Liquid ingress protection and design of electronic circuits for negative pressure wound therapy systems

Abstract

The approach described herein may provide a mitigation against the risk of one or more malfunctions of the electronics of the negative pressure wound therapy device. The one or more malfunctions may include reverse current flow, overcurrent flow, liquid ingress, or inadvertent activation. The approach described herein may provide protection against a single failure (or greater protection against multiple failures). Advantageously, a mitigation may be provided against the risk of causing burns or other discomfort to the patient, or the risk of fire.

Description

[Technical field]

[0001] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments described herein relate to devices, systems, and methods for treating wounds using bandages in combination with negative pressure wound therapy, for example. [Background technology]

[0002] 2. Description of Related Art Treatment of open or chronic wounds that are too large to close naturally or otherwise not healed by application of negative pressure to the wound site is well known in the art. Negative pressure wound therapy ("NPWT") systems currently known in the art involve placing a fluid-impermeable or semi-permeable cover over the wound, using various means to seal the cover against the patient's tissue surrounding the wound, and connecting a source of negative pressure (such as a vacuum pump) to the cover in such a manner that negative pressure is created and maintained beneath the cover. Such negative pressure is believed to promote wound healing by promoting the formation of granulation tissue at the wound site and assisting the body's normal inflammatory process while simultaneously removing excess fluid that may contain harmful cytokines and / or bacteria. However, further improvements in NPWT are needed to fully realize the therapeutic benefits. Summary of the Invention

[0003] The negative pressure wound therapy system may include a negative pressure source. The negative pressure source may be configured to provide negative pressure to a wound covered with a wound dressing and to aspirate fluid from the wound. The negative pressure wound therapy system may include a circuit board. The circuit board may be configured to support a plurality of electronic components. The plurality of electronic components may include a control circuit. The control circuit may be configured to control the operation of the negative pressure source. The circuit board may be configured to support a plurality of traces electrically connecting the plurality of electronic components. The plurality of traces may include a first set of traces that may be configured to transmit one or more digital signals and a second set of traces that may be configured to transmit one or more analog signals. The control circuit may be configured to detect a degradation of an electrical signal on at least one trace of the first or second set of traces. The degradation may be caused by one or more of liquid intrusion or condensation on the circuit board. The control circuit may be configured to temporarily or permanently cease providing negative pressure to the wound in response to detecting a degradation of the electrical signal caused by one or more of liquid intrusion or condensation.

[0004] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features. The negative pressure wound therapy system may include a wound dressing. At least one of the negative pressure source or the circuit board may be configured to be at least partially supported by the wound dressing. The circuit board may be configured to support the negative pressure source. The liquid intrusion may occur as a result of the negative pressure source drawing fluid from the wound. The degradation of the electrical signal may be caused by a short circuit as a result of one or more of the liquid intrusion or condensation. The degradation of the electrical signal may be caused by a short circuit between two traces from the first set of traces, or between a trace from the first set of traces and ground or power. The two traces from the first set of traces may include portions that are not coated with the water resistant material. The trace from the first set of traces may include portions that are not coated with the water resistant material. The short circuit may be formed due to a liquid contacting a portion not coated with the water resistant material or a portion not coated with the water resistant material. The trace from the second set of traces may correspond to a feedback line of the negative pressure source. The control circuitry may be configured to detect the degradation of the electrical signal based at least in part on a short across the feedback line. The traces from the second set of traces may be part of a circuit configured to detect excessive temperature. The control circuitry may be configured to detect the degradation of the electrical signal by determining that the circuitry configured to detect excessive temperature has inaccurately detected the excessive temperature. The control circuitry may be configured to determine that the circuitry configured to detect excessive temperature has inaccurately detected the excessive temperature based on a process temperature detected by an additional temperature sensor.

[0005] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features: The negative pressure wound therapy system may include at least one battery. The control circuit may be configured to drain the at least one battery in response to detecting a degradation of the electrical signal. The plurality of electronic components may include a resistor network and a switch. The control circuit may be configured to open the switch and drain the at least one battery through the resistor network. The plurality of electronic components may include a conductive surface and a switch. The control circuit may be configured to open the switch and drain the at least one battery into the conductive surface. Temporarily ceasing the provision of negative pressure to the wound may include preventing the negative pressure source from being activated to provide negative pressure to the wound for a first period of time. The control circuit may be configured to activate the negative pressure source to provide negative pressure to the wound in response to expiration of the first period of time. The first period of time may correspond to a period of time for clearing errors caused by one or more of liquid intrusion or condensation on a circuit board. Permanently ceasing the provision of negative pressure to the wound may include preventing the negative pressure source from being activated to provide negative pressure to the wound. The control circuit may be configured to detect degradation of the electrical signal based on data obtained from one or more of a moisture sensor or an electronic fuse (eFuse). The control circuit may be configured to temporarily or permanently cease provision of negative pressure by one or more of blowing a fuse, blowing a fuse, opening a switch, or opening a relay. The control circuit may be configured to generate an alarm in response to detecting the degradation of the electrical signal. The control circuit may include a programmable controller. The programmable controller may be configured to detect degradation of the electrical signal and execute instructions to temporarily or permanently cease provision of negative pressure to the wound in response to detecting the degradation of the electrical signal.

[0006] The negative pressure wound therapy system may include a negative pressure source configured to provide negative pressure to a wound covered with a wound dressing. The system may include a printed circuit board. The system may include electronic circuitry supported by the printed circuit board and configured to control operation of the negative pressure source. The system may include at least one fuse configured to provide overcurrent protection. The at least one fuse may be located on the printed circuit board and is not surrounded by a conductive material, which may prevent the formation of a heat sink for the at least one fuse.

[0007] The negative pressure wound therapy system of any of the preceding paragraphs, and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features: The conductive material may include a conductive metal forming at least one of a ground plane or a power plane supported by a printed circuit board. The printed circuit board may include a top layer and a bottom layer. The at least one fuse may not be surrounded by conductive material on the top layer and the bottom layer.

[0008] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features. The system may include a power source supported by a printed circuit board and configured to provide power to the negative pressure source and the electronic circuit. The at least one fuse may be interposed between the power source and one or more components of the electronic circuit. The power source may include a first battery and a second battery. The at least one fuse may include a first fuse interposed between the first battery and one or more components of the electronic circuit and a second fuse interposed between the second battery and one or more components of the electronic circuit. At least one terminal of the power source may be separated from a proximal conductive component supported by the printed circuit board by a clearance. At least one terminal of the power source may be electrically connected to the at least one fuse. The clearance may be at least twice the thickness of the printed circuit board. The system may include a switch connected to the power source and configured to prevent reverse current flow. The switch may include a transistor and a body diode connected across the transistor. The switch may be configured to prevent reverse current flow to a positive terminal of the power source. The printed circuit board may be flexible.

[0009] The negative pressure wound therapy system may include a power source. The system may include a negative pressure source configured to provide negative pressure to a wound covered with a wound dressing. The system may include an electronic circuit configured to receive power from the power source and control the provision of power to the negative pressure source. The electronic circuit may include a first activation control and a second activation control separate from the first activation control. The electronic circuit may be configured to operate in an inactive mode in which power is not provided to the negative pressure source, and in an active mode in which power is provided to the negative pressure source. The electronic circuit may be configured to transition to an active mode in which power is provided to the negative pressure source in response to activation of the first activation control. The electronic circuit may be configured to prevent transition to the active mode regardless of activation of the first activation control in response to the second activation control being activated.

[0010] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features: The first activation control may be a first tab configured to be activated when removed. The second activation control may be a second tab configured to be activated when removed, or a jumper configured to be activated when removed. The second activation control may be an optical sensor configured to be activated by exposure to light. Activation of the second activation control may prevent unintentional transition of the electronic circuitry from an inactive mode to an active mode. Unintentional transition of the electronic circuitry from an inactive mode to an active mode may be triggered by exposure to one or more of light or elevated temperature.

[0011] The negative pressure wound therapy system may include a power source. The system may include a negative pressure source configured to provide negative pressure to a wound covered with a wound dressing. The system may include an electronic circuit configured to receive power from the power source and control the provision of power to the negative pressure source. The electronic circuit may include an activation control. The electronic circuit may be configured to operate in an inactive mode in which power is not provided to the negative pressure source. The electronic circuit may be configured to operate in an active mode in which power is provided to the negative pressure source in response to activation of the activation control. The system may include a controller configured to operate the negative pressure source and transition the electronic circuit from the active mode to the inactive mode in response to a determination that a period of time has not elapsed following activation of the controller.

[0012] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features: The system may include an interface configured to transition the electronic circuitry to an inactive mode in response to receiving a signal from the controller.

[0013] The negative pressure wound therapy system may include a power source configured to provide power at a first and a second level. The system may include a negative pressure source configured to provide negative pressure to a wound covered with a wound dressing. The negative pressure source may be configured to be powered by power at the second level. The system may include a controller configured to operate the negative pressure source. The controller may be configured to be powered by the power at the first level. The system may include a switch configured to receive power at the second level. The switch may be configured to toggle between providing a signal to the controller in response to a user input, the signal causing activation or deactivation of the negative pressure source.

[0014] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features: The controller may be configured to operate in an active mode and a sleep mode in which the controller consumes less power than the active mode. The controller may be configured in the active mode to activate or deactivate the negative pressure source in response to receiving a first type of input from the switch. The controller may be configured in the active mode to transition to a sleep mode in response to receiving a second type of input from the switch. The second type of input may be different from the first type of input. The switch may be a button. The first type of input may be a button press for a first duration. The second type of input may be a button press for a second duration different from the first duration. The switch may be the only user interface component that may be operated by a user (e.g., receive input from a user).

[0015] The negative pressure wound therapy system of any of the preceding paragraphs and / or any of the apparatus, systems, or devices disclosed herein may include one or more of the following features: The system may include a wound dressing, and at least one of the negative pressure source, the electronic circuitry, or the controller may be at least partially supported by the wound dressing.

[0016] Disclosed herein is a negative pressure wound therapy system of any of the preceding paragraphs, and / or a method of operating any of the devices, apparatus, or systems disclosed herein.

[0017] Any of the features, components, or details of any of the arrangements or embodiments disclosed in the present application, including but not limited to any of the device embodiments disclosed herein and any of the negative pressure wound therapy embodiments disclosed herein, can be combined with any other features, components, or details of any of the arrangements or embodiments disclosed herein to form new arrangements and embodiments. [Brief description of the drawings]

[0018] [Figure 1A] 1A, 1B, and 1C illustrate a wound dressing incorporating a negative pressure source and / or other electronic components within the wound dressing. [Figure 1B] Same as above. [Figure 1C] Same as above. [Figure 2A] 2A and 2B illustrate an electronic unit that may be incorporated into a wound dressing. [Figure 2B] Same as above. [Diagram 3] FIG. 3 is an exploded perspective view of an electronic assembly that encloses an electronic unit within a housing. [Figure 4A] FIG. 4A illustrates a bottom perspective view of the electronic assembly of FIG. [Figure 4B] FIG. 4B illustrates a top perspective view of the electronic assembly of FIG. [Figure 5A] FIG. 5A is an exploded view of a wound dressing incorporating an electronic assembly within the wound dressing layer. [Figure 5B] Ibid. Figure 5B illustrates a cross-sectional layout of the material layers of a wound dressing incorporating an electronic assembly within the dressing. [Figure 6A] 6A, 6B and 7A, 7B show components of an electronic assembly. [Figure 6B] Same as above. [Figure 7A] Same as above. [Figure 7B] Same as above. [Figure 8] FIG. 8 shows the pump outlet mechanism. [Figure 9A] 9A and 9B show an implementation for reverse polarity protection. [Figure 9B] Same as above. [Figure 10A] Figure 10A illustrates a latch circuit. Figures 10B, 10C, and 10D illustrate improvements to the latch circuit. [Figure 10B] Same as above. [Figure 10C] Same as above. [Figure 10D] Same as above. [Figure 11] FIG. 11 illustrates a circuit having a play / pause switch. [Figure 12A] 12A, 12B, 12C, 12D, and 12E illustrate thermal isolation of one or more fuses. [Figure 12B] Same as above. [Figure 12C] Same as above. [Figure 12D] Same as above. [Figure 12E] Same as above. [Figure 13] FIG. 13 illustrates the clearance of a track that is not protected by one or more fuses. [Figure 14A] 14A and 14B illustrate the formation of electrical connections for one or more fuses. [Figure 14B] Same as above. [Figure 15]FIG. 15 shows the electronics and other components of the TNP system. [Figure 16] FIG. 16 shows a block diagram of the TNP system electronics. [Figure 17] FIG. 17 shows a schematic diagram of a portion of a TNP system. [Figure 18] FIG. 18 shows a block diagram of a portion of the TNP system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] overview The embodiments disclosed herein relate to devices and methods for treating wounds with reduced pressure, including a source of negative pressure and wound dressing components and devices, including but not limited to wound overlays, backing layers, cover layers, drapes, sealing layers, spacer layers, absorbent layers, transmission layers, wound contact layers, packaging materials, fillers, and / or fluid connectors, which devices and components may be collectively referred to herein as dressings.

