Integrated passive and wireless sensor

Patent metadata

Field	Value
Publication number	US-9768888-B2
Application number	US-201414528448-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Oct 31, 2013
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A passive and wireless sensor is provided for sensing at least one of magnetic field, temperature or humidity. The sensor can provide only one of the sensing functions, individually or any combination of them simultaneously. It can be used for various applications where magnetic field changes, temperature and/or humidity need to be measured. In one or more embodiments, a surface acoustic wave (SAW) sensor is provided that can measure one or more of a magnetic field (or current that generates the magnetic field), temperature and humidity. In one or more embodiments, a magnetoimpedence (MI) sensor (for example a thin film giant magnetoimpedance (GMI) sensor), a thermally sensitive (for example a Lithium Niobite (LiNbO 3 )) substrate, and a humidity sensitive film (for example a hydrogel film) can be used as sensing elements.

First claim

The invention claimed is:

1. A sensor apparatus comprising:
at least one input transducer for receiving a signal and generating surface acoustic waves from the signal;
a first surface acoustic wave propagation path for receiving a first surface acoustic wave from the at least one input transducer, the first surface acoustic wave propagation path including a first reflector transducer coupled with or operating as a first sensor; and
a second surface acoustic wave propagation path for receiving a second surface acoustic wave from the at least one input transducer, the second surface acoustic wave propagation path including a second reflector transducer operating as a second sensor and coupled with a third sensor,
wherein the first and second sensors are selected from the group consisting of a humidity sensor a temperature sensor, and combinations thereof,
wherein the third sensor includes a magnetic field sensor that is a magneto-impedance sensor.

2. The sensor apparatus of claim 1 , wherein a phase shift or an amplitude change or both are obtained in a surface acoustic wave generated by the at least one input transducer on a reflection of the surface acoustic wave by at least one reflector transducer in the first and second surface acoustic wave propagation paths.

3. The sensor apparatus of claim 1 , wherein the at least one input transducer comprises an inter-digital transducer.

4. The sensor apparatus of claim 1 , further including a piezoelectric substrate.

5. The sensor apparatus of claim 1 , wherein the magnetic field sensor changes impedance upon changes of a magnetic field, changing the surface acoustic wave reflected by its associated reflector transducer.

6. The sensor apparatus of claim 1 , wherein the first sensor includes a humidity sensor that is a delay line coupling the at least one input transducer and a reflector transducer, the delay line coated with a humidity sensitive film.

7. The sensor apparatus of claim 1 , further including a thermally sensitive substrate.

8. The sensor apparatus of claim 1 , the sensor apparatus being a single component.

9. A system comprised of the sensor apparatus of claim 1 , a transceiver and one or more antennas.

10. The sensor apparatus of claim 1 , wherein a resonant frequency of the first sensor in the first surface acoustic wave propagation path is the same as resonant frequencies of the second reflector transducer and the third sensor in the second surface acoustic wave propagation path.

11. A sensor apparatus comprising:
at least one input transducer for receiving a signal and generating surface acoustic waves from the signal;
a first surface acoustic wave propagation path for receiving a first surface acoustic wave from the at least one input transducer, the first surface acoustic wave propagation path including a first reflector transducer coupled with or operating as a first sensor; and
a second surface acoustic wave propagation path for receiving a second surface acoustic wave from the at least one input transducer, the second surface acoustic wave propagation path including a second reflector transducer operating as a second sensor and coupled with a third sensor,
wherein the first sensor comprises a humidity sensor and the third sensor comprises a magnetic field sensor,
wherein the second reflector transducer operates as a temperature sensor and is coupled with the magnetic field sensor, the first and second surface acoustic wave propagation paths being protected against influencing each other.

12. A method of sensing a change in one or more measurands, comprising the steps of:
receiving a signal and generating surface acoustic waves from the signal;
propagating a surface acoustic wave along a first surface acoustic wave propagation path and a second surface acoustic wave propagation path, the first surface acoustic wave propagation path including a first reflector transducer coupled with or operating as a first sensor, the second surface acoustic wave propagation path including a second reflector transducer operating as a second sensor and coupled with a third sensor, wherein the first and second sensors are selected from the group consisting of a humidity sensor, a temperature sensor, and combinations thereof;
reflecting the surface acoustic wave propagated along the first surface acoustic wave propagation path;
reflecting the surface acoustic wave propagated along the second surface acoustic wave propagation path; and
determining a phase shift or an amplitude change or both between the surface acoustic wave reflected in the first surface acoustic wave propagation path and the surface acoustic wave reflected in the second surface acoustic wave propagation path thereby sensing a change in at least one of humidly, magnetic field or temperature as a measurand,
wherein the third sensor includes a magnetic field sensor that changes impedance upon changes of a magnetic field, causing a phase shift or an amplitude change or both of a surface wave reflected by its associated second reflector transducer.

13. The method of claim 12 , wherein the signal is received by an input inter-digital transducer that generates the surface acoustic waves from the signal.

14. The method of claim 12 , wherein the first and second surface acoustic wave propagation paths are provided on a piezoelectric substrate.

15. The method of claim 12 , wherein the signal is received by an input transducer that generates the surface acoustic wave from the signal, wherein the first sensor includes a humidity sensor that is a delay line coupling the input transducer and the first reflector transducer coupled with the humidity sensor, the delay line coated with a humidity sensitive hydrogel.

16. The method of claim 12 , wherein the first and second surface acoustic wave propagation paths are formed on a thermally sensitive substrate.

17. The method of claim 12 , wherein a resonant frequency of the first sensor in the first surface acoustic wave propagation path is the same as resonant frequencies of the second reflector transducer and the third sensor in the second surface acoustic wave propagation path.

18. A method of sensing a change in one or more measurands, comprising the steps of:
receiving a signal and generating surface acoustic waves from the signal;
propagating a surface acoustic wave along a first surface acoustic wave propagation path and a second surface acoustic wave propagation path, the first surface acoustic wave propagation path including a first reflector transducer coupled with or operating as a first sensor, the second surface acoustic wave propagation path including a second reflector transducer operating as a second sensor and coupled with a third sensor, wherein the first sensor comprises a humidity sensor, the second sensor comprises a temperature sensor, and the third sensor comprises a magnetic field sensor;
reflecting the surface acoustic waves propagated along the first and second surface acoustic wave propagation paths;
protecting the first and second surface acoustic wave propagation paths against influencing each other; and
determining a phase shift or an amplitude change or both between the surface acoustic wave reflected in the first surface acoustic wave propagation path and the surface acoustic wave reflected in the second surface acoustic wave propagation path thereby sensing a change in at least one of humidly, magnetic field or temperature as a measurand.

Assignees

• Univ King Abdullah Sci & Tech

Inventors

• Li Bodong
• Kosel Jürgen

Classifications

• G01K1/00

  Details of thermometers not specially adapted for particular types of thermometer (circuits for reducing thermal inertia G01K7/42) · CPC title

• G01K11/265

  using surface acoustic wave [SAW] · CPC title

• G01N2291/02845

  Humidity, wetness · CPC title

• H04B11/00 Primary

  Transmission systems employing ultrasonic, sonic or infrasonic waves · CPC title

• G01R33/093

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title