Symmetrical comparison of subepidermal moisture levels

Abstract

To provide an apparatus and a method for measuring sub-epidermal moisture at bisymmetric locations on patients to identify damaged tissue for clinical intervention.SOLUTION: The apparatus comprises: first and second sensors comprising a first electrode and a second electrode, and placed against the skin of a patient; a circuit electronically coupled to the first and second electrodes and configured to measure an electrical property between the first and second electrodes of the sensors and provide information regarding the electrical property; and a processor configured to receive the information from the circuit and convert the information into a sub-epidermal moisture (SEM) value. The apparatus determines a difference between a first SEM value corresponding to the electrical property as measured by the first sensor at a first location on the skin of the patient and a second SEM value corresponding to the electrical property as measured by the second sensor at a second location on the skin of the patient, where the second location is bisymmetric relative to the first location.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Application No. 62 / 454,455, filed February 3, 2017, and U.S. Provisional Application No. 62 / 521,871, filed June 19, 2017, each of which is incorporated by reference in its entirety.

[0002] The present disclosure provides an apparatus and computer readable medium for measuring subepidermal water in a patient to identify damaged tissue for clinical action. The present disclosure also provides a method for determining damaged tissue. [Background technology]

[0003] Skin is the largest organ in the human body and is easily exposed to various kinds of damage and injury.When skin and its surrounding tissues cannot redistribute external pressure and mechanical force, ulcers can form.Even gentle pressure, such as the pressure on the back skin surface created by the weight of a patient lying on his back, can cause bedsores when exposed for a long period of time.In the presence of other damage, such as neuropathy and weakening of peripheral tissues that can be induced by diabetes, even intermittent exposure to gentle levels of pressure and stress can cause ulcers, such as foot ulcers.

[0004] Pressure ulcers affect approximately 2.5 million people each year in the United States and a similar number in Europe. In long-term and critical care settings, up to 25% of elderly and bedridden patients develop pressure ulcers. Approximately 60,000 U.S. patients die each year from infections and other complications from pressure ulcers.

[0005] It is desirable for patients as well as society to detect tissue damage before the skin is broken and to take appropriate therapeutic action to avoid further deterioration of the underlying tissue. The average cost to treat pressure-induced damage at the first visible signs (stage 1 ulcer) is only $2,000, but this increases to $129,000 if the ulcer is deep enough to expose muscle or bone (stage 4 ulcer). The current standard for detecting pressure ulcers is by visual inspection, which is subjective, unreliable, untimely, and lacking specificity. Summary of the Invention

[0006] In an aspect, the present disclosure provides and includes an apparatus for identifying damaged tissue, the apparatus including: first and second sensors, each comprising a first electrode and a second electrode, each of the sensors configured to be placed on the skin of a patient; a circuit electrically coupled to the first and second electrodes and configured to measure an electrical characteristic between the first electrode and the second electrode of each of the sensors to provide information regarding the electrical characteristic; and a circuit electrically coupled to and receiving information from the circuit and converting the information into a subepidermal moisture (SEM) value. and a non-transitory computer readable medium electrically coupled to the processor and including instructions stored on the non-transitory computer readable medium that, when executed on the processor, performs steps of determining a difference between a first SEM value corresponding to an electrical characteristic measured by a first sensor at a first location on the patient's skin and a second SEM value corresponding to an electrical characteristic measured by a second sensor at a second location on the patient's skin, wherein the second location is symmetrical to the first location.

[0007] In one aspect, an apparatus for identifying damaged tissue is provided by the present disclosure comprising: a substrate configured to be placed on a surface of a patient's skin; a plurality of sensors disposed on the substrate at respective plurality of locations, each sensor comprising a pair of electrodes; a circuit electrically coupled to each pair of electrodes of the plurality of sensors and configured to measure an electrical characteristic between a portion of the electrode pairs of the plurality of sensors to provide information regarding the measured electrical characteristic; a processor electrically coupled to the circuit and configured to receive information regarding the electrical characteristic from the circuit and convert the plurality of electrical characteristics into a respective plurality of subepidermal moisture (SEM) values; and a non-transitory computer readable medium electrically coupled to the processor and comprising instructions stored on the non-transitory computer readable medium that, when executed on the processor, performs the steps of: identifying a first sensor and a second sensor at first and second locations that are symmetrical with respect to the patient's skin from the plurality of SEM values, and comparing a first SEM value associated with the first sensor to a second SEM value associated with the second sensor.

[0008] In one aspect, there is provided by the present disclosure an apparatus for identifying damaged tissue, the apparatus comprising: a device body; two sensors, comprising a first sensor and a second sensor, disposed on the device body such that the two sensors are capable of simultaneously positioning the first sensor at a first location on a patient's skin and positioning the second sensor at a second location symmetrical to the first location; a circuit electrically coupled to each of the two sensors and configured to measure an electrical property from each of the two sensors; a processor electrically coupled to the circuit and configured to receive a first electrical property measurement from the first location, receive a second electrical property measurement from the second location, convert the first electrical property measurement to a first SEM value, and convert the second electrical property measurement to a second SEM value; and a non-transitory computer readable medium electrically coupled to the processor and comprising instructions, when executed on the processor, to perform the steps of determining a difference between the first SEM value and the second SEM value.

[0009] In one aspect, the present disclosure provides a method for identifying damaged tissue, the method including obtaining a first subepidermal moisture (SEM) value from a first location on a patient's skin, obtaining a second SEM value from a second location that is symmetrical to the first location, and determining a difference between the first SEM value and the second SEM value. [Brief description of the drawings]

[0010] 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 emphasized that the items shown are examples and are intended for illustrative discussion of aspects of the present disclosure. In this regard, the description and the drawings, taken alone or together, will make apparent to one skilled in the art how aspects of the present disclosure may be practiced.