[0020] The systems and methods disclosed herein may be used to detect liquid ingress and / or condensation (sometimes collectively referred to as liquid ingress) in a wound dressing including electronics (e.g., a support) that includes one or more electronic components. Condensation may be caused by an enclosure that is not tight enough to allow some ingress of fluid and may be exacerbated by one or more of humidity or temperature (such as in a negative pressure wound therapy system supported by the dressing). Liquid ingress may occur as a result of aspiration of fluid from the wound or patient misuse (such as exposure to fluids in the system). The systems and methods disclosed herein may include control circuitry that causes the delivery of therapy through the wound dressing. The control circuitry may disable the delivery of therapy upon detection of liquid ingress and / or condensation in the electronics. The control circuitry may then re-enable the delivery of therapy or may permanently disable the delivery of therapy. The systems and methods disclosed herein may enable the detection of liquid ingress and / or condensation by detecting degradation of digital and / or analog communications in the electronics. Additionally, the systems and methods disclosed herein may enable detection of liquid intrusion and / or condensation based on signals received from one or more electronic components. Liquid intrusion and / or condensation may cause one or more malfunctions in the electronics that may result in injury or other complications to the patient and / or system. For example, it may cause degradation of electrical communications, which may lead to an increase in temperature. This may cause discomfort or injury to the patient (burns, fire, etc.). The electronics may be damaged. The systems and methods disclosed herein may further enable mitigation of the degradation of electrical communications caused by liquid intrusion and / or condensation as a result of detecting liquid intrusion and / or condensation (e.g., by generating an alarm, blowing a fuse, etc.). This may reduce the risk of causing discomfort or injury to the patient and improve safety and comfort.

[0021] It will be understood that wounds are referred to throughout this specification. The term wound should be understood to be broadly interpreted and include open and closed wounds where the skin is torn, incised, or perforated, or where trauma causes bruising, or any other surface or other condition or defect in the patient's skin, or others that would benefit from reduced pressure treatment. Thus, a wound is broadly defined as any damaged area of ​​tissue where fluid may or may not be produced. Examples of such wounds include, but are not limited to, abdominal wounds, or other large or incisional wounds as a result of surgery, trauma, sternotomy, fasciotomy, or any other condition, dehiscence wounds, acute wounds, chronic wounds, subacute wounds and dehiscence wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, bruises, burns, diabetic ulcers, bedsores, stomas, surgical wounds, traumatic ulcers, and venous ulcers.

[0022] It will be appreciated that embodiments of the present disclosure are generally applicable for use in NPWT or topical negative pressure ("TNP") therapy systems. In brief, negative pressure wound therapy may assist in the closure and healing of many forms of "hard to heal" wounds by reducing tissue edema, promoting blood flow and granular tissue formation, and removing excessive exudate, reducing bacterial load (and therefore infection risk). In addition, the therapy may result in less wound disturbance and more rapid healing. TNP therapy systems may also assist in the healing of surgically closed wounds by removing fluids and helping to stabilize tissues in an apposed position of closure. Further beneficial uses of TNP therapy may be found in grafts and flaps, where removing excess fluids is important and grafts are required to be in close proximity to tissue to ensure tissue viability.

[0023] As used herein, a level of reduced pressure or negative pressure, such as -XmmHg, represents a pressure level relative to normal ambient atmospheric pressure, which may correspond to 760mmHg (or 1 atm, 29.93 inHg, 101.325 kPa, 14.696 psi, 1013.25 mbar, etc.). Thus, a negative pressure value of -XmmHg reflects an absolute pressure of XmmHg less than 760mmHg, or in other words, an absolute pressure of (760-X)mmHg. Additionally, a negative pressure "lower" or "smaller" than XmmHg corresponds to a pressure closer to atmospheric pressure (e.g., -40mmHg is lower than -60mmHg). A negative pressure "higher" or "larger" than -XmmHg corresponds to a pressure further away from atmospheric pressure (e.g., -80mmHg is higher than -60mmHg). In some cases, the local ambient atmospheric pressure is used as a reference point, and such local pressure may not necessarily be, for example, 760 mmHg.

[0024] The negative pressure range may be approximately -80 mmHg, or between about -20 mmHg and -200 mmHg. Note that these pressures are relative to normal ambient atmospheric pressure, which may be 760 mmHg. Thus, -200 mmHg would effectively be about 560 mmHg. In some cases, the pressure range may be between about -40 mmHg and -150 mmHg. Alternatively, pressure ranges of -75 mmHg or less, -80 mmHg or less, or greater than -80 mmHg may be used. Also, in some cases, pressure ranges below -75 mmHg may be used. Alternatively, pressure ranges of approximately -100 mmHg or even above -150 mmHg may be provided by the negative pressure device.

[0025] The systems and methods disclosed herein relate to the use of wound dressings. The wound dressings may include one or more electrical components to provide a therapy function to the wound. To provide a therapy function, the wound dressings may be connected to a control circuit that causes the wound dressing to perform a wound therapy (e.g., TNP therapy, ultrasound therapy, compression therapy, light therapy, etc.). The control circuit may drive the wound dressing by providing a drive signal to the wound dressing that causes the wound dressing to perform a wound therapy. Additionally, the control circuit may utilize digital and / or analog communication (e.g., functional breakdown or attenuation of digital or analog communication) to detect the presence of liquid particles (e.g., manufacturing board residue, bag residue, blood, human exudate, water, condensation, etc.) and / or solid particles (e.g., solder, defective coating, etc.). The liquid particles and solid particles may be conductive particles that can act as a path to transmit an electric current from a first location to a second location.

[0026] The disclosed systems and methods can detect liquid intrusion. The term liquid intrusion may be used generally to describe the intrusion of liquid and / or solid particles. For example, liquid intrusion from a patient's wound may be detected. Certain portions of the wound dressing and / or control circuitry may be susceptible to liquid intrusion. For example, the inlet of a negative pressure source may be a high-risk area for liquid intrusion. In response to the control circuitry detecting a degradation in digital and / or analog communication, a liquid intrusion event may be identified. Parameters of the liquid intrusion detection may be managed and / or set by the user. For example, the user may be able to set an amount of liquid that will trigger a liquid intrusion detection. As another example, the user may be able to set an amount of liquid that will trigger mitigation. Mitigation may include one or more of stopping therapy, generating an alarm and / or alert to the user, reporting the detection (e.g., via wired and / or wireless communication) to the user or a third party. For example, an alert may be generated to the user identifying that a liquid intrusion event has occurred. In response, the dressing may be removed from the patient. Liquid intrusion detection can promote patient comfort and safety (eg, by reducing the risk of patient burns, fire, discomfort, etc.).

[0027] Wound dressing The negative pressure source (e.g., pump) and some or all other components of the TNP system, such as power sources, sensors, connectors, user interface components (buttons, switches, speakers, screens, etc.), can be integrated with the wound dressing. The material layers can include a wound contact layer, one or more absorbent layers, one or more permeable or spacer layers, and a backing or cover layer that covers the one or more absorbent and permeable or spacer layers. The wound dressing can be placed over the wound and sealed to the wound with the pump and / or other electronic components contained under the cover layer within the wound dressing. The dressing can be provided as a single article with all wound dressing elements (including the pump) pre-attached and integrated into a single unit. The periphery of the wound contact layer can be attached to the periphery of the cover layer that encloses all the wound dressing elements, as illustrated in Figures 1A, 1B, and 1C.

[0028] The pump and / or other electronic components can be configured to be located adjacent to or next to the absorbent and / or permeable layers so that the pump and / or other electronic components are still a single item applied to the patient. The pump and / or other electronics can be located away from the wound site. Although certain features disclosed herein may be described as relating to systems and methods for controlling the operation of a negative pressure wound therapy system in which the pump and / or other electronic components are located in or on the wound dressing, the systems and methods disclosed herein are applicable to any negative pressure wound therapy system or any medical device. FIGS. 1A, 1B, and 1C illustrate a wound dressing incorporating a negative pressure source and / or other electronic components within the wound dressing. FIGS. 1A, 1B, and 1C illustrate a wound dressing 100 in which the pump and / or other electronics are located away from the wound site. The wound dressing can include an electronics area 161 and an absorbent area 160. The dressing may include a wound contact layer 110 (not shown in Figures 1A, 1B) and a moisture vapor permeable film, cover layer or backing layer 113 positioned over the contact layer and other layers of the dressing. The wound dressing layer and the components of the electronics area and absorbent area may be covered by one continuous cover layer 113, as shown in Figures 1A, 1B, and 1C.

[0029] A layer of porous material 111 may be located above the wound contact layer 110. As used herein, the terms porous material, spacer, and / or permeable layer may be used interchangeably to refer to a layer of material within the dressing that is configured to distribute negative pressure across the wound area. This porous or permeable layer 111 allows fluids, including liquids and gases, to permeate away from the wound site into the upper layers of the wound dressing. In particular, the permeable layer 111 preferably ensures that the absorbent layer can maintain an open air channel to transmit negative pressure over the wound area even when it absorbs a significant amount of exudate. The layer 111 should preferably remain open under normal pressures that would be applied during negative pressure wound therapy, as described above, so that the entire wound site experiences equal negative pressure. The layer 111 may be formed from a material having a three-dimensional structure. For example, a knitted or woven spacer fabric (e.g., Baltex 7970 weft knit polyester), or a nonwoven fabric may be used.

[0030] Additionally, one or more absorbent layers (such as layers 122, 151) may be utilized to absorb and retain exudate aspirated from the wound. Superabsorbent material may be used in the absorbent layers 122, 151. One or more layers 122, 151 of absorbent material may be provided above the transmission layer 111. In use, each of the absorbent layers experiences a negative pressure, and the material of the absorbent layer may be selected to absorb liquid under such conditions. The absorbent layers 122, 151 may include a composite including a superabsorbent powder, a fibrous material such as cellulose, and a bonding fiber. The composite may be an aeolian, thermally bonded composite.

[0031] The electronics area 161 may include a source of negative pressure (e.g., a pump) and some or all other components of the TNP system that may be integrated with the wound dressing, such as power sources, sensors, connectors, user interface components (such as buttons, switches, speakers, screens, etc.), etc. For example, the electronics area 161 may include a button or switch (shown in FIGS. 1A, 1B as covered by a pull tab). The button or switch may be used to operate the pump (pump on, off, etc.).

[0032] The electronics area 161 of the dressing can include one or more layers of transparent or spacer material and / or absorbent material, and the electronic components can be embedded within the one or more layers of transparent or spacer material and / or absorbent material. The layers of transparent or absorbent material can have recesses or cutouts for embedding the electronic components therein while providing structure to prevent collapse. As shown in FIG. 1C, recesses 128 and 129 can be provided in absorbent layers 151 and 122, respectively.

[0033] As used herein, the top layer, uppermost layer, or upper layer refers to the layer that is furthest from the skin or wound surface while the dressing is in use and positioned on the wound. Thus, the bottom layer, lowermost layer, or lower layer refers to the layer that is closest to the skin or wound surface while the dressing is in use and positioned on the wound. Furthermore, a layer can have a proximal wound-facing surface, referred to as the side or surface of the layer closest to the skin or wound, and a distal surface, referred to as the side or surface of the layer furthest from the skin or wound.

[0034] The cover layer may include a cutout 172 positioned over at least a portion of the aperture 128 in the absorbent layer 122 to allow access to and fluid communication with at least a portion of the underlying absorbent layers 122 and 151, the transmission layer 111, and the wound contact layer 110. An electronic assembly, as described below, may be positioned within the apertures 128, 129, and 172 of the first and second absorbent materials 151 and 122 and the cover layer 113. The electronic assembly may include a pump, a power supply, and a printed circuit board, as described with reference to Figures 3 and 4A-B.

[0035] Prior to use, the dressing may include one or more delivery layers 146 adhered to the bottom surface of the wound contact layer. The delivery layer 146 may cover the adhesive or apertures on the bottom surface of the wound contact layer 110. The delivery layer 146 may provide support to the dressing and may aid in sterilization and proper placement of the dressing on the patient's wound and skin. The delivery layer 146 may include a handle that a user can use to separate the delivery layer 146 from the wound contact layer 110 prior to applying the dressing to the patient's wound and skin.

