Sensor devices for structural health monitoring

• US 7,034,660 B2
• Filed: 04/03/2002
• Issued: 04/25/2006
• Est. Priority Date: 02/26/1999
• Status: Expired due to Term

• Current Assignee: Yasumi Capital, LLC (Intellectual Ventures LLC)
• Original Assignee: SRI International, Inc.
• Inventors: Watters, David G., Huestis, David L., Bahr, Alfred J., Priyantha, Namal, Jayaweera, Palitha
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Shimizu, M
• Application Number:
  US10/115,872
• Publication Number:
  US 20020154029A1
• Time in Patent Office: 1,483 Days
• Field of Search: 340/10.41, 340/10.4, 340/42, 340/44, 340/870.07, 340/870.16, 340/870.17, 340/870.31, 205/775.5, 205/777, 205/776.5, 342/44, 342/50, 342/51
• US Class Current: 340/10.41
• CPC Class Codes: E01D 22/00 Methods or apparatus for repairing or strengthening existing bridges electrochemical desalination or re-alkalisation C04B41/00; Methods or apparatus for dismantling bridges
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01D 5/48 using wave or particle radiation means G01D5/26 takes precedence
• CPC Class Codes: G01K 3/04 in respect of time
• CPC Class Codes: G01K 5/483 using materials with a configuration memory, e.g. Ni-Ti alloys
• CPC Class Codes: G01M 5/0008 of bridges
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0083 by measuring variation of impedance, e.g. resistance, capacitance, induction
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection
• CPC Class Codes: G01N 27/4035 Combination of a single ion-sensing electrode and a single reference electrode G01N27/406 and G01N27/413 take precedence
• CPC Class Codes: G06K 19/0717 the sensor being capable of sensing environmental conditions such as temperature history or pressure
• CPC Class Codes: H04Q 2209/47 using RFID associated with sensors
• CPC Class Codes: H04Q 2209/823 where the data is sent when the measured values exceed a threshold, e.g. sending an alarm
• 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

Described herein are wireless interrogation systems and methods that rely on a complementary sensing device and interrogator. The sensing device is disposed to measure a parameter indicative of the health of a structure. A sensor reading from the sensor indicates the level of a parameter being monitored or whether one or more particular physical or chemical events have taken place. Using wireless techniques, the interrogator probes the device to determine its identity and its current sensor reading. This often includes transmission of a wireless signal through portions of the structure. When activated, the device responds with a wireless signal that identifies the device and contains information about the parameter being measured or a particular sensor state corresponding to the parameter. The identity of the device allows it to be distinguished from a number of similar devices. Thus this invention finds particular usefulness in the context of an array of devices that can be probed by a wireless interrogation unit. In one embodiment, the devices are passive and derive power from the interrogation signal.

Claims

1. A sensor device comprising:

a sensor that detects a parameter indicative of the health of a structure comprising a metal;

an encapsulation that seals internal components of the sensor from the surrounding structure;

a port that permits passage of an ion from outside the device to the sensor,

a transponder in electrical communication with the sensor and that transmits a wireless signal through a portion of the structure indicating the parameter status when triggered by a wireless interrogation signal; and

an identification source in electrical communication with the transponder that uniquely identifies the device.

2. The device of claim 1 wherein the device does not contain a power source.

3. The device of claim 1 wherein the sensor detects one of:

the resistance of a metal element included in the structure, concentration of an ion found in the structure, pH in the structure, conductivity of a metal element included in the structure, and corrosion of a surrogate.

4. The device of claim 1 wherein the device is embedded in the structure.

5. The device of claim 1 further comprising temperature compensation circuitry that alters a sensor reading according to temperature of the device.

6. The device of claim 1 wherein the transponder comprises:

a ferrite; and

at least one wire wound around the ferrite.

7. The device of claim 1 wherein the device includes a microchip that rectifies a signal provided to the transponder.

8. The device of claim 1 wherein the sensor comprises an electrochemical cell.

9. The device of claim 1 wherein the sensor detects one of humidity, temperature, and pressure.

10. The device of claim 1 further comprising an amplifier for increasing the strength of a received incident signal, a modulator for modifying the incident signal with information provided by the sensor, and an antenna or antennas for receiving and transmitting the incident signal.

11. The device of claim 1 wherein the device communicates information related to the parameter being detected using a bit stream inversion.

12. The device of claim 1 wherein the sensor detects the level of a chemical that is aggressive to the health of the structure.

13. The device of claim 12 wherein the sensor detects the level of an ion that facilitates corrosion of the metal.

14. The device of claim 1 wherein the identification source comprises a microchip that stores a unique number for the sensor device.

15. The device of claim 14 wherein the microchip also stores a second unique number for the device that indicates when the sensor has detected a threshold level for the parameter being sensed.

16. The device of claim 15 wherein the threshold corresponds to a chloride ion concentration.

17. The device of claim 1 wherein the device is directionally dependent and includes a port that limits sensor detection to a specific direction.

18. The device of claim 17 wherein the event is a threshold for the parameter.

19. The device of claim 1 wherein the transponder comprises:

a ferrite; and

a wire wound around the ferrite.

20. A device embedded in a structure comprising concrete, the device comprising:

a sensor embedded in the concrete that detects a parameter;

a partial encapsulation that seals internal components of the device including the sensor, a transponder and identification source from the concrete;

a permeable cementitious membrane that permits passage of an ion from the concrete to the sensor;

the transponder in electrical communication with the sensor and that transmits a wireless signal through a portion of the concrete indicating the parameter status; and

the identification source in electrical communication with the transponder that uniquely identifies the device.

21. The device of claim 20 wherein the transponder transmits the wireless signal when triggered by a wireless interrogation signal provided by an interrogator.

22. The device of claim 20 wherein the structure is included in a bridge.

23. The device of claim 20 wherein the sensor and transponder are passive.

24. The device of claim 20 wherein the sensor detects one of:

resistance of a metal element included in the structure, concentration of an ion found in the structure, pH in the structure, conductivity of a metal element included in the structure, and corrosion of a surrogate.

25. The device of claim 20 further comprising temperature compensation circuitry that alters a sensor reading according to temperature of the device.

26. The device of claim 20 wherein the device includes a microchip that rectifies a signal provided to the transponder.

27. The device of claim 20 wherein the sensor comprises an electrochemical cell.

28. The device of claim 20 wherein the structure comprises a metal.

29. The device of claim 28 wherein the sensor detects a parameter indicative of the health of the structure.

30. The device of claim 29 wherein the sensor detects a parameter indicative of the health of the metal.

31. The device of claim 30 wherein the sensor detects the presence of an ion that facilitates corrosion of the metal.

32. The device of claim 31 wherein the structure comprises concrete and the sensor detects chloride ion concentration in the concrete.

33. The device of claim 20 wherein the identification source comprises a microchip that stores a unique number for the device.

34. The device of claim 33 wherein the microchip also stores a second unique number for the device that indicates when the sensor has detected a threshold level for the parameter being sensed.

35. The device of claim 34 wherein the permeable cementitious membrane permits the passage of chloride ions from outside the device to the sensor.