[0011] [Figure 1A] 1 is a diagram of a plan view of a toroidal sensor; [Figure 1B] 1B is a cross-sectional illustration of the toroidal sensor of FIG. 1A. [Figure 1C] 1B is an illustration of an idealized electric field map produced by the toroidal sensor of FIG. 1A upon activation. [Figure 2A] 1 provides examples of paired symmetrical locations of the sacrum in accordance with the present disclosure. [Figure 2B] 1 provides examples of pairs of symmetrical locations on the bottom surfaces of both feet in accordance with the present disclosure. [Figure 2C] 1 provides examples of paired symmetrical locations on the lateral and plantar surfaces of both feet in accordance with the present disclosure. [Diagram 3] 1 is a diagram of an apparatus with one coaxial sensor. [Figure 4A] 1 is a first exemplary device with two sensors according to the present disclosure. [Figure 4B] 1 is a second exemplary apparatus according to the present disclosure, including two sensors and configured to determine SEM values ​​at symmetrical locations. [Diagram 5]1 is an exemplary device including multiple sensors according to the present disclosure. [Figure 6] 1 is a first exemplary array of electrodes. [Figure 7] 1 is an exemplary array of electrodes according to the present disclosure. [Figure 8A] 8 illustrates a first example of how an array of electrodes as disclosed in FIG. 7 can be configured to form a sensor in accordance with the present disclosure. [Figure 8B] 8 illustrates a second example of how the array of electrodes disclosed in FIG. 7 can be configured to form a sensor in accordance with the present disclosure. [Figure 9A] 1 illustrates an example of a first sensor formed with an array of electrodes according to the present disclosure. [Figure 9B] 9B illustrates an example of how a second sensor may be formed to overlap the first sensor of FIG. 9A according to the present disclosure. [Figure 10] 8B shows an example of how the sensor shown in FIG. 8A is formed from an array of electrodes that is larger than the portion of the patient's skin that is positioned in the array, in accordance with the present disclosure. [Figure 11A] 1 illustrates the locations of the left and right feet for SEM measurements according to the present disclosure. [Figure 11B] 1 is a plot of SEM values ​​associated with known relative locations for identifying symmetric locations in accordance with the present disclosure. [Figure 12A] 1 illustrates an exemplary configuration of a substrate shaped to be positioned at a known location on a patient's skin in accordance with the present disclosure. [Figure 12B] 12B illustrates a front view of the exemplary configuration of FIG. 12A according to the present disclosure. [Figure 13] 1 depicts an integrated system for measuring, evaluating, storing, and transferring SEM values ​​in accordance with the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] This description is not intended to be a detailed enumeration of all the different ways in which the disclosure may be implemented or all the features that may be added to the disclosure. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. Thus, the disclosure contemplates that in some embodiments of the disclosure, any feature or combination of features described herein may be excluded or omitted. In addition, numerous modifications and additions to the various embodiments suggested herein will be apparent to those skilled in the art in light of the disclosure, and which do not depart from the disclosure. In other cases, well-known structures, interfaces, and processes have not been shown in detail so as not to unnecessarily obscure the invention. No part of this specification is intended to be construed as denying any portion of the entire scope of the invention. Thus, the following description is intended to illustrate some specific embodiments of the disclosure, without exhaustively specifying all permutations, combinations, and modifications thereof.

[0013] 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 belongs. The terms used in the description of the present disclosure herein are for the purpose of describing particular aspects or embodiments only and are not intended to be limiting of the present disclosure.

[0014] All publications, patent applications, patents, and other references cited herein are incorporated by reference in their entirety for the teachings relevant to the sentence and / or paragraph in which the reference is presented. References to technology used herein are intended to refer to technology as commonly understood in the art, including modifications to the technology or substitutions of equivalent technology that would be apparent to one of ordinary skill in the art.

[0015] U.S. Patent Application Serial No. 14 / 827,375 discloses an apparatus that uses radio frequency (RF) energy to measure subepidermal capacitance using a bipolar sensor similar to sensor 90 shown in Figure 1, where the subepidermal capacitance corresponds to the moisture content of a target area of ​​a patient's skin. The '375 application also discloses arrays of these bipolar sensors of various sizes.

[0016] U.S. Patent Application No. 15 / 134,110 discloses an apparatus for measuring subepidermal moisture (SEM) similar to the device shown in FIG. 3, which emits and receives RF signals at a frequency of 32 kHz through a single coaxial sensor to generate a bioimpedance signal, which is then converted to an SEM value.

[0017] Both U.S. Patent Application Nos. 14 / 827,375 and 15 / 134,110 are incorporated herein by reference in their entireties.

[0018] It is specifically contemplated that the various features of the present disclosure described herein may be used in any combination, unless the context indicates otherwise. Further, the present disclosure also contemplates that in some embodiments of the present disclosure, any feature or combination of features described herein may be excluded or omitted.

[0019] The methods disclosed herein include and comprise one or more steps or acts for achieving the described method. The steps and / or acts of the method may be interchanged with one another without departing from the scope of the present invention. In other words, unless a specific order of steps or acts is required for the proper operation of an embodiment, the order and / or use of specific steps and / or acts may be modified without departing from the scope of the present invention.

[0020] 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 dictates otherwise.

[0021] As used herein, "and / or" refers to and includes any and all possible combinations of one or more of the associated listed items, as well as the lack of combination if otherwise interpreted ("or").

[0022] The terms "about" and "approximately" when used herein when referring to a measurable value such as a length, frequency, or SEM value are intended to encompass variations of as much as ±20%, ±10%, ±5%, ±1%, ±0.5%, or ±0.1% of the specified amount.

[0023] As used herein, phrases such as "between X and Y" and "between about X and Y" should be interpreted to include X and Y. As used herein, phrases such as "between about X and Y" mean "between about X to about Y," and phrases such as "about X to Y" mean "about X to about Y."

[0024] As used herein, the term "subepidermal moisture" or "SEM" refers to an increase in tissue fluid and local edema caused by vascular leakage and other changes that modify the underlying structure of damaged tissue in the presence of continued pressure on the tissue, apoptosis, necrosis, and inflammatory processes.

[0025] As used herein, a "system" may be a collection of devices in wired or wireless communication with each other.

[0026] As used herein, "probing" refers to the use of radio frequency energy to penetrate the skin of a patient.

[0027] As used herein, a "patient" may be a human or animal subject.

[0028] As used herein, "symmetric" refers to a pair of locations that are approximately equidistant from an axis of symmetry.

[0029] As used herein, "Δ" refers to the calculated difference between two SEM values.

[0030] FIG. 1A is a plan view of a toroidal sensor 90 comprising a center electrode 110 and a ring electrode 120. In one embodiment, the electrodes 110 and 120 are disposed on a common surface of a substrate 100, as shown in the cross section of the sensor 90 shown in FIG. 1B. In one embodiment, the substrate 100 is rigid, e.g., a sheet of FR4 printed circuit board (PCB). In one embodiment, the substrate 100 is flexible, e.g., a sheet of polyimide. In one embodiment, the substrate 100 is a combination of rigid and flexible elements. In one embodiment, the electrodes 110 and 120 are covered with a cover layer 130 that is non-conductive to isolate the electrodes 110 and 120 from each other and / or from external contact. In one embodiment, some portions of the cover layer 130 are conductive in one direction, allowing the electrodes 110 and 120 to be in electrical contact with an object disposed on the cover layer 130 while remaining electrically isolated from adjacent electrodes. In one embodiment, the cover layer 130 is rigid and planar, thereby providing a flat exterior surface. In one embodiment, the cover layer 130 conforms to the underlying electrodes 110 and 120 and the substrate 100 such that there are no gaps or voids between the substrate 100 and the cover layer 130. When a voltage is applied across the electrodes 110 and 120, an electric field 140 is generated between the electrodes 110 and 120, which extends outward from the plane of the electrodes 110 and 120 to a distance 150, also referred to as the depth of the electric field, as shown in FIG. 1C. The diameter of the center electrode 110, the inner and outer diameters of the ring electrode 120, and the gap between the electrodes 110 and 120 can be altered by changing the characteristics of the electric field 140, such as the depth of the electric field 150.