[0036] Electronic assemblies integrated into wound dressings 2A and 2B illustrate an electronic unit 267 that can be incorporated into a wound dressing. FIG. 2A illustrates a top view of the electronic unit. FIG. 2B illustrates the bottom or wound-facing side of the electronic unit. The electronic unit 267 can include a pump 272 and one or more power sources 268, such as batteries. The electronic unit 267 can include a circuit board 276 configured to electrically communicate with the pump 272 and / or the power source 268. The circuit board 276 can be flexible or substantially flexible.

[0037] As shown in FIG. 2A, the electronics unit 267 may include a single button or switch 265 on a top surface of the unit. The single button or switch 265 may be used as an on / off button or switch to stop and start operation of the pump and / or electronic components. The electronics unit 267 may also include one or more vents or exhaust apertures 264 on the circuit board 276 for venting air exhausted from the pump. As shown in FIG. 2B, a pump outlet exhaust mechanism 274 (sometimes referred to as a pump exhaust mechanism or pump outlet mechanism) may be attached to the outlet of the pump 272.

[0038] The electronic unit 267 may include a pump inlet protection mechanism 280 positioned on a portion of the electronic unit closest to the absorbent area and aligned with the inlet of the pump 272, as shown in FIG. 2B. The pump inlet protection mechanism 280 is positioned between the pump inlet and the absorbent area or layer of the dressing. The pump inlet protection mechanism 280 may include a hydrophobic material to prevent fluid from entering the pump 272. The pump inlet protection mechanism 280 (or any of the inlet protection mechanisms disclosed herein) may include a filter.

[0039] The top surface of the electronic unit 267 may include one or more indicators 266 to indicate the status of the pump and / or the pressure level within the dressing. The indicators may be small LED lights or other light sources visible through a dressing component on the indicator or through holes in the dressing component. The indicators may be green, yellow, red, orange, or any other color. For example, there may be two lights, one green light and one orange light. The green light may indicate that the device is working properly, and the orange light may indicate that there is some problem with the pump (e.g., leak, saturated level of the dressing, blockage downstream of the pump, blockage of the exhaust, low battery, etc.).

[0040] The power source 268 can be in electrical communication with the circuit board 276. One or more power connections are connected to a surface of the circuit board 276. The circuit board 276 can have other electronics integrated therein. For example, the circuit board 276 can support a variety of sensors, including, but not limited to, one or more pressure sensors, temperature sensors, optical sensors and / or cameras, and / or saturation indicators.

[0041] Figure 3 illustrates an electronic assembly 300 that encloses an electronic unit within a housing. As illustrated in Figure 3, the housing of the electronic assembly 300 can include a plate 301 and a flexible film 302 that encloses an electronic unit 303 therein. The electronic unit 303 can include a pump 305, an inlet protector 310, a pump exhaust mechanism 306, a power supply 307, and a circuit board 309. The circuit board 309 can be flexible or substantially flexible.

[0042] As shown, the pump exhaust mechanism 306 can be an enclosure such as a chamber. The electronics unit 303 and pump 305 can be used without the inlet protection mechanism 310. However, the pump exhaust mechanism 306 and pump 305 can be seated within an extended casing 316.

[0043] The flexible film 302 can be attached to the plate 301 to form a fluid-tight seal and housing around the electronic components. The flexible film 302 can be attached to the plate at its periphery by heat welding, adhesive bonding, ultrasonic welding, RF welding, or any other attachment or bonding technique.

[0044] The flexible film 302 may include an aperture 311. The aperture 311 may allow the inlet protection feature 310 to be in fluid communication with the absorbent and / or permeable layers of the wound dressing. The periphery of the aperture 311 of the flexible film 303 may be sealed or attached to the inlet protection feature 310 by forming a fluid-tight seal and enclosure around the inlet protection feature 310, thereby keeping the electronic component 303 protected from fluids within the dressing. The flexible film 302 may be attached to the inlet protection feature 310 at the periphery of the inlet protection feature 310 by heat welding, adhesive bonding, ultrasonic welding, RF welding, or any other attachment or bonding technique. The inlet protection feature 310 may prevent wound exudate or liquid from the wound and collected within the absorbent area 160 of the wound dressing from entering the pump and / or electronic components of the electronic assembly 300.

[0045] The electronic assembly 300 illustrated in FIG. 3 can be incorporated into a wound dressing such that, as described herein, in communication with apertures in the casing 316 and circuit board 309, air from within the dressing can be pumped through the inlet protection mechanism 310 towards the pump exhaust mechanism 306 when the dressing is applied to a patient's body.

[0046] 4A and 4B illustrate an electronic assembly 400 including a pump inlet protection mechanism 410 sealed to the exterior of a flexible film 402, similar to that described with reference to Fig. 3. Also shown is an exhaust mechanism 406, which may be similar to exhaust mechanism 306.

[0047] FIG. 4A shows the wound-facing underside of the electronic assembly 400. FIG. 4B shows the top surface of the plate 401 (which may face the patient or user) of the electronic assembly 400. The top surface of the plate 401 may include an on / off switch or button cover 443 (shown as a pull tab), an indicator 444, and / or one or more vent holes 442. Removal of the pull tab 443 may cause activation of the electronic assembly 400, such as providing power from a power source to the electronic assembly. Further details of the operation of the pull tab 443 are described in PCT International Application No. PCT / EP2018 / 079745, filed October 30, 2018, entitled “SAFE OPERATION OF INTEGRATED NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES,” which is incorporated herein by reference in its entirety.

[0048] An electronic assembly 400 having a pump inlet protection mechanism 410 extending from and sealed to the film 402 may be positioned within the aperture 172 of the cover layer 113 and absorbent layer (122, 151) as shown in FIG. 1C. The periphery of the electronic assembly 400 may be sealed to the top surface of the outer periphery of the aperture 172 of the cover layer 113 as shown in FIG. 1C and described in more detail herein with reference to FIGS. 5A and 5B. The electronic assembly 400 may be sealed to the cover layer 113 using a sealant gasket, adhesive, heat welding, adhesive bonding, ultrasonic welding, RF welding, or any other attachment or bonding technique. The electronic assembly 400 may be permanently sealed to the cover layer 113 and cannot be removed from the cover layer without destroying the dressing.

[0049] In some embodiments, the electronic assembly 400 may be utilized with a single dressing and disposed of with the dressing, hi some cases, the electronic assembly 400 may be utilized with a series of dressings.

[0050] FIG. 5A shows a wound dressing, such as the one of FIG. 1C, incorporating an electronic assembly 500 into the wound dressing layer 590. FIG. 5B illustrates a cross-section of a wound dressing incorporating the electronic assembly of FIG. 5A. The electronic assembly 500 can be provided within an aperture 172 in the cover layer and apertures 129 and 128 in the first and second absorbent layers 122, 151. The electronic assembly 500 can be sealed to the periphery of the aperture 172 in the cover layer. The dressing can include a wound contact layer 110, a moisture vapor permeable film, a cover layer or backing layer 113 positioned over the contact layer 110 and other layers of the dressing. A layer of porous material 111 can be positioned above the wound contact layer 110. As used herein, the terms porous material, spacer, and / or transmission layer can be used interchangeably to refer to a layer of material configured to distribute negative pressure across the wound area within the dressing. This porous or permeable layer 111 allows fluids, including liquids and gases, to permeate away from the wound site into the upper layers of the wound dressing. Additionally, one or more absorbent layers (such as layers 122, 151) can be utilized to absorb and retain exudate drawn from the wound. One or more layers 122, 151 of absorbent material can be provided above the permeable layer 111. There can be a small aperture absorbent layer 151 and a large aperture absorbent layer 122. The absorbent layer 151 with small apertures can be positioned above the absorbent layer 122 that includes large apertures. In some cases, the absorbent layer 151 with small apertures can be positioned below the absorbent layer 122 with large apertures. Prior to use, the dressing can include one or more delivery layers 146 adhered to the bottom surface of the wound contact layer. The delivery layer 146 can cover the adhesive or apertures on the bottom surface of the wound contact layer 110.

[0051] 6A and 6B and 7A and 7B illustrate an electronic assembly 1500 having a pump inlet protection feature 1710 and a pump exhaust feature 1074 on a pump 1072. The assembly 1500 may include cavities 1082 and 1083 (shown in FIGS. 7A and 7B) on the pump inlet protection feature 1710 and the pump exhaust feature 1074, respectively. The inlet protection and pump exhaust features may be glued to the inlets and outlets of the pumps described herein. The assembly 1500 may be assembled using an adhesive and allowed to cure before incorporation into the electronic assembly.

[0052] The pump inlet may be covered by or fitted to the pump inlet protection mechanism 1710. The pump inlet protection 1710 may be pressed onto the pump inlet as illustrated by the arrow in FIG. 7A. This may be a friction fit. A port in the pump inlet protection 1710 that receives a portion of the pump inlet may be sized and shaped to complementarily fit around the pump inlet. The pump inlet protection 1710 may be bonded to the pump inlet using a silicone sealant or any other sealant or sealing technique. FIG. 7B illustrates the pump inlet protection mechanism 1710 covering the pump inlet and the pump exhaust mechanism 1074 covering the pump outlet. The pump exhaust mechanism 1074 may include one or more apertures or vents 1084 to allow gas drawn by the pump to be exhausted from the pump exhaust mechanism 1074. In some cases, the pump exhaust mechanism's return valve and / or filter membrane may be included within the pump exhaust mechanism 1074.

[0053] 7A and 7B illustrate a pump inlet protection mechanism 1710 and a pump exhaust mechanism 1074 having cavities 1082 and 1083. A pump assembly including the pump inlet protection mechanism 1710 and the pump exhaust mechanism 1074 can be disposed on a surface of a circuit board 1081. When the pump assembly is in contact with the surface of the circuit board 1081, the cavities 1082 and 1083 can at least partially enclose sensors on the circuit board 1081, such as pressure sensors 1091 and 1092 on the circuit board 1081, as illustrated in FIG.

[0054] Pressure sensors 1091 and 1092 shown in Figure 6B can be used to measure and / or monitor the pressure level at the wound and atmospheric pressure. Pressure sensor 1091 can be used to measure and / or monitor the pressure at the wound (e.g., under a wound dressing), which can be accomplished by measuring and / or monitoring the pressure in a fluid flow path connecting the negative pressure source or pump 1072 and the wound. Pressure sensor 1091 can measure and / or monitor the pressure in cavity 1082 of pump inlet protection mechanism 1710 shown in Figures 7A and 7B. Power source 1068 (shown as two batteries in Figure 6A) can provide power to the negative pressure source 1072 and the electronics.

[0055] A pressure sensor 1092 can be used to measure and / or monitor the pressure outside the wound dressing. The pressure sensor 1092 can measure and / or monitor the pressure within the cavity 1083 of the pump exhaust mechanism 1074 shown in Figures 7A and 7B. The pressure sensor 1092 can measure the pressure outside the wound dressing, which can be relative atmospheric pressure since atmospheric pressure varies depending on, for example, the altitude used, or the pressurized environment in which the TNP device may be used. These measurements can be used to establish a desired negative pressure differential (or set point) at the wound relative to the external pressure.

[0056] The circuit board 1081 (including any of the circuit boards described herein) may include at least control circuitry, such as one or more processors or controllers, that can control the delivery of negative pressure by the negative pressure source 1072 according to a comparison of the pressure monitored by pressure sensor 1091 and the pressure monitored by pressure sensor 1092. The control circuitry may operate the negative pressure source 1072 in a first mode (which may be referred to as an initial pump-down mode) in which the control circuitry activates the negative pressure source 1072 to establish a negative pressure set point at the wound. The set point may be set to a value in the range of, for example, about -70 mmHg to about -90 mmHg, among others. Once the set point is established, which may be verified based on the difference between the pressure measured by pressure sensor 1091 (or wound pressure) and the pressure measured by pressure sensor 1092 (or external pressure), the control circuitry may stop (or pause) the operation of the negative pressure source 1072. The control circuit may operate the negative pressure source 1072 in a second mode (which may be referred to as a maintenance pump down mode) in which the control circuit periodically activates the negative pressure source 1072 to re-establish the negative pressure set point when the wound is depressurized as a result of one or more leaks. The control circuit may activate the negative pressure source 1072 in response to the wound pressure (monitored by the pressure sensor 1091) becoming more positive than a negative pressure threshold, which may be set to the same or a lower negative pressure as the set point.

