wearable subsystem may include a second alignment member, which may be configured to engage with each other to facilitate correct alignment and connection between the sensing accessory and the wearable subsystem. The first alignment member may include at least one opening in the connector region of the sensing accessory, and the second alignment member may include at least one raised member, wherein the at least one raised member may be configured to be received in the at least one opening. 
     In an embodiment, the second alignment member may include a center raised key member and a peripheral raised member. The center raised key member may be provided generally in the center of the bottom housing and the peripheral raised member may be arranged proximate the hinge. The first alignment member may include a center key opening configured to receive the center raised key member and a peripheral opening configured to receive the peripheral raised member. The wearable subsystem may further include a plurality of conductive members configured to contact the plurality of connection points to electrically connect the wearable subsystem to the sensing accessory. The plurality of conductive members may be arranged proximate and surrounding the center raised key member. 
     In another embodiment, the second alignment member may include first and second raised members. The first alignment member may include a first opening configured to receive the first raised member and a second opening configured to receive the second raised member. In such an embodiment, the wearable subsystem may also include a plurality of conductive members arranged between the first and second raised member for electrically connecting the wearable subsystem to the sensing accessory. 
     In an embodiment, the leakage detection system may include a charging dock configured to connect to the wearable subsystem to charge a rechargeable battery of the wearable subsystem. The charging dock may also be configured to wirelessly communicate with the wearable subsystem to receive leakage signals and send an alert to a user. 
     In an embodiment, the plurality of conductive members may comprise a plurality of raised conductive pads. 
     In any of the foregoing embodiments, the tail region may be flexible to allow the wearable subsystem to be attached to a user or to the ostomy appliance at various locations when the wearable subsystem is attached to the sensor accessory. 
     The wearable subsystem may be configured to analyze signals received from the sensing accessory, communicate with external devices, and alert a user to notify a leakage event and/or a status of the ostomy appliance, for example, via sound, vibration, and/or light. In an embodiment, the wearable subsystem may be configured to poll resistance measurements from the plurality of sensors to collect resistance data and process the resistance data through an algorithm to determine an ostomy effluent leakage event, and alert a user according the severity of the leakage event. The wearable subsystem may also be configured to detect and communicate a connectivity status between the wearable subsystem and the sensing accessory and a faulty sensor to a user or to an external device. 
     In some embodiments, the wearable subsystem may include a rechargeable battery. In such embodiments, the leakage detection system may further include a charging dock for charging the rechargeable battery of the wearable subsystem. The charging dock may also be configured to wirelessly communicate with the wearable subsystem to receive leakage signals and send an alert to a user. 
     In an embodiment, the charging dock may comprise a housing configured to receive the wearable subsystem and charging pins. The wearable subsystem may include conductive pads configured to electrically connect to the charging pins. The charging dock may also include a device for generating a sound and/or light to alert a user and a wireless communication module for communicating with the wearable subsystem and/or a mobile application. 
     In an embodiment, the leakage detection system may also include a mobile application configured to wirelessly communicate with the wearable subsystem and/or the charging dock. The mobile application may be provided as an application for a mobile phone. In such an embodiment, the wearable subsystem may be configured to transmit data to the mobile application. The transmitted data may include raw resistance measurements as received from the sensing accessory and/or processed data generated by processing the resistance measurements at the wearable subsystem. The processed data may include a leakage event information and/or a summary of the resistance measurements. 
     The mobile application may be configured to provide means for a user to interact with the leakage detection system to set user&#39;s preferences for alerts and to review information about the ostomy appliance. The information may include leakage patterns, historical data of user&#39;s ostomy appliance usage, and/or ostomy appliance usage trends. The mobile application may also be configured to connect a user to ostomy training materials, experts at ostomy appliance suppliers, and/or ostomy clinicians. Further, the mobile application may be configured to check a connectivity between the mobile application and the wearable subsystem and/or a connectivity between the mobile application and the charging dock and alert a user. 
     In an embodiment, the mobile application may be configured to receive a leakage event information from the wearable subsystem and alert a user through alert functions of a mobile phone. Further, the mobile application may be configured to transmit data to a cloud server for storage and analysis to provide a prediction of a leakage event based on user&#39;s historical data, comparison data against leakage patterns of other users, product recommendations based on user&#39;s leakage patterns, and/or a prompt for re-ordering ostomy products. The mobile application may also be configured to manage a storage of photographs of user&#39;s stoma and/or peristomal skin for tracking with user&#39;s leakage patterns. 
