Device for measuring tissue viability

Abstract

The present disclosure provides devices and methods for measuring subepidermal moisture as an indication of tissue viability and providing information about the location of non-viable tissue boundaries.

Description

[0001] This application is a divisional application of the application filed on February 2, 2018, application number 201880004146.X (international application number PCT / US2018 / 016736), entitled "Measurement of Tissue Viability".

[0002] Cross Reference to Related Applications

[0003] This application claims the benefit of priority of U.S. Provisional Application No. 62 / 454,487, filed February 3, 2017, and U.S. Provisional Application No. 62 / 521,926, filed June 19, 2017, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0004] The present disclosure provides devices and methods for measuring the type and extent of tissue damage around a burn or other type of wound. BACKGROUND

[0005] Severe wounds and burns can have areas of damage of varying degrees around the wound site. Effective treatment can require removal of non-viable tissue, but assessing tissue viability visually can be difficult. For open wounds such as burns, there can be areas of non-viable tissue immediately around the wound, while more distant tissue can be less damaged and characterized by swelling called "edema" but still viable and likely to recover.

[0006] Common methods of burn assessment are to assess visual and tactile features, i.e., wound appearance, capillary bleaching and refill, capillary staining, and sensitivity of the burn wound to light touch and pinprick. Estimating burn depth is difficult. In addition, burn wounds are dynamic and can develop over time, and changes are not immediately visually apparent. SUMMARY

[0007] In one aspect, the present disclosure provides and includes an apparatus for mapping a damaged area surrounding a wound, the apparatus comprising: a plurality of electrodes embedded on a substrate configured to be placed on a tissue area including the wound, wherein a combination of the electrodes is capable of forming a plurality of virtual capacitive sensors each configured to measure a capacitance of a tissue area proximate to the respective virtual capacitive sensor, a plurality of visual indicators embedded on the substrate, a drive circuit electrically connected to the electrodes and visual indicators, a processor electrically connected to the drive circuit, and a non-transitory computer readable medium electrically connected to the processor and including instructions stored thereon that, when executed on the processor, perform the steps of: receiving information about the measured capacitance from a subset of the plurality of virtual capacitive sensors via the drive circuit, determining a boundary between living tissue and non-living tissue, and activating a portion of the plurality of visual indicators via the drive circuit to indicate the boundary.

[0008] In one aspect, the present disclosure provides and includes an apparatus for determining a depth of a burn wound, the apparatus comprising: a pair of electrodes capable of forming a capacitive sensor configured to measure a capacitance of a tissue area proximate to the pair of electrodes, a drive circuit electrically connected to the capacitive sensor, a processor electrically connected to the drive circuit, and a non-transitory computer readable medium electrically connected to the processor and including instructions stored thereon that, when executed on the processor, perform the steps of: receiving information about the measured capacitance from the capacitive sensor via the drive circuit, comparing the information to a data array including pairs of capacitances and burn depths, and determining a depth of a burn wound associated with the measured capacitance.

[0009] In one aspect, the present disclosure provides and includes an apparatus for mapping a damaged area surrounding a wound, the apparatus comprising: a plurality of electrodes embedded on a substrate configured to be placed on a portion of a tissue area including the wound, wherein a pair of electrodes is capable of forming a capacitive sensor configured to measure a capacitance of a tissue area proximate to the capacitive sensor, a projector capable of projecting a visual indicator onto the tissue area including the wound, a drive circuit electrically connected to the plurality of electrodes and projector, a processor electrically connected to the drive circuit, and a non-transitory computer readable medium electrically connected to the processor and including instructions stored thereon that, when executed on the processor, perform the steps of: receiving information about the measured capacitance from one or more of the formed capacitive sensors, determining a first boundary between a first type of tissue and a second type of tissue, and causing the projector to project the visual indicator to indicate the boundary.

[0010] In one aspect, the present disclosure provides and includes a method for mapping a damaged area around a wound, the method comprising: obtaining capacitance measurements on a tissue area including the wound using a plurality of electrodes; converting each of the measured capacitances to a related subepidermal moisture (SEM) value; and marking a first boundary encompassing tissue areas associated with SEM values less than a first threshold value. BRIEF DESCRIPTION OF DRAWINGS

[0011] Some aspects of the present disclosure are described herein, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is to be understood that the

[0012] Figure 1A A ring-shaped bioimpedance sensor is disclosed.

[0013] Figure 1B A ring-shaped sensor according to Figure 1A produces an idealized field map when activated.

[0014] Figure 1C A SEM scanner including a sensor according to Figure 1A is disclosed.

[0015] Figure 2 is a first exemplary electrode array.

[0016] Figure 3 is an exemplary electrode array according to the present disclosure.

[0017] Figure 4A shows how the electrode array disclosed in Figure 3 may be configured to form a first example of a bioimpedance sensor according to the present disclosure.

[0018] Figure 4B shows how the electrode array disclosed in Figure 3 may be configured to form a second example of a bioimpedance sensor according to the present disclosure.

[0019] Figure 5A depicts an exemplary 3rd degree burn with an open wound.

[0020] Figure 5B depicts a cross-section of a wound according to Figure 5A .

[0021] Figure 6 provides an example plot 600 of how SEM values according to the present disclosure vary over a wound according to Figure 5A .

[0022] Figure 7 A first exemplary aspect of a SEM sensing device according to the present disclosure is disclosed.

[0023] Figure 8A A second exemplary aspect of a SEM sensing device according to the present disclosure is disclosed.

[0024] Figure 8B A third exemplary aspect of a SEM sensing device according to the present disclosure is disclosed.

[0025] Figure 9 Aspects of a device for mapping an area of injury according to the present disclosure are disclosed. DETAILED DESCRIPTION

[0026] The present disclosure describes the measurement of various electrical properties and the derivation of SEM values indicative of the accumulation or depletion of extracellular fluid (ECF), also known as interstitial fluid, and the application of this information in assessing tissue viability. Examples are provided that apply to thermal burns but are also applicable to other types of wounds. These examples are not limiting and the principles shown can be applied to a greater range of injuries and conditions than the specific examples. For example, the devices and methods disclosed in relation to 3rd degree burns can be used with equal efficacy in relation to open incisions, gangrene, ulcers or other similar injuries.

[0027] By determining the amount of SEM in the tissue surrounding an actual injury, the assessment of tissue viability around a wound or burn can be improved. In general, the tissue immediately surrounding a wound will exhibit a reduced SEM level, indicating a lower level of tissue viability. Further away from the wound, the tissue will exhibit increasing levels of moisture or edema. The values can be very high around the edges of low moisture tissue, indicating a high degree of injury and ultimately a high risk of tissue death. As the distance from the wound increases, the SEM values can gradually decrease, with a moderately elevated SEM level indicating an injury with a higher chance of tissue survival. Mapping the low viability tissue area and the surrounding edema area, as indicated by the decreasing tissue moisture levels, can provide important guidance to the clinician during the treatment of a wound.