[0057] Embodiments of the wound dressings, wound treatment devices, and methods described herein may be combined with or in addition to one or more features described in PCT International Application No. PCT / EP2017 / 060464, entitled "NEGATIVE PRESSURE WOUND THERAPY DEVICE ACTIVATION AND CONTROL," filed May 3, 2017; U.S. Pat. No. 8,734,425; and U.S. Pat. No. 8,905,985, each of which is incorporated by reference in its entirety herein.

[0058] One or more self-adhesive gaskets can be applied to the pump inlet protection feature 1710 and the pump exhaust feature 1074 to seal the pump inlet and pump exhaust cavities 1082 and 1083 around the sensors on the circuit board 1081, as well as around the exhaust feature vents and corresponding vents of the circuit board 1081 (as described herein). A preformed adhesive sheet can be used to form sealing gaskets between the pump inlet and pump exhaust cavities 1082 and 1083 and the sensors on the circuit board 1081, as well as between the exhaust feature vents and the vents of the circuit board 1081. In some cases, adhesive can be used to seal the pump inlet protection 1710 and the pump exhaust feature 1074 cavities 1082 and 1083 around the sensors on the circuit board 1081, as well as around the exhaust feature vents 1084 and corresponding vents of the circuit board. As described herein, the electronic assembly 1500 may be embedded within a layer of the dressing, such as within a notch or recess within which the electronic assembly may be placed.

[0059] The pump inlet protection feature 1710 can provide a large surface area available for the vacuum drawn by the pump inlet. The pump inlet (shown as a rounded protrusion in FIG. 7A ) can fit within a recess in the pump inlet protection feature 1710. The pump inlet can be attached by a friction fit and / or can form a complementary fit with the recess in the pump inlet protection feature.

[0060] The pump inlet protection mechanism 1710 can allow air or gas to pass through but can block liquid from reaching the negative pressure source. The pump inlet protection mechanism 1710 can include a porous material. The pump inlet protection mechanism 1710 can include one or more porous polymeric molded components. The pump inlet protection mechanism 1710 can include a hydrophobic or substantially hydrophobic material. The material included in the pump inlet protection mechanism 1710 can have a pore size ranging from approximately 5 microns to approximately 40 microns. In some cases, the pore size can be approximately 10 microns. The pump inlet protection mechanism 1710 can include a polymer that can be one of a hydrophobic polyethylene or a hydrophobic polypropylene. In some cases, the pump inlet protection mechanism can include a Porvair Vyon material having a pore size of 10 microns. Any of the pump inlet protection mechanisms described herein can include one or more features of the pump inlet protection mechanism 1710.

[0061] The pump exhaust mechanism 1074 (or any of the pump exhaust or outlet mechanisms described herein) may include a check valve or check valve 1210, as shown in FIG. 8. The check valve 1210 may be any suitable mechanical one-way valve, such as, for example, a reed valve, a duckbill valve, a ball valve, a loose-leaf valve, or an umbrella valve, among others. The check valve may be similar to any of the check valves described in PCT International Application No. PCT / EP2017 / 055225, entitled "WOUND TREATMENT APPARATUSES AND METHODS WITH NEGATIVE PRESSURE SOURCE INTEGRATED INTO WOUND DRESSING," filed March 6, 2017, which is incorporated herein by reference in its entirety. The pump exhaust mechanism 1074 may be bonded to the outlet of the pump using a sealant, for example, a silicone sealant. The outlet or exhaust of the pump exhaust mechanism 1074 can include an antimicrobial film and / or other filter membrane that filters gases that are exhausted outside the NPWT system, such as the atmosphere. As shown, the pump exhaust mechanism 1074 can be a substantially sealed housing or chamber to prevent ingress of gases or fluids other than through the vent 1084.

[0062] Any of the embodiments described herein may be incorporated by reference in any of the following applications: International Application No. PCT / EP2018 / 074694, filed September 13, 2018, entitled "NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES AND METHODS WITH INTEGRATED ELECTRONICS"; International Application No. PCT / EP2018 / 074701, filed September 13, 2018, entitled "NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES AND METHODS WITH INTEGRATED ELECTRONICS"; International Application No. PCT / EP2018 / 079345, filed October 25, 2018, entitled "NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES AND METHODS WITH INTEGRATED ELECTRONICS"; International Application No. PCT / EP2018 / 079345, filed March 10, 2020, entitled "EXHAUST BLOCKAGE DETECTION FOR NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES AND METHODS WITH INTEGRATED ELECTRONICS"; The present invention may further or alternatively include one or more features described in International Application No. PCT / EP2020 / 056317, entitled "PRESSURE WOUND TREATMENT APPARATUSES," each of which is incorporated herein by reference in its entirety.

[0063] Reverse polarity protection It may be important to protect any of the electronic devices described herein, such as the electronic unit 267 or electronic assembly 1500, from reverse current. Reverse current may damage one or more electronic components, which may cause one or more of an unsafe delivery of therapy or an interruption of therapy. As described herein, reverse current may be caused by bending a circuit board of the electronic unit or electronic assembly. FIG. 9A shows a circuit 1505A through which a reverse current 1508 may flow. The circuit 1505A may include two battery cells 1502 and 1504 (which may correspond to the power source 1068). In some cases, the battery cells 1502 and 1504 may be connected in series to increase the output voltage. For example, each of the battery cells 1502 and 1504 may be a 3V cell, and the combined output of both cells may be 6V. The combined output of both cells may be referred to as a high voltage. The output of one of the battery cells, such as the battery cell 1502, may be referred to as a low voltage (e.g., 3V). In some cases, the output (or low voltage) of one of the battery cells can provide power to one or more electronic components to the controller via connection 1545, as shown in FIG. 9B. The low voltage power connection 1545 can be at the same potential as the LAT_IN terminal described herein. Both outputs of the battery cells (or high voltage), which may be enabled by the latch circuit described herein, can power one or more other electronic components, such as a negative pressure source. Reverse current 1508 can undesirably flow from the positive terminal of one of the battery cells to another terminal of one of the battery cells (which may be the positive terminal, as shown in FIG. 9A).

[0064] The battery cell 1502 may have terminals 1514 and 1512 (which may be positive and negative terminals, respectively). The battery cell 1504 may have terminals 1518 and 1516 (which may be positive and negative terminals, respectively). The fuse 1582 may protect the circuit 1505A from an overcurrent provided by one or more battery cells (such as the battery cell 1502 or both battery cells 1502 and 1504). Although multiple fuses 1582 are illustrated in FIG. 9A, only one fuse will be thrown into the circuit 1505A during manufacturing. The multiple fuses (such as three fuses) illustrate three possible fuse footprints formed on the circuit board from which a single appropriate fuse 1582 may be selected during manufacturing. The fuse 1584 may protect the circuit 1505A from an overcurrent provided by both battery cells. Although multiple fuses 1584 are illustrated in FIG. 9A, only one fuse 1584 will be thrown, as described herein. The fuses 1582 and 1584 may be connected to the terminals of the respective battery cells 1502 and 1584 before any other electronic components are connected to the battery cells.

[0065] The components of the circuit 1505A may be supported by a circuit board. As described herein (such as with respect to the circuit board 276), the circuit board may be flexible or substantially flexible to accommodate positioning on and wear by the patient. Bending of the board may result in shorting the circuit ground connection to the high voltage supply rail (connected to the positive terminal 1518), which may cause the fuse 1582 to open (or blow). As shown, a reverse current path may be created in which current flows to the positive terminal of either the battery cell 1504 or 1502. The reverse current 1508 may flow from the positive terminal of the high voltage supply rail (such as the positive terminal 1518 of the battery cell 1504), through the diode 1503, and into the positive terminal of the low voltage supply rail (such as the positive terminal 1514 of the battery cell 1502). The diode 1503 may be configured to provide protection against electrostatic discharge. The diode 1503 may be a Zener diode. In some cases, the fuse 1582, even after it has been blown, may not protect against reverse current 1508. Reverse current flow may be undesirable, for example, because it may increase the temperature or damage either one or both of the battery cells or other circuit components (which may be supported by a wound dressing positioned on the patient), causing discomfort to the patient, burning the patient, or otherwise compromising the patient's comfort or safety, as well as initiating a fire.

[0066] Referring to FIG. 9B, the switch 1520 can provide reverse current (or reverse polarity) protection to the illustrated circuit 1505B. As shown, the switch 1520 can be a transistor (such as a p-channel FET or PNP transistor) with a body diode connected in parallel across the transistor. Under normal operating conditions, the body diode is forward biased (or conducting), which places the source terminal (S) of the switch 1520 at about 2.4V and the gate terminal (G) at about 0V. As a result, the switch 1520 turns on, thereby allowing current to flow across the transistor (whose internal resistance may be relatively small, such as about 50mOhms or less or more), bypassing the body diode. Under a fault condition (such as when the circuit ground connection is shorted to a high voltage supply rail), the gate terminal (G) voltage will be equal to or greater than the source terminal (S) voltage. As a result, the switch 1520 turns off, which can block the flow or reverse current. In some cases, the body diode can block reverse current flow (e.g., because the body diode is reverse biased). Thus, the switch 1520 and the body diode can provide reverse polarity protection without incurring a diode forward voltage drop, thereby allowing full power to be provided to one or more electronic components, such as the controller 1550.

[0067] In some instances, a diode (such as a Schottky diode) or a transistor with a resistor can be used as a switch to provide reverse polarity protection (e.g., instead of the transistor and body diode shown in FIG. 9B). Schottky diodes can have a low forward voltage drop. As a result, when such a Schottky diode is forward biased, less energy is wasted as heat and efficient power delivery to one or more electronic components can be achieved.

[0068] Improved latch circuit As described herein, a play / pause switch (such as switch 265) may be configured to start and pause the delivery of negative pressure wound therapy. It may be advantageous to prevent inadvertent activation of the electronics during manufacture, shipping, or storage for a variety of reasons, including conserving power source capacity, preventing the initiation of an end-of-life countdown for a device configured to provide therapy for a limited period of time (such as 7 days), or preventing an accident during manufacturing (such as the creation of a spark that ignites gases used for sterilization). To prevent inadvertent activation, the electronics may include circuitry for isolating at least some of the electronic components from the power source. For example, such circuitry may isolate the negative pressure source from a high voltage power source (such as a 6V source). As described herein, an activation switch (such as pull tab 443) may be located on an exterior surface for easy access by a user. As described herein, removal of the pull tab may cause activation of the electronics.

[0069] FIG. 10A illustrates a circuit 1600A that can isolate a negative pressure source. The circuit 1600A can include a power source 1602, and pins or terminals LAT_IN 1612 (representing a latch circuit pin-in) and LAT_OUT 1614 (representing a latch circuit pin-out). The power source 1602 can be connected to the terminal 1612. The power source 1602 can correspond to the output of the battery cells 1502 and 1504 connected in series and provide a high voltage. The latch circuit 1605 can be interposed between the power source 1602 and one or more electronic components that draw power (such as current) from the power source 1602. As illustrated, the negative pressure source 1604 can draw power from the power source 1602 and connect to the LAT_OUT terminal 1614. When the latch circuit 1605 is in an on state (or activated state), current can flow between the terminals 1612 and 1614. When the latch circuit 1605 is in the off state (or stopped state), no current flows between terminals 1612 and 1614, regardless of the state of the play / pause switch.

[0070] The latch circuit 1605 may include an activation switch or control 1620 (e.g., a pull tab). When the activation control 1620 is not activated (e.g., the pull tab is not removed), switches 1632 and 1634 (shown as transistors) are off so that no current flows between terminals 1612 and 1614. When the activation control 1620 is activated (e.g., the pull tab is removed), current from the power source 1602 can flow (e.g., to ground). This turns on switch 1632 (e.g., a p-channel FET or PNP transistor), which allows current to flow between terminals 1612 and 1614. Turning on switch 1632 may turn on switch 1634 (e.g., an n-channel FET or NPN transistor). The gate of switch 1636 may be connected to a capacitor 1636, which may be charged as a result of the current flow between terminals 1612 and 1614. As long as the capacitor 1636 remains charged, the switch 1636 may remain on, which in turn may keep the switch 1632 on. As a result, the latch circuit 1605 may be a self-latching circuit. The latch circuit 1605 may operate such that when the activation control 1620 is activated, the circuit 1605 remains activated and allows current flow between the terminals 1612 and 1614.

[0071] When the latch circuit 1605 is in an on state (or active state) and allows current flow between terminals 1612 and 1614, the negative pressure source 1604 can receive power from the power source 1602. As a result, the delivery of negative pressure wound therapy can be controlled via the play / pause switch.

