Passive surface acoustic wave sensing system

• US 8,384,524 B2
• Filed: 11/25/2009
• Issued: 02/26/2013
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Cobianu, Cornel, Georgescu, Ion, Bostan, Cazimir
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): NWUGO, OJIAKO K
• Application Number:
  US12/626,407
• Publication Number:
  US 20100127834A1
• Time in Patent Office: 1,189 Days
• Field of Search: 340 51- 55, 340 101- 105, 3405721-5729, 235375-385
• US Class Current: 340/10.1
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: H04Q 2213/13003 Constructional details of switching devices

Abstract

The present disclosure relates generally to wireless detection systems. In one illustrative embodiment, a wireless detection system includes a plurality of surface acoustic wave (SAW) sensors, and an electronic reader for interrogating the plurality of SAW sensors. In some instances, each of the surface acoustic wave based sensors includes an integrated sensor coil. The electronic reader may include a plurality of reader coils and a controller. The controller may be configured to interrogate the plurality of surface acoustic wave based sensors using a time division interrogation. In some cases, each of the plurality of reader coils is inductively coupled to only one of the integrated coils of the SAW sensors at any given time.

Claims

1. A sensing system comprising:

a plurality of surface acoustic wave based sensors, each of the surface acoustic wave based sensors including a sensor coil and a surface acoustic wave device, wherein each sensor coil, when energized, is configured to energize and interrogate the corresponding surface acoustic wave device to obtain a corresponding sensor value, wherein each sensor coil can be energized through inductively coupling;

an electronic reader including;

a plurality of reader coils, wherein when the electronic reader is aligned with the plurality of surface acoustic wave based sensors, each of the plurality of reader coils of the electronic reader is aligned with and inductively coupled to a corresponding one of the sensor coils of the plurality of surface acoustic wave based sensors;

a multiplexer coupled to the plurality of reader coils;

a memory;

a controller coupled to the multiplexer and the memory;

wherein;

the controller is configured to control the multiplexer such that the multiplexer energizes only one of the plurality of reader coils at a given time to read the sensor value from the energized one of the plurality of surface acoustic wave based sensors; and

the memory stores one or more calibration coefficients for each of the plurality of surface acoustic wave based sensors, the controller is configured to retrieve one or more of the calibration coefficients from the memory, and apply the calibration coefficients to the sensor values interrogated from the corresponding surface acoustic wave based sensors.

2. The sensing system of claim 1 wherein the controller sequentially interrogates the plurality of surface acoustic wave based sensors.

3. The sensing system of claim 2 wherein the controller sends the multiplexer an address to selectively energize one of the plurality of reader coils, waits for a sensor value to be interrogated from the corresponding surface acoustic wave based sensor, before selectively energizing another reader coil.

4. The sensing system of claim 3 wherein the controller applies one or more of the calibration coefficients to the sensor value.

5. The sensing system of claim 3 wherein the memory includes a look-up table storing the calibration coefficients, the calibration coefficients being selected using the address used for selectively energizing one of the plurality of reader coils.

6. The sensing system of claim 1 wherein the electronic reader is configured to wirelessly communicate with one or more mobile devices.

7. A detection system comprising:

a plurality of sensors, each of the plurality of sensors including a surface acoustic wave device and a corresponding sensor coil, wherein the sensor coil, when energized, is configured to energize and interrogate the corresponding surface acoustic wave device to obtain a sensor value;

a plurality of reader coils each aligned with one of the sensor coils of the plurality of sensors, each of the plurality of reader coils, when energized, is configured to energize the corresponding one of the sensor coils through inductively coupling, which energize and interrogate the corresponding surface acoustic wave device to obtain the corresponding sensor value; and

a controller coupled to the plurality of reader coils, wherein the controller is configured to sequentially energize the plurality of reader coils individually to sequentially energize and interrogate each of the corresponding plurality of sensors.

8. The detection system of claim 7, wherein the controller is configured to wait a period of time to receive a return signal from an energized reader coil before energizing a next reader coil.

9. The detection system of claim 7, wherein the controller includes a multiplexer to sequentially energize the plurality of reader coils.

10. The detection system of claim 9, wherein the controller provides an address to the multiplexer to select one of the reader coils and, when a reader coil is selected, the multiplexer sends an electrical signal to energize the selected reader coil, wherein the selected reader coil induces a current in a corresponding one of the sensor coils by inductively coupling.

11. The detection system of claim 10, wherein the current in the sensor coil provides power to the surface acoustic wave device.

12. The detection system of claim 10, wherein the controller includes a memory, the memory including a plurality of calibration coefficients each corresponding to one of the plurality of sensors, wherein each of the plurality of calibration coefficients is selected using the address provided to the multiplexer to select one of the reader coils.

13. The detection system of claim 12, wherein the memory includes a look-up table.

14. The detection system of claim 12, wherein the controller is configured to apply the calibration coefficients to values received by interrogating the plurality of sensors.

15. The detection system of claim 7, wherein each of the plurality of reader coils are configured to inductively couple with only one of the plurality of sensor coils.

16. The detection system of claim 7, wherein the controller is configured to wirelessly communicate with one or more mobile devices.

17. The detection system of claim 16, wherein the wireless communication is in accordance with a Bluetooth protocol.

18. A wireless detection system comprising:

a plurality of surface acoustic wave based sensors, each of the surface acoustic wave based sensors including a sensor coil and a surface acoustic wave device, wherein each sensor coil, when energized, is configured to energize and interrogate the corresponding surface acoustic wave device to obtain a corresponding sensor value;

an electronic reader including a plurality of reader coils and a controller, wherein each of the plurality of reader coils is configured to inductively couple to a corresponding one of the sensor coils; and

the controller is configured to sequentially activate the plurality of reader coils to sequentially interrogate the plurality of surface acoustic wave based sensors using time division interrogation.

19. The wireless detection system of claim 18, wherein the time division interrogation includes energizing a first reader coil of the plurality of reader coils using a multiplexer to inductively couple the first reader coil to a corresponding sensor coil.

20. The wireless detection system of claim 19, wherein the controller waits to receive a return signal from the first reader coil before energizing a second reader coil of the plurality of reader coils.