     Other aspects, objectives and advantages will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The benefits and advantages of the present embodiments will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
         FIG.  1    is a perspective illustration of an ostomy pouch appliance and a leakage detection system according to an embodiment; 
         FIG.  2    is a schematic illustration of an ostomy pouch appliance including leakage detection sensors according to an embodiment; 
         FIG.  3    is a graph of resistance measured by a sensing accessory according to an embodiment; 
         FIG.  4    is a schematic illustration of leakage sensors comprising a plurality of conductive traces according to an embodiment; 
         FIGS.  5 A- 5 C  are schematic illustrations of leakage sensors comprising a plurality of conductive traces, wherein some portions of the conductive traces are masked, according an embodiment; 
         FIG.  6    is a perspective illustration of a sensing accessory engaged with a wearable subsystem according to an embodiment; 
         FIG.  7    is an exploded view of a sensing accessory according to an embodiment; 
         FIG.  8    is a perspective illustration of a sensing accessory according an embodiment; 
         FIG.  9    is an exploded view of the sensing accessory of  FIG.  8   ; 
         FIG.  10    is a schematic illustration of leakage sensors comprising a plurality of conductive traces according to an embodiment; 
         FIG.  11    is a schematic illustration of leakage sensors comprising a plurality of conductive traces according to another embodiment; 
         FIG.  12    is a perspective illustration of a wearable subsystem according to an embodiment; 
         FIG.  13    is a perspective illustration of the wearable subsystem of  FIG.  12    connected to a sensor accessory according to an embodiment; 
         FIG.  14    is an exploded view of a wearable subsystem according to an embodiment; 
         FIG.  15    is a perspective illustration of a wearable subsystem and a sensor accessory attached to an ostomy pouch appliance according to an embodiment; 
         FIG.  16    is a perspective illustration of a wearable subsystem according to an embodiment; 
         FIG.  17    is a perspective illustration of the wearable subsystem of  FIG.  16    and a connector region of a sensing accessory configured to engage the wearable subsystem according to an embodiment; 
         FIG.  18    is a perspective illustration of the wearable subsystem and the sensing accessory of  FIG.  17    and an adhesive pad for attaching the wearable subsystem to a user or an ostomy pouch appliance according to an embodiment; 
         FIG.  19    is an illustration of a wearable subsystem attached to a body-side of an ostomy pouch appliance according to an embodiment; 
         FIG.  20    is an illustration of a wearable subsystem attached to a distal-side of an ostomy pouch appliance according an embodiment; 
         FIG.  21    is an illustration of a wearable subsystem attached to a user according to an embodiment; 
         FIG.  22    is a schematic illustration of a sensing accessory attached to an ostomy skin barrier and fitted around a stoma according to an embodiment; 
         FIGS.  23 A- 24 D  are illustrations of a charging dock according to an embodiment; 
         FIG.  24    is a block diagram for a method of detecting an ostomy effluent according to an embodiment; and 
         FIG.  25    is a diagram showing communication between subsystems of an ostomy leakage detection system according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     While the present disclosure is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described presently preferred embodiments with the understanding that the present disclosure is to be considered an exemplification and is not intended to limit the disclosure to the specific embodiments illustrated. The words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
     An ostomy leakage detection system may be configured to detect ostomy effluent leakage under a skin barrier and alert a user. The ostomy leakage detection system can provide multiple benefits to the user. For example, the system may allow the user to intervene and change a skin barrier and/or ostomy pouch system before a leak progresses to cause embarrassment and inconvenience to the user. Further, the ostomy leakage detection system can assist in maintaining user&#39;s skin health by alerting a leakage in its early stage to prevent a prolonged skin exposure to ostomy effluent, which can lead to skin health complications. The ostomy leakage detection system can also support user&#39;s emotional well-being by reducing anxiety associated with a risk of leakage. 
     In an embodiment, the ostomy leakage detection system may comprise four subsystems—a sensing accessory, a wearable subsystem, a mobile application, and a charging dock. The sensing accessory may be provided as an accessory for an ostomy pouch system. The sensing accessory may include sensors for detecting the presence of ostomy effluent. The sensing accessory may be configured to communicates leakage detection signals to the wearable subsystem. The wearable subsystem may be configured to perform at least some processing of the leakage detection signals and alert a user of a leakage event. The wearable subsystem may be configured to communicate wirelessly with the mobile application. The mobile application may be a digital subsystem housed on a mobile device. The mobile application may be configured to process leak detection data and provide an alert or other information about an ostomy appliance to a user. The charging dock may be configured to recharge and communicate with the wearable subsystem and send out an alert, for example, when the system is in use at night. 
       FIG.  1    shows an ostomy leakage detection system  10  according to an embodiment. The ostomy leakage detection system  10  may generally comprise a sensing accessory  12 , a wearable subsystem  14 , a charging dock  16 , and a mobile application (not shown). The sensing accessory  12  may be configured as an ostomy accessory that can be attached to an ostomy skin barrier, for example, an ostomy barrier of a one-piece pouch system or a faceplate for a two-piece pouch system. A one-piece ostomy pouch system  18  comprising an ostomy barrier  20  according to an embodiment is shown in  FIG.  1   . 
     Sensing Accessory 
     The sensing accessory may be configured to detect an ostomy effluent leakage by providing sensors at a site of leakage under an ostomy barrier. The sensing accessory may comprise a plurality of sensors configured to detect the presence of fluid. The plurality of sensors may include conductivity sensors, thermistors, or other sensors. In an embodiment, the sensing accessory may comprise a plurality of conductivity sensors formed from conductive traces arranged in close proximity. The conductive traces are also referred to herein as electrodes. When fluid bridges the conductive traces or saturates an adjacent hydrocolloid adhesive, a change in conductivity may be measured, which may be used to determine an ostomy effluent leakage. The sensors may be disposed on a circuit substrate. The circuit substrate may be configured to provide a suitable mechanical support to preserve the conductivity of the traces. 
     The conductive traces may be formed by printing a circuit substrate using a conductive ink via a conventional printing process, for example, screen printing. The conductive ink may comprise carbon black, graphite, silver (Ag), or a silver and silver chloride blend (Ag/AgCl). Each of the plurality of conductive traces may have a width and arranged spaced apart from each other. The parameters of the conductive traces may be configured to provide a particular resistance of a sensor circuit. 
     In an embodiment, the sensing accessory may be configured to detect a leakage based on a change in resistance across a pair of conductive traces making up a sensor.  FIG.  2    is a schematic cross-sectional illustration of two pairs of conductive traces configured to measure resistance of a skin barrier adhesive, wherein R 1  is resistance between a first pair of conductive traces and R 2  is resistance between a second pair of conductive traces. In the embodiment of  FIG.  2   , the leakage detection system may be configured to determine a leakage event from a decrease in resistance R 2  between the second pair of conductive traces upon exposure to ostomy effluent. 
       FIG.  3    is a graph displaying resistance data collected from a sensing accessory comprising a plurality of sensors according to an embodiment, wherein a drop of resistance is recorded at multiple sensors as a leakage progresses outward and contacts different sensors. As shown, the resistance drops from a value exceeding a measurement range of a processor (&gt;2 MΩ) to very low (approximately 1 kΩ). In this embodiment, the resistance of the sensors may be negligible when compared to the large magnitude of a resistance change upon exposure to ostomy fluid. Thus, the sensors for the sensing accessory may be formed from conductive traces of various thicknesses and arrangements as long as the resistance of the conductive trace is low relative to the baseline (dry) resistance between the conductive traces. 
