Method and apparatus for the detection of the response of a sensing device

• US 6,868,350 B2
• Filed: 04/11/2003
• Issued: 03/15/2005
• Est. Priority Date: 04/11/2003
• Status: Active Grant

• Current Assignee: Therm-O-Disc Incorporated (Emerson Electric Company)
• Original Assignee: Therm-O-Disc Incorporated (Emerson Electric Company)
• Inventors: Khadkikar, Prasad S., Zimmermann, Bernd D., Bostic, Lance A.
• Primary Examiner(s): Bui, Bryan
• Application Number:
  US10/411,894
• Publication Number:
  US 20040204920A1
• Time in Patent Office: 704 Days
• Field of Search: 702/45, 702/53, 702/57, 702/65, 702/79, 702/116, 702/193, 702/189, 732/042.2, 732/042.5, 732/042.7, 205/775, 205/782.5, 205/787
• US Class Current: 702/65
• CPC Class Codes: G01F 1/696 Circuits therefor, e.g. constant-current flow meters
• CPC Class Codes: G01N 27/12 of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid , for detecting components in the fluid
• CPC Class Codes: G01N 33/0063 using a threshold to release an alarm or displaying means alarm arrangements G08B, e.g. fire alarm actuated by the presence of smoke or gases G08B17/10, for other abnormal conditions G08B21/00
• CPC Class Codes: G01P 5/12 using variation of resistance of a heated conductor

Abstract

A method for operating a sensing device. The method comprising: a sensor film having an electrical resistance that is adapted to change in response to the presence of a predetermined condition; detecting the presence of the predetermined condition; measuring the electrical resistance of the sensor film at a first time; measuring the electrical resistance of the sensor film at a second time; determining a rate of change of the electrical resistance between the first time and the second time; and comparing the rate of change of the electrical resistance against a threshold value.

Claims

1. A method for operating a sensing device comprising:

providing a sensor having an electrical resistance that is adapted to change in response to a predetermined condition;

measuring the electrical resistance of the sensor at a first time;

measuring the electrical resistance of the sensor at a second time;

determining a rate of change of the electrical resistance between the first time and the second time; and

comparing the rate of change of the electrical resistance against a threshold value.

2. The method of claim 1, further comprising:

generating a signal to a control device if the rate of change of the electrical resistance exceeds the threshold value; and

operating an indicating device when the rate of change of the electrical resistance exceeds the threshold value.

3. The method of claim 2, further comprising displaying the comparison results on a computer monitor in at least one of a graphical and numerical manner.

4. The method of claim 2, further comprising alerting the user of the sensing device in at least one of a visual and audio signal.

5. The method of claim 1, wherein providing a sensor having an electrical resistance that is adapted to change in response to a predetermined condition comprises providing a sensor film comprising a matrix of a plurality of carbon black filled silicone.

6. The method of claim 1, wherein providing a sensor having an electrical resistance that is adapted to change in response to a predetermined condition comprises providing a sensor having an electrical resistance that is adapted to change in response to the presence of a target analyte.

7. The method of claim 1, further comprising determining the n^th order derivative of the rate of change, where n≧

1.

8. A method for operating a sensing device comprising:

providing a sensor probe having an electrical resistance that is adapted to change in response to the presence of a target analyte;

measuring the electrical resistance of the sensor probe at a first time;

measuring the electrical resistance of the sensor probe at a second time;

sending signals representing the electrical resistance measurements to a control device; and

determining a rate of change of the signals with the control device.

9. The method of claim 8, further comprising:

comparing the rate of change of the signal against a threshold value with the control device; and

operating an indicating device when the rate of change of the signal exceeds the threshold value.

10. The method of claim 9, further comprising alerting the user of the sensing device with at least one of a visual and audio signal.

11. The method of claim 9, further comprising controlling an appliance when the rate of change of the signal exceeds the threshold value.

12. The method of claim 9, further comprising determining the n^th order derivative of the rate of change, where n≧

1.

13. A method for operating a sensing device comprising:

providing a sensor probe comprising a sensor film having an electrical resistance that is adapted to change in response to the presence of a target analyte;

measuring the electrical resistance of the sensor film at a first time;

measuring the electrical resistance of the sensor film at a second time;

determining a rate of change of the electrical resistance between the first time and the second time; and

generating a signal representing the rate of change of the electrical resistance measured between the first and second time.

14. The method of claim 13, further comprising:

sending the signal to a control device; and

comparing the signal to a threshold value with the control device.

15. The method of claim 14, further comprising:

informing a user of the sensing device when the signal exceeds the threshold value; and

controlling an appliance when the signal exceeds the threshold value.

16. The method of claim 13, further comprising determining the n^th order derivative of the rate of change, where n≧

1.

