Sensing system and method

• US 8,736,281 B2
• Filed: 11/28/2008
• Issued: 05/27/2014
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Cambridge Enterprises Limited, Investech Partners Investments, LLC, Chancellor Masters & Scholars of The University of Cambridge (University of Cambridge)
• Original Assignee: Cambridge Enterprises Limited, Chancellor Masters & Scholars of The University of Cambridge (University of Cambridge)
• Inventors: Lowe, Christopher R., Tannock, Quentin, Stevenson, Adrian, Jain, Karishma
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): MCANDREW, CHRISTOPHER P
• Application Number:
  US12/742,380
• Publication Number:
  US 20120007607A1
• Time in Patent Office: 2,006 Days
• Field of Search: 324/639
• US Class Current: 324/639
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence
• CPC Class Codes: G01D 5/16 by varying resistance
• CPC Class Codes: G01M 5/0033 by determining damage, crack or wear
• CPC Class Codes: G01M 5/0083 by measuring variation of impedance, e.g. resistance, capacitance, induction
• CPC Class Codes: G01N 2011/0066 electrical properties
• CPC Class Codes: G01N 2011/0073 acoustic properties
• CPC Class Codes: G01N 22/02 Investigating the presence of flaws
• CPC Class Codes: G01N 35/00871 Communications between instruments or with remote terminals
• CPC Class Codes: H04Q 2209/40 using a wireless architecture
• CPC Class Codes: H04Q 2209/845 where the measuring is synchronized between sensing devices
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A sensing system comprises a material having a matrix structure in which a plurality of sensing elements are embedded, the sensing elements having electron distribution and/or transport properties that change in response to a change in a physical or chemical property of the material. The sensing system further comprises a receiver, including an antenna, the receiver arranged to receive a source RF signal and a returned RF signal, the returned RF signal being received from the material. A change in the electron distribution and/or transport properties of the sensing elements cause the source RF signal to change, such that a change in a property of the material can be determined from the returned RF signal. A corresponding method of sensing a change in a property of a material is also provided.

Claims

1. A sensing system comprising:

a material having a matrix structure, composed of an elastomer or epoxy resin, in which a plurality of sensing particles are embedded such that the sensing particles are dispersed within and surrounded by the matrix structure, the sensing particles include nanoparticles comprising at least one of single wall carbon nanotubes, multiwall carbon nanotubes, gold nanorings, magnetic nanoparticles, nanowires and spherical nanoparticles, and the sensing particles have electron distribution and/or transport properties that change in response to a change in a physical or chemical property of the material such that the sensing particles that exhibit a microwave resonance behaviour that leads to harmonic generation and frequency doubling; and

a receiver, including an antenna, the receiver arranged to receive, from the material, a returned RF signal resulting from interrogation of, the material by a source RF signal;

a coupling mechanism facilitating the exchange of RF energy between the material and the antenna; and

circuitry arranged to determine at least one of the mechanical, electrical and chemical status of the material;

wherein a change in the electron distribution and/or transport properties of the sensing particles cause the returned RF signal to change, such that a change in a property of the material can be determined from the returned RF signal.

2. The sensing system according to claim 1, wherein the sensing particles are arranged to alter dielectric properties of the material.

3. The sensing system according to claim 1, wherein the sensing particles are arranged to alter magnetic properties of the material.

4. The sensing system according to claim 1, wherein the sensing particles include pores.

5. The sensing system according to claim 1, wherein the resonance frequency of the sensing particles is changed by a change in an electrical and/or mechanical property of the material.

6. The sensing system according to claim 5, wherein the sensing particles comprise particles that cause the change in the returned RF signal via magnetostriction, converse piezoelectricity, magnetic direct generation or electron coupling, such that resonance is induced in the returned RF signal.

7. The sensing system according to claim 1, wherein the resonance Q factor of the sensing particles is changed by a change in an electrical and/or mechanical property of the material.

8. The sensing system according to claim 1, wherein the sensing particles are arranged, upon interaction with the source RF signal, to generate harmonic frequencies of the source RF sign al in the returned RF signal.

9. The sensing system according to claim 1, wherein the material comprises a polymer.

10. The sensing system according to claim 1, wherein the material comprises a nanocomposite material.

11. The sensing system according to claim 10, wherein the material comprises an elastomer or epoxy matrix.

12. The sensing system according to claim 1, wherein the sensing particles are substantially equally spaced within the material.

13. The sensing system according to claim 1, wherein the change in the property of the material is in response to an environmental change, the environmental change being a change in stress, strain, temperature, pH, hydration, volume distortion, density fluctuations, contamination, radiation or icing of the material.

14. The sensing system according to claim 1, wherein the source RF signal is pulse, frequency, phase or digitally modulated.

15. The sensing system according to claim 1, further comprising:

at least one transmitter, wherein the at least one transmitter is arranged to transmit the source RF signal.

16. The sensing system according to claim 8, wherein the sensing system is arranged to determine an amplitude ratio between the source RF signal generated by a transmitter and the returned RF signal at twice the frequency of the source RF, in order to monitor local interactions between the sensing particles.

17. The sensing system according to claim 15, wherein the source RF signal is arranged to heat a site of the material at which the change in the property of the material is determined.

18. The sensing system according to claim 1, wherein the antenna comprises a directional antenna.

19. The sensing system according to claim 1, wherein the antenna comprises one of a parabolic or a phase array antenna structure.

20. The sensing system according to claim 1, wherein the antenna is arranged to direct the source RF signal towards a predetermined target site of a structure comprising the material.

21. The sensing system according to claim 1, wherein the sensing system is arranged to determine a resonance frequency of the material as a function of time and the change in the returned RF signal is a change in the determined resonance frequency.

22. The sensing system according to claim 15, wherein the sensing system is arranged to combine the returned RF signals from plural source RF signals in order to obtain spatial information in respect of the material.

25. The sensing system according to claim 1, wherein the source RF signal comprises background radio energy.

26. The sensing system according to claim 25, wherein the receiver includes two antennae, a first of which is arranged to receive the returned RF signal and a second of which is arranged to receive the source RF signal.

27. The sensing system according to claim 1, wherein the change in the returned RF signal is a change between the returned signal received from a first position of the material and the returned signal received from a second position of the material.

23. A method of sensing a change in a property of a material, the material having a matrix structure composed of an elastomer or epoxy resin, in which a plurality of sensing particles are embedded such that the sensing particles are dispersed within and surrounded by the matrix structure, the sensing particles include nanoparticles comprising at least one of single wall carbon nanotubes, multiwall carbon nanotubes, gold nanorings, magnetic nanoparticles, nanowires and spherical nanoparticles, and the sensing particles have electron distribution and/or transport properties that change in response to a change in a physical or chemical property of the material such that the sensing particles that exhibit either a microwave resonance behaviour that leads to harmonic generation and frequency doubling, the method comprising the steps of:

interrogating the material with a source RE signal;

receiving a returned RE signal from the material; and

determining at least one of the mechanical, electrical and chemical status of the material from the returned RF signal, wherein a change in the returned RF signal is caused by the change in the electron distribution and/or transport properties of the sensing particles.

24. The method of claim 23, further comprising the step of generating a source RF signal.

28. The method of claim 24, wherein the step of determining the change in the property of the material comprises determining a change in resonant frequency of the material.

29. The method of claim 24, wherein the step of determining the change in the property of the material comprises determining a change in an amplitude ratio between the source RF signal generated by a transmitter and the returned RF signal at twice the frequency of the source RF signal.