     In an embodiment, the sensing accessory  12  may include a plurality of conductive traces as shown in  FIG.  4    and  FIG.  5 A- 5 C . Each of the conductive traces may be configured to have a width of about 0.002 inches and arranged spaced apart from each other with a gap of about 0.002 inches. In other embodiments, the conductive traces may be configured wider or narrower and arranged in various configurations. In an embodiment, the gap between the conductive traces may be about 0.01 inches. In an embodiment, a plurality of radially spaced layers of conductive traces may be configured and arranged to fit within a space defined by an ostomy pouch system barrier. 
     The sensing accessory  12  may comprise a plurality of sensors formed from a plurality of substantially elliptical conductive traces arranged around a center opening for receiving a stoma. “Substantially elliptical conductive traces” as used herein include conductive traces having various elliptical shapes, such as circular, oval, etc. Each of the plurality of sensors may be arranged at different radial distances from the center opening. Each sensor may cover a portion of the area surrounding the central opening. In the embodiment of  FIG.  4    and  FIGS.  5 A- 5 C , the sensors may be arranged in five layers at different radial distances. Four sensor layers are labeled L 1 , L 2 , L 3 , and L 4  as best shown in  FIGS.  5 A and  5 C . Each of the four layers L 1 , L 2 , L 3 , and L 4  may be configured to substantially surround the center opening, such that a leakage in any radial direction may be detected. The plurality of sensors may also include three ground traces G 1 , G 2 , G 3 , wherein G 1  is arranged between L 1  and L 2 , G 2  is arranged between a fifth sensor and L 3 , and G 3  is arranged adjacent L 4  as best shown in  FIGS.  5 A and  5 C . In such an embodiment, the sensing accessory  12  may be configured to measure resistance between L 1  and G 1  (first level sensor), between L 2  and G 1  (second level sensor), between G 2  and L 3  (third level sensor), and between L 4  and G 3  (fourth level sensor). 
     In this embodiment, the fifth sensor layer may be arranged between L 2  and G 2  and may be subdivided into four quadrants SW, NW, NE, and SE, which corresponds to intercardinal directions with a tail of the sensing accessory  12  oriented at South as shown in  FIGS.  5 A and  5 C . The four quadrants may be evenly spaced at about 90 degrees, each quadrant covering about quarter of the area around the center opening. In this embodiment, a lower portion of NW sensor (LNW), a lower portion of NE sensor (LNE), and tail portions of the sensors and ground traces may be covered with a masking layer as best shown in  FIG.  5 B . In other embodiments, the fifth layer may comprise more than four or less than four subdivisions and/or unevenly divided subdivisions. The fifth sensor layer comprising subdivided sensor sections may be configured to detect a radial direction of a leakage according to a change in resistance measured at one or more of the subdivisions. The sensors arranged at different radial distances may be configured to track a progression of ostomy effluent leakage. By only subdividing some layers, the total number of sensors may be reduced while preserving the location-detection function. 
     In an embodiment, the conductive traces may be printed on a circuit substrate using a conductive ink. Suitable materials for the circuit substrate may include, but are not limited to polyester (PET), polyethylene (PE), polyurethane film (PU), or thermoplastic polyurethane (TPU) film. The circuit substrate may be configured to provide an excellent bonding surface for the conductive ink, prevent mechanical damage to the conductive ink, and adhere to hydrocolloid adhesive layer. In some embodiments, the circuit substrate and the conductive ink may be configured to provide at least some degree of elasticity to allow stretching of the sensing accessory  12 . In an embodiment, the sensing accessory  12  may comprise a PET circuit substrate having a thickness of about 0.001 inches to about 0.010 inches, preferably about 0.003 inches. 
     In some embodiments, the sensing accessory  12  may include masking layers covering some portions of the conductive traces. The masking layers may be formed from a film or a masking material. The masking layer may be configured to prevent bridging of the conductive traces by fluid in the covered portions. In an embodiment, a making layer may cover a tail region of the conductive traces. The making layer may extend into a portion of sensors and connector regions. In the embodiment of  FIGS.  5 A- 5 C , lower portions of the NW and NE sensors (LNW, LNE) may be covered by masking layers, which allows for leakage detection only in the exposed portions of the sensors. The tail portion may be masked to prevent false leak detection resulting from sensors being bridged by fluid outside of an ostomy skin barrier area.  FIG.  5 A  illustrates exposed portions of the conductive traces of the sensing accessory  12 , while  FIG.  5 B  illustrates masked portions of the conductive traces. In some embodiments, the masking layer may be configured to promote adhesion between a hydrocolloid adhesive layer of a skin barrier and the sensing accessory  12 . 
     The sensing accessory  12  may be configured to be compatible with existing ostomy appliances and to adapt to various stoma sizes and shapes. A center opening of the sensing accessory  12  may be configured to align with an opening in an ostomy barrier to receive a stoma. When the sensing accessory  12  is placed on the ostomy barrier, a backing layer of the sensing accessory may be attached to a hydrocolloid layer of the ostomy barrier. The backing layer may be formed from a suitable material, such as an adhesive, a dead-stretch film, etc. The backing layer may be configured to allow a user to adapt the shape of the center opening, for example, by cutting or molding, to fit a stoma. The backing layer may be provided with labels to guide and limit cutting or shaping of the sensing accessory  12  to prevent damaging of the sensing accessory circuitry. 
     In some embodiments, the sensing accessory  12  may be configured to be molded to conform to the convexity of a convex ostomy barrier. In an embodiment, the sensing accessory  12  may comprise a stretchable printed circuit system to conform to a convex ostomy barrier. In such an embodiment, a circuit substrate, printed conductive traces, and masking layers may be formed from stretchable materials, such as the Dupont INTEXAR system. In another embodiment, the sensing accessory may include slits and voids configured and arranged in a non-stretchable circuit substrate, such as PET, to conform the sensing accessory to a convex barrier. 