[0072] The switch 1632 (or switch 1634) can be a transistor with a lower gate threshold voltage. This can facilitate one or more of reducing power dissipated by the transistor in the event of a short circuit (e.g., as a result of the transistor's low on-resistance) or reducing the time until the fuse opens (as described below). For example, the transistor's gate threshold voltage can be -1.0V or less, -0.5V or less, -0.4V or less, etc. Further details of the latch circuit are disclosed in U.S. Publication No. 2020 / 0338243, published October 29, 2020, entitled "SAFE OPERATION OF INTEGRATED NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES," which is incorporated herein by reference in its entirety.

[0073] In some cases, the latch circuit 1605 may be inadvertently activated. For example, during manufacturing, at least a portion of the electronic components may be coated with a water-resistant material. The coating may be cured by exposure to high temperature or light (such as ultraviolet (UV) light). During curing, the switch 1632 may be inadvertently turned on through exposure to one or more of the high temperature or light. This may occur as a result of an increase in leakage current through the switch 1632, which may charge the capacitor 1636 and cause the switch 1634 to turn on.

[0074] To prevent unintentional activation, the approach illustrated in Figures 10B, 10C, and 10D may be used. Referring to Figure 10B, circuit 1600B may be similar to circuit 1600A, except that an activation switch or control 1622 is positioned as shown in circuit 1600B. The activation control 1622 may be a pull tab. When the activation control 1622 is activated (e.g., the pull tab is removed), the LAT_OUT terminal 1614 is connected to ground. As a result, the current provided by the power supply 1602 flows to ground instead of the negative pressure source 1604, thereby preventing activation of the negative pressure source. In this implementation, the activation control 1622 may be activated during manufacturing to prevent inadvertent activation and then deactivated. For example, the pull tab may be removed during curing and then reinstalled.

[0075] In some instances, the activation control 1622 may be an optical sensor (such as a photodiode) that turns on in response to exposure to light. For example, the optical sensor may be turned on by exposure to light during curing. After curing is complete, the optical sensor turns off.

[0076] 10C, circuit 1600C may be similar to circuits 1600A and 1600B, except that a temporary link 1624 (such as a jumper) to ground is positioned as shown. The temporary link 1624 may be a pull tab or another conductive component. The temporary link 1624 may be positioned in circuit 1600C to prevent unintentional activation, for example, during manufacturing. The temporary link 1624 may then be removed to allow activation and delivery of negative pressure wound therapy.

[0077] Referring to circuit 1600D of FIG. 10D, controller 1550 can detect inadvertent activation and implement appropriate corrective action. Controller 1550 can control interface 1628 (which can be a switch, such as a transistor). For example, controller 1550 can have an analog output that controls interface 1628. Controller 1550 can activate interface 1628 (such as turning on a transistor), which can connect line 1626 (connected to LAT_OUT terminal 1614) to ground. As a result, capacitor 1636 is discharged, turning off switch 1634, which in turn turns off switch 1632. Effectively, this deactivates the latch circuit. The current provided by power supply 1602 flows to ground rather than to negative pressure source 1604, thereby preventing operation of the negative pressure source.

[0078] During manufacturing, the controller 1550 can be activated (e.g., by touching a test point on the circuit board). Activating the controller 1550 can be performed to ensure that the controller is operational. As described herein, the controller 1550 can operate in a low power mode (e.g., sleep mode) until one or more of the latch circuits are activated and the play / pause button is activated (e.g., pressed). The controller 1550 can monitor the duration since being activated. The controller can also be connected to the LAT_OUT 1614 terminal. After expiration of a threshold period, the controller 1550 can allow current flow to the LAT_OUT terminal 1614 by not activating the interface 1628. The period can be long enough to accommodate one or more of the completion of manufacturing (during which inadvertent activation may occur) and transporting the device to a medical facility for use on a patient. In some cases, the period can be 24 hours or less, 36 hours, 48 ​​hours or more, etc.

[0079] Activation of the latch circuit 1605 before the expiration of the period is likely caused by inadvertent activation. Thus, the controller 1550 can activate the interface 1628, which prevents current flow from the power source 1602 to the LAT_OUT terminal 1614 and prevents activation of the negative pressure source. In some cases, the circuit 1600D can include one or more of the activation control 1622 or the temporary link 1624.

[0080] Play / Pause Switch As described herein, the play / pause switch (such as a button or slide switch) can allow a user to apply or pause the application of negative pressure wound therapy. An output from the play / pause switch can be provided to a controller, which can determine whether the play / pause switch has been activated or deactivated. In response to activation of the play / pause switch (such as pressing a button or sliding a slide switch), the controller can attempt to activate the negative pressure source. When the latch circuit is activated (e.g., current is provided from the power source 1602) such that power is provided to the negative pressure source, the controller can activate the negative pressure source and provide negative pressure wound therapy. However, if the latch circuit is not activated (e.g., because the activation control 1620 is not activated), the controller cannot activate the negative pressure source because the negative pressure source is isolated from the power source.

[0081] In some cases, power to the play / pause switch may be provided from a power source not controlled by the latch circuit. For example, low voltage power to the play / pause switch from one of the battery cells by connecting the play / pause switch to the LAT_IN terminal (which may be connected to a 3V power source, for example). Activation of the play / pause switch may cause the controller to perform one or more actions related to attempting to activate the negative pressure source, regardless of the activation state of the latch circuit. This may cause unnecessary consumption of power (e.g., from the battery cell 1502) because the controller will attempt to activate (or deactivate) the negative pressure source in response to activation of the play / pause button (e.g., a button press or slide of a slide switch, etc.) even when the latch circuit is not activated. In some cases, to conserve power, the controller may operate in a low power mode (e.g., a sleep mode) when the latch circuit is not activated. In response to receiving an output from the play / pause button, the controller may be configured to 1) switch its mode of operation to a higher power mode (e.g., wake up from sleep), 2) attempt to activate (or deactivate) the negative pressure source, 3) determine that such attempt has failed because the latch circuit has not been activated, and 4) revert to operating in the lower power mode. Performing these actions may result in unnecessary waste of power.

[0082] Alternatively, it may be advantageous to provide power to the play / pause switch from a power source isolated by a latch circuit. In this way, if the latch circuit is not activated, the play / pause switch may not provide any output in response to being manipulated (e.g., pressed by a user). In some cases, the play / pause switch may be connected to the LAT_OUT terminal 1614 (e.g., 6V). FIG. 11 illustrates a circuit 1700 embodying such an implementation. A play / pause switch 1720 (e.g., a button) may be connected to an output of the latch circuit 1605, which may be LAT_OUT. As shown, a resistor R45 may be interposed between the LAT_OUT terminal 1614 and the play / pause switch 1720. An output 1730 of the play / pause switch 1720 may be provided to the controller 1550. The output 1730 may be a signal corresponding to the output at the LAT_OUT terminal 1614 (e.g., 6V). Advantageously, the play / pause switch 1720 may provide an output (such as the voltage provided by the LAT_OUT terminal) only when the latch circuit 1605 is activated, which may be triggered by activation of the activation control 1620.

[0083] In some cases, the play / pause switch can relay one or more outputs to the controller 1550 beyond binary on and off. For example, multiple sequential button presses (or switch slides) can power off the electronics (e.g., one or more of disabling a latch circuit, or operating the controller in a low power mode, which may be accomplished by discharging the capacitor 1636 as described herein). As another example, multiple different sequential button presses (or switch slides) can cause adjustment of one or more parameters of the negative pressure wound therapy, such as the negative pressure set point, the duty cycle of the negative pressure source, etc. As yet another example, a short button press (or switch slide) can cause negative pressure to be applied for a limited period of time (e.g., to facilitate testing and validation during manufacturing). As yet another example, a long button press (or switch slide) can power off the electronics, for example, after testing and validation during manufacturing is completed. The controller may detect one or more of a variety of different press sequences or durations of one or more button presses (or switch slides) and take appropriate action (or have appropriate action taken) in response to the detection. Such detection (or any of the other detections disclosed herein) may be performed by the controller executing appropriate firmware or software. Advantageously, even though the play / pause switch may be the single control provided to the user, the play / pause switch may be used to provide a variety of multiple user inputs.

[0084] Overcurrent Protection 9A, fuses 1582 and 1584 can provide overcurrent protection (or provide overcurrent protection) for battery cells 1502 and 1504, respectively. Although multiple fuses F1-1 through F1-3 (also referred to as group F1-x) and F2-1 through F2-3 (also referred to as group F2-x) are illustrated, in some cases only one fuse from each of groups F1-x and F2-x may be embedded on the circuit board represented by circuit 1505A. As illustrated in FIG. 9A, only fuses F1-1 and F2-1 may be thrown on the circuit board.

[0085] The fuses 1582 and 1584 may be configured to provide protection against overcurrent. Overcurrent may be caused by liquid intrusion (such as liquid aspirated from a wound), which may cause one or more short circuits. For example, the fuse 1582 may protect against overcurrent when the battery cell 1502 alone or both the battery cells 1582 and 1584 provide power. The fuse 1582 may be configured to open (or blow) when the current in the circuit meets a first maximum current threshold. As another example, the fuse 1584 may protect against overcurrent when both the battery cells 1502 and 1504 provide power. The fuse 1584 may be configured to open when the current in the circuit meets a second maximum current threshold (which may be the same or different from the first maximum current threshold). In some cases, the second maximum current threshold current may correspond to a maximum current threshold of the negative pressure source 1604. In some embodiments, the first maximum current threshold current may correspond to a maximum current threshold of the controller 1550.

[0086] In some cases, at least one of the fuses 1582 or 1584 may be configured to open when the current in the circuit does not meet a first or second maximum current threshold. For example, the second maximum current threshold may be about 500 mA (or less or more), which may correspond to the maximum current threshold of the negative pressure source. However, the fuse 1584 may be selected to be configured to open at a current less than the maximum current of the negative pressure source when the negative pressure source is operating discontinuously such that the negative pressure source is unlikely to consume full power. For example, the negative pressure source may be started and stopped for alternating durations (such as pulse on and pulse off). In such cases, the negative pressure source is unlikely to draw the full power provided to it. As a result, the fuse 1584 may be selected to be configured to open at a current less than 500 mA. Advantageously, this may promote additional patient protection and safety.

[0087] Selecting one or more of the fuses 1582 and 1584 may also involve temperature considerations. The electronics may be supported by a dressing positioned on the patient, allowing one or more electronic components to increase in temperature as a result of excessive (or near excessive) current flow, causing discomfort to the patient, burning the patient, or compromising the patient's comfort or safety and potentially causing a fire. To address such risks, one or more of the fuses 1582 or 1584 may be fast acting fuses. Such fuses may have a fast response time for opening (e.g., about 5 seconds or less or more). As a result, one or more of the fuses 1582 or 1584 may advantageously act quickly to protect the patient from overcurrent and temperature. To facilitate conserving power supply capacity, it may be advantageous to select a fuse with a lower resistance. For example, the resistance of the fuse may be about 200 mOhms (or less or more).

[0088] One or more of fuses 1582 or 1584 may be a one-time fuse that will need to be replaced after providing overcurrent protection, or a resettable fuse (or positive temperature coefficient, PTC) that can provide overcurrent protection multiple times before requiring replacement.

[0089] FIG. 12A illustrates a layout 1800A of a circuit board. Region 1810 can indicate where fuse F1 is located (this fuse is removed from the circuit board for ease of illustration). As shown, region 1810 includes a conductive metal (such as copper) that surrounds fuse F1. The conductive metal can be part of a ground or power plane of the circuit board. Such a design can be disadvantageous because the conductive metal can provide a heat sink for fuse F1. In some cases, it can be important to allow the fuse to "warm up" so that it blows quickly when an overcurrent is applied. Being surrounded by conductive metal can prevent fuse F1 from warming up. As a result, there can be an undesirable delay before fuse F1 reaches the temperature required to blow.

[0090] Thermal isolation can solve these problems. Figures 12B and 12C show layouts 1800B and 1800C of a circuit board (which may be a double-sided or two-layer printed circuit board) on which thermal isolation of fuse F1-1 (and other fuses F1-2, F1-3) is implemented. Layout 1800B of Figure 12B may illustrate the top layer of the circuit board. One or more electronic components may be located on the top layer. As illustrated by the blank space (or void) in region 1820, conductive metal (such as copper) is removed from the area of ​​the top layer where fuse F1-1 (and other fuses F1-2 and F1-3) are located. Conductive metal may also be removed from the area surrounding fuse F1-1 (and other fuses F1-2 and F1-3). Such removal of conductive metal may prevent the formation of a heat sink on the top layer of fuse 1582.