[0028] The description is not intended to be a detailed list of all different ways in which this disclosure can be implemented or all features that can be added to this disclosure. For example, a feature shown with respect to one embodiment may be incorporated into other embodiments, and a feature shown with respect to a particular embodiment may be removed from that embodiment. Therefore, this disclosure is contemplated that in some embodiments of this disclosure, any features or combinations of features set forth herein may be excluded or omitted. Furthermore, various variations and additions to the various embodiments presented herein will be apparent to those skilled in the art without departing from this disclosure. In other instances, well-known structures, interfaces, and processes have not been shown in detail so as not to unnecessarily obscure the invention. It is intended that nothing in this specification should be construed as denying any part of the full scope of the invention. Therefore, the following description is intended to illustrate some specific embodiments of this disclosure, rather than to exhaustively describe all permutations, combinations, and variations thereof.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. The terminology used in the description herein is for the purpose of describing particular embodiments or aspects only and is not intended to limit this disclosure.

[0030] All publications, patent applications, patents, and other references cited herein are incorporated in their entirety by reference for the teaching purposes relating to the sentences and / or paragraphs presented therein. References to techniques employed herein are intended to indicate techniques commonly understood in the art, including variations of those techniques or substitutions for equivalent techniques that are obvious to those skilled in the art.

[0031] U.S. Patent Applications Nos. 14 / 827,375 and 15 / 134,110 are incorporated herein by reference in their entirety.

[0032] Unless the context otherwise requires, it is specifically intended that the various features disclosed herein may be used in any combination. Furthermore, this disclosure also contemplates that in some embodiments of this disclosure, any features or combinations of features set forth herein may be excluded or omitted.

[0033] The methods disclosed herein include one or more steps or actions for implementing the described methods. The method steps and / or actions may be interchanged with each other without departing from the scope of the invention. In other words, unless a specific order of steps or actions is required for the correct operation of the embodiments, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the invention.

[0034] As used in the description of this disclosure and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0035] As used herein, "and / or", "and / or" means and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ("or").

[0036] The terms "about" and "approximately," as used herein when referring to a measurable value such as a length, frequency, or SEM value, are meant to encompass variations that can exist in the values that are preparatory to use in a test or study.

[0037] As used herein, phrases such as "between" and "between about" are meant to encompass the range of values between the two specific values unless otherwise stated.

[0038] The terms "comprise" and "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] As used herein, the conjunctive term "consisting essentially of means that the scope of the claim should be interpreted to encompass the specific materials or steps recited in the claim, as well as those that do not materially affect the basic and novel characteristic(s) of the disclosed disclosure. Thus, the term "consisting essentially of, when used in the claims of the present disclosure, is not intended to be construed as equivalent to "comprising."

[0040] As used herein, the term "subepidermal moisture" or "SEM" refers to an increase in tissue fluid and local edema due to vascular leakage and other changes that alter the underlying structure of damaged tissue in the presence of tissue sustained pressure, apoptosis, necrosis, and inflammation processes.

[0041] As used herein, a "system" can be a collection of devices in wired or wireless communication with each other.

[0042] As used herein, "interrogation" means the use of radio frequency energy to penetrate the skin of a patient.

[0043] As used herein, a "patient" can be a human or animal subject.

[0044] As used herein, a "3rd degree burn" refers to a full-thickness burn that penetrates the dermis and affects deeper tissue.

[0045] Figure 1AA ring-shaped bioimpedance sensor 90 is disclosed. In this exemplary configuration, a center electrode 110 is surrounded by a ring-shaped electrode 120. Without being limited by a particular theory, the gap between the two electrodes of the sensor 90 can affect the depth of the field that penetrates below the substrate of the sensor 90. In one aspect, a ground plane (not visible in Figure 1A is parallel to and separated from the plane of the electrodes. In one aspect, the ground plane extends beyond the outer diameter of the ring-shaped electrode 120. Without being limited by a particular theory, the ground plane can confine the field between the electrodes 110 and 120 to a single side of the plane of the electrodes 110 and 120, the single side of the plane being on the opposite side of the plane of the electrodes 110 and 120 relative to the ground plane.

[0046] Figure 1B A ring-shaped sensor is disclosed Figure 1A by a drive circuit (not shown in Figure 1B ) when activated. In one aspect, when a voltage is applied between the two electrodes 110, 120, an electric field 140 is generated between the electrodes 110 and 120, the electric field 140 extending outward from the plane of the electrodes 110 and 120 to a field depth 150. In one aspect, the diameter of the center electrode 110, the inner and outer diameters of the ring-shaped electrode 120, and the gap between the two electrodes 110 and 120 can be varied to change the characteristics of the field 140, such as the field depth 150.

[0047] In use, the drive circuit can measure an electrical characteristic or parameter, including one or more of the electrical resistance, capacitance, inductance, impedance, reluctance, or other electrical characteristic sensed by the electric field 140. Depending on the type of drive circuit employed in the device, the sensor of the device can be a bipolar radio frequency sensor, a bioimpedance sensor, a capacitive sensor, or a SEM sensor. In one aspect, the measured electrical parameter is related to the moisture content of the epidermis of the patient at a depth determined by the geometry of the electrodes 110 and 120, the frequency and strength of the electric field 140, and other operating characteristics of the device drive circuit. In one aspect, the measured moisture content is equal to the SEM content, which has a predetermined range of values. In one aspect, the predetermined range can be in the range of 0 to 20, such as 0 to 1, 0 to 2, 0 to 3, 0 to 4, 0 to 5, 0 to 6, 0 to 7, 0 to 8, 0 to 9, 0 to 10, 0 to 11, 0 to 12, 0 to 13, 0 to 14, 0 to 15, 0 to 16, 0 to 17, 0 to 18, 0 to 19. In one aspect, the predetermined range can be scaled by a factor or multiple based on the values provided herein.

[0048] Figure 1C Top and bottom views of a SEM scanner 170 are provided, the SEM scanner 170 including a drive circuit similar to Figure 1AThe electronics of sensor 174 of sensor 90 measure the capacitance between electrodes 110 and 120. The capacitance is converted to a SEM value that is displayed on display 176.

[0049] These aspects of sensor 90 and SEM scanner 170 are disclosed in WO 2016 / 172263, from which U.S. Patent Application No. 15 / 134,110 is a national stage entry.

[0050] Figure 2 An exemplary array of electrodes 290 according to the present disclosure is depicted. In one aspect, array 290 is composed of individual electrodes 300 arranged in a regular pattern on a substrate 292 in the present example. In one aspect, each electrode 300 is connected to a circuit configured to measure an electrical parameter (through conductive elements not shown in the middle) such as described with respect to Figures 2 to 4B Figure 4A In one aspect, a predetermined subset of electrodes 300 are selectively connected to a common element of the circuit to create a "virtual sensor." In one aspect, a particular electrode 310 is connected as a center electrode similar to electrode 110, and six electrodes 320A-F are connected together as a "virtual ring" electrode similar to electrode 120. In one aspect, two individual electrodes are connected to the circuit to form a virtual sensor, for example, electrodes 310 and 320A are connected as two electrodes of a sensor, respectively. In one aspect, one or more electrodes 300 are connected together to form one electrode or the other electrode of a two-electrode sensor. Figure 1A Figure 1A Any pair of electrodes (whether composed of a single electrode or a group of electrodes connected together to form a virtual electrode) is connected to electronics configured to measure an electrical characteristic or parameter including one or more of resistance, capacitance, inductance, impedance, reluctance, or other electrical characteristic through one or more of sensors 90, 174, 290, 430, 440, or other two-electrode sensor.

