Array of RFID tags with sensing capability

Patent metadata

Field	Value
Publication number	US-9317795-B2
Application number	US-201113287235-A
Country	US
Kind code	B2
Filing date	Nov 2, 2011
Priority date	Nov 2, 2011
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

An RFID sensing system and method. An array of sensing elements is disposed on a surface of a mat, wherein each sensing element includes an RFID microchip, an antenna operatively coupled to the microchip, and a pressure-sensitive material disposed on at least the antenna. An RFID reader is provided for interrogating the array of sensing elements. An antenna operatively coupled to the reader communicates with each sensing element disposed on the mat. Each sensing element in the array, in response to an interrogation signal, transmits a signal to the reader via the coupled antenna when a subject placed on the mat compresses the section of pressure-sensitive material for the sensing element.

First claim

What is claimed:

1. An RFID sensing system comprising:
an array of sensing elements disposed on a surface of a mat, wherein each sensing element includes an RFID microchip, an antenna operatively coupled to the microchip, and a pressure-sensitive material disposed on at least the antenna;
an RFID reader for interrogating the array of sensing elements; an antenna operatively coupled to the reader for communicating with each sensing element disposed on the mat;
wherein each sensing element in the array, in response to an interrogation signal, transmits a signal to the reader via the coupled antenna when a subject placed on the mat compresses the pressure-sensitive material for the sensing element,
wherein the transmitted signal corresponds to the change in pressure attributable to the placement of the subject on the mat,
wherein the reader determines the change in pressure by altering the output power and determining the power level at which an identifier ID associated with a sensing element starts to read.

2. The RFID sensing system of claim 1 , wherein the pressure-sensitive material comprises a conductive foam.

3. The RFID sensing system of claim 2 , further comprising a pressure-sensitive overlaminate material separating the sensing element antenna from the conductive foam.

4. The RFID sensing system of claim 1 , wherein the pressure-sensitive material comprises a quantum tunneling composite.

5. The RFID sensing system of claim 1 , wherein the antenna operatively coupled to the reader comprises a near field antenna.

6. The RFID sensing system of claim 1 , wherein the antenna operatively coupled to the reader comprises a far field antenna.

7. The RFID sensing system of claim 2 , wherein the resistance of the conductive foam decreases as the foam is compressed.

8. The RFID sensing system of claim 2 , wherein the conductive foam is coated with a plurality of conductive particles.

9. The RFID sensing system of claim 2 , wherein the conductive foam is coated with carbon.

10. The RFID sensing system of claim 1 , wherein the antenna operatively coupled to the microchip comprises a structure operating at an ultra high frequency (UHF).

11. The RFID sensing system of claim 1 , wherein the signal transmitted by each sensing element represents a change in sensitivity for the sensing element resulting from absorption of energy at an operating frequency of the sensing element caused by compression of the pressure-sensitive material.

12. An RFID sensing system comprising:
an array of sensing elements disposed on a surface of a mat, wherein each sensing element includes an RFID microchip, an antenna operatively coupled to the microchip, and a pressure-sensitive material disposed on at least the antenna;
an RFID reader for interrogating the array of sensing elements;
a transmission line coupled to a port of the reader and to each element in the array of sensing elements;
wherein each sensing element in the array, in response to an interrogation signal, transmits a signal to the reader via the coupled transmission line when a subject placed on the mat compresses the pressure-sensitive material for the sensing element,
wherein the transmitted signal corresponds to the change in pressure attributable to the placement of the subject on the mat,
wherein the reader determines the change in pressure by altering, the output power and determining the power level at which an identifier ID associated with a sensing element starts to read.

13. The RFID sensing system of claim 12 , wherein the pressure-sensitive material comprises a conductive foam.

14. The RFID sensing system of claim 13 , further comprising a pressure-sensitive over laminate material separating the sensing element from the conductive foam.

15. The RFID sensing system of claim 12 , wherein the pressure-sensitive material comprises a quantum tunneling composite.

16. The RFID sensing system of claim 12 , wherein the signal transmitted by each sensing element represents a change in sensitivity for the sensing element resulting from absorption of energy at an operating frequency of the sensing element caused by compression of the pressure-sensitive material.

17. The RFID sensing system of claim 12 , wherein the transmission line comprises any one of a microstrip, a twin wire line, and a stripline.

18. An RFID sensing system comprising:
an array of sensing elements disposed on a surface of a mat, wherein each sensing element includes an RFID microchip, an antenna operatively coupled to the microchip, and a pressure-sensitive material disposed on at least the antenna;
a multi-port RFID reader for interrogating the array of sensing elements;
a plurality of transmission lines each coupled to a separate port of the reader and to an associated plurality of sensing elements in the array of sensing elements;
wherein each sensing element in the array, in response to an interrogation signal, transmits a signal to a reader port via the associated transmission line when a subject placed on the mat compresses the pressure-sensitive material for the sensing element,
wherein the transmitted signal corresponds to the change in pressure attributable to the placement of the subject on the mat,
wherein the reader determines the change in pressure by altering the output power and determining the power level at which an identifier ID associated with a sensing element starts to read.

19. The RFID sensing system of claim 12 , wherein the signal transmitted by each sensing element represents a change in sensitivity for the sensing element resulting from absorption of energy at an operating frequency of the sensing element caused by compression of the pressure-sensitive material.

20. The RFID sensing system of claim 12 , wherein each transmission line comprises any one of a microstrip, a twin wire line, and a stripline.

21. An RFID sensing system comprising:
an array of sensing elements disposed on a surface of a mat, wherein each sensing element includes an RFID microchip, an antenna operatively coupled to the microchip, and a pressure-sensitive material disposed on at least the antenna;
an RFID reader for interrogating the array of sensing elements;
a fixed near field coupler disposed in proximity to the mat for linking the array of sensing elements with the reader via a transmission line disposed on the mat;
wherein each sensing element in the array, in response to an interrogation signal, transmits a signal to the reader via the transmission line and near field coupler when a subject placed on the mat compresses the pressure-sensitive material for the sensing element,
wherein the transmitted signal corresponds to the change in pressure attributable to the placement of the subject on the mat˜
wherein the reader determines the change in pressure by altering the output power and determining the power level at which an identifier ID associated with a sensing element starts to read.

22. The RFID sensing system of claim 21 , wherein the pressure-sensitive material comprises a conductive foam.

23. The RFID sensing system of claim 22 , further comprising a pressure-sensitive overlaminate material separating the sensing element antenna from the conductive foam.

24. The RFID sensing system of claim 21 , wherein the pressure-sensitive material comprises a quantum tunneling composite.

25. The RFID sensing system of claim 21 , wherein the signal transmitted by each sensing element represents

Assignees

• Forster Ian James
• Avery Dennison Corp

Inventors

• Forster Ian James

Classifications

• A61B2562/0247

  Pressure sensors · CPC title

• A61B2562/066

  in a matrix array · CPC title

• A61B5/6891

  Furniture · CPC title

• A61B5/447

  specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed · CPC title

• G06K19/0717 Primary

  the sensor being capable of sensing environmental conditions such as temperature history or pressure · CPC title