[0091] Layout 1800C of FIG. 12C may illustrate the bottom layer of a circuit board. The bottom layer may be used primarily for wiring and soldering. As illustrated by the blank space (or void) in region 1820, conductive metal (such as copper) is removed from the area on the bottom layer where fuse F1-1 (as well as other fuses F1-2 and F1-3) are located. Conductive metal may also be removed from the area surrounding fuse F1-1 (as well as other fuses F1-2 and F1-3). Such removal of conductive metal may prevent the formation of a heat sink on the bottom layer of fuse 1582.

[0092] 12D and 12E illustrate layouts 1800D and 1800E of a circuit board in which thermal isolation of fuse F2-1 (as well as other fuses F2-2 and F2-3) is implemented. Layout 1800D of FIG. 12D may illustrate a top layer of a circuit board. As illustrated by the blank space (or void) in region 1830, conductive metal (such as copper) is removed from the area of ​​the top layer where fuse F2-1 (as well as other fuses F2-2 and F2-3) is located. Conductive metal may also be removed from the area surrounding fuse F2-1 (as well as other fuses F2-2 and F2-3). Such removal of conductive metal may prevent the formation of a heat sink on the top layer of fuse 1584.

[0093] Layout 1800E of FIG. 12E may illustrate a bottom layer of a circuit board. As illustrated by the blank space (or void) in area 1830, conductive metal (such as copper) is removed from the area on the bottom layer where fuse F2-1 (as well as other fuses F2-2 and F2-3) are located. Conductive metal may also be removed from the area surrounding fuse F2-1. Such removal of conductive metal may prevent the formation of a heat sink on the bottom layer of fuse 1584.

[0094] The removal of the conductive metal can provide clearance around one or more of the fuses 1582 or 1584. For example, the clearance can be about 2-3 mm (or less or more). In addition to providing thermal insulation, the clearance can avoid the creation of shorts and blowing one or more of the fuses due to bending or cracking of the printed circuit board (which can be flexible or substantially flexible).

[0095] In some cases, the circuit board may be a single layer printed circuit board or a printed circuit board having more than two layers. Similar approaches to thermal isolation may be implemented with such circuit boards.

[0096] In some implementations, one or more of the fuses 1582 or 1584 can be replaced with a current-limited load switch (such as a Texas Instrument TPS255xx series switch). The current-limited load switch can have an adjustable current limit and can be configured to open at a desired maximum current threshold. The current-limited load switch can have a low resistance (which can be advantageous to conserve power supply capacity). For example, the resistance can be about 85 mOhms (or less or more), which may be lower than the resistance of a fuse. The current-limited load switch can open the circuit quickly (i.e., has a short latch-off time, such as about 10 milliseconds or less), which can be faster than a fuse.

[0097] As mentioned above, switch 1632 (or switch 1634) can be a FET with a lower gate threshold voltage, which can reduce the time it takes for one or more of fuses 1582 or 1584 to open because such a switch can conduct increased current (e.g., as a result of the reduced impedance of the FET). As a result, this can allow the fuse to respond more quickly to an overcurrent.

[0098] In some cases, not all portions of the conductive traces or tracks in the circuit board are protected by the fuse(s) 1582 or 1584. Such portions may be referred to as unfused tracks. Because the circuit board may be flexible or substantially flexible, it may be advantageous to increase the clearance (or separation) between the unfused track(s) and the conductive components proximate such track(s). With reference to FIG. 13, region 1902 illustrates terminal 1512 of battery cell 1502. With reference to FIG. 9A, this terminal is positioned in front of fuse 1582, resulting in an unfused track. It may be advantageous to increase the clearance between terminal 1512 and the proximal conductive components (such as a ground plane). The increased clearance may be at least twice (or more) the thickness of the printed circuit board. For example, the clearance may be about 2-3 mm (or less or more).

[0099] With reference to FIG. 13, area 1904 illustrates terminal 1518 of battery cell 1504. With reference to FIG. 9A, this terminal is positioned in front of fuse 1584, resulting in an unfused track. It may be advantageous to increase the clearance between terminal 1518 and proximal conductive components (such as power planes). The increased clearance may be at least twice the thickness of the printed circuit board (or more). For example, the clearance may be about 2-3 mm (or less or more).

[0100] Increasing the clearance can advantageously prevent shorting of the terminals of one or more battery cells and can improve electrical insulation. One or more of the battery cells can reach high temperatures (such as about 90° C. or higher) when shorted, which can cause discomfort to the patient, burn the patient, or start a fire. Increasing the clearance can promote patient comfort and safety.

[0101] Referring to FIG. 9A, groups of fuses F1-x and F2-x are illustrated. As described herein, only one of each fuse of the group may be thrown onto the circuit board. Due to the miniaturization of the circuit board, the footprints of fuses F1-1, F1-2, and F1-3 in group F1-x and the three fuses F2-1, F2-2, and F2-3 in group F2-x may be positioned close to each other. As a result, there may be a risk of creating a short circuit with the exposed footprint of an unpopulated fuse, especially when the circuit board is flexed. For example, the fuses may be positioned on the circuit board using surface mount technology (SMT). SMT may utilize solder balls to attach the fuses onto the circuit board, which creates a risk of splashes, residue, whiskers, etc., which may create one or more short circuits.

[0102] To solve these problems, painting with a solder mask can be used to prevent the formation of electrical connections with the exposed terminals of the uninstalled fuse. The areas not painted with solder mask can correspond to conductive areas where one or more electrical connections are to be made. With reference to FIG. 14A, which illustrates the formation of electrical connections for fuse F2-1, areas 2002 and 2004 may not be covered with solder mask when the circuit board is manufactured. The manufacturing process may have sufficient precision and tolerance to correctly position the solder mask while excluding areas as small as 2002 and 2004. Areas 2002 and 2004 can correspond to the location of the terminals or pads of fuse F2-1. With reference to FIG. 14B, the manufacturing process may then form solder paste in areas 2002 and 2004 where no solder mask is located. These areas of solder paste are illustrated as 2012 and 2014. Conductive pads (which may be formed, for example, from gold) may be created in regions 2002 and 2004 after painting with a solder mask (as shown in FIG. 14A) and prior to the formation of the solder paste. As a result, electrical contacts for fuse F2-1 may be formed without risk of creating one or more shorts with the exposed terminals of the surrounding fuses F2-2 and F2-3. A similar approach may be used to form electrical connections for fuses F1-x (such as fuse F1-1). The use of a solder mask may facilitate precise control of the placement of the conductive components and avoid the creation of shorts.

[0103] liquid ingress protection It may be possible for liquid to enter the electronic assembly of the TNP system (such as any of assemblies 400, 500, or 1500). This may be particularly likely when the electronic assembly is positioned on a dressing that is placed on a patient, as described herein. For example, wound exudate absorbed by the dressing may penetrate the electronic assembly even if the assembly is sealed. As another example, condensation may form. As yet another example, the patient may expose the electronics to liquid (e.g., by taking a shower while the wound dressing is positioned on the patient). With reference to FIG. 15, liquid may enter the electronic assembly 2000 through the pump inlet protection mechanism 1710 (e.g., because the negative pressure source can draw fluid through an inlet covered by the inlet protection mechanism 1710). With reference to FIG. 15, liquid may enter through the pump exhaust mechanism 1074 (e.g., through one or more vents 1084). Wound exudate, other bodily fluids (such as blood) that may be introduced into the wound, or medicinal fluids may be conductive and, if in contact with the electronics, may undesirably interfere with the operation of the TNP system, causing discomfort or injury to the patient. To ensure patient comfort, safety, and correct delivery of therapy, it may be advantageous to detect the intrusion of liquid and take one or more corrective actions in response to the detection. The one or more corrective actions may include at least one of providing an indication (such as via one or more indicators described herein), pausing or stopping the negative pressure source, stopping the TNP system (such as temporarily or permanently), and the like. For example, the TNP system may prevent the user from reactivating the application of negative pressure during a first period of time (e.g., based on the time required to clear an error caused by the liquid ingress) and allow the user to reactivate the application of negative pressure after the expiration of the first period of time. Additionally, the TNP system may permanently disable reactivation of the application of negative pressure.

[0104] With reference to FIG. 15, a pressure sensor (such as pressure sensor 1091) may be positioned to measure pressure in a fluid flow path connecting the negative pressure source 1072 to the wound. The pressure sensor 1091 may be positioned in or proximal to the pump inlet protection mechanism 1710. In addition to measuring pressure, the pressure sensor 1091 may measure a temperature, such as an internal temperature of the TNP system or one or more electronic components. Another pressure sensor (such as pressure sensor 1092) may measure the pressure of the surrounding environment. In addition to measuring pressure, the pressure sensor 1092 may measure a temperature, such as an external temperature. The pressure sensor 1092 may be positioned in or proximal to the pump exhaust mechanism 1074 (which may be in fluid communication with the surrounding environment). To facilitate communication with the surrounding environment, there may be one or more vents 1084 in the pump exhaust mechanism 1074, as shown in FIG. 15. Additionally, there may be one or more vents in a portion of a circuit board (such as the circuit board 1081) proximate to the one or more vents 1084.

[0105] 16 shows a block diagram 2100 of the electronics of the TNP system (which may be any of the systems described herein). The electronics may be positioned on the wound dressing as described herein. The electronics may include an internal pressure sensor 1091, an external pressure sensor 1092, a negative pressure source 1072, a controller 2110 (which may be any of the controllers described herein, such as controller 1550), digital signal lines or traces (hereinafter lines) 2122 and 2124, and memory 930. Lines 2122 and 2124 may support a digital communication protocol between controller 2110 and one or more of memory 930, pressure sensor 1091, or pressure sensor 1092. The digital communication protocol may include an I 2 It can be C, PMBus, SMBus, SPI, USB, BMS, IEEE1394 (or Firewire), CAN, etc. For example, lines 2122 and 2124 are 2The wires 2122 and 2124 may be serial data (SDA) and serial clock (SCL) lines used by the TNP protocol. The internal pressure sensor 1091 and / or the external pressure sensor 1092 may measure the pressure in the fluid flow path. One or more of the wires 2122 and 2124 may be electrically connected to the internal pressure sensor 1091 and / or the external pressure sensor 1092. For example, at least a portion of one or more of the wires 2122 and 2124 may not be coated with a water-resistant material. This may be due to exposing one or more test points used during manufacturing (such as for verification). Alternatively or additionally, a portion of the wires 2122 and 2124 (or any other conductive wire or trace) may be exposed to create a conductive path to detect the occurrence of liquid intrusion. For example, a guard ring for detecting liquid intrusion may be created. Further or different areas of the TNP system may be exposed to detect liquid intrusion. As described herein, the TNP system may detect liquid intrusion using digital signal traces (e.g., by detecting shorts across electrical wires) and / or analog signal traces (e.g., by detecting shorts to ground).

[0106] The pressure sensors 1091, 1092 and the controller 2110 may be supported by a circuit board, such as the circuit board 1081. For example, the lines 2122 and 2124 may be electrical traces on or within the circuit board 1081 that connect one or more of the pressure sensors 1091, 1092, and the controller 2110. The circuit board 1081 may support one or more electrical traces for transmitting one or more digital signals and one or more electrical traces for transmitting one or more analog signals.

[0107] Liquid ingress detection may be performed by detecting degradation of the digital signal (such as any one or more of an attenuation, interruption, decrease, change, or decrease). For example, liquid ingress detection may be performed by detecting a short between line 2122 and line 2124 (which may be performed by detecting an I 2(which may correspond to the SDA and SCL lines of the I.C protocol). The lines 2122 and 2124 may electrically connect the controller 2100 to one or more of the pressure sensors 1091, 1092. During normal operation, data and clocks may be transmitted across the lines 2122 and 2124. As a result of liquid ingress, the lines 2122 and 2124 may be shorted together, or one or more of the lines 2122 or 2124 may be shorted to ground or a power source. For example, a pull-up resistor located between a power source and one of the lines 2122 or 2124 may be bypassed as a result of the short created by the liquid. This may cause degradation of one or more signals transmitted across one or more of the lines 2122 or 2124. For example, the introduction of a fluid may change the impedance and / or capacitance of the lines 2122 and 2124. As a result, one or more of the voltage, current, or timing parameters of the transmitted signals may change, for example, due to the ingress of liquid. 2 It may not be compliant with the C protocol.

