Robust chemiresistor sensor

• US 20040200722A1
• Filed: 04/11/2003
• Published: 10/14/2004
• 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., Blok, Edward J., Donnelly, Donald E., Starling, Jared, Sterken, Robert, Volz, Charles L.
• Granted Patent: US 7,112,304 B2
• Time in Patent Office: Days
• US Class Current: 204/403.01
• CPC Class Codes: G01N 27/125 Composition of the body, e.g. the composition of its sensitive layer
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A chemiresistor sensor probe for detecting target analytes. The probe includes a body having a first control surface and a second control surface recessed within the first. A sensor film comprises numerous conductive particles disposed upon the second surface. The film swells upon absorbing one or more analytes for which it has an affinity, thus causing the conductive particles to become more dispersed and increasing the resistance between the particles. The thickness of the film is equal to the distance between the first surface and the second surface, thus permitting the thickness to be controlled by varying the distance between the control surfaces. The robustness of the sensor probe is enhanced by placing a porous or mesh electrode along with, or in place of, a chemical binding agent between the film and the terminals. The robustness is also improved by placing a diode in series with the sensor circuit.

Claims

1. A chemiresistor sensor probe for detecting the presence of one or more analytes comprising:

a probe body;

a first control surface located on an exterior of said probe body;

a second control surface recessed within said first control surface;

a pair of terminals; and

a sensor film located on said second control surface, said sensor film having a thickness that is equal to a distance between said second control surface and said first control surface and is in electrical contact with said pair of terminals.

2. The chemiresistor sensor probe of claim 1, further comprising at least two apertures disposed within said first control surface, said second control surface located between said apertures.

3. The chemiresistor sensor probe of claim 1, further comprising a mechanical bond between said terminals and said sensor film.

4. The chemiresistor sensor probe of claim 3, wherein said terminals each further comprise a conductive plate in electrical contact with said sensor film, said conductive plate providing a mechanical bond between said sensor film and said terminals.

5. The chemiresistor sensor probe of claim 3, wherein said terminals each further comprise a conductive mesh plate in electrical contact with said sensor film, said conductive mesh plate providing a mechanical bond between said sensor film and said terminals.

6. The chemiresistor sensor probe of claim 1, further comprising a chemical bond between said terminals and said sensor film.

7. The chemiresistor sensor probe of claim 1, further comprising at least one aperture within each of said terminals for receipt of a positioning rod for positioning said terminals within said probe body during manufacturing.

8. The chemiresistor sensor probe of claim 1, wherein said probe body is comprised of a molded polymer.

9. The chemiresistor sensor probe of claim 1, further comprising a protective cap placed atop said first control surface.

10. The chemiresistor sensor probe of claim 1, wherein said sensor film is a crosslinked, polymeric matrix.

11. The chemiresistor sensor probe of claim 1, further comprising a sensor circuit having a diode to prevent bypass leakage from negatively affecting the performance of said sensor probe.

12. A method of producing a sensor probe for detecting the presence of one or more analytes, said method comprising:

positioning at least two terminals within a mold, said mold pre-formed to produce a probe body having a first control surface and a second control surface recessed within said first control surface;

injecting a molding compound within said mold to form said probe body with said terminals secured within said probe body; and

applying a sensor film to said second control surface, said sensor film having a thickness that is equal to a distance between said second control surface and said first control surface.

13. The method of claim 12, wherein said sensor film is a crosslinked, polymeric matrix.

14. The method of claim 12, further comprising:

placing a plurality of conductive materials within said sensing film, said conductive materials becoming more dispersed within said film as said film swells upon absorbing said analytes, thus increasing a resistance of said film as measured by said terminals.

15. The method of claim 12, further comprising:

applying said film in excess and removing a portion of said film extending beyond said first control surface such that said thickness of said film is equal to said distance between said second control surface and said first control surface.

16. The method of claim 12, further comprising:

providing said terminals with a conductive plate in electrical contact with said sensor film, said conductive plate creating a mechanical bond between said terminals and said film.

17. The method of claim 12, further comprising:

providing said terminals with a conductive mesh plate in electrical contact with said sensor film, said conductive mesh plate