[0031] 2A shows the sacral region of the back of a patient 10. An axis of symmetry 12 can be drawn down the center of the back, dividing the back into left and right mirror images. Location 14 is approximately the same distance from and approximately the same height as axis symmetry 12 and is therefore considered to be the left and right mirror locations of the back of patient 10.

[0032] 2B shows the left foot 20L and right foot 20R of patient 10 as they would be seen if patient 10 were lying on his back on a bed (not shown) with an observer standing at the foot of the bed. With respect to the soles 22L and 22R of feet 20L and 20R, locations 24L and 24R are located in approximately equivalent locations, e.g., on the posterior surface, i.e., the same distance from the heel and the same distance from the medial side of the respective foot 20L or 20R, and are considered to be symmetrical locations.

[0033] 2C illustrates additional exemplary symmetrical locations 26L and 26R located on the lateral sides of feet 20L and 20R, as well as symmetrical locations 28L and 28R located on soles 22L and 22R of feet 20L and 20R, respectively. In one aspect, locations 26R and 30R are considered symmetrical with respect to foot 20R when considered alone without reference to foot 20L.

[0034] Without being limited to a particular theory, a comparison of SEM measurements taken at symmetric locations can compensate for offsets in readings of a particular patient from a population of patients. For example, a patient may be dehydrated on the particular day that measurements are taken. A comparison of SEM values ​​of healthy tissue from the same patient while dehydrated may vary from the SEM value of the same tissue at the same location when the patient is fully hydrated. If tissue at one location is healthy while tissue at symmetric locations is damaged, a comparison of readings taken at symmetric locations will exclude the "common mode" effect of dehydration at both locations and provide a more robust indication that tissue is damaged at one location.

[0035] FIG. 3 illustrates an exemplary SEM measurement device 170 with one toroidal sensor 174 disposed on an underside 172 of the device body. The device 170 may be used to perform measurements at multiple locations, e.g., a first measurement at a first location and a second measurement at a second location that is symmetrical to the first location. In one embodiment, the device 170 includes a processor that may be configured by instructions stored on a non-transitory computer-readable medium to determine one or more characteristics of measurements taken at the multiple locations or a parameter associated with or derived from the measurements, e.g., a difference between, an average of, or each difference from a common average of SEM values ​​obtained from each of the multiple measurements. In one embodiment, the device 170 includes a display configured to show one or more parameters associated with the measurements, e.g., a delta between SEM values ​​obtained from measurements taken at two symmetrical locations.

[0036] FIG. 4A shows an exemplary SEM measurement device 180 with two sensors 184A and 184B located at separate locations on a device body 182 according to the present disclosure. An exemplary usage is to place the device 180 against a patient's body (not shown) to simultaneously position a first sensor 184A at a first location and a second sensor 184B at a second location, both locations on the surface of the patient's skin. In one embodiment, the device body 182 is rigid, maintaining the sensors 184A and 184B at a fixed separation distance and fixed orientation from each other. In one embodiment, the sensors 184A and 184B are aligned on a common plane as shown in FIG. 4A. In one embodiment, the device body 182 is flexible, which allows the sensors 184A and 184B to be oriented at an angle relative to each other. In one embodiment, one or more of the sensors 184A and 184B are movable, which allows the angle between the movable sensor and the other sensor to change.

[0037] In use, the device 180 can measure electrical properties or parameters including one or more electrical characteristics selected from the group consisting of resistance, capacitance, inductance, impedance, magnetoresistance, and other electrical characteristics with one or more sensors 184A and 184B. In one embodiment, the sensors 184A and 184B are configured as toroidal sensors as shown in FIG. 1A with a center electrode 110 and a ring electrode 120. In one embodiment, the sensors 184A and 184B are provided in other configurations as discussed in this application. In one embodiment, the sensors 184A and 184B include a ground plate (not shown) adjacent to and separated from a portion of the electrodes 110 and 120. In one embodiment, the ground plate shields the electrodes 110 and 120 from interference or modifies the shape of the electric field of the sensors 184A and 184B (similar in concept to the electric field 140 of FIG. 1C). In one embodiment, the ground plate is disposed on a side of the substrate opposite the side on which the electrodes 110 and 120 are disposed. In one embodiment, the device 180 comprises a circuit (not shown) configured to electrically couple to the electrodes 110 and 120 of each sensor 184A and 184B and measure an electrical characteristic between the electrodes 110 and 120. In one embodiment, the ground plate couples to a ground or equivalent floating reference of the circuit. In one embodiment, the circuit is configured to determine and provide information regarding the measured electrical characteristic. In one embodiment, the device 180 makes measurements on the sensors 184A and 184B essentially simultaneously. In one embodiment, the device 180 makes measurements sequentially with a time interval between measurements ranging from zero to one second or more. In one embodiment, measurements by the device 180 are triggered by activation of a button (not visible in FIG. 4A) or actuator. In one embodiment, measurements by apparatus 180 are automatically triggered based on input from a switching element (not shown in FIG. 4A ) that is part of apparatus 180, such as a contact sensor, pressure sensor, light sensor, or other type of proximity detection device that in one embodiment is positioned proximate to one or more of sensors 184A and 184B. In one embodiment, multiple switching elements must be activated simultaneously to provide the input to make a measurement.

[0038] In one aspect, the device 180 comprises a processor (not shown) that couples to the circuit and receives information about the measured electrical property from the circuit. In one aspect, the information is in the form of an analog signal, e.g., a voltage, or a digital signal. In one aspect, the processor is configured to directly couple to the sensors 184A and 184B and directly measure the electrical property. In one aspect, the processor is configured to convert the received electrical property to an SEM value. In one aspect, the processor is configured with machine-readable instructions stored on a non-transitory computer-readable medium that is electrically coupled to the processor. In one aspect, the instructions are read into the processor from the medium when the device 180 is powered on.

[0039] In one embodiment, the measured electrical parameters relate to the water content of the patient's epidermis at a depth determined by the geometry of the electrodes of sensors 184A and 184B, the frequency and strength of the electric field 140 associated with FIG. 1C produced by sensors 184A and 184B, and other operational characteristics of device 180. In one embodiment, the water content is equivalent to the SEM content and the values ​​are a predefined scale. In one embodiment, the predefined scale may range from 0 to 20, e.g., 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 embodiment, the predefined scale may be scaled by a factor or multiple based on values ​​provided herein. In one embodiment, multiple measurements are taken while varying one or more of the operating characteristics between readings, thereby providing information about the water content at various skin depths.