[0051] Another exemplary array 400 of electrodes 410 according to the present disclosure is depicted. In one aspect, each electrode 410 is an approximate hexagon separated from each electrode surrounding electrode 410 by a gap 420. In one aspect, electrodes 410 are one of circular, square, pentagonal, or other regular or irregular shape. In one aspect, gaps 420 are uniform between all electrodes 410. In one aspect, gaps 420 vary between multiple electrodes. In one aspect, electrodes 410 can be interconnected to form a two-electrode sensor as described below with respect to

[0052] Figure 3 Figure 5A Figure 5B ​​​​The virtual sensor.

[0053] Figure 4A An array 400 of electrodes 410 configured to form a sensor 430, for example, connected to measurement circuitry, is depicted in accordance with the present disclosure. In one aspect, a single hexagonal electrode 410 labeled with "1" forms a center electrode, and electrode rings 410 labeled with "2" are interconnected to form a ring electrode. In one aspect, the electrodes 410 between the center electrode and the ring electrode are electrically "floating." In one aspect, the electrodes 410 between the center electrode and the ring electrode are grounded or connected to a floating ground. In one aspect, the electrodes 410 located outside the ring electrode are electrically "floating." In one aspect, the electrodes 410 located outside the virtual ring electrode are grounded or connected to a floating ground.

[0054] Figure 4B An alternative aspect in accordance with the present disclosure is depicted in which an array 400 of electrodes 410 has been configured to form a virtual sensor 440. In one aspect, a plurality of electrodes 410 denoted by "1" are interconnected to form a center electrode, and a double wide electrode ring denoted by "2" is interconnected to form a ring electrode. In one aspect, various numbers and locations of electrodes 410 are interconnected to form virtual electrodes of various sizes and shapes.

[0055] Figure 5A An exemplary wound, in this case a 3rd degree burn 500 with an open wound 510, is depicted. The response of the tissue surrounding the wound of a 3rd degree burn can include three zones. In one aspect, the innermost zone 520 located in the center of the wound will have necrosis, no perfusion of oxygen, and irreversible damage due to protein coagulation. In one aspect, a second zone 530 (also referred to as a "stasis zone") is a ring surrounding the first zone 520 in which perfusion is reduced and SEM is falling. Without being limited by a particular theory, capillaries can be non-functional in the second zone 530, resulting in increased permeability of capillaries and arterioles and subsequent ischemia-reperfusion injury. There can be a possibility of tissue recovery in the second zone 530 if the cascade of free radicals and cellular damage leading to apoptosis can be prevented. In one aspect, surrounding the second zone 530 is a hyperemic zone 540 in which the tissue is damaged but still maintains good perfusion and will generally heal. Without being limited by a particular theory, the size, shape, and depth of the wound 510 and zones 520, 530, 540 depend on the details of the event that caused the damage. In accordance with the present disclosure, assessment of burn depth and degree is one component on which treatment decisions are based, as inaccuracies can result in unnecessary surgery or patient stays that are too long.

[0056] Figure 5B is Figure 5A a cross-section of the burn 500 shown in FIG. 5B Figure 5AA cross-section taken along line A-A in FIG. 5. In one aspect, the first area 520 can extend under the open wound 510 and extend to the sides. In one aspect, the area 530 can extend under one or both of the open wound 510 and the area 520. In one aspect, at a distance from the open wound 510, there will be unimpaired or "normal" tissue 540.

[0057] Depending on whether the impaired areas 530 and 540 extend through the skin into subcutaneous tissue, a burn can be characterized as a "partial thickness" burn or a "full thickness" burn, according to the present disclosure. Superficial partial thickness injuries, such as blisters of a 2nddegree burn, are viable and will typically heal with an antimicrobial dressing. Deep partial thickness wounds are more like full thickness burns and can require surgical excision and grafting to achieve improved function and cosmetic results. Partial thickness wounds are more complicated to treat because it is difficult to determine whether there are viable structures and the wound can heal. Any inaccuracies related to the diagnosis can impact treatment because superficial burns can be operated on to heal the wound.

[0058] Burn wounds are a challenging problem because they are dynamic and have the ability to change and develop over time. In the area 520, heating of the tissue results in complete necrosis of the dermis and all dermal structures and fat necrosis. Without being limited by a particular theory, the area 520 has a lower than normal water content and remains low after the injury due to destruction of local blood vessels, which prevents perfusion into the necrotic area.

[0059] Without being limited by a particular theory, in the area 530, restoration of blood flow after the initial heat exposure can restore perfusion and oxygenation. While not limited by theory, restoration of oxygenation can be important for cell survival, but also triggers a series of events that result in the production of free radicals that cause further tissue damage. Burn edema accumulation can occur in a two-phase pattern. In the first phase, there is a rapid increase in interstitial fluid within the first hour after injury, and there is about 80% of total edema at 4 hours after injury. The second phase is characterized by a gradual increase in fluid accumulation over the next 12 to 24 hours. In non-burn injuries, fluid movement from capillaries to interstitium can typically be balanced by lymphatic clearance so that excess fluid does not accumulate. However, in burn injuries, fluid and protein movement into the extravascular space can occur very rapidly and edema ensues because the lymphatic vessels cannot keep up with the rate of fluid and protein clearance, again without being limited by theory. Thus, in one aspect, the amount of edema in the area 540 is less than the amount of edema in the area 530, but the amount of SEM is still above normal, again without being limited by a particular theory. Plotting the edema pattern allows for an assessment of which tissues are at risk.

[0060] Figure 6An example plot 600 is depicted showing how SEM values according to the present disclosure vary over burn 500. SEM values taken along cross-section A-A are plotted as curve 610, where the x-axis is position along cross-section A-A and the y-axis is SEM value. Reference line 612 represents normal tissue SEM values, which can be a standard reference value or a measured value of known undamaged tissue on the patient.

[0061] In one aspect, curve 610 generally shows a region 620 where SEM values are greater than reference line 612. In one aspect, curve 610 in region 620 can be only slightly elevated as shown at the bottom of the shaded region, or can be significantly increased as shown at the top of shaded region 620. In one aspect, peak 622 of region 620 indicates the degree or depth of damage in region 530.

[0062] In one aspect, point 630 on curve 610 indicates the transition from region 530 to region 540. In one aspect, the SEM value is higher than reference line 612 but not so high as to indicate a risk that the tissue will not recover. In one aspect, the location of the transition from region 530 to region 540 can be identified as the x-axis position of point 630 on curve 610 using known SEM value magnitudes. In one aspect, the magnitude of the SEM value at point 630 can be a value selected from the group consisting of a predetermined value, a predetermined increase above the reference SEM value, a percentage of the reference SEM value, a percentage of peak 622, and other values determined from curve 610.