     The sensing accessory  12  may include a hydrocolloid adhesive layer to provide an interface between an ostomy pouch system and user&#39;s skin. The adhesive may be configured similar to known hydrocolloid adhesives on ostomy products—e.g. absorbing fluid while maintaining adhesion to the skin. The adhesive may be configured to change conductivity upon exposure to fluid to enable leakage detection by measuring the conductivity or resistance of the adhesive. In an embodiment, the sensing accessory  12  may include a hydrocolloid adhesive layer configured to exhibit a resistance drop from greater than 2 MΩ to about 1 kΩ when the hydrocolloid adhesive layer absorbs ostomy effluent. The adhesive may also be configured to have other desirable properties, such as pH balancing or infusion of skin-friendly ingredients. 
     The adhesive layers of the sensing accessory  12  may be covered by release liners. The release liner may be formed from a silicone-coated film and may include a tab to facilitate removal. In an embodiment, the sensing accessory  12  may include two release liners, each covering opposing surfaces of the sensing accessory  12 . The release liners may be arranged such that the release liner tabs may be offset as shown in  FIG.  6   . Alternatively, the release liners may be arranged such that the tabs may be aligned, wherein one tab may be bigger than the other to facilitate a correct order of removal. In the embodiment of  FIG.  6   , the release liners may be labeled to guide a user through removal of the release liners, assembling of the sensing accessory with an ostomy pouch system, and attaching the assembled sensing accessory and ostomy pouch system to user&#39;s body. 
     The sensing accessory  12  may be manufactured through progressive assembly of constituent materials. At least some of the materials, for example, a circuit substrate, tail cover, release liners, etc., may be provided in a roll form and processed and cut into shape, for example, by die-cutting, for assembly. The hydrocolloid adhesive may be extruded into a roll having a specified thickness, which may be cut in line and assembled. Alternatively, the hydrocolloid adhesive may be molded on top of the assembled circuit, then cut to shape. 
     The sensing accessory  12  may be coupled to the wearable subsystem  14 . The conductive traces, which form the sensors, may extend beyond the periphery of an ostomy skin barrier and to a connector region configured to engage the wearable subsystem  14 . The portion of the sensing accessory  12  that extends between a sensor region and the connector region is referred to herein as a tail or tail region as shown in  FIGS.  4  and  7   . Selecting a flexible substrate for the sensing accessory  12  may allow a user to position the wearable subsystem  14  in a variety of locations on their skin, ostomy pouch, or clothing. 
     A layout of the terminating sections of the conductive traces may be configured to correspond to conductive connecting sections of the wearable subsystem  14 . This allows an electrical connection to be formed between the conductive traces of the sensing accessory  12  and a processor of the wearable subsystem  14 .  FIGS.  5 A,  5 B and  7    illustrate an embodiment of a sensing accessory connector region comprising two openings in the substrate, which function as alignment members corresponding to raised alignment members of a wearable subsystem  14 . The alignment members may be configured to facilitate correct alignment and connection between the sensing accessory  12  and the wearable subsystem  14 . 
       FIG.  7    shows an exploded view of the sensing accessory  12  according to an embodiment. The sensing accessory  12  may generally comprise an adhesive layer  13 , a sensor layer  15  and a barrier-side layer (also referred to herein as a backing layer)  17 . A center opening  19  configured to receive a stoma may extend through the sensing accessory  12 . The center opening  19  may be formed by respective openings provided in individual layers of the sensing accessory  12 . Each layer  13 ,  15 ,  17  of the sensing accessory  12  may have a proximal side and a distal side. When the sensor accessory  12  is attached to a user, the respective proximal sides generally face the user and the respective distal sides generally face away from the user. 
     The adhesive layer  13  may be disposed on a body-side of the sensing accessory  12 . In an embodiment, the proximal side of the adhesive layer  13  may form at least a portion of the body-side surface of the sensor accessory  12 . The proximal side of the adhesive layer  13  may be configured to adhere to the peristomal skin surface of a user and seal around the stoma. The adhesive layer  13  may be formed from a medical-grade pressure sensitive adhesive that can adhesively secure the sensing accessory  12  to the user. In an embodiment, the adhesive layer  13  may be formed from a hydrocolloid adhesive. A release liner  21  may be provided on the proximal side of the adhesive layer  13  to cover the adhesive, which may be removed before attaching the sensing accessory  12  to user&#39;s skin. 
     The barrier-side layer  17  may be formed from a flexible material that is generally soft and non-irritable to user&#39;s skin, such as an adhesive, polymeric film, nonwoven or foam material. In an embodiment, the barrier-side layer  17  may be formed from an adhesive, such as a hydrocolloid adhesive. In such an embodiment, a release liner  22  may be provided on the distal side of the barrier-side layer  17  to cover the adhesive, which may be removed before applying the sensing accessory  12  to an ostomy barrier or faceplate. 
     The sensor layer  15  may include sensors formed from an electrically conductive circuitry  24 , such as a plurality of electrodes, conductive traces or the like. The electrically conductive circuitry  24  may be disposed on a circuit substrate  26 . In an embodiment, the sensor layer  15  may include a sensor region  28 , a connector region  30  and a tail region  32  arranged therebetween. The electrically conductive circuitry  24  may be arranged in a predetermined pattern in the sensor region  28 . For example, the electrically conductive circuitry  24  may be generally arranged in a circular or semi-circular pattern. Other suitable patterns are envisioned as well, such as an oval or oblong pattern, or other closed or substantially closed loop pattern. The electrically conductive circuitry  24  in the sensor region  28  may be arranged at one or more radial distances from the center opening  19 . For example, the conductive circuitry  24  may comprise a plurality of electrically conductive traces arranged at a plurality of different, radial distances from the center opening  19 . 
     In an embodiment, the tail region  32  may generally be formed as an elongated section extending from the sensor region  28  to the connector region  30 . The tail region  32  may extend beyond an outer periphery of the first adhesive layer  13  and/or the barrier-side layer  17  in a direction radially outward from the center opening  19 . The electrically conductive circuitry  24  may extend along the tail region  32 . In an embodiment, the tail region  32  may be flexible along at least a portion of its length such that it may be folded or wrapped. 