[0108] Such degradation may be detected by the controller 2110. For example, the controller 2110 may 2 The controller 2110 may detect one or more errors signaled by the C interface. As another example, the controller 2110 may be unable to read pressure from one or more of the pressure sensors 1091 or 1092, or may read a pressure outside an acceptable pressure range. In response to detecting liquid ingress, the controller 2110 may take one or more corrective actions. These may include permanently or temporarily disabling the negative pressure source, permanently or temporarily disabling the TNP system, or providing an indication of liquid ingress.

[0109] As described herein, at least some portions of wires 2122 and 2124 may remain exposed (or uncoated). Liquid ingress may cause the formation of an electrical short (e.g., connection) between wires 2122 and 2124 (or between one or more of wires 2122 or 2124 and ground and / or power). This may occur because the liquid is conductive (e.g., wound exudate). An electrical short may be based on current flowing along an unintended path with reduced impedance. As a result, excess current flows in the electronic device. Excess current flowing through the TNP system may cause a rapid increase in temperature, potentially resulting in burns, fires, etc.

[0110] Similarly, a short between lines 2122 and 2124, or a short on one or more of lines 2122 or 2124, may render memory 930 inaccessible. For example, controller 2110 may attempt to access memory 930 (e.g., to read from or write to memory 930) and, in response to being unable to access the memory, may determine that memory 930 is inaccessible. In some cases, controller 2110 may determine that memory 930 is inaccessible based on not receiving a response to a request to access memory 930 for a threshold period of time.

[0111] Additionally or alternatively, in addition to detecting liquid ingress based on detecting degradation of a digital signal as described herein, detecting liquid ingress may be performed by detecting degradation of an analog signal. For example, the controller 2110 may detect a change in voltage, or a change in voltage reaching a certain threshold (e.g., an out-of-range voltage). The controller 2110 may use an analog signal trace to detect the degradation. The controller 2110 may detect voltages on an analog-to-digital converter, a comparator, a feedback line, etc. As described herein, the degradation may be caused by a short circuit (such as a short to ground, a power supply, or between two or more traces).

[0112] Based on detection of degradation of one or more digital or analog signals, the electronics (such as the controller 2110) can mitigate the effects of liquid intrusion (e.g., to protect the TNP system). For example, in response to detecting the degradation, the controller 2110 can temporarily or permanently stop providing negative pressure to the wound. Alternatively or additionally, the controller 2110 can mitigate the effects of liquid intrusion by generating an indication (such as an alarm), blowing a fuse, opening a fuse, opening a switch, or opening a relay.

[0113] As described herein, electronic devices may include one or more batteries. In response to detecting liquid intrusion, the controller 2110 may deplete (or discharge) one or more batteries to promote patient safety and / or for environmental reasons (such as for waste management without risk of fire or explosion). For example, U.S. regulations generally provide that a lithium battery cell is considered discharged when its voltage falls below 2V under a current of C / 100 (C is the rated capacity of the battery in ampere hours).

[0114] The circuit for depleting the one or more batteries may be a smart discharge circuit that utilizes a load to control the temperature during discharging of the one or more batteries. For example, the one or more batteries may become hot as a result of depletion, which may cause discomfort or injury to the patient. The circuit for depleting the one or more batteries may be covered to protect the circuit from liquid ingress. The circuit for depleting the one or more batteries may include a switch (such as a transistor) and a load (e.g., a resistor or resistor network including multiple resistors with different resistances) connected to the switch. Different resistors in the network may be used to control the temperature during discharging. The load may include a conductive surface (e.g., a copper surface) of a circuit board. The controller 2110 may activate the switch and deplete the one or more batteries through the load. The controller 2110 may track the temperature of the TNP system (e.g., the temperature of the one or more batteries) and deplete the one or more batteries based on the temperature. The controller 2110 may measure a feedback current and deplete the one or more batteries based on the feedback current. For example, the feedback current may be a proxy for temperature. In response to detecting that the feedback current and / or temperature does not meet (e.g., falls below) a particular temperature threshold indicative of an elevated temperature, the controller 2110 can activate a switch to begin discharging one or more batteries. Tracking of the discharge temperature can be performed based on readings of one or more of the pressure sensors 1091 or 1092, although it can be advantageous to track the temperature using a separate temperature sensor (in the event that the pressure sensor 1091 or 1092 is compromised by liquid ingress).

[0115] Multiple temperature thresholds may be used to facilitate discharge through the resistor network. For example, in response to a temperature not meeting (e.g., falling below) a first temperature threshold, discharge may be performed through a first higher resistance resistor in the network. In response to a temperature meeting the first temperature threshold but not meeting a second temperature threshold associated with a temperature higher than the first temperature threshold, discharge may be performed through a second resistor in the network (having a lower resistance than the first resistor).

[0116] The following is an example of detecting liquid ingress using an analog signal trace. FIG. 17 shows a diagram of a circuit 2200 configured to perform excessive temperature detection in a TNP system (which may be any of the TNP systems described herein). The temperature sensor 2210 may monitor the temperature of one or more components of the TNP system. For example, the temperature sensor 2210 may monitor the temperature of a negative pressure source or a boost converter (or boost regulator). The boost converter may increase the power provided by a power source (such as power supply 1068) to a power level sufficient to power a negative pressure source (such as negative pressure source 1072). The temperature sensor 2210 may be a thermostat. The temperature monitored by the temperature sensor 2210 (which may be output as a voltage signal) may be provided to a comparator 2220 (e.g., as input 2224). The comparator 2220 may be an operational amplifier. The other input 2222 to the comparator 2220 may correspond to a temperature threshold, such as a maximum temperature threshold, at which the TNP system is designed to operate safely and effectively. For example, the maximum temperature threshold may be approximately 40 degrees Celsius or less, 41 degrees Celsius or less, 42 degrees Celsius or less, 48 ​​degrees Celsius or less, 50 degrees Celsius or less, etc. The output 2226 of the comparator 2220 may indicate whether the temperature monitored by the temperature sensor 2210 meets the temperature threshold. The output 2226 may be used to control a switch 2240, such as a transistor (in this case, the output 2226 may control the gate of the transistor). The output of the switch 2240 may be used to override the output of a latch circuit, which may facilitate the provision of power from the power source to one or more of the other electronic components, such as the boost converter or the negative pressure source 1072. The latch circuit may be activated by removal of a pull tab, as described herein. If the temperature monitored by the temperature sensor 2210 meets the temperature threshold, the switch 2240 is turned on. This overrides the output of the latch circuit, which may shut down the negative pressure source (e.g., by shutting down the boost converter).For example, activation of switch 2240 can drive output 2202 to a low voltage (e.g., ground) and provide an indication to the controller to shut down the negative pressure source. In some cases, overriding output 2202 can deactivate the boost converter. Further details of overtemperature detection are described in International Patent Publication No. WO2022 / 073762, entitled "TEMPERATURE MONITORING AND CONTROL FOR NEGATIVE PRESSURE WOUND THERAPY SYSTEMS," which is incorporated herein by reference in its entirety.

[0117] As a result of liquid ingress, the terminals of the temperature sensor 2210 may be shorted. As another example, the inputs 2222 and 2224 to the comparator 2220 may be shorted. Such one or more shorts caused by liquid ingress may activate the switch 2240, thus indicating overheating. The controller 2110 may verify whether the detected overheating is inaccurate by analyzing a temperature measured by another temperature sensor, such as a temperature measured by one or more of the pressure sensors 1091 or 1092. The temperature measured by the temperature sensor 2210 and the temperature measured by one or more of the pressure sensors 1091 or 1092 should correlate. The controller 2110 may determine that the overheating detection is inaccurate based on the temperature measured by another temperature sensor not meeting or approaching (5% or less, 10% or less, 20% or less, within, etc.) a maximum temperature threshold. Based on verification of the temperature measured by another temperature sensor, the controller may determine that overheating was inaccurately detected and conclude that this error was caused by liquid intrusion.

[0118] The following is another example of detecting liquid ingress using analog signal traces. FIG. 18 shows a block diagram 2300 of a circuit configured to drive a negative pressure source (such as pump 1072). In some cases, the negative pressure source can include a piezoelectric pump (such as a pump operated by a piezoelectric actuator or transducer). Such a pump can be driven by an H-bridge circuit 2310 that can switch the polarity of the voltage applied to the negative pressure source. The H-bridge circuit 2310 can receive power 2312 (e.g., from a boost converter) and a drive signal 2314 (e.g., from the controller 2110). The drive signal 2314 can be a periodic signal at a desired duty cycle, e.g., a square wave or a sine wave signal. The H-bridge circuit 2310 can generate an output drive signal to drive the negative pressure source. The output drive signal can be an electrical signal scaled by the received power 2312 (e.g., at or substantially at the voltage level of the received power 2312) with a duty cycle corresponding to the drive signal 2314.

[0119] A feedback signal (or feedback current) 2316 can be used to monitor the current 2320 provided to the negative pressure source. The feedback current can be used, for example, to determine the efficiency of the negative pressure source, to protect the negative pressure source from unsafe currents. The feedback current 2316 can be measured across a resistor 2330 (or feedback resistor).

[0120] Liquid ingress in a TNP system may short the terminals of resistor 2330. For example, liquid ingress may short feedback resistor 2330 to ground. This may cause the H-bridge circuit 2310 to detect an error. The controller 2110 may then detect the error and determine liquid ingress as a result. In some cases, the controller 2110 may directly detect the error across the feedback resistor 2330.

[0121] In some instances, liquid intrusion detection based on degradation of one or more digital signals may be faster than detection based on degradation of one or more analog signals. The controller 2110 can directly receive or process the one or more digital signals. For example, the controller 2110 can process the one or more digital signals by executing firmware or software that can determine the cause of the error due to degradation of the one or more digital signals and detect the liquid intrusion.

[0122] Alternatively or additionally, the TNP system may also include one or more electronic components (e.g., humidity sensor, electronic fuse, etc.) for detecting liquid intrusion. The controller 2110 can detect liquid intrusion based on signals received from the one or more electronic components. For example, the controller 210 can detect liquid intrusion based on receiving a signal from a humidity sensor that identifies a change in humidity (e.g., an increase in humidity) and / or that the humidity reaches a particular threshold (e.g., 75% relative humidity). The humidity sensor may measure absolute humidity, relative humidity, or a particular humidity. Additionally, the controller 2110 can detect liquid intrusion based on receiving a signal from an electronic fuse (or eFuse) that identifies an overcurrent or overvoltage condition.

[0123] summary Medical devices, including negative pressure wound therapy devices, may be held to higher safety standards. For example, the IEC 60601-1 technical standard for the safety of performance of medical electrical equipment provides that type BF or CF medical devices (connected electrically to the patient but not directly to the heart) must be single-fault safe. This means that such devices must remain free of unacceptable risk during their expected useful life under a single fault condition (a condition in which a single means for reducing risk is defective or a single abnormal condition exists).

[0124] The approaches described herein can provide a mitigation against the risk of one or more malfunctions of the electronic device. The one or more malfunctions can include reverse current flow, overcurrent flow, or inadvertent activation. The approaches described herein can provide protection against a single fault (or greater protection against multiple faults). Advantageously, a mitigation can be provided against the risk of causing burns or other discomfort to a patient, or the risk of fire.

[0125] The disclosed approach for detecting degradation of a digital or analog signal can facilitate early sensing of liquid intrusion, condensation, or other conductive material intrusion and can be applied to any wearable medical device. This can facilitate early risk control of medical device safety and patient safety, including early alarm generation, prevention of patient discomfort or injury, prevention of fire, etc. As described herein, portions of one or more conductive lines or traces can be exposed (e.g., uncoated) to create a protective region or area (e.g., a guard ring) for liquid ingress detection. The disclosed approach can be inexpensive to implement, as it may require no additional electronic components or very few additional electronic components.

[0126] Other Variations Although the specific embodiments described herein relate to an integrated negative pressure wound therapy system in which the negative pressure source is supported by the dressing, the systems and methods described herein are applicable to any negative pressure wound therapy system or medical system, particularly systems that are positioned on (or worn by) a patient. For example, the systems and methods described herein for controlling operation can be used in fluid-resistant (e.g., waterproof) negative pressure wound therapy systems or medical systems. Such systems can be configured with a negative pressure source and / or electronics that are external to the wound dressing, such that the negative pressure source and / or electronics are positioned in a fluid-proof housing. Additionally, such systems can be configured for use in ultrasound delivery devices, negative pressure devices powered by an external power source, negative pressure devices with separate pumps, and medical devices in general.