[0040] In one embodiment, capacitance measurements are made simultaneously at sensors 184A and 184B when a contact sensor (not visible in FIG. 4A) determines that sensors 184A and 184B are in proper contact with two symmetrical locations on the patient's skin. In one embodiment, the simultaneous capacitance measurements are compared to one another to determine if tissue beneath one of the symmetrical locations is damaged. In one embodiment, the capacitance measurements are individually converted to SEM values ​​corresponding to the water content of the tissue proximate to each sensor 184A and 184B, and the SEM values ​​are compared. In one embodiment, the comparison is performed using effective voltage, capacitance values, or other intermediate signals.

[0041] In one embodiment, the difference between the SEM values ​​is determined, and a difference exceeding a predetermined threshold indicates tissue damage at one of the locations where the corresponding capacitance measurement is performed. In one embodiment, the average value of the SEM values ​​obtained at each symmetrical location is determined and compared. In one embodiment, the median or mode of the SEM values ​​obtained at each symmetrical location is determined and compared. In one embodiment, the damage is indicated to be at the location associated with the larger SEM value. In one embodiment, the damage is indicated to be at the location associated with the smaller SEM value. In one embodiment, the determination of whether there is tissue damage includes one or more of the following: comparing the individual SEM values ​​to one or more predetermined ranges or thresholds, and comparing the difference to one or more predetermined ranges or thresholds. In one embodiment, the predetermined range may be 0.1 to 8.0, for example, 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 embodiment, the predetermined range may be 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 embodiment, the predetermined range may be 4.1 to 8.0, for example, 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 threshold is 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, 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, 3.16, 3.17, 3.18, 3.19, 3.20, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27, 3.28, 3.29, 3.30, 3.31, 3.32, 3.33, 3.34, 3.35, 3.36, 3.37, 3.38, 3.39, 3.40, 3.41, 3.42, 3.43, 3.44, 3.45, 3.46, 3.47, 3.48, 3.49, 3.50, 3.51, 3.52, 3.53, 3.54, 3.55 It may be 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 embodiment, the predetermined threshold may be in the range of 0.1 to 8.0, for example, 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 embodiment, the predetermined range or threshold may be scaled by a factor or multiple based on the values ​​provided herein. It will be understood that the predetermined value is not limited by design, but rather one of skill in the art can select the predetermined value based on the given SEM units. In one aspect, the ranges and thresholds disclosed herein vary depending on one or more characteristics of the patient, such as the particular bilateral location, the part of the patient's body where the measurement is being taken, age, height, weight, family history, ethnicity, and other physical characteristics or health conditions.

[0042] One or more regions may be defined on the body. In one embodiment, measurements made within a region are considered comparable to each other. A region may be defined as an area on the skin of the body, and measurements may be made at any point within that area. In one embodiment, a region corresponds to an anatomical area (e.g., heel, ankle, lower back). In one embodiment, a region is defined as a set of two or more specific points relative to an anatomical feature, and measurements are made only at the specific points. In one embodiment, a region may include multiple non-contiguous areas on the body. In one embodiment, a set of specific locations may include points within multiple non-contiguous areas.

[0043] In one embodiment, the region is defined by a surface area, which may be, for example, 5 to 200 cm2, 5 to 100 cm2, 5 to 50 cm2, or 10 to 50 cm2, 10 to 25 cm2, or 5 to 25 cm2.

[0044] In one embodiment, measurements may be made in a specific pattern or portion thereof. In one embodiment, a pattern of readings is made in a pattern with the relevant target area at the center. In one embodiment, measurements are made in one or more circular patterns of increasing or decreasing size, in a T-shaped pattern, at a set of specific locations, or randomly across a tissue or region. In one embodiment, a pattern may be located on the body by defining a first measurement location of the pattern relative to an anatomical feature, and the remaining measurement locations of the pattern are defined as offsets from the first measurement location.

[0045] In one embodiment, multiple measurements are made across a tissue or region, and the difference between the lowest and highest measurement of the multiple measurements is recorded as the delta value of the multiple measurements, hi one embodiment, 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 made across a tissue or region.

[0046] In one embodiment, a threshold value may be established for at least one region. In one embodiment, a threshold value of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or other value may be established for the at least one region. In one embodiment, a delta value is recognized as significant when the delta values ​​of multiple measurements made within a region meet or exceed the threshold value associated with the region. In one embodiment, each of the multiple regions has a different threshold value. In one embodiment, two or more regions may have a common threshold value.

[0047] In one embodiment, the threshold has both a delta value component and a time-dependent component, and a delta value is recognized as significant if the delta value is greater than a predetermined number over a predetermined portion of the time interval. In one embodiment, the predetermined portion of the time interval is defined as at least X days, where multiple measurements taken on that day result in a delta value that is equal to or greater than a predetermined number within measurements for a total of Y consecutive days. In one embodiment, the predetermined portion of the time interval may be defined as 1, 2, 3, 4, or 5 consecutive days, where multiple measurements taken on that day result in a delta value that is equal to or greater than a predetermined number. In one embodiment, the predetermined portion of the time interval may be defined as a portion of a different specific period (such as a week, month, hour, etc.).

[0048] In one aspect, the threshold has a trend aspect where the change in the Δ value of consecutive measurements is compared to one another. In one aspect, the trend threshold is defined as a predetermined change in the Δ value over a predetermined length of time, and a determination that the threshold has been met or exceeded is significant. In one aspect, a significant determination causes an alert to be issued. In one aspect, a trend line may be calculated from a portion of the individual measurements of the consecutive measurements. In one aspect, a trend line may be calculated from a portion of the Δ values ​​of the consecutive measurements.

[0049] In one embodiment, the number of measurements made within a single region may be less than the number of measurement locations defined in the pattern. In one embodiment, a Δ value is calculated after a predetermined initial number of readings, less than the number of measurement locations defined in the pattern, are made within a region and after each additional reading within the same region, where additional readings are not made once the Δ value meets or exceeds a threshold value associated with that region.

[0050] In one aspect, the number of measurements within a single region may exceed the number of measurement locations defined in the pattern, hi one aspect, a Δ value is calculated after each additional reading.

[0051] In one embodiment, a quality metric may be generated for each of the multiple measurements. In one embodiment, the quality metric is selected to assess the reproducibility of the measurements. In one embodiment, the quality metric is selected to assess the skill of the clinician who performed the measurements. In one embodiment, the quality metric may include one or more statistical parameters, such as an average, mean, or standard deviation. In one embodiment, the quality metric may include one or more of a comparison of the individual measurements to a predefined range. In one embodiment, the quality metric may include a comparison of the individual measurements to a pattern of values, such as a comparison of measurements at predefined locations to a range associated with each predefined location. In one embodiment, the quality metric may include a determination of which measurements are made across healthy tissue, and one or more assessments of consistency within this subset of "healthy" measurements, such as a range, standard deviation, or other parameter.