     The connector region  30  may include a plurality of connection points  34  electrically connected to the conductive circuitry  24 . The connection points  34  may include an externally accessible portion configured for electrical connection to an external device, such as the wearable subsystem  14 . In this manner, the connection points  34  may provide an electrical connection between the wearable subsystem  14  and the electrically conductive circuitry  24 . The externally accessible portion of the connection points  34  may be any suitable electrical interface for forming an electrical connection between two electrical components, such as one or more electrically conductive contacts, pins, and the like. 
     The connector region  30  may also include one or more alignment members  36 . The one or more alignment members  36  may be configured to engage corresponding alignment members of the wearable subsystem  14  to facilitate positioning of the connector region  30  relative to the wearable subsystem  14  to ensure electrical connection therebetween. In an embodiment, the one or more alignment members  36  of the connector region  30  may be an opening, recess or slot. The corresponding alignment members of the wearable subsystem  14  may be one or more projections configured for receipt in the opening, recess or slot of the connector region  30 . 
     In an embodiment, the sensing accessory  12  may be configured to detect a leakage by measuring resistance between electrodes. For example, the sensing accessory  12  may be configured to detect a change in resistance between electrodes triggered by ostomy effluent bridging the electrodes as a leakage propagates. In the embodiment of  FIG.  7   , the electrically conductive circuitry  24  may comprise a plurality of electrodes arranged on the proximal side of the sensor region  28 , such that the electrodes may be positioned adjacent and in contact with the adhesive layer  13  to measure resistance of the adhesive layer  13 . The plurality of electrodes  24  may extend along the proximal side of the tail region  32  and along a portion of the connector region  30  to the connection points  34 . In such an embodiment, a masking element may be used to prevent shorting between electrodes in the areas where detection is not desired. For example, a masking element  38  may be provided on the body-side of the sensing accessory  12  to cover the plurality of electrodes  24  in the tail region  32 . 
       FIG.  22    is a schematic illustration of the sensing accessory  12  attached to an ostomy barrier  20  and fitted around a stoma  2  according to an embodiment. The sensing accessory  12  may be configured such that a first conductive trace or electrode  25  of the electrically conductive circuitry  24  may be arranged adjacent a center opening  19  with a minimum space therebetween of about 0.25 inches to allow for fitting around the stoma  2  without damaging the electrically conductive circuitry  24 . 
       FIGS.  8  and  9    illustrate a sensing accessory  112  according to another embodiment. The sensing accessory  112  may be configured similar to the sensing accessory  12 , generally comprising an adhesive layer  113 , a sensor layer  115  and a barrier-side layer  117 . The adhesive layer  113  may be formed from a hydrocolloid adhesive and disposed on a body-side of the sensing accessory  112  for attachment to a user. A release liner  121  including a tab  123  may be provided on the proximal side of the adhesive layer  113 . The barrier-side layer  117  may be formed from an adhesive, and a release liner  122  including a tab  125  may be provided on a distal side of the barrier-side layer  117 . The release liners  121 ,  122  may be arranged such that the tabs  123 ,  125  are offset from each other as best shown in  FIG.  8   . Indicator labels  127 ,  129  may be provided on each side of the sensing accessory  112  to guide assembling of the sensing accessory  112  with an ostomy appliance and attachment of the same to a user. 
     The sensor layer  115  may comprise a generally ring-shaped sensor region  128 , a connector region  130  and a tail region  132  connecting the sensor region  128  and the connector region  130 . The sensor region  128  may comprise sensors formed from an electrically conductive circuitry  124 , which may extend through the tail region  132  and to connection points  134  in the connector region  130 . The tail region  132  may be formed as an elongated section extending between the sensor region  128  and the connector region  130 . The connection points  134  may be configured to electrical connect the sensing accessory  112  to an external device, such as the wearable subsystem  14 . The exposed portions of the tail region  132  that are not covered by the adhesive layer  113  and the barrier-side layer  117  may be covered by tail covers  135 ,  137 . 
       FIG.  10    illustrates an electrically conductive circuitry  224  arranged on a proximal side of the sensor region  128  according to an embodiment. The electrically conductive circuitry  224  may comprise a plurality of substantially circular conductive traces, also referred to herein as circular electrodes, L 1 , L 2 , L 4 , L 5 , G 1 , G 2 , G 3 , and a plurality of arc shaped conductive traces, also referred to herein as electrode arcs, Q 1 , Q 2 , Q 3 , Q 4 . Each of the circular electrodes may be arranged at a different radial distance from a center opening  119  and configured to determine a radial progress of ostomy effluent leakage. 
     In this embodiment the electrically conductive circuitry  224  may include four electrode arcs arranged in different sections of the sensor region  128  to determine a location of a leak in the sensor region  128 . A first electrode arc Q 1  may be arranged to extend along a southeast (SE) quadrant of the sensor region  128 . A second electrode arc Q 2  may be arranged to extend along an east half of the sensor region  128 , wherein a lower portion of the second electrode arc Q 2  that extends adjacent the first electrode arc Q 1  may be covered with a making layer (similar to the masked LNE shown in  FIG.  5 B ), such that the exposed portion the second electrode arc Q 2  only extends along a northeast (NE) quadrant of the sensor region  128 . A third electrode arc Q 3  may be arranged to extend along a west half of the sensor region  128 , wherein a lower portion of the third electrode arc Q 3  that extends adjacent a fourth electrode arc Q 4  may be covered with a making layer (similar to the masked LNW shown in  FIG.  5 B ), such that the exposed portion the third electrode arc Q 3  only extends along a northwest (NW) quadrant of the sensor region  128 . The fourth electrode arc Q 4  may be arranged to extend along a southwest (SW) quadrant of the sensor region  128 . In this embodiment, a change in electrical resistance measured by one of the four electrode arcs may be used to determine the location of a leakage. In other embodiments, the electrically conductive circuitry  224  may include less than four electrode arcs or more than four electrode arcs, which may be arranged in different sections of the sensor region  128  and configured to identify a leakage location. 