[0063] In one aspect, the predetermined SEM value can be in the range of 0.1 to 8.0, such as 0.1 to 1.0, 1.1 to 2.0, 2.1 to 3.0, 3.1 to 4.0, 4.1 to 5.0, 5.1 to 6.0, 6.1 to 7.0, 7.1 to 8.0, 0.1 to 7.5, 0.5 to 8.0, 1.0 to 7.0, 1.5 to 6.5, 2.0 to 6.0, 3.0 to 5.5, 3.5 to 5.0, or 4.0 to 4.5. In one aspect, the predetermined SEM value can be in the range of 0.1 to 4.0, such as 0.5 to 4.0, 0.1 to 3.5, 1.0 to 3.5, 1.5 to 4.0, 1.5 to 3.5, 2.0 to 4.0, 2.5 to 3.5, 2.0 to 3.0, 2.0 to 2.5, or 2.5 to 3.0. In one aspect, the predetermined SEM value can be in the range of 4.1 to 8.0, such as 4.5 to 8.0, 4.1 to 7.5, 5.0 to 7.5, 5.5 to 7.0, 5.5 to 7.5, 6.0 to 8.0, 6.5 to 7.5, 6.0 to 7.0, 6.0 to 6.5, or 6.5 to 7.0. In one aspect, the predetermined SEM value can be about 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, or 7.5. In one aspect, the predetermined SEM value can be scaled by a factor or multiple based on the values provided herein.

[0064] In one aspect, the predetermined increase can be in the range of 0.1 to 8.0, such as 0.1 to 1.0, 1.1 to 2.0, 2.1 to 3.0, 3.1 to 4.0, 4.1 to 5.0, 5.1 to 6.0, 6.1 to 7.0, 7.1 to 8.0, 0.1 to 7.5, 0.5 to 8.0, 1.0 to 7.0, 1.5 to 6.5, 2.0 to 6.0, 3.0 to 5.5, 3.5 to 5.0, or 4.0 to 4.5. In one aspect, the predetermined increase can be in the range of 0.1 to 4.0, for example, 0.5 to 4.0, 0.1 to 3.5, 1.0 to 3.5, 1.5 to 4.0, 1.5 to 3.5, 2.0 to 4.0, 2.5 to 3.5, 2.0 to 3.0, 2.0 to 2.5, or 2.5 to 3.0. In one aspect, the predetermined increase can be in the range of 4.1 to 8.0, such as 4.5 to 8.0, 4.1 to 7.5, 5.0 to 7.5, 5.5 to 7.0, 5.5 to 7.5, 6.5 to 8.0, 6.5 to 7.5, 6.0 to 7.0, 6.0 to 6.5, or 6.5 to 7.0. In one aspect, the predetermined increase can be about 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, or 7.5. In one aspect, the predetermined increase can be scaled by a factor or multiple based on the values provided herein.

[0065] In one aspect, the reference SEM value is represented by reference line 612. In one aspect, the reference SEM value can be in the range of 0.1 to 8.0, such as 0.1 to 1.0, 1.1 to 2.0, 2.1 to 3.0, 3.1 to 4.0, 4.1 to 5.0, 5.1 to 6.0, 6.1 to 7.0, 7.1 to 8.0, 0.1 to 7.5, 0.5 to 8.0, 1.0 to 7.0, 1.5 to 6.5, 2.0 to 6.0, 3.0 to 5.5, 3.5 to 5.0, or 4.0 to 4.5. In one aspect, the reference SEM value can be in the range of 0.1 to 4.0, such as 0.5 to 4.0, 0.1 to 3.5, 1.0 to 3.5, 1.5 to 4.0, 1.5 to 3.5, 2.0 to 4.0, 2.5 to 3.5, 2.0 to 3.0, 2.0 to 2.5, or 2.5 to 3.0. In one aspect, the reference SEM value can be in the range of 4.1 to 8.0, such as 4.5 to 8.0, 4.1 to 7.5, 5.0 to 7.5, 5.5 to 7.0, 5.5 to 7.5, 6.0 to 8.0, 6.5 to 7.5, 6.0 to 7.0, 6.0 to 6.5, or 6.5 to 7.0. In one aspect, the reference SEM value can be about 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, or 7.5. In one aspect, the reference SEM value can be scaled by a factor or multiple based on the values provided herein.

[0066] In one aspect, the peak can be in the range of 0.1 to 8.0, such as 0.1 to 1.0, 1.1 to 2.0, 2.1 to 3.0, 3.1 to 4.0, 4.1 to 5.0, 5.1 to 6.0, 6.1 to 7.0, 7.1 to 8.0, 0.1 to 7.5, 0.5 to 8.0, 1.0 to 7.0, 1.5 to 6.5, 2.0 to 6.0, 3.0 to 5.5, 3.5 to 5.0, or 4.0 to 4.5. In one aspect, the peak can be in the range of 0.1 to 4.0, such as from 0.5 to 4.0, 0.1 to 3.5, 1.0 to 3.5, 1.5 to 4.0, 1.5 to 3.5, 2.0 to 4.0, 2.5 to 3.5, 2.0 to 3.0, 2.0 to 2.5, or 2.5 to 3.0. In one aspect, the peak can be in the range of 4.1 to 8.0, such as 4.5 to 8.0, 4.1 to 7.5, 5.0 to 7.5, 5.5 to 7.0, 5.5 to 7.5, 6.0 to 8.0, 6.5 to 7.5, 6.0 to 7.0, 6.0 to 6.5, or 6.5 to 7.0. In one aspect, the peak can be about 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, or 7.5. In one aspect, the peak can be scaled by a factor or multiple based on the values provided herein.

[0067] One or more regions can be defined on the body. In one aspect, measurements taken within a region are considered equivalent to one another. A region can be defined as an area on the skin of the body where measurements can be taken at any point within the region. In one aspect, a region corresponds to an anatomical region (e.g., heel, ankle, lower back). In one aspect, a region can be defined as a set of two or more specific points relative to an anatomical feature where measurements are only taken at the specific points. In one aspect, a region can include multiple non-contiguous regions on the body. In one aspect, the set of specific locations can include points in multiple non-contiguous regions.

[0068] In one aspect, the area is defined by a surface area. In one aspect, the area can be, for example, 5 to 200 cm 2 , 5 to 100 cm 2 , 5 to 50 cm 2 or 10 to 50 cm 2 , 10 to 25 cm 2 or 5 to 25 cm 2 .

[0069] In one aspect, the measurements can be taken in a specific pattern or portion thereof. In one aspect, the pattern of readings is formed in a pattern in which the target area of interest is centered. In one aspect, the measurements are taken in one or more circular patterns, T-shaped patterns, a set of specific locations, or randomly across the tissue or area, increasing or decreasing in size. In one aspect, the pattern can be located on the body by defining a first measurement location of the pattern relative to an anatomical feature, with the remaining measurement locations of the pattern defined as offsets from the first measurement location.

[0070] In one aspect, multiple measurements are taken on the tissue or area, and the difference between the lowest measurement and the highest measurement of the multiple measurements is recorded as a delta value for the multiple measurements. In one aspect, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more measurements are taken on the tissue or area.

[0071] In one aspect, a threshold value can be established for at least one area. In one aspect, a threshold value of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or other value can be established for at least one area. In one aspect, a delta value is identified as valid when the delta value of multiple measurements taken within an area meets or exceeds the threshold value associated with that area. In one aspect, each of a plurality of areas has a different threshold value. In one aspect, two or more areas can have a common threshold value.