17. A method for operating a sensing device comprising:

providing an electrical component having an electrical resistance adapted to change in response to the presence of a flow of a fluid;

measuring the electrical resistance of the electrical component at a first time;

measuring the electrical resistance of the electrical component at a second time; and

determining a rate of change of the electrical resistance between the first time and the second time.

18. The method of claim 17, further comprising:

determining a flow rate of the fluid based on the rate of change of the electrical resistance; and

comparing the flow rate of the fluid against a threshold value.

19. The method of claim 18, further comprising:

generating a signal to a control device when the flow rate of the fluid exceeds the threshold value; and

informing a user of the sensing device when the control device receives the signal.

20. The method of claim 19, further comprising controlling an appliance when the control device receives the signal.

21. The method of claim 17, wherein providing an electrical component having an electrical resistance adapted to change in response to the presence of a flow of a fluid comprises providing a thermistor adapted to change in electrical resistance in response to a change in temperature.

22. The method of claim 17, further comprising determining the n^th order derivative of the rate of change, where n≧

1.

23. A sensor comprising:

a sensor film having an electrical resistance that is adapted to change in response to the presence of a predetermined condition;

means for measuring the electrical resistance of the sensor film during a period of time;

means for generating a first signal corresponding to the electrical resistance measurements;

means for differentiating the first signal;

means for generating a second signal corresponding to the differential of the first signal; and

means for comparing the second signal with a threshold value and generating a third signal when the second signal exceeds the threshold value.

24. The sensor of claim 23, further comprising:

means for displaying the comparison results to a user of the sensor; and

means for controlling an appliance when the third signal is generated.

25. The sensor of claim 24, wherein the means for displaying the comparison results to a user of the sensor is a computer monitor.

26. The sensor of claim 23, wherein the sensor is a chemiresistor sensor.

27. The sensor of claim 23, wherein the sensor film is a matrix comprising a plurality of carbon black filled silicone.

28. The sensor of claim 23, further comprising means for determining the n^th order derivative of the second signal, where n≧

1.

29. A sensing device comprising:

a sensor probe;

an electrical component having an electrical resistance electrically connected to the sensor probe, the electrical resistance of the electrical component adapted to change in response to the presence of a predetermined condition; and

a control device electrically connected to the electrical component, the control device for measuring the electrical resistance of the electrical component during a time period, and generating a first signal corresponding to the electrical resistance measurements, and determining a rate of change of the first signal, and generating a second signal corresponding to the rate of change of the first signal, and comparing the second signal with a threshold value.

30. The sensing device of claim 29, wherein the control device further is operative to control an appliance when the second signal exceeds the threshold value.

31. The sensing device of claim 29, further comprising an indicating device for informing a user when the second signal exceeds the threshold value.

32. The sensing device of claim 29, wherein the electrical component is a sensor film.

33. The sensing device of claim 32, wherein the sensor film is a matrix comprising a plurality of carbon black silicone.

34. The sensing device of claim 29, wherein the predetermined condition is the presence of a target analyte.

35. The sensing device of claim 29, wherein the electrical component is a thermistor having a temperature adapted to change based on the presence of the predetermined condition.

36. The sensing device of claim 35, wherein the predetermined condition is a rate of flow of a fluid.

37. The sensing device of claim 29, wherein the electrical component is encapsulated by a thermally-conductive polymer.

38. The sensing device of claim 29, wherein the control device is further used for determining the n^th order derivative of the second signal, where n≧

1.

39. A sensor probe comprising:

an electrical component having an electrical resistance electrically connected to the sensor probe, the electrical resistance of the electrical component adapted to change in response to the presence of a predetermined condition;

a measurement module that measures the electrical resistance of the electrical component during a time period and generates a first signal corresponding to the electrical resistance measurements;

a differentiator that determines a rate of change of the first signal and generates a second signal corresponding to the differential of the first signal; and

a comparator that compares the second signal with a threshold value.

40. The sensor probe of claim 39, further comprising a control device that controls an appliance when the second signal exceeds the threshold value.

41. The sensor probe of claim 39, further comprising an indicating device that informs a user when the second signal exceeds the threshold value.

42. The sensor probe of claim 39, wherein the electrical component is a sensor film.

43. The sensor probe of claim 42, wherein the sensor film is a matrix comprising a plurality of carbon black silicone.

44. The sensor probe of claim 39, wherein the predetermined condition is the presence of a target analyte.

45. The sensor probe of claim 39, wherein the electrical component is a thermistor having a temperature adapted to change based on the presence of the predetermined condition.

46. The sensor probe of claim 45, wherein the predetermined condition is a rate of flow of a fluid.

47. The sensor probe of claim 39, wherein the electrical component is encapsulated by a thermally-conductive polymer.

48. The sensor probe of claim 39, wherein the differentiator further determines the n^th order derivative of the second signal, where n≧

1.