     In the embodiment of  FIG.  10   , the circular electrodes may comprise four level sensors L 1 , L 2 , L 4 , L 5  and three ground electrodes G 1 , G 2 , G 3 , wherein resistance measured between a level sensor and a ground electrode may be analyzed to determine a leakage. In this embodiment, first and second level sensors L 1 , L 2  may share a first ground electrode G 1 , wherein resistance measured between a first lever sensor L 1  and the first ground electrode G 1  may be analyzed to determine a level 1 leakage, and resistance measured between the first ground electrode G 1  and a second level sensor L 2  may be analyzed to determine a level 2 leakage. A second ground electrode G 2  may be shared between the electrode arcs Q 1 , Q 2 , Q 3 , Q 4  and a fourth level sensor L 4 , wherein resistance measured between the electrode arcs Q 1 , Q 2 , Q 3 , Q 4  and the second ground electrode G 2  may be analyzed to determine a level 3 leakage at a specific quadrant, and resistance measured between the second ground electrode G 2  and the fourth level sensor L 4  may be analyzed to determine a level 4 leakage. A level 5 leakage, which is the most critical leakage level in this embodiment, may be determined by analyzing resistance measured between a fifth level sensor L 5  and a third ground electrode G 3 . 
       FIG.  11    illustrates an electrically conductive circuitry  324  arranged on a proximal side of the sensor region  128  according to another embodiment. The electrically conductive circuitry  324  may comprise a plurality of substantially circular conductive traces C 1 , C 2 , C 3 , C 4 , and a plurality of arc shaped conductive traces Q 1 , Q 2 , Q 3 , Q 4 . In this embodiment the electrically conductive circuitry  324  may include four electrode arcs arranged in different sections of the sensor region  128  to determine a location of a leak in the sensor region  128 . A first electrode arc Q 1  may be arranged to extend along a SE quadrant of the sensor region  128 . A second electrode arc Q 2  may be arranged to extend along an east half of the sensor region  128 , wherein an upper portion Q 2 U extends along a NE quadrant of the sensor region  128  and a lower portion Q 2 L, which may be masked, extends along a SE quadrant of the sensor region  128 . A third electrode arc Q 3  may be arranged to extend along a west half of the sensor region  128 , wherein an upper portion Q 3 U extends along a NW quadrant of the sensor region  128  and a lower portion Q 3 L, which may be masked, extends along a SW quadrant of the sensor region  128 . A fourth electrode arc Q 4  may be arranged to extend along a southwest (SW) quadrant of the sensor region  128 . 
     In this embodiment, a change in resistance measured between a first circular electrode C 1  and a second circular electrode C 2  may be analyzed to determine a level 1 leakage. A change in resistance measured between the second circular electrode C 2  and the first electrode arc Q 1  may be analyzed to determine a level 2 leakage in the SE quadrant. A change in resistance measured between the second circular electrode C 2  and the upper portion of the second electrode arc Q 2 U may be analyzed to determine a level 2 leakage in the NE quadrant. A change in resistance measured between the second circular electrode C 2  and the upper portion of the third electrode arc Q 3 U may be analyzed to determine a level 2 leakage in the NW quadrant. A change in resistance measured between the second circular electrode C 2  and the fourth electrode arc Q 4  may be analyzed to determine a level 2 leakage in the SW quadrant. A change in resistance measured between the first electrode arc Q 1  and a third circular electrode C 3  may be analyzed to determine a level 3 leakage in the SE quadrant, wherein a detection algorithm may set a higher threshold for leakage detection to compensate for a greater distance between the first electrode arc Q 1  and the third circular electrode C 3 . A change in resistance measured between the upper portion of the second electrode arc Q 2 U and the third circular electrode C 3  may be analyzed to determine a level 3 leakage in the NE quadrant. A change in resistance measured between the upper portion of the third electrode arc Q 3 U and the third circular electrode C 3  may be analyzed to determine a level 3 leakage in the NW quadrant. A change in resistance measured between the fourth electrode arc Q 4  and the third circular electrode C 3  may be analyzed to determine a level 3 leakage in the SW quadrant, wherein a detection algorithm may set a higher threshold for leakage detection to compensate for a greater distance between the first electrode arc Q 4  and the third circular electrode C 3 . A change in resistance measured between the third circular electrode C 3  and a fourth circular electrode C 4  may be analyzed to determine a level 4 leakage. 
     Wearable Subsystem 
     The wearable subsystem  14  may function as a relay between the sensing accessory  12  and a user or other subsystems of the leakage detection system  10 . The wearable subsystem  14  may be configured to physically and electronically connect to the sensing accessory  12  and receive and analyze signals from the sensing accessory  12 . The wearable subsystem  14  according to an embodiment is shown in  FIGS.  12  and  13   . The wearable subsystem  14  may comprise a hinged case, an imbedded circuit board, a battery, a motor, and alignment members  40  that correspond to alignment members  36  of the sensing accessory  12 . The circuit board may include conductive members  24  configured to contact terminal ends of sensing traces of the sensing accessory  12 , such as the connecting points  34  ( FIG.  7   ). In this embodiment, the conductive members  24  comprising a plurality of raised conductive pads may be arranged generally in a center area of a bottom housing of the wearable subsystem  14 . 
     The alignment members  40  may comprise two raised members, each of which may be arranged on each side of the conductive members  24  as shown in  FIG.  12   . In such an embodiment, the alignment members  36  of the sensing accessory  12  may be defined by two openings in the connector region  30 , which may be configured to receive the raised alignment members  40  of the wearable subsystem  14 . The alignment members  36 ,  40  may be configured to facilitate correct attachment of the wearable subsystem  14  to the sensing accessory  12  to ensure electrical connection therebetween. A user may form a connection between the sensing accessory  12  and the wearable subsystem  14  by aligning the corresponding alignment members  36 ,  40  as shown in  FIG.  13    and closing the wearable subsystem  14 . 
     The circuit board of the wearable subsystem  14  may include a processor and other components to analyze signals received from the sensing accessory  12 , communicate with external devices, such as a mobile device and a charging dock  16 , and alert a user vis sound, vibration, LEDs, etc. to notify a system status.  FIG.  14    is an exploded view of a wearable subsystem  14  according to an embodiment. 
     In an embodiment, the wearable subsystem  14  may be secured to an ostomy pouch  18  or user via adhesive pads  39  attached to the sensing accessory  12  as shown in  FIG.  15   . The adhesive pads  39  may be covered with release liners, which may be removed before use. 
