Micropower differential sensor measurement

• US 6,714,763 B2
• Filed: 08/09/2002
• Issued: 03/30/2004
• Est. Priority Date: 01/24/2000
• Status: Expired due to Term

• Current Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Original Assignee: MicroStrain, Inc. (Spectris PLC)
• Inventors: Arms, Steven W., Townsend, Christopher P., Hamel, Michael John
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Nguyen, Thuan T.
• Application Number:
  US10/215,752
• Publication Number:
  US 20020190785A1
• Time in Patent Office: 599 Days
• Field of Search: 455/41.1, 455/41.2, 455/41.3, 455/414.1, 455/67.11, 455/67.15, 455/550.1, 455/554.1, 455/554.2, 455/555, 455/572, 455/115.1, 455/127.1, 340/505, 340/539.1, 340/448, 340/572.1, 340/636.2, 340/825, 340/10.1, 340/10.33, 340/10.34, 340/10.4, 342/42, 342/44.51
• US Class Current: 73/786
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

Claims

1. A method of using an electronic circuit, comprising the steps of:

a) providing a circuit comprising a sensor, a circuit for reading said sensor, and a circuit for transmitting data;

b) wirelessly providing power to each of said circuits from a remote source of power;

c) sensing a change in a condition with said sensor;

d) reading said sensor with said circuit for reading said sensor, wherein only a single pulse stimulation signal to said sensor is needed to read said sensor;

e) providing said reading to a transmitting circuit; and

f) transmitting said data with said transmitting circuit.

2. The method as recited in claim 1, wherein said reading depends on a time constant of a reactive element.

3. The method as recited in claim 1, further comprising the step of generating an ID for inclusion with said data.

4. The method as recited in claim 1, wherein in said sensing step (a) said sensor is for detecting a change in displacement, strain, speed, acceleration, temperature, pressure, or force.

5. The method as recited in claim 1, wherein in said providing step (a) said sensor comprises a differential sensor.

6. The method as recited in claim 5, wherein said differential sensor comprises a peak strain detection linear displacement sensor.

7. The method as recited in claim 5, wherein in said differential sensor comprises variable capacitors, variable inductors, or variable resistors.

8. The method as recited in claim 1, wherein in said providing step (a) said sensor can measure peak displacement or peak strain.

9. The method as recited in claim 1, wherein in said providing step (a) said circuits are implantable.

10. The method as recited in claim 1, wherein in said providing step (a) said circuit for reading said sensor comprises a comparator.

11. The method as recited in claim 10, wherein said circuit for reading said sensor comprises a pair of comparators.

12. The method as recited in claim 1, wherein in said sensing step (c) said condition comprises an environmental condition.

13. The method as recited in claim 1, wherein in said sensing step (c) said condition is a condition of a smart structure.

14. The method as recited in claim 1, wherein in said transmitting step (f) said data corresponds to peak displacement or peak strain.

15. The method as recited in claim 1, wherein in said transmitting step (f) said data comprises both direction and magnitude of change in said condition.

16. The method as recited in claim 1, wherein in said transmitting step (f) power for transmitting is provided from said remote source of power.