[0072] In one aspect, the threshold value has a delta value component and a time component, in which the delta value is identified as valid when the delta value is greater than a predetermined number for a predetermined portion of a time interval. In one aspect, the predetermined portion of the time interval is defined as a minimum of X days, in which the multiple measurements taken on a day produce a delta value that is greater than or equal to the predetermined number for a total of Y consecutive measurement days. In one aspect, the predetermined portion of the time interval can be defined as 1, 2, 3, 4, or 5 consecutive days, in which the multiple measurements taken on a day produce a delta value that is greater than or equal to the predetermined number. In one aspect, the predetermined portion of the time interval can be defined as some portion of a different specific time period (week, month, hour, etc.).

[0073] In one aspect, the threshold has a trend aspect, where the change in delta values of successive measurements are compared to each other. In one aspect, the trend threshold is defined as a predetermined change in delta values over a predetermined length of time, where a determination that the threshold has been met or exceeded is valid. In one aspect, a valid determination will result in an alert being issued. In one aspect, a trend line can be calculated from a portion of the measurements of successive measurements. In one aspect, a trend line can be calculated from a portion of the delta values of successive measurements.

[0074] In one aspect, the number of measurements taken within a single region can be less than the number of measurement locations defined in the pattern. In one aspect, a delta value is calculated after a predetermined initial number of readings are taken in a region and after each additional reading in the same region, the number of readings being less than the number of measurement locations defined in the pattern, where additional readings are not taken once the delta value reaches or exceeds the threshold associated with the region.

[0075] In one aspect, the number of measurements taken within a single region can exceed the number of measurement locations defined in the pattern. In one aspect, a delta value will be calculated after each additional reading.

[0076] In one aspect, a quality metric can be generated for each of the plurality of measurements. In one aspect, the quality metric is selected to assess the repeatability of the measurements. In one aspect, the quality metric is selected to assess the skill of the clinician taking the measurements. In one aspect, the quality metric can include one or more statistical parameters, such as mean, average, or standard deviation. In one aspect, the quality metric can include one or more of comparing individual measurement values to a predetermined range. In one aspect, the quality metric can include comparing individual measurement values to a pattern of values, such as comparing measurement values at predefined locations to an associated range for each predefined location. In one aspect, the quality metric can include one or more assessments of which measurements are taken on healthy tissue and the consistency within the subset of "healthy" measurements, such as range, standard deviation, or other parameter.

[0077] In one aspect, the measurement values, such as thresholds, are determined by a SEM Scanner Model 200 (Bruin Biometrics, LLC, Los Angeles, CA). In another aspect, the measurements are determined by other SEM scanners.

[0078] In one aspect, the measurements are based on capacitance measurements of a reference benchmark device. In one aspect, the capacitance measurements can depend on the location of any electrode in the device and other aspects. Such variations can be compared to a benchmark SEM device, such as SEM Scanner Model 200 (Bruin Biometrics, LLC, Los Angeles, CA). Those of ordinary skill in the art will appreciate that the measurements described herein can be adjusted to accommodate the range of differential capacitances by reference to the benchmark device.

[0079] In one aspect, the percentage according to the present disclosure can be in the range of 0-100%, such as 0-50%, 25-75%, 50-100%, 0-10%, 5-15%, 10-20%, 15-25%, 20-30%, 25-35%, 30-40%, 35%-45%, 40-50%, 0-25%, 15-35%, 25-50%, 45-55%, 50-60%, 55-65%, 60-70%, 65-75%, 40-55%, 50-75%, 70-80%, 75%-85%, 80-90%, 85-95%, 90-100%, 65-85%, or 75-100%. In one aspect, the percentage according to the present disclosure can be about 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

[0080] In one aspect, point 640 on curve 610 indicates the transition from the area 530 where edema has occurred to the area 520 where the tissue has a lower than normal moisture content. In one aspect, the measured SEM value equal to the normal value of reference line 612 indicates that a portion of the sensor is located on tissue with a higher than normal moisture content, while the remaining portion of the sensor is located on tissue with a lower than normal moisture content. In one aspect, point 640 on line A-A is approximately the location of the edge of area 520. If it is desired to resect the necrotic tissue from the patient, marking the skin at this point provides a reference for the surgeon of the edge of the necrotic tissue.

[0081] In one aspect, SEM values are measured continuously at one or more points near the open wound 510, for example, at 30 minute intervals for the first 4 hours, can provide information about the extent of tissue damage. In one aspect, the continuous measurements can be performed at approximately 5 minute intervals, 10 minute intervals, 15 minute intervals, 20 minute intervals, 25 minute intervals, 35 minute intervals, 40 minute intervals, 45 minute intervals, 50 minute intervals, 60 minute intervals, 90 minute intervals, or 120 minute intervals. In one aspect, the continuous measurements can be taken at time intervals within the first 1 hour, 2 hours, 3 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours after the injury. In one aspect, the values and location of the points 622 within the first 4 hours after the injury can indicate the depth of the burn and the risk of tissue depth in certain areas. The outward progression of peak SEM values on the x-axis can indicate the severity of reperfusion injury.

[0082] In one aspect, the measurements of SEM values can be made using a single sensor device (e.g., SEM Scanner 170 of Figure 1B ) and recorded, plotted, and evaluated.

[0083] Other types of wounds (e.g., incisions) can suffer from a zone of tissue death proximal to the open wound 510. As the level of edema still indicates tissue viability, the same sensing and classification methods will provide valuable information to the clinician treating the injury. Thus, the methods and apparatus described for the example burn can also be applied to other types of injuries.

[0084] The methods and apparatus disclosed herein can also be used to track the healing process of an injury, such as a burn, a cut, an ulcer, and other types of tissue damage. The closure of the skin over the wound is not the end of the healing process, and it can take up to a year for the tissue under the epidermis to return to its original state after the skin has closed. Regular assessment of the original wound site will show whether the healing continues to progress or has stopped or reversed. For example, pressure ulcers are known to suffer from a high recurrence rate at the same location as the first ulcer. This is thought to be a combination of the continued pressure on the site and the weakened tissue structure resulting from incomplete healing. Without continuous measurement of the tissue state, for example, using a SEM Scanner, a caregiver can treat a closed wound as a healed wound and not continue treatment that can prevent recurrence. Measurements of the surrounding tissue at locations away from the original wound can serve as a reference for "normal" tissue measurements. Changes or lack of trends in the measurements of the previous wound site relative to the reference provide continued assurance that the tissue is progressing toward a fully healed state.

[0085] This monitoring of tissue improvement after wound healing is also useful for monitoring the performance and efficacy of wound healing therapies. As an example, an electrical stimulation device can be used once the wound is closed to accelerate the healing process of the underlying tissue. Even if not impossible, it can be difficult to manually or visually assess the progress of healing. SEM scanning devices can be used to establish one or more SEM measurements at the closed wound site, periodic measurements, and trend analysis to verify the effectiveness of the healing device and measure adjacent tissue as a reference to fully healed tissue. In certain embodiments, the healing device can be adjusted based on the measurements or trends of measurements made by the SEM scanner, such as a change in frequency or voltage of an electrical stimulation device. In certain embodiments, a different device or therapy can be used to stop or replace the use of the healing device or therapy based on the SEM measurements or trends. In certain embodiments, a wound can be judged "healed" based on SEM measurements, and the healing therapy can be stopped, modified, or replaced with a prophylactic therapy. In certain embodiments, the difference between the current SEM reading of the wound site and a reference value from nearby healthy tissue is a measure of the degree of recovery of the tissue at the wound site, with a zero difference being a full cure and return to the original state.