       FIGS.  16  and  17    show a wearable subsystem  114  according to another embodiment. The wearable subsystem  114  may be configured similar to the wearable subsystem  14 , generally comprising a hinged case, an imbedded circuit board, a battery, a motor, and an alignment member  140  that correspond to an alignment member  136  of the sensing accessory  112 . The circuit board may include conductive members  124  configured to contact the connecting points  134  of the sensing accessory  112 . 
     In this embodiment, the wearable subsystem alignment member  140  may comprise a center raised key member  141  and a peripheral raised member  143 . The center raised key member  141  may be arranged generally in the center of a bottom housing of the wearable subsystem  114 , while the peripheral raised member  143  may be arranged proximate a hinge  145 . The alignment member  136  of the sensing accessory  112  may be defined by openings in the connector region  130 , which may be configured to receive the raised alignment member  140  of the wearable subsystem  14 . In this embodiment, the alignment member  136  may include a center key opening  138  configured to receive the center raised key member  141  and a peripheral opening  139  configured to receive the peripheral raised member  143 . The alignment members  136 ,  140  may be configured to facilitate correct attachment of the wearable subsystem  114  to the sensing accessory  112  to ensure electrical connection therebetween. In an embodiment, the wearable subsystem  114  may be attached to an ostomy pouch or user via an adhesive pad  102  as shown in  FIGS.  18 - 21   . 
     During use, the wearable subsystem  14 ,  114  may poll resistance measurements from conductive traces to collect resistance data, which may be processed through an algorithm for determining an ostomy effluent leakage event. The algorithm may consider resistance measurements and other factors, such as resistance measurements from neighboring conductive traces, a change in resistance from recent prior resistance measurements, historical data from prior uses, etc. 
     Upon a detection of an ostomy effluent leakage event, the wearable subsystem  14 ,  114  may alert a user via sound, vibration, light, etc. according the leakage event. An alert may be sent based on resistance measurements received from multiple sensors, patterns in measurements, user preference inputs, signals received from other components of the ostomy leakage detection system, such as a mobile application and/or charging dock. 
     The wearable subsystem  14 ,  114  may be configured to communicate data to a mobile application. The data may be raw sensor data as received from the sensing accessory  12 ,  112  or processed data processed by the wearable subsystem  14 ,  114 , which may include a summarized data and/or a leakage event information. The wearable subsystem  14 ,  114  may also be configured to communicate system conditions, such as the connectivity of the sensing accessory  12 ,  112 , a faulty sensor, a state of battery, etc. The wearable subsystem  14 ,  114  may be powered by a battery or recharged by the charging dock  16 . The wearable subsystem  14 ,  114  may include conductive pads on a charge circuit portion of the circuit board, which may be configured to contact pins on the charging dock  16 . 
     Charging Dock 
     A charging dock  16  according to an embodiment is shown in  FIGS.  23 A-D . The charging dock  16  may comprise a medical grade power supply unit and a housing including charging pins  52  for electronically connecting to the wearable subsystem  14 ,  114 . The housing may also include additional components, for example, a speaker and LEDs for sending alerts and feedback to a user, and a wireless communication module for communicating with the wearable subsystem  14 ,  114  and a mobile application. 
     The charging dock  16  may be configured to recharge a rechargeable battery of the wearable subsystem  14 ,  114 . When the wearable subsystem  14 ,  114  is placed in a recessed area  54  of the charging dock  16 , an electrical connection may be formed between the charging pins  52  and conductive pads of the wearable subsystem  14 ,  114 . A charging circuit of the wearable subsystem  14 ,  114  may be configured to ensure a safe recharge. 
     In an embodiment, the charging dock  16  may be configured to provide an additional means for alerting a user about leakage events. When the charging dock  16  is in wireless communication with the wearable subsystem  14 ,  114 , the user may have an option to receive leak alerts from the charging dock  16 . This option may be most advantageous at night when other means of alerting may not be as effective for users during sleep. For example, a vibration alert from the wearable subsystem  14 ,  114  may not be effective to rouse a sleeping user. The user may also power down or disable sounds from a mobile phone at night. As such, the user may opt to receive alerts from the charging dock  16 . The wearable subsystem  14 ,  114  may be configured to determines a leakage event and send a signal to the charging dock  16  via Bluetooth communication. The charging dock  15  may be configured to send an audible alert through a speaker and/or a visual alert through LEDs when a leakage event signal is received. Certain aspects of the alert, such as volume and duration, may be configurable by the user. 
     Mobile Application 
     The mobile application may be configured to provide means for users to interact with the ostomy leakage detection system  10 . For example, a user may set preferences for alerts and review historical data, such as analysis of leakage patterns and usage trends, by using the mobile application. The mobile application may also be configured to functions as a resource for connecting the user to support, such as training materials, experts at the manufacturer, and ostomy clinicians. 
     The mobile application may be configured to communicate with the wearable subsystem  14 ,  114  and the charging dock  16  over Bluetooth. The mobile application may be configured to confirm these connections and alerts if a subsystem is unavailable. The mobile application may be configured to alert the user about leakage events and/or system issues through alert functions of a mobile phone, such as sound and vibration. 
     The mobile application may be configured to relay data to a cloud server for storage and/or data analysis, for example prediction of leaks based on repeated wears, comparison to the leakage patterns of other users of the system, or other factors. A communication link between a cloud system and the mobile application may allow for additional features, such as product recommendations based on leakage patterns or other data, re-ordering of products in a convenient or automatic format, direct consultation with a clinician, storage of photographs of the stoma or peristomal skin for tracking alongside leakage patterns, etc. 
     A diagram of communication between subsystems of the ostomy leakage detection system  10  and communication between the ostomy leakage detection system  10  and a cloud system according to an embodiment is shown in  FIG.  25   . 