[0052] In one embodiment, the measurements, e.g., the threshold values, are determined by a SEM Scanner Model 200 (Bruin Biometrics, LLC, Los Angeles, Calif.) In another embodiment, the measurements are determined by another SEM scanner.

[0053] In one embodiment, the measurements are based on capacitance measurements with reference to a reference device. In one embodiment, the capacitance measurements may depend on the location of any electrodes in the device and other aspects. Such variations may be compared to a reference SEM device, such as a SEM Scanner Model 200 (Bruin Biometrics, LLC, Los Angeles, CA). Those skilled in the art will understand that the measurements described herein may be adjusted to accommodate the capacitance range of differences with reference to a reference device.

[0054] In one embodiment, the device 180 is capable of storing a plurality of measurements and calculation results. In one embodiment, a device according to the present disclosure may also include other components, such as a camera or barcode scanner (not visible in FIG. 4A), and may be capable of storing the output of the components. In one embodiment, the device 180 includes a component (not visible in FIG. 4A) for transferring the stored data, for example, via a Bluetooth, WiFi, or Ethernet connection, to another device, such as a personal computer as shown in FIG. 13, a server, a tablet, or a smartphone.

[0055] 4B shows another embodiment of device 186 configured to determine SEM values ​​at symmetrical locations. In one embodiment, device 186 includes hinge 188 so that the separation distance between sensor 187A and sensor 187B can be changed. In one embodiment, sensors 184A and 184B are aligned with device body elements 186A and 186B to achieve a desired relative orientation, e.g., parallel to one another, at a predetermined separation distance. In one embodiment, one or more of sensors 187A and 187B are movable, such that the angle between the movable sensor and the other sensor can be changed to match the orientation of the skin under each of sensors 187A and 187B, for example, when device 185 is closed around the ankle to position sensors 187A and 187B over locations 26R and 30R shown in FIG. 2C.

[0056] FIG. 5 illustrates an exemplary mat assembly 190 comprising an array 92 comprising a plurality of sensors 90 according to the present disclosure. In one embodiment, the mat assembly 192 comprises a mat 200 in which the sensors 90 are disposed. In one embodiment, the sensors 90 are embedded within the mat 200. In one embodiment, the sensors 90 are located on the top surface of the mat 200. In one embodiment, the sensors 90 have a cover layer (not visible in FIG. 5) thereon. In one embodiment, the sensors 90 comprise conductive electrodes exposed on the top surface of the sensors 90 to provide electrical contact with an object proximate to the top of the mat, e.g., the feet of a patient standing on the mat. In one embodiment, the sensors 90 are toroidal sensors as shown in FIG. 1A. In one embodiment, the sensors 90 have a single type and configuration. In one embodiment, the sensors 90 vary in size and type within the array 92. In one embodiment, the sensors 90 have one or more alternative configurations as discussed in connection with FIGS. 6, 7, 8A, and 8B. In one embodiment, mat assembly 190 couples, either directly or through cable 194, to electronics assembly 192. In one embodiment, electronics assembly 192 comprises circuitry (not visible in FIG. 4A ) coupled to electrodes of sensor 90, and a processor (not visible in FIG. 4A ) coupled to the circuitry, as previously discussed with respect to device 180.

[0057] In one embodiment, mat assembly 190 includes one or more pressure sensors, temperature sensors, light sensors, and contact sensors (not visible in FIG. 5) disposed at one or more respective locations across mat 200. In one embodiment, one or more measurements using sensors 90 are triggered by input from one or more of the pressure sensors, temperature sensors, light sensors, and contact sensors.

[0058] In one aspect, the mat assembly 190 is configured as a floor mat, and detection of a person standing on the mat assembly 190 by activation of one or more of the pressure, temperature, light, and contact sensors, e.g., detection of the person's weight by a pressure sensor, initiates measurement by one or more of the sensors 90. In one aspect, the sensor 90 operates in a "detection mode" capable of detecting when a person steps on the mat assembly 190, and transitions to a "measurement mode" upon determining that a person is standing on the mat assembly 190.

[0059] In one embodiment, mat assembly 190 is configured as a handheld device that can be placed against the surface of the patient's skin, for example, against the patient's back or against the soles of one or both feet while the patient is lying in bed. In one embodiment, mat assembly 190 includes one or more of a support tray, a stiffening element, and a conformal pad (not shown in FIG. 5) to aid in placing sensor 90 against the surface of the patient's skin.

[0060] FIG. 6 illustrates an exemplary electrode array 290 according to the present disclosure. The array 290 consists of individual electrodes 300 arranged in a regular pattern on a substrate 292 in this embodiment. In one embodiment, each electrode 300 is separately coupled (through conductive elements not shown in FIGS. 6-8B) to a circuit as described with respect to FIG. 4A configured to measure an electrical parameter. In one embodiment, a "virtual sensor" is created by selective connection of a given subset of the electrodes 300 to a common element of the circuit. In this embodiment, a particular electrode 310 is connected as a center electrode similar to electrode 110 in FIG. 1A, and six electrodes 320A-320F are connected together as a "virtual ring" electrode similar to electrode 120 in FIG. 1A. In one embodiment, two individual electrodes are individually connected to the circuit to form a virtual sensor, e.g., electrodes 310 and 320A are individually connected as two electrodes of a sensor. In one embodiment, one or more electrodes 300 are connected together to form either one of the electrodes of a two-electrode sensor.

[0061] FIG. 7 illustrates another exemplary array 400 of electrodes 410 according to the present disclosure. In this example, each of the electrodes 410 is an approximate hexagon separated from each of the surrounding electrodes 410 by gaps 420. In one embodiment, the electrodes 410 are one of a circle, a square, a pentagon, or other regular or irregular shape. In one embodiment, the gaps 420 are uniform among all the electrodes 410. In one embodiment, the gaps 420 vary among the various electrodes. In one embodiment, the gaps 420 have a width narrower than the cross-section of each of the electrodes 410. In one embodiment, the electrodes 410 may be interconnected to form a virtual sensor as described below with respect to FIGS. 8A and 8B.

[0062] FIG. 8A illustrates an array 400 of electrodes 410, e.g., connected to a measurement circuit, configured to form an exemplary sensor 430 according to the present disclosure. In one embodiment, a single hexagonal electrode 410, labeled "1", forms a center electrode, and a ring of electrodes 410, labeled "2", are interconnected to form a ring electrode. In one embodiment, the electrodes 410 between the center electrode and the ring electrode are electrically "floating". In one embodiment, the electrodes 410 between the center electrode and the ring electrode are grounded or connected to a floating ground. In one embodiment, the electrodes 410 outside the ring electrode are electrically "floating". In one embodiment, the electrodes 410 outside the virtual ring electrode are grounded or connected to a floating ground.