[0086] Figure 7 Aspects of an SEM sensing device 700 according to the present disclosure are depicted. In one aspect, a flexible substrate 710 has a plurality of SEM sensors 720 arranged on a common surface of the substrate 710. In one aspect, the sensors 720 comprise a ring-shaped sensor 90 as shown in Figure 1A In one aspect, the sensors 720 comprise an electrode array 290 as shown in Figure 2 In one aspect, the sensors 720 comprise an electrode array 400 as shown in Figure 3 In one aspect, the sensors 720 are connected to electronics (not shown in Figure 7 ) that provide excitation and measure the SEM values of the tissue under the respective sensors 720.

[0087] In one aspect, the SEM sensing device 700 includes visual indicators 730 arranged on the substrate 710. In one aspect, the visual indicators 730 are on a first surface of the substrate 710, while the sensors 720 are on a second surface of the substrate 710 opposite the first surface. In one aspect, the visual indicators 730 are disposed between at least some of the sensor pairs 720. In one aspect, the visual indicators 730 can be light emitting devices (LEDs). In one aspect, the visual indicators 730 can emit a single color of light. In one aspect, the visual indicators 730 can selectively emit one of a plurality of colors of light. In one aspect, the visual indicators 730 can be selectively turned on or off. In one aspect, the visual indicators 730 are connected to electronics (not shown in Figure 7The electronics provide excitation and selective control of the visual indicators 730 (not shown).

[0088] In one aspect, the electronics of the present disclosure actuate each visual indicator 730 with light of a color selected based on the SEM values measured by the sensors 90 arranged on each side of the respective visual indicator 730. This provides a color-coded map of the individual zones 520, 530, and 540 for a given wound 500.

[0089] In one aspect, the visual indicators 730 can be disposed on the same surface of the substrate 710 as the sensors 720. In one aspect, the visual indicators 730 include marker elements (not shown) that can selectively mark the patient’s skin on which the SEM sensing apparatus 700 is placed. In one aspect, the electronics of the present disclosure can actuate the marker elements of the visual indicators 720 disposed along one or more boundaries between the zones 520, 530, and 540. In one aspect, the electronics of the present disclosure can actuate the marker elements to mark the boundary between the zone 520 and the zone 530, indicating the outer edge of non-viable tissue. Figure 7 In one aspect, the electronics of the present disclosure can actuate the marker elements of the visual indicators 730 disposed along one or more boundaries between the zones 520, 530, and 540. In one aspect, the electronics of the present disclosure can actuate the marker elements to mark the boundary between the zone 520 and the zone 530, indicating the outer edge of non-viable tissue. Figure 5A and 5B In one aspect, the electronics of the present disclosure can actuate the marker elements of the visual indicators 730 disposed along one or more boundaries between the zones 520, 530, and 540. In one aspect, the electronics of the present disclosure can actuate the marker elements to mark the boundary between the zone 520 and the zone 530, indicating the outer edge of non-viable tissue.

[0090] Figure 8A and Figure 8B Aspects of a SEM sensing apparatus 702 according to the present disclosure are disclosed. In one aspect, an array 740 of electrodes 742 is disposed on a substrate 712. In one aspect, the electrodes 742 are similar to the electrodes 300 of Figure 2 In one aspect, the electrodes 742 are similar to the electrodes 410 of Figure 3 In one aspect, the electrodes 742 are similar to the electrodes 410 of

[0091] In one aspect, the SEM sensing apparatus 702 includes a plurality of perforations 750. In one aspect, the perforations 750 are disposed between pairs of electrodes 742, as shown in Figure 8B In use, the SEM sensing apparatus 702 can be placed on the patient’s skin over a wound, and the clinician marks the patient’s skin under the guidance of the SEM values measured between pairs of electrodes 742.

[0092] In one aspect, the SEM sensing apparatus 700 can include visual indicators 730 and perforations 750, allowing the clinician to mark the patient’s skin under the guidance of the colors of the various visual indicators 730.

[0093] Figure 9Aspects of an apparatus 800 for mapping a damaged area around a wound in accordance with the present disclosure are disclosed. In one aspect, a patient's arm 20 has a burn 501 with an open wound 511. In one aspect, the apparatus 800 includes an instrument head 810 with an optical system 815 overhanging the arm 20, the optical system 815 including a camera (not visible in Figure 9 ) that views an area 825 on the arm 20 and a projector (not visible in Figure 9 ) that can project one or more images onto the area 825, the area 825 including the wound 511 and tissue around the wound 511. In one aspect, a SEM sensing device 840 is connected to electronics (not shown in Figure 9 ) that also control the optical system 815. In one aspect, the SEM sensing device 840 is connected to the electronics of the present disclosure by a cable 845. In one aspect, the SEM sensing device 840 includes a wireless connection in place of the cable 845. In one aspect, the SEM sensing device 840 includes a fiducial 850 that is visible to the camera when the apparatus 800 is in use. In one aspect, the SEM sensing device 840 includes a single bioimpedance sensor and thus measures ECF at a single point at a time.

[0094] In use, a user can take multiple measurements in the area 825 with the SEM sensing device 840. At each measurement, the camera can observe and record the position of the fiducial 850 in its field of view. In one aspect, a reference mark (not shown in Figure 9 ) can be made on the arm 20 to record the position of the arm 20 in the field of view and enable the arm 20 to be moved during evaluation. As the set of measurements increases, the electronics of the present disclosure determine the location of a boundary between tissue types (e.g., between living and non-living tissue) and cause the projector to project an indicator image along this boundary. In Figure 9 , these images are shown as dots 710. In one aspect, the projected images can include a line, a colored area, a shaded area from a first color to a second color, a shaded area from one intensity of a color to a different intensity of the same color, or other visual indicators that provide guidance to the condition of the tissue in the area 825.

[0095] In one aspect, the electronics of the present disclosure can be connected to a printer (not shown in Figure 9and can cause the printer to produce a picture of the arm 20, the wound 511 is photographed by the camera and overlaid with markings equivalent to those described as being provided by the projector. In one aspect, repeated measurements and printing of new pictures can be made with the SEM sensing device 800, thereby creating a pictorial history of the progression of the damage around the wound. In one aspect, the electronics of the present disclosure can be connected to a storage device (e.g., a server) and configured to store information about the images of the arm 20 and the wound 511 and the measurements and locations of the measurements made by the SEM sensing device 840 one or more times.

[0096] From the foregoing, it will be appreciated that the present application can be embodied in various ways, including but not limited to the following:

[0097] Example 1. A device for mapping a damage area around a wound, the device comprising: a plurality of electrodes embedded on a substrate, the substrate configured to be placed on a tissue area including a wound, wherein a combination of the electrodes is capable of forming a plurality of virtual capacitive sensors, each virtual capacitive sensor configured to measure a capacitance of the tissue area proximate to the respective virtual capacitive sensor, a plurality of visual indicators embedded on the substrate, a driving circuit electrically connected to the electrodes and the visual indicators, a processor electrically connected to the driving circuit, and a non-transitory computer readable medium electrically connected to the processor and comprising instructions stored thereon that, when executed on the processor, perform the steps of: receiving information about the measured capacitances from a subset of the plurality of virtual capacitive sensors via the driving circuit, determining a boundary between living tissue and non-living tissue, and activating a portion of the plurality of visual indicators via the driving circuit to indicate the boundary.