     Method of Detecting Ostomy Effluent Leakage 
     The sensing accessory  12 ,  112  may be configured to detect an ostomy effluent leakage by measuring a change in resistance between electrodes, which are also referred to herein as conductive traces. When ostomy effluent bridges two electrodes, a resistance measurement between the electrodes may drop substantially to indicate a leakage event. In an embodiment, resistance below a pre-determined threshold resistance value of 1 MΩ may identify a leakage event, which is selected to provide a necessary level of sensitivity to distinguish an ostomy effluent leakage event from other events causing a change in resistance, for example, user&#39;s perspiration. 
       FIG.  24    is a block diagram for a method of detecting an ostomy effluent leakage using the ostomy leakage detection system  10  according to an embodiment. The steps of the method of detecting an ostomy effluent leakage may be configured for accurate determination of leakage events and to minimize false detections. The method may include the step of providing a sensing accessory  12 ,  112  comprising a plurality of sensors, for example, 8 sensors, arranged adjacent an adhesive or embedded in the adhesive. Each of the plurality of sensors may be formed from a pair of conductive traces configured to measure resistance of the adhesive. 
     The method may also include the step of determining whether the sensing accessory  12 ,  112  is electrically connected to the wearable subsystem  14 ,  114 . In the step of “Is a sensor connected?”  400 , the wearable subsystem  14 ,  114  may send a signal to the sensing accessory  12 ,  112  requesting a return signal. If no signal is returned, the wearable subsystem  14 ,  114  may determine that the sensing accessory  12 ,  112  is not connected and increase a disconnect timer in the step of “Increment disconnect timer”  402 . The wearable subsystem  14 ,  114  may also send the disconnect timer data to an external device, such as user&#39;s phone, when the sensing accessory  12 ,  112  is not connected to the wearable device  14 ,  114  in the step of “Push time to phone”  404 . 
     When the wearable device  14 ,  114  detects the sensing accessory  12 ,  112 , the wearable device  14 ,  114  may pull a resistance measurement signal from each sensor in the step of “Input signal from sensor (T=2 s)”  406 . In an embodiment, the wearable device  14 ,  114  may be configured to pull and receive a resistance measurement every 2 seconds. The signal received from each sensor may be processed separately in the step of “Enter for loop to evaluate each sensor individually (sensor=1:8)”  408 . The signals may be processed by a processor provided in the wearable device  14 ,  114  to determine whether a resistance measured by a sensor is outside a predetermined range of acceptable resistance values in the step of “Are resistance values abnormal?”  410 . 
     If the resistance measurement is outside the predetermined range of acceptable resistance values, for example, negative recorded resistance values, the sensor may be flagged in the step of “Increment sensor flag”  412 . In the step of “Is sensor flag=5?”  414 , the number of abnormal resistance measurements that fall outside the predetermined range of acceptable resistance values may be counted. If the number of abnormal resistance measurements reaches five, the wearable device  14 ,  114  may determine that an abnormal event has occurred and may send an alert to an external device, such as user&#39;s phone, in the step of “Push to phone to prompt user to reconnect wearable”  416 . The alert may also instruct a user to take an action such as reconnecting the wearable subsystem  14 ,  114  to the sensing accessory  12 ,  112 . 
     In an embodiment, an abnormal resistance value may not be entered in a ring buffer, which is configured to store resistance measurements, and a new resistance measurement from the same sensor or a resistance measurement from a different sensor may be taken. If an issue is detected at a sensor in the step of “Did this sensor have an issue? (Flag=5)”  418 , but the resistance measurements for the same sensor returns to a normal value within the predetermined range of acceptable resistance values for 10 subsequent consecutive seconds, the issue may be cleared and the resistance measurement data may be entered in the ring buffer in the steps of “Has data collection returned to normal values for 10 seconds?”  420 , “Clear sensor issue”  422 , and “Ring buffer (n=5)”  424 . 
     In an embodiment, the ring buffer may be configured to hold a current resistance measurement and four previous resistance measurements for each sensor, wherein the resistance measurements may be used to calculate a median filter value (a median of the five resistance measurements) in the step of “Median filter”  426 . The ring buffer may be continuously pushed through the median filter which is a median of the last five resistance measurements. In an embodiment, the predetermined range of acceptable resistance values may be set at less than a threshold resistance value of 1 MΩ. In the step of “Is resistance&lt;1000 kΩ?”  428 , whether a median filter value of a sensor is less than the threshold value may be determined. If the median filter value of the sensor is less than the threshold value, the status of that sensor is checked in the step of “Is sensor in leak state?”  430 . If the sensor is not already in a leak state, a leak count of the sensor may be incremented in the step of “Increment Leak Count”  432 . In the step of “Is leak count=3?”  434 , the number of median filter values that are less than the threshold value may be counted (i.e. leak count). If the leak count of the sensor reaches three, the sensor may be determined to be in a leak state and an alert including information regarding the leak state, such as the location of the sensor, may be pushed to an external device, such as user&#39;s phone in the step of “Alert user of leak and sensor enters leak state”  436 . 
     If the median filter value of the sensor is determined to be greater than or equal to the threshold value (1 MΩ) in the step of “Is resistance&lt;1000 kΩ?”  428 , a resistance measurement from a next sensor is taken, and the steps of detecting an ostomy effluent leakage  408 ,  410 ,  412 ,  414 ,  416 ,  418 ,  420 ,  422 ,  424 ,  426 ,  428 ,  430 ,  432 ,  434 ,  436  may be repeated until resistance measurements from all of the sensors, for example eight sensors, are processed. If the median filter values of all of the sensors are determined to be greater than or equal to the threshold value or the maximum detectable resistance value, for example, 1541 kΩ,, in the step of “Are all sensors≥1000 kΩ?”  438 , the count of Clear for the sensors may be increased in the step of “Increment Clear variable”  440 . If sensors are Clear for 5 consecutive times in the step of “Is Clear=5?”, which may be 10 seconds in the embodiments wherein the resistance measurements are taken every 2 seconds, the sensors may be determined to be in a clear state and new resistance measurements are taken from the sensors for a next round of the leak detection analysis. If one or more sensors is determined to be in a leak state, leakage alerts may be cleared when a user changes the barrier in the step of “Assume barrier change and clear all alerts”  444 . 
     From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present disclosure. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.