[0127] Any of the embodiments disclosed herein may be implemented using any of the following techniques: U.S. Pat. No. 7,779,625, entitled "DEVICE AND METHOD FOR WOUND THERAPY," issued on Aug. 24, 2010; U.S. Pat. No. 7,964,766, entitled "WOUND CLEANSING APPARATUS IN SITU," issued on June 21, 2011; U.S. Pat. No. 8,235,955, entitled "WOUND TREATMENT APPARATUS AND METHOD," issued on August 7, 2012; U.S. Pat. No. 7,753,894, entitled "WOUND CLEANSING APPARATUS WITH STRESS," issued on July 13, 2010; and U.S. Pat. No. 7,753,894, entitled "WOUND CLEANSING APPARATUS WITH STRESS," issued on July 1, 2014; each of which is incorporated herein by reference in its entirety. No. 8,764,732, entitled "WOUND DRESSING", issued on August 19, 2014; U.S. Patent No. 8,808,274, entitled "WOUND DRESSING", issued on June 23, 2015; U.S. Patent No. 9,061,095, entitled "WOUND DRESSING AND METHOD OF USE", issued on September 18, 2018; U.S. Patent No. 10,076,449, entitled "WOUND DRESSING AND METHOD OF TREATMENT", filed on January 30, 2015, published on July 9, 2015 as U.S. Publication No. 2015 / 0190286, entitled "WOUND DRESSING AND METHOD OF TREATMENT"; U.S. Patent Application No. 14 / 418908, entitled "TISSUE DRESSING" issued on March 19, 2019; No. 10,231,878, filed July 12, 2012, entitled "WOUND DRESSING AND METHOD OF TREATMENT," PCT International Application No. PCT / GB2012 / 000587, filed May 22, 2013, entitled "APPARATUSES AND METHODS FOR NEGATIVE PRESSURE WOUND THERAPY," International Application No. PCT / IB2013 / 001469, filed July 31, 2013, entitled "WOUND DRESSINGPCT International Application No. PCT / IB2013 / 002102, entitled "WOUND DRESSING AND METHOD OF TREATMENT", filed July 31, 2013; PCT International Application No. PCT / IB2013 / 002060, entitled "WOUND DRESSING AND METHOD OF TREATMENT", filed March 12, 2013; PCT International Application No. PCT / IB2013 / 00084, entitled "REDUCED PRESSURE APPARATUS AND METHODS", filed April 26, 2016; PCT International Application No. PCT / EP2016 / 059329, entitled "REDUCED PRESSURE APPARATUSES", filed April 26, 2017; PCT International Application No. PCT / EP2017 / 059883, entitled "WOUND TREATMENT APPARATUSES AND METHODS WITH NEGATIVE PRESSURE SOURCE INTEGRATED INTO WOUND DRESSING", filed on March 6, 2017; PCT International Application No. PCT / EP2017 / 055225, entitled "WOUND TREATMENT APPARATUSES AND METHODS WITH NEGATIVE PRESSURE SOURCE INTEGRATED INTO WOUND DRESSING", filed on September 13, 2018; PCT International Application No. PCT / EP2018 / 074694, entitled "NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES AND METHODS WITH INTEGRATED ELECTRONICS", filed on September 13, 2018; PCT International Application No. PCT / EP2018 / 074701, filed on October 25, 2018, entitled "NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES AND METHODS WITH INTEGRATED ELECTRONICS"The present invention may be used in conjunction with one or more features disclosed in PCT International Application No. PCT / EP2018 / 079345, entitled "SAFE OPERATION OF INTEGRATED NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES," filed on October 30, 2018, and PCT International Application No. PCT / EP2018 / 079745, entitled "SAFE OPERATION OF INTEGRATED NEGATIVE PRESSURE WOUND TREATMENT APPARATUSES," filed on October 30, 2018.

[0128] Although certain embodiments described herein relate to wound dressings, the systems and methods disclosed herein are not limited to wound dressings or medical applications. The systems and methods disclosed herein are generally applicable to electronic devices in general, such as electronic devices that can be worn or applied by a user.

[0129] Values ​​such as thresholds, limits, periods, etc. provided herein are not intended to be absolute values ​​and therefore may be approximate values. In addition, any thresholds, limits, periods, etc. provided herein may be fixed or changed automatically or by a user. Furthermore, as used herein, terms expressing a relative degree, such as exceeding, over, under, etc., in relation to a reference value are intended to encompass equality to the reference value. For example, exceeding a positive reference value can encompass being equal to or greater than the reference value. Moreover, as used herein, terms expressing a relative degree, such as exceeding, over, under, etc., in relation to a reference value are intended to encompass the inverse of the disclosed relationship, such as below, under, over, etc., in relation to the reference value. Also, although various process blocks may be described with respect to determining whether a value reaches or does not reach a particular threshold, the blocks may be similarly interpreted with respect to, for example, whether a value is (i) below or above a threshold, or (ii) meeting or not meeting a threshold.

[0130] It is to be understood that a feature, substance, characteristic, or group described in connection with a particular aspect, embodiment, or example may be applied to any other aspect, embodiment, or example described herein, unless incompatible therewith. All of the features disclosed in this specification (including any of the accompanying claims, abstract, and drawings), or all of the steps of any method or process disclosed in the same, may be combined in any combination, except combinations in which at least some of such features or steps are mutually exclusive. Protection is not limited to the details of any of the preceding embodiments. Protection extends to any novel, or any novel combination of features disclosed in this specification (including any of the accompanying claims, abstract, and drawings), and / or to any novel, or any novel combination of steps of any method or process disclosed in the same.

[0131] Although specific embodiments have been described, these embodiments are presented merely as examples and are not intended to limit the scope of protection. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications may be made in the methods and systems described herein. Those skilled in the art will recognize that in some embodiments, the actual steps performed in the illustrated or disclosed processes may differ from the steps shown in the figures. In some embodiments, certain steps of the above-described processes may be removed and others may be added. For example, the actual steps or order of steps performed in the disclosed processes may differ from those shown in the figures.

[0132] Various components illustrated in the figures or disclosed herein may be implemented as software or firmware on a processor, controller, ASIC, FPGA, or dedicated hardware. The software or firmware may include instructions stored in a non-transitory computer-readable memory. The instructions may be executed by a processor, controller, ASIC, FPGA, or dedicated hardware. Hardware components such as controllers, processors, ASICs, FPGAs, and the like may include logic circuitry. Furthermore, the features and characteristics of certain embodiments disclosed above may be combined in various ways to form additional embodiments, all of which will fall within the scope of the present disclosure.

[0133] Although the present disclosure includes specific embodiments, examples, and applications, it will be understood by those skilled in the art that the present disclosure extends beyond the scope of the specifically disclosed embodiments to other alternative embodiments or uses and obvious modifications and equivalents thereof, including embodiments that do not provide all of the features and advantages described herein. Thus, the scope of the present disclosure is not intended to be limited by the specific disclosure of preferred embodiments herein, but may be defined by the claims presented herein or hereafter.

[0134] Conditional language such as "can," "could," "might," or "may," unless specifically stated otherwise or interpreted otherwise within the context in which it is used, is typically intended to convey that certain embodiments include certain features, elements, or steps, while other embodiments do not. Thus, such conditional language is not necessarily intended to suggest that the features, elements, or steps are in any way required by one or more embodiments, or that one or more embodiments necessarily include logic for determining, with or without user input or instruction, whether those features, elements, or steps are included in or should be performed in any particular embodiment. Terms such as "comprising," "including," and "having" are synonymous and are used in an inclusive, non-limiting manner and do not exclude additional elements, properties, acts, operations, and the like. Also, the term "or" is used in an inclusive sense (not an exclusive sense), e.g., when used to connect a list of elements, it means one, some, or all of the elements in the list. Further, the term "each" as used herein, in addition to having its ordinary meaning, can also refer to any subset of the series of elements to which the term "each" applies.

[0135] Conjunctive phrases such as "at least one of X, Y, and Z," unless specifically stated otherwise, are to be construed otherwise in accordance with the context in which they are generally used to suggest that an item, term, etc., can be either X, Y, or Z. Thus, such conjunctive phrases are not necessarily intended to suggest that a particular embodiment requires that it includes at least one X, at least one Y, and at least one Z.

[0136] Phrases expressing degrees as used herein, such as the terms "approximately," "about," "generally," and "substantially," are intended to describe a value, amount, or characteristic that is close to a given value, amount, or characteristic that still performs a desired function or produces a desired result. For example, the terms "approximately," "about," "generally," and "substantially" can refer to an amount that is within less than 10%, within less than 5%, within less than 1%, within less than 0.1%, and within less than 0.01% of a given amount.

[0137] The scope of the disclosure is not intended to be limited by the specific disclosure of preferred embodiments in this section or elsewhere herein, but may be defined by the claims presented in this section or elsewhere herein, or presented hereafter. The claim language should be interpreted broadly based on the language employed in the claims, and not limited to the examples described herein or during the prosecution of this application, which examples should be interpreted as non-exclusive.

Claims

Claim 1 A negative pressure wound therapy system comprising: a negative pressure source configured to provide negative pressure to a wound covered by a wound dressing and to aspirate liquid from the wound; a circuit board supporting a plurality of electronic components, the plurality of electronic components including a control circuit configured to control the operation of the negative pressure source, the circuit board supporting a plurality of traces electrically connecting the plurality of electronic components, the plurality of traces including a first set of traces configured to transmit one or more digital signals and a second set of traces configured to transmit one or more analog signals; comprising; wherein the control circuit is further configured to: detect degradation of an electrical signal on at least one of the traces of the first or second set of traces, the degradation being caused by one or more of liquid ingress and condensation onto the circuit board; in response to detection of the degradation of the electrical signal caused by one or more of the liquid ingress and condensation, temporarily or permanently stop providing negative pressure to the wound. A negative pressure wound therapy system further configured as such. Claim 2 The system according to claim 1, further comprising the wound dressing, wherein at least one of the negative pressure source and the circuit board is at least partially supported by the wound dressing. Claim 3 The system according to claim 1 or 2, wherein the circuit board supports the negative pressure source. Claim 4 The system according to claim 1 or 2, wherein the liquid ingress results from the negative pressure source aspirating fluid from the wound. Claim 5 The system according to claim 1 or 2, wherein the degradation of the electrical signal is caused by a short circuit as a result of one or more of the liquid ingress and condensation. Claim 6 The system according to claim 1 or 2, wherein the degradation of the electrical signal is caused by a short circuit between two traces from the first set of traces or between a trace from the first set of traces and ground or power. Claim 7 Two of the traces from the first set of traces include a plurality of portions that are not coated with a water-resistant material, or the trace from the first set of traces includes a portion that is not coated with a water-resistant material, and the short circuit is formed by a liquid that contacts the plurality of portions that are not coated with a water-resistant material or the portion that is not coated with a water-resistant material. The system according to claim 6.

8. The trace from the second set of traces corresponds to the feedback line of the negative pressure source, and the control circuit is configured to detect the deterioration of the electrical signal based at least in part on a short circuit across the feedback line. The system according to claim 1 or 2.

9. The trace from the second set of traces is part of a circuit configured to detect an excessive temperature, and the control circuit is configured to detect the deterioration of the electrical signal by determining that the circuit configured to detect an excessive temperature has performed an inaccurate detection of the excessive temperature. The system according to claim 1 or 2.

10. The control circuit is configured to determine that the circuit configured to detect an excessive temperature has performed an inaccurate detection of the excessive temperature based on the processing temperature detected by an additional temperature sensor. The system according to claim 9.

11. Further comprising at least one battery, and the control circuit is further configured to consume at least one of the batteries in response to the detection of the deterioration of the electrical signal. The system according to claim 1 or 2.

12. The plurality of the electronic components further includes a resistor network or a conductive surface and a switch, and the control circuit is configured to open the switch and consume at least one of the batteries through the resistor network or the conductive surface. The system according to claim 11.

13. Temporarily stopping the provision of negative pressure to the wound includes preventing the negative pressure source from being activated to provide negative pressure to the wound during a first period, and the control circuit is further configured to activate the negative pressure source to provide negative pressure to the wound in response to the expiration of the first period. The system according to claim 1 or 2.

14. The system according to claim 13, wherein the first period corresponds to a period for clearing an error caused by one or more of the intrusion and condensation of the liquid onto the circuit board.

15. The system according to claim 1 or 2, wherein permanently stopping providing negative pressure to the wound includes preventing the negative pressure source from being activated to provide negative pressure to the wound.

16. The control circuit is a humidity sensor, and an electronic fuse (eFuse), further configured to detect the deterioration of the electrical signal based on data obtained from one or more of them. The system according to claim 1 or 2.

17. The control circuit is blowing the fuse, opening the fuse, opening the switch, and opening the relay, configured to temporarily or permanently stop providing negative pressure by one or more of them. The system according to claim 1 or 2.

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