[0098] Example 2. The device of example 1, wherein the substrate comprises a plurality of perforations that allow marking the tissue along the boundary.

[0099] Example 3. The device of example 1, wherein the circuit is configured to selectively drive pairs of electrodes and measure a capacitance between each pair of electrodes.

[0100] Example 4. The device of example 3, wherein each pair of electrodes that is selectively driven forms one of the plurality of virtual capacitive sensors.

[0101] Example 5. The device of example 1, wherein the circuit is configured to selectively drive a subset of the plurality of electrodes to form a virtual center electrode and a virtual ring electrode and measure a capacitance between the virtual center electrode and the virtual ring electrode.

[0102] Example 6. The device of example 5, wherein each of the plurality of virtual capacitive sensors comprises a virtual center electrode and a virtual ring electrode.

[0103] Example 7. The apparatus of Example 1, wherein the instructions further comprise the steps of converting each measured capacitance to a related subepidermal moisture (SEM) value associated with the virtual capacitive sensor used to measure the capacitance, comparing a first portion of the SEM values to a first threshold, and identifying a corresponding tissue region of the virtual capacitive sensor associated with a SEM value greater than the first threshold as viable.

[0104] Example 8. The apparatus of Example 7, wherein the instructions further comprise the steps of comparing a second portion of the SEM values to a second threshold, and identifying a corresponding tissue region of the virtual capacitive sensor associated with a SEM value less than the second threshold as non-viable.

[0105] Example 9. The apparatus of Example 7, wherein each of the plurality of visual indicators independently comprises a first display mode and a second display mode.

[0106] Example 10. The apparatus of Example 9, wherein the instructions further comprise the steps of activating a third portion of the plurality of visual indicators in the first display mode to indicate a viable tissue region, and activating a fourth portion of the plurality of visual indicators in the second display mode to indicate a non-viable tissue region.

[0107] Example 11. The apparatus of Example 9, wherein the visual indicators are light emitting devices (LEDs), the first display mode comprises emitting light having a first characteristic, and the second display mode comprises emitting light having a second characteristic.

[0108] Example 12. The apparatus of Example 11, wherein the first characteristic comprises a first spectral content, and the second characteristic comprises a second spectral content different from the first spectral content.

[0109] Example 13. An apparatus for determining a depth of a burn wound, the apparatus comprising a pair of electrodes capable of forming a capacitive sensor configured to measure a capacitance of a tissue region proximate to the pair of electrodes, a drive circuit electrically connected to the capacitive sensor, a processor electrically connected to the drive circuit, and a non-transitory computer readable medium electrically connected to the processor and comprising instructions stored thereon that, when executed on the processor, perform the steps of receiving information about the measured capacitance of the capacitive sensor via the drive circuit, comparing the information to a data array comprising pairs of capacitances and burn depths, and determining a depth of a burn wound associated with the measured capacitance.

[0110] Example 14. The apparatus of Example 13, wherein the step of receiving information about the measured capacitances comprises receiving a first capacitance measured at a first location of known unaffected tissue, receiving a second capacitance measured at a second location within the burn wound, and determining a capacitance difference between the first capacitance and the second capacitance; the data array comprises pairs of capacitance differences and burn depths; the step of comparing the information to the data array comprises comparing the capacitance difference to the data array; and the step of determining the depth of the burn wound comprises identifying the depth of the burn wound associated with the capacitance difference.

[0111] Example 15. The apparatus of Example 13, wherein the instructions further comprise the step of converting each measured capacitance to an associated sub-epidermal moisture (SEM) value, the data array comprises pairs of SEM values and burn depths, the step of comparing the information to the data array comprises comparing the SEM value to the data array, and the step of determining the depth of the burn wound comprises identifying the depth of the burn wound associated with the SEM value.

[0112] Example 16. An apparatus for mapping a damaged area surrounding a wound, the apparatus comprising: a plurality of electrodes embedded on a substrate, the substrate configured to be placed on a portion of a tissue area including a wound, wherein pairs of electrodes are capable of forming a capacitance sensor, the capacitance sensor configured to measure a capacitance of the tissue area proximate to the capacitance sensor, a projector capable of projecting a visual indicator onto the tissue area including the wound, a drive circuit electrically connected to the plurality of electrodes and the projector, a processor electrically connected to the drive circuit, and a non-transitory computer readable medium electrically connected to the processor and comprising instructions stored thereon that, when executed on the processor, perform the steps of: receiving information about measured capacitances from one or more of the formed capacitance sensors, determining a first boundary between a first type of tissue and a second type of tissue, and causing the projector to project the visual indicator to indicate the boundary.

[0113] Example 17. The apparatus of Example 16, wherein the first type of tissue is living tissue and the second type of tissue is non-living tissue.

[0114] Example 18. The apparatus of Example 17, wherein the first boundary is identified by the steps of: converting each measured capacitance to a related sub-epidermal moisture (SEM) value associated with the capacitance sensor used to measure the capacitance, identifying a corresponding tissue area of a virtual capacitance sensor associated with a SEM value greater than a threshold value as viable, identifying a corresponding tissue area of the capacitance sensor associated with a SEM value less than the threshold value as non-viable; and marking the first boundary between the viable area and the non-viable area.

[0115] Example 19. The device of Example 16, wherein the instructions further comprise the step of determining a second boundary between the second type of tissue and a third type of tissue.

[0116] Example 20. The device of Example 19, wherein the first type of tissue is necrotic tissue, wherein the second type of tissue is tissue in a stagnant region, and wherein the third type of tissue is tissue in a hyperemic region.

[0117] Example 21. The device of Example 20, wherein the first boundary and the second boundary are identified by the steps of converting each of the measured capacitances to a related subepidermal moisture (SEM) value associated with the capacitance sensor used to measure the capacitance, identifying a corresponding tissue region of the capacitance sensor associated with an SEM value less than a first threshold value as necrotic tissue, marking the first boundary on an outer edge of the necrotic tissue region, identifying a tissue region in a stagnant region, the stagnant region comprising tissue immediately surrounding the necrotic tissue region and corresponding to capacitance sensors associated with SEM values greater than the first threshold value and comprising a location associated with a peak SEM value and tissue immediately surrounding the location associated with the peak SEM value and corresponding to capacitance sensors associated with SEM values greater than a second threshold value, marking the second boundary on an outer edge of the stagnant region; and identifying a tissue region in a hyperemic region, the hyperemic region comprising tissue immediately surrounding the stagnant region and corresponding to capacitance sensors associated with SEM values less than the second threshold value but greater than the first threshold value.

[0118] Example 22. A method for mapping a region of injury surrounding a wound, the method comprising: obtaining capacitance measurements on a tissue region including a wound using a plurality of electrodes; converting each of the measured capacitances to a related subepidermal moisture (SEM) value; and marking a first boundary encompassing a tissue region associated with an SEM value less than a first threshold value.

