SEM scanner sensing apparatus, system and methodology for early detection of ulcers

• US 9,398,879 B2
• Filed: 08/17/2015
• Issued: 07/26/2016
• Est. Priority Date: 05/08/2010
• Status: Active Grant

• Current Assignee: Bruin Biometrics LLC, Regents of the University of California (University of California)
• Original Assignee: Bruin Biometrics LLC, Regents of the University of California (University of California)
• Inventors: Sarrafzadeh, Majid, Kaiser, William, Mehrnia, Alireza, Bates-Jensen, Barbara M., Wang, Frank, Flesch, Michael, Boystak, Joseph, Lam, Yeung
• Primary Examiner(s): Kahelin, Michael
• Assistant Examiner(s): TRAN, THO Q
• Application Number:
  US14/827,375
• Publication Number:
  US 20150366499A1
• Time in Patent Office: 344 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0214 Capacitive electrodes
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 2562/066 in a matrix array
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/0533 Measuring galvanic skin response
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/443 Evaluating skin constituents, e.g. elastin, melanin, water
• CPC Class Codes: A61B 5/445 Evaluating skin irritation or skin trauma, e.g. rash, eczema, wound, bed sore
• CPC Class Codes: A61B 5/447 specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/6844 Monitoring or controlling distance between sensor and tissue
• CPC Class Codes: A61B 5/7271 Specific aspects of physiological measurement analysis A61B5/316, A61B5/349 and A61B5/374 take precedence
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence

Abstract

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.

Claims

1. A scanner for sensing sub-epidermal moisture from a location external to a patient'"'"'s skin, said scanner comprising:

an array of bipolar radiofrequency (RF) sensors embedded on a flexible substrate comprising a substrate layer;

wherein each bipolar RF sensor in said array comprises

a first electrode in the form of an annular ring having an inner diameter and an outer diameter and

a second electrode comprising an outer radius having a diameter smaller than the inner diameter of the first electrode;

wherein said second electrode is concentric with said first electrode;

wherein said first electrode is embedded on a first side of said substrate layer and wherein said second electrode is embedded on a second side of said substrate layer;

wherein said array of bipolar RF sensors is configured to emit and receive RF energy to interrogate into the derma of the patient'"'"'s skin to sense sub-epidermal moisture; and

wherein each of the bipolar RF sensors are individually wired to independently interrogate into the derma of the patient'"'"'s skin; and

wherein each of the bipolar RF sensors in said array is configured to measure an equivalent sub-epidermal capacitance of a target region of skin; and

wherein said sub-epidermal capacitance corresponds to the moisture content of the target region of skin.

2. The scanner as recited in claim 1, further comprising interface electronics coupled to the array of sensors, wherein said interface electronics is configured to control the emission and reception of RF energy by the bipolar RF sensor.

3. The scanner as recited in claim 1,

wherein said array of bipolar RF 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 said first and second sensors interrogate the skin at different depths.

4. The scanner as recited in claim 1, 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.

5. The scanner as recited in claim 1, 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.

6. The scanner as recited in claim 1, further comprising:

an array of pressure sensors positioned in line with said array of bipolar RF sensors;

wherein said pressure sensor is configured to measure an applied pressure of the flexible substrate at corresponding locations on the patient'"'"'s skin.

7. The scanner as recited in claim 1, wherein said array of bipolar RF sensors is configured to measure sub-epidermal moisture for generating a sub-epidermal moisture image of the surface of the patient'"'"'s skin without using a scanning motion.

8. The scanner as recited in claim 1, wherein the flexible substrate comprises Kapton®

or Polyimide.

9. An apparatus for sensing sub-epidermal moisture from a location external to a patient'"'"'s skin, said apparatus comprising:

a bipolar radiofrequency (RF) sensor embedded on a flexible substrate comprising a substrate layer;

wherein said bipolar RF sensor comprises a sensing pad having a first electrode embedded on a first side of said substrate layer and a second electrode embedded on a second side of said substrate layer;

a conformal pressure pad disposed adjacent and beneath said flexible substrate, wherein said conformal pressure pad is configured to support said flexible substrate while allowing said flexible substrate to conform to a non-planar sensing surface of the patient'"'"'s skin; and

interface electronics coupled to the bipolar RF sensor, wherein said interface electronics are configured to control emission and reception of RF energy by the bipolar RF sensor to interrogate into the derma of the patient'"'"'s skin to sense sub-epidermal moisture; and

wherein said bipolar RF sensor is configured to measure an equivalent sub-epidermal capacitance of a target region of skin; and

wherein said sub-epidermal capacitance corresponds to the moisture content of the target region of skin.

10. The apparatus as recited in claim 9, further comprising:

an annular spacer adjacent and underneath said conformal pressure pad;

wherein said annular spacer comprises a central opening configured to allow said conformal pressure pad to deflect freely into said central opening.

11. The apparatus as recited in claim 9, further comprising a biocompatible cover layer disposed over said first side of said substrate layer.

12. The apparatus as recited in claim 9, further comprising a cover layer disposed under said second side of said substrate layer.

13. The apparatus as recited in claim 9, 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 bipolar RF sensor.

14. The apparatus as recited in claim 9:

wherein said first electrode comprises an annular ring having an inner diameter and an outer diameter, wherein said second electrode comprises a diameter smaller than the inner diameter of the first electrode; and

wherein said second electrode is concentric with said first radius.

15. The apparatus as recited in claim 9, wherein the interface electronics are configured to transmit data retrieved from said bipolar RF sensor.

16. The apparatus as recited in claim 9, further comprising:

a pressure sensor positioned in line with said bipolar RF sensor;

said pressure sensor configured to measure an applied pressure of the flexible substrate at a location on the patient'"'"'s skin.

17. The apparatus as recited in claim 9, wherein the flexible substrate comprises Kapton®

or Polyimide.