[0063] 8B illustrates an alternative embodiment in which an array 400 of electrodes 410 is configured to form a virtual sensor 440 according to the present disclosure. In one embodiment, multiple electrodes 410, indicated by "1", are interconnected to form a center electrode, while a double-wide ring of electrodes, indicated by "2", are interconnected to form a ring electrode. In one embodiment, various numbers and positions of electrodes 410 are interconnected to form virtual electrodes of various sizes and shapes.

[0064] 9A and 9B show an example configuration of an electrode array 400 in which a sensor 430 can be formed at multiple overlapping locations according to the present disclosure. In FIG. 9A, a virtual sensor 430A is formed with a center electrode 432 formed by a single electrode 410, indicated by "1", and a ring electrode 434 formed by multiple electrodes 410, indicated by "2". This same array 400 is shown in FIG. 9B, where a new virtual sensor 430B is formed with a center electrode 436, indicated by "3", and a ring electrode 438, indicated by "4". The location of the virtual sensor 430A is indicated by a dark outline. It can be seen that the virtual sensor 430B overlaps with the location of the virtual sensor 430A, allowing measurements to be made with a resolution finer than the diameter of the sensor 430.

[0065] FIG. 10 illustrates how a sensor 430 may be formed from an array 400 of electrodes that is larger than the portion of the patient's skin that is positioned relative to the array, in accordance with the present disclosure. In this example, a contour of a contact area 450 of the plantar 22R of the right foot 20R of the patient 10, as viewed from underneath the foot 20R and in relation to FIGS. 2A-2C, is shown superimposed on the array 400. In this example, a sensor 430C is formed where a portion of the sensor 430C extends beyond the edge of the contact area 450. In such a position, the capacitance or other electrical parameter measured by the sensor 430C is lower than the capacitance measured by the sensor 430D, which is positioned completely within the contact area 450. It will be appreciated that the sensor 430 may be formed at any point within the array 400 and may overlap the contact area at any level within the range of 0-100%, depending on the location of the sensor 430.

[0066] In one embodiment, the two sensors may overlap by 0-50%, e.g., 0-10%, 5-15%, 10-20%, 15-25%, 20-30%, 25-35%, 30-40%, 35%-45%, 40-50%, 0-25%, 15-35%, or 25-50%. In one embodiment, the two sensors may overlap by 25-75%, e.g., 25-35%, 30-40%, 35%-45%, 40-50%, 45-55%, 50-60%, 55-65%, 60-70%, 65-75%, 25-50%, 40-55%, or 50-75%. In one embodiment, the two sensors may overlap by 50-100%, e.g., 50-60%, 55-65%, 60-70%, 65-75%, 70-80%, 75%-85%, 80-90%, 85-95%, 90-100%, 50-75%, 65-85%, or 75-100%.

[0067] In one aspect, the array of sensors 400 may further comprise a plurality of contact sensors (not shown on FIG. 10) on the same planar surface as each of the electrodes and around each of the electrodes to ensure complete contact of the one or more virtual sensors to the skin surface. The plurality of contact sensors may be a plurality of pressure sensors, a plurality of light sensors, a plurality of temperature sensors, a plurality of pH sensors, a plurality of sweat sensors, a plurality of ultrasound sensors, a plurality of bone growth stimulator sensors, or a combination of a plurality of these sensors. In some embodiments, the plurality of contact sensors may comprise 4, 5, 6, 7, 8, 9, or 10 or more contact sensors around each electrode.

[0068] 11A and 11B show an example of how a comparison of SEM values ​​associated with sensors at known relative locations can identify symmetrical locations in accordance with the present disclosure. In this example, sensors 430 are formed at non-overlapping locations marked "A" through "H" in FIG. 11A across contact area 450R of right foot 20R. The SEM values ​​measured at each location are plotted in the graph of FIG. 11B. In this example, the SEM values ​​at locations "A" and "H" are low or zero, reflecting the lack of overlap of sensor 430 with contact area 450 at those locations. The SEM values ​​associated with locations "B" and "G" are higher because sensor 430 overlaps a portion of contact area 450 at those locations. The SEM values ​​for location CDEF are higher and, in this example, are approximately the same, indicating that sensor 430 is completely within contact area 450 at those locations. In one embodiment, an SEM measurement device such as device 180 may determine that certain locations, e.g., locations "C" and "F," are symmetrical about centerline 452R of right foot 20R. In one embodiment, if a similar set of measurements is made at locations A'-H' of left foot 20L, locations on each foot 20L and 20R, e.g., locations E and E', may be determined to be approximately symmetrical.

[0069] 12A and 12B show an exemplary embodiment of a sensor assembly 500 configured to be placed at a known location on a patient's skin in accordance with the present disclosure. In this example, the sensor assembly 500 has a shaped substrate 510 configured to conform to the rear and bottom surfaces of the heel of the foot 20. In one embodiment, the shaped substrate 510 may be suitable for use on both the left foot 20L and the right foot 20R. In one embodiment, the sensor assembly 500 includes one or more sensors 520 disposed on an inner surface of the shaped substrate 510. In this example, the sensor 520 is configured as a toroidal sensor as shown in FIG. 1A. In one embodiment, the inner surface of the shaped substrate 510 is lined with an array 400 of electrodes 410 associated with FIG. 7, such that a virtual sensor may be formed at any location. In one embodiment, sensors of other shapes and configurations are provided on the inner surface of the shaped substrate 510. In one embodiment, the shaped substrate 510 is a flexible panel (not shown in FIG. 12A) that can be conformed to the patient's skin, for example, wrapped around the back of the ankle. In one embodiment, the sensor assembly 500 includes a cable 530 for connecting the sensor 520 to one or more of a power source, a circuit configured to measure one or more of capacitance or other electrical properties, a processor, a communications subsystem, or other type of electronics assembly (not shown in FIG. 12A).

[0070] FIG. 12B shows an exemplary configuration of a sensor assembly 500 in which multiple sensors 520 are disposed on a molded substrate 510 such that when the sensor assembly 500 is placed against the patient's skin, for example around the back and bottom of the right heel, the sensors 520 are positioned at locations 26R, 28R, and 30R associated with FIG. 2C, as well as on the center of the back of the heel. This allows multiple SEM measurements to be made at repeatable locations on the heel with the sensor assembly 500 in a single position. In one embodiment (not shown in FIGS. 12A and 12B), the sensor assembly 500 is configured to be placed on a portion of the patient's back, thus providing the ability to make measurements at symmetrical locations on the back. In one embodiment, the molded substrate 510 is configured to match the anatomical features of the patient's target area. In one embodiment, the molded substrate 510 includes markings or other indicators that can be aligned with the patient's body features to allow measurements to be made at the same location at intervals over a period of time that typically ranges from a few hours to a few weeks. In one embodiment, the sensor assembly 500 is incorporated into the lining of a garment or shoe or other article of apparel. In one embodiment, the sensor assembly 500 is incorporated into a sheet, blanket, liner, or other type of bedding. In one embodiment, the sensor assembly 500 includes wireless communication capabilities, such as passive radio frequency identification (RFID) or inductive coupling, to allow activation of the sensor 520 without a physical connection to the sensor assembly 500.

[0071] FIG. 13 shows a schematic diagram of an integrated system 600 for measuring, evaluating, storing, and transferring SEM values ​​according to the present disclosure. In this example, the system 600 includes an SEM measurement device 180 as discussed in connection with FIG. 4A, with the ability to wirelessly communicate with a WiFi access point 610. The device 180 communicates with one or more of an SEM application running on a server 640, a laptop computer 620, a smartphone 630, or an application running on another digital device. In one embodiment, the laptop computer 620 and the smartphone 630 are carried by a user of the device 180, e.g., a nurse, and the application provides feedback and information to the user. In one embodiment, information received from the device 180 for the patient is stored in a database 650. In one embodiment, information received from the device 180 is transferred via a network 645 to another server 660, which stores a portion of the information in the patient's electronic medical record (EMR) 670. In one embodiment, information retrieved from device 180 or from database 650 or EMR 670 is transferred to an external server 680 and then to a computer 685, for example a computer in the physician's office providing care for the patient.

[0072] From the foregoing, it will be appreciated that the present invention can be embodied in a variety of ways, including but not limited to the following.

[0073] Embodiment 1. An apparatus for identifying damaged tissue, the apparatus comprising: a first sensor and a second sensor, each of the first and second sensors comprising a first electrode and a second electrode, each of the sensors configured to be placed on a patient's skin; a circuit electrically coupled to the first and second electrodes and configured to measure an electrical characteristic between the first electrode and the second electrode of each of the sensors to provide information regarding the electrical characteristic; and a circuit electrically coupled to the circuit and receiving information from the circuit and converting the information into a subepidermal moisture (SEM) value. and a non-transitory computer readable medium electrically coupled to the processor and including instructions stored on the non-transitory computer readable medium, the instructions, when executed on the processor, performing a step of determining a difference between a first SEM value corresponding to an electrical characteristic measured by a first sensor at a first location on the patient's skin and a second SEM value corresponding to an electrical characteristic measured by a second sensor at a second location on the patient's skin, wherein the second location is symmetrical to the first location.

[0074] Embodiment 2. The device of embodiment 1, wherein a difference above a predetermined threshold indicates damaged tissue in one of the first and second locations.

[0075] Embodiment 3. An apparatus as described in embodiment 1, wherein the circuitry is electrically coupled to the first and second electrodes of each of the first and second sensors, and the circuitry is configured to convert a first electrical property measured with the first sensor to a first SEM value and to convert a second electrical property measured with the second sensor to a second SEM value.

[0076] Embodiment 4. The device of embodiment 2, further comprising a substrate configured to be placed at a known position on the patient's skin, the first and second sensors being disposed on the substrate such that when the substrate is placed at the known position on the patient's skin, the first and second sensors are positioned at symmetrical locations on the patient's skin.

[0077] Embodiment 5. The device of embodiment 1, further comprising a gap between the first electrode and the second electrode.

[0078] Embodiment 6. The device of embodiment 1, wherein the electrical property comprises one or more electrical components selected from the group consisting of resistance, capacitance, inductance, impedance, and magnetoresistance.

[0079] Embodiment 7. An apparatus for identifying damaged tissue, the apparatus comprising: a substrate configured to be placed on a surface of a patient's skin; a plurality of sensors disposed on the substrate at respective plurality of locations, each sensor comprising a pair of electrodes; a circuit configured to electrically couple to each pair of electrodes of the plurality of sensors and to measure an electrical characteristic between a portion of the electrode pairs of the plurality of sensors to provide information regarding the measured electrical characteristic; a processor configured to electrically couple to the circuit and receive information regarding the electrical characteristic from the circuit and convert the plurality of electrical characteristics into a respective plurality of subepidermal moisture (SEM) values; and a non-transitory computer readable medium electrically coupled to the processor and comprising instructions stored on the non-transitory computer readable medium, the instructions, when executed on the processor, perform the steps of: identifying a first sensor and a second sensor at first and second locations that are symmetrical with respect to the patient's skin from the plurality of SEM values, and comparing a first SEM value associated with the first sensor to a second SEM value associated with the second sensor.

[0080] Embodiment 8. The apparatus of embodiment 7, wherein the instructions further include determining a difference between the first SEM value and the second SEM value, and providing an indication that tissue is damaged at one of the first and second locations if the difference exceeds a predetermined threshold.

[0081] Embodiment 9. The device of embodiment 7, wherein the instructions further include steps of determining a difference between the first SEM value and the second SEM value, determining which of the first SEM value and the second SEM value is greater than the other, and providing an indication that tissue is damaged at the location associated with the greater SEM value if the difference exceeds a predetermined threshold.

[0082] Embodiment 10. The device of embodiment 7, wherein the electrical property comprises one or more electrical components selected from the group consisting of resistance, capacitance, inductance, impedance, and magnetoresistance.

[0083] Embodiment 11. A device for identifying damaged tissue, the device comprising: a device body; two sensors, comprising a first sensor and a second sensor, disposed on the device body such that the two sensors can simultaneously position the first sensor at a first location on a patient's skin and position the second sensor at a second location symmetrical to the first location; a circuit electrically coupled to each of the two sensors and configured to measure an electrical property from each of the two sensors; a processor electrically coupled to the circuit and configured to receive a first electrical property measurement from the first location and a second electrical property measurement from the second location, convert the first electrical property measurement to a first subepidermal moisture (SEM) value and convert the second electrical property measurement to a second SEM value; and a non-transitory computer readable medium electrically coupled to the processor and including instructions, when executed on the processor, that perform the steps of determining a difference between the first SEM value and the second SEM value.

[0084] Embodiment 12. A device as described in embodiment 11, wherein each of the two sensors is disposed at two ends of the device body while aligned in a common plane.

[0085] Embodiment 13. A device as described in embodiment 11, wherein the device body is rigid and maintains the two sensors at a fixed separation distance and fixed orientation relative to each other.

[0086] Embodiment 14. A device as described in embodiment 11, wherein the device body is flexible and allows the two sensors to be oriented at an angle relative to each other.

[0087] Embodiment 15. The device of embodiment 14, wherein the device body comprises a hinge.

[0088] Embodiment 16. An apparatus as described in embodiment 11, wherein each of the two sensors comprises a first electrode and a second electrode separated by a gap.

[0089] Embodiment 17. The device of embodiment 16, wherein the electrical property is measured between the first electrode and the second electrode.

[0090] Embodiment 18. An apparatus as described in embodiment 11, wherein each of the two sensors comprises multiple electrodes separated by a gap.

[0091] Embodiment 19. A device as described in embodiment 18, wherein the plurality of electrodes are selectively activated to form a virtual ring electrode and a virtual center electrode.

[0092] Embodiment 20. The device of embodiment 11, wherein the electrical property comprises one or more of the electrical characteristics selected from the group consisting of resistance, capacitance, inductance, impedance, and magnetoresistance.

[0093] Embodiment 21. The apparatus of embodiment 11, wherein the first electrical property measurement and the second electrical property measurement are measured simultaneously.

[0094] Embodiment 22. An apparatus as described in embodiment 21, wherein the apparatus further comprises a contact sensor positioned in proximity to one of the two sensors, and the simultaneous measurement is triggered by activation of the contact sensor.

[0095] Embodiment 23. The device described in embodiment 22, wherein the contact sensor is a pressure sensor or an optical sensor.

[0096] Embodiment 24. The device of embodiment 11, wherein the instructions further include providing an indication that tissue is damaged at one of the first and second locations if the difference exceeds a predetermined threshold.

[0097] Embodiment 25. The device of embodiment 11, wherein the instructions further include determining the greater of the first SEM value and the second SEM value, and if the difference exceeds a predetermined threshold, providing an indication that tissue is damaged at the location associated with the greater SEM value.

[0098] Embodiment 26. A method for identifying damaged tissue, the method comprising: obtaining a first subepidermal moisture (SEM) value from a first location on a patient's skin; obtaining a second SEM value from a second location that is symmetrical to the first location; and determining a difference between the first SEM value and the second SEM value.

[0099] Embodiment 27. The method of embodiment 26, further comprising providing an indication that tissue is damaged at one of the first and second locations if the difference exceeds a predetermined threshold.

[0100] Embodiment 28. The method of embodiment 26, further comprising determining the greater of the first SEM value and the second SEM value, and providing an indication that tissue is damaged at the location associated with the greater SEM value if the difference exceeds a predetermined threshold.

[0101] Although the present invention has been described with reference to particular embodiments, those skilled in the art will recognize that various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but will include all embodiments that come within the scope and spirit of the appended claims.

Claims

1. 1. An apparatus for identifying damaged tissue, the apparatus comprising: a substrate configured to be placed on a surface of a patient's skin; an electrode array comprising a plurality of electrodes, each electrode of the plurality of electrodes being disposed on the substrate at a respective plurality of locations, and any two adjacent electrodes of the plurality of electrodes being separated from each other by a gap; a circuit electrically coupled to each electrode of the plurality of electrodes and configured to measure a plurality of electrical properties and provide information regarding the measured plurality of electrical properties; a processor electrically coupled to the circuitry and configured to receive the information from the circuitry regarding the measured electrical properties and convert the measured electrical properties into a respective plurality of subepidermal moisture (SEM) values; A non-transitory computer-readable medium electrically coupled to the processor and including instructions stored on the non-transitory computer-readable medium, the instructions, when executed on the processor, identifying a subset of a first plurality of electrodes at a first location and a subset of a second plurality of electrodes at a second location from the plurality of SEM values, the first location and the second location being bilaterally symmetrical about the patient's skin; and and a non-transitory computer-readable medium for performing the steps of: comparing a first average SEM value associated with a subset of the first plurality of electrodes to a second average SEM value associated with a subset of the second plurality of electrodes.

2. The instruction: determining a difference between the first average SEM value and a second average SEM value; and providing an indication of tissue damage at one of the first location and the second location if the difference exceeds a predetermined threshold.

3. The instruction: determining a difference between the first average SEM value and a second average SEM value; determining which of the first and second average SEM values ​​is greater than the other; and providing an indication that tissue is damaged at a location associated with the larger average SEM value if the difference exceeds a predetermined threshold.

4. The apparatus of claim 1 , wherein each electrical characteristic of the plurality of electrical characteristics comprises one or more electrical components selected from the group consisting of resistance, capacitance, inductance, impedance, and magnetoresistance.

5. The apparatus of claim 1 , wherein the electrodes of a subset of the first plurality of electrodes are selectively activated to form a first virtual ring electrode and a first virtual center electrode.

6. The apparatus of claim 1 , wherein each electrical characteristic of the measured plurality of electrical characteristics is measured simultaneously.

7. The apparatus of claim 1 , wherein the electrodes of a subset of the second plurality of electrodes are selectively activated to form a second virtual ring electrode and a second virtual center electrode.

8. 2. The apparatus of claim 1, wherein the electrodes of each of the first subset of the plurality of electrodes and the second subset of the plurality of electrodes are selectively activated to form first and second virtual ring electrodes and first and second virtual center electrodes.

9. The apparatus of claim 1 , wherein each electrode of the plurality of electrodes has a shape selected from the group including a hexagon, a pentagon, a square, a triangle, and a circle.

10. The apparatus of claim 1 , wherein each electrode of the plurality of electrodes has a regular shape.

11. 11. The apparatus of claim 9 or 10, wherein the gap separating any two adjacent electrodes selected from the plurality of electrodes is uniform.

12. The apparatus of claim 11 , wherein the gap separating any two adjacent electrodes has a width narrower than a cross-section of each of the plurality of electrodes.

13. The device of claim 1 , wherein the gap separating any two adjacent electrodes selected from the plurality of electrodes can be different.

14. The apparatus of claim 1 , wherein the subset of the first plurality of electrodes and the subset of the second plurality of electrodes include one or more shared electrodes.

15. a subset of the first plurality of electrodes are selectively activated to form a first virtual ring electrode and a first virtual center electrode; The apparatus of claim 14 , wherein the electrodes of a subset of the second plurality of electrodes are selectively activated to form a second virtual ring electrode and a second virtual center electrode.

16. The apparatus of claim 15 , wherein the locations of the first and second virtual ring electrodes overlap one another.

17. The apparatus of claim 16 , wherein the locations of the first and second virtual center electrodes overlap one another.

18. The apparatus of claim 1 , wherein the plurality of locations are arranged in a regular pattern on a surface of the substrate.

19. The device of claim 1 , wherein the electrode array is larger than the portion of the patient's skin positioned relative to the electrode array.

20. The device of claim 1 , wherein the substrate is rigid, flexible, or a combination of rigid and flexible elements.

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