[0119] Example 23. The method of Example 22, further comprising: marking a second boundary surrounding the first boundary, the second boundary comprising a tissue region associated with an SEM value greater than the first threshold value and comprising a location associated with a peak SEM value and tissue immediately surrounding the location associated with the peak SEM and corresponding to capacitance sensors associated with SEM values greater than a second threshold value.

[0120] While this application has been described with reference to particular aspects, it will be apparent to those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the present application. In addition, many modifications can be made to the teachings of the present application to adapt its teachings to particular situations and materials without departing from the scope of the application. Therefore, it is contemplated to cover within this application all aspects falling within the scope and spirit of the appended claims.

Claims

1. An apparatus for determining burn wound depth, the apparatus comprising: a plurality of electrodes capable of forming one or more virtual capacitive sensors configured to measure a capacitance of a region of tissue proximate each of the one or more virtual capacitive sensors, wherein each of the one or more virtual capacitive sensors comprises two virtual electrodes and a gap therebetween, wherein each of the virtual electrodes comprises one or more electrodes of the plurality of electrodes, and wherein the gap can be varied to change a characteristic of an electric field, a drive circuit electrically connected to each of the one or more virtual capacitive sensors, a processor electrically connected to the drive circuit, and a non-transitory computer readable medium electrically connected to the processor and comprising instructions stored thereon that, when executed on the processor, perform the following steps: receiving information about the measured capacitance from the one or more virtual capacitive sensors via the drive circuit, comparing the information to a data array comprising capacitances associated with burn depths, wherein pairs of capacitances and burn depths are formed, wherein each pair comprises a single capacitance and its corresponding burn depth, and determining a depth of the burn wound associated with the measured capacitance.

2. The apparatus of claim 1, wherein: the step of receiving information about the measured capacitance comprises: receiving a first capacitance measured at a first location of known unaffected tissue, receiving a second capacitance measured at a second location within the burn wound, and determining a capacitance difference between the first capacitance and the second capacitance; the data array comprises pairs of capacitance differences associated with burn depths; the step of comparing the information to the data array comprises comparing the capacitance difference to the data array comprising capacitance differences associated with burn depths, wherein pairs of capacitance differences and burn depths are formed, wherein each pair comprises a single capacitance difference and its corresponding burn depth; and the step of determining a depth of the burn wound comprises identifying the depth of the burn wound associated with the capacitance difference.

3. The apparatus of claim 1, wherein: the instructions further comprise the step of converting each measured capacitance to an associated sub-epidermal moisture (SEM) value, the data array comprises pairs of SEM values and burn depths, the step of comparing the information to the data array comprises comparing the SEM value to the data array comprising SEM values associated with burn depths, wherein pairs of SEM values and burn depths are formed, wherein each pair comprises a single SEM value and its corresponding burn depth, and the step of determining a depth of the burn wound comprises identifying the depth of the burn wound associated with the SEM value.

4. An apparatus for mapping a region of damage surrounding a wound, the apparatus comprising: A sensing device comprising: a plurality of electrodes embedded on a substrate configured to be placed on a portion of a tissue area including a wound, wherein a combination of the plurality of electrodes is capable of forming a plurality of virtual capacitive sensors, each of the virtual capacitive sensors including two or more electrodes of the plurality of electrodes and configured to measure a capacitance of a tissue area proximate to the respective virtual capacitive sensor, an optical system comprising: a camera configured to take pictures of the tissue area including the wound; and a projector capable of projecting a plurality of visual indicators onto the tissue area including the wound, a fiducial on the sensing device, the fiducial being visible to the camera when the device is in use, a driving circuit electrically connected to the plurality of electrodes and the optical system, a processor electrically connected to the driving circuit, and a non-transitory computer readable medium electrically connected to the processor and comprising instructions stored thereon that, when executed on the processor, perform the steps of: receiving, by the driving circuit, information about one or more of the measured capacitances from a subset of the plurality of virtual capacitive sensors, determining a first boundary between a first type of tissue and a second type of tissue, and causing the projector to project the plurality of visual indicators to indicate the first boundary.

5. The apparatus of claim 4, wherein, The first type of tissue is living tissue and the second type of tissue is non-living tissue.

6. The apparatus of claim 5, wherein, The first boundary is identified by the steps of: converting each of the one or more measured capacitances to a related sub-epidermal moisture (SEM) value associated with each of the virtual capacitive sensors used to measure the capacitances, identifying a region of the corresponding living tissue of each of the virtual capacitive sensors associated with a SEM value greater than a threshold value, identifying a region of the corresponding non-living tissue of each of the virtual capacitive sensors associated with a SEM value less than the threshold value, and marking the first boundary between the region of living tissue and the region of non-living tissue.

7. The apparatus of claim 4, wherein, The instructions further comprise the step of determining a second boundary between the second type of tissue and a third type of tissue.

8. The apparatus of claim 7, wherein, The first type of tissue is necrotic tissue, wherein the second type of tissue is tissue in a stagnant region, and wherein the third type of tissue is tissue in a hyperemic region.

9. The apparatus of claim 8, wherein, The first boundary and the second boundary are identified by the steps of: converting each of the one or more measured capacitances to a related sub-epidermal moisture (SEM) value associated with each of the virtual capacitive sensors used to measure the capacitances, identifying a region of the corresponding tissue of each of the virtual capacitive sensors associated with a SEM value less than a first threshold value as necrotic tissue, marking the first boundary on an outer edge of the necrotic tissue, identifying a congestion area comprising tissue immediately surrounding the necrotic tissue and tissue areas corresponding to each of the virtual capacitive sensors associated with SEM values greater than the first threshold value, and including the area associated with the peak SEM value, and tissue immediately surrounding the area associated with the peak SEM value and areas corresponding to each of the virtual capacitive sensors associated with SEM values greater than a second threshold value, marking the second boundary on the outer edge of the congestion area, and identifying a hyperemic area comprising tissue immediately surrounding the congestion area and tissue areas corresponding to each of the virtual capacitive sensors associated with SEM values less than the second threshold value but greater than the first threshold value.

10. The device of claim 1, wherein each of the one or more virtual capacitive sensors comprises a virtual center electrode surrounded by a virtual ring electrode.

11. The device of claim 10, wherein the drive circuit is configured to select one or more electrodes from the plurality of electrodes to form the virtual center electrode, and to select more than two electrodes from the electrodes to form the virtual ring electrode.

12. The device of claim 11, wherein the drive circuit is further configured to measure the capacitance between the virtual center electrode and the virtual ring electrode.

13. The apparatus of claim 1, wherein, the characteristic of the electric field comprises a depth of the electric field.

14. The device of claim 4, wherein the camera is configured to take and record a position of the fiducial in its field of view at each measurement.

15. The device of claim 4, wherein the plurality of visual indicators for indicating the first boundary are selected from the group consisting of: a dot, a line, a color area, a shade area from a first color to a second color, a shade area from one color intensity to a different intensity of the same color.

16. The apparatus of claim 1, wherein, the gap between the two virtual electrodes making up each of the one or more virtual capacitive sensors is uniform.

17. The apparatus of claim 1, wherein, the gap between the two virtual electrodes making up each of the one or more virtual capacitive sensors is variable.

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