SEM SCANNER SENSING APPARATUS, SYSTEM AND METHODOLOGY FOR EARLY DETECTION OF ULCERS
A handheld, conforming capacitive sensing apparatus configured to measure Sub-Epidermal Moisture (SEM) as a mean to detect and monitor the formation of pressure ulcers. The device incorporates an array of electrodes which are excited to measure and scan SEM in a programmable and multiplexed manner by a battery-less RF-powered chip. The scanning operation is initiated by an interrogator which excites a coil embedded in the apparatus and provides the needed energy burst to support the scanning/reading operation. Each electrode measures the equivalent sub-epidermal capacitance corresponding and representing the moisture content.
1 . An apparatus for sensing sub-epidermal moisture from a location external to a patient's skin, comprising:
a bipolar RF sensor embedded on a flexible substrate;
a conformal pressure pad disposed adjacent and underneath the substrate;
wherein the conformal pressure pad is configured to support the flexible substrate while allowing the flexible substrate to conform to a non-planar sensing surface of the patient's skin; and
interface electronics coupled to the sensor;
wherein said interface electronics are configured to control emission and reception of RF energy to interrogate the patient's skin.
2 . An apparatus as recited in claim 1 , further comprising:
an annular spacer adjacent and underneath the conformal pressure pad;
wherein the annular spacer comprises a central opening configured to allow the conformal pressure pad to deflect freely into the central opening.
3 . An apparatus as recited in claim 1 , further comprising:
an array of bipolar RF sensors spaced across the flexible substrate;
wherein each of the sensors is independently coupled to the interface electronics to independently interrogate the patient's skin.
4 . An apparatus as recited in claim 3 :
wherein each of the sensors is configured to measure an equivalent sub-epidermal capacitance of a target region of skin;
said sub-epidermal capacitance corresponding to the moisture content of the target region of skin.
5 . An apparatus as recited in claim 4 :
wherein the array of sensors comprises a first sensor having a first contact area and a second sensor having a second contact area larger than the first sensor; and
wherein the first and second sensors interrogate the skin at different depths.
6 . An apparatus as recited in claim 4 :
wherein the substrate comprises a substrate assembly comprising a substrate layer; and
wherein the sensor comprises a sensing pad having a first electrode embedded on a first side of the substrate and a second electrode embedded on a second side of the substrate.
7 . An apparatus as recited in claim 6 , further comprising a biocompatible cover layer disposed over said first side of said substrate layer.
8 . An apparatus as recited in claim 6 , further comprising a cover layer disposed under said second side of said substrate layer.
9 . An apparatus as recited in claim 6 , further comprising:
a stiffener layer disposed under said second side of said substrate layer;
wherein the stiffener layer comprises a footprint substantially similar to that of the sensor array.
10 . An apparatus as recited in claim 6 :
wherein said first electrode comprises an annular ring having an inner radius and an outer radius;
wherein said second electrode comprises an outer radius having a smaller diameter than the inner radius of the first electrode; and
wherein said second electrode is concentric with said first radius.
11 . An apparatus as recited in claim 1 , wherein the interface electronics are configured to transmit data retrieved from said sensors.
12 . An apparatus as recited in claim 4 , further comprising:
a pressure sensor positioned in line with said RF sensor;
said pressure sensor configured to measure an applied pressure of the substrate at a location on the patient's skin.
13 . An apparatus as recited in claim 1 , wherein the flexible substrate comprises Kapton or Polyimide.
14 . A scanner for sensing sub-epidermal moisture from a location external to a patient's skin, comprising:
an array of bipolar RF sensors embedded on a flexible substrate; and
a conformal pressure pad disposed adjacent and underneath the substrate;
wherein the conformal pressure pad is configured to support the flexible substrate while allowing the flexible substrate to conform to a non-planar sensing surface of the patient's skin;
wherein said sensor array is configured to emit and receive RF energy to interrogate the patient's skin; and
wherein each of the sensors are independently are individually wired to independently interrogate the patient's skin.
15 . A scanner as recited in claim 14 , further comprising:
interface electronics coupled to the sensor;
wherein said interface electronics is configured to control the emission and reception of RF energy.
16 . A scanner as recited in claim 14 , further comprising:
an annular spacer adjacent and underneath the conformal pressure pad;
wherein the annular spacer comprises a central opening configured to allow the conformal pressure pad to deflect freely into the central opening.
17 . A scanner as recited in claim 14 :
wherein each of the sensors is configured to measure an equivalent sub-epidermal capacitance of a target region of skin;
said sub-epidermal capacitance corresponding to the moisture content of the target region of skin.
18 . A scanner as recited in claim 14 :
wherein the array of sensors comprises a first sensor having a first contact area and a second sensor having a second contact area larger than the first sensor; and
wherein the first and second sensors interrogate the skin at different depths.
19 . A scanner as recited in claim 14 :
wherein each sensor comprises a first electrode in the form of an annular ring having an inner radius and an outer radius and a second electrode comprising an outer radius having a smaller diameter than the first electrode; and
wherein said second electrode is concentric with said first radius.
20 . A scanner as recited in claim 19 :
wherein the substrate comprises a substrate assembly comprising a substrate layer; and
wherein the first electrode is embedded on a first side of the substrate and the second electrode embedded on a second side of the substrate.
21 . A scanner as recited in claim 20 , further comprising:
an upper biocompatible cover layer disposed over said first side of said substrate layer and a lower cover layer disposed under said second side of said substrate layer.
22 . A scanner as recited in claim 20 , further comprising:
a stiffener layer disposed under said second side of said substrate layer;
wherein the stiffener layer comprises a footprint substantially similar to that of the sensor array.
23 . A scanner as recited in claim 14 , further comprising:
an array of pressure sensors positioned in line with said RF sensor;
said pressure sensors are configured to measure an applied pressure of the substrate at corresponding locations on the patient's skin.
24 . A method for monitoring the formation of pressure ulcers at a target location of a patient's skin, comprising:
positioning a flexible substrate adjacent the target location of the patient's skin;
the flexible substrate comprising one or more bipolar RF sensors;
conforming the flexible substrate to the patient's skin at the target location;
exciting the one or more bipolar RF sensors to emit RF energy into the patient's skin; and
measuring the capacitance of the skin at the target location as an indicator of the Sub-Epidermal Moisture (SEM) at the target location.
25 . A method as recited in claim 24 :
wherein the one or more sensors comprise an array of sensors disposed across said substrate; and
wherein the one or more sensors are individually controlled to independently excite the one or more sensors.
26 . A method as recited in claim 24 , further comprising:
measuring an applied pressure of the substrate at the target location on the patient's skin.
27 . A method as recited in claim 25 , further comprising:
measuring an applied pressure of the substrate on the patient's skin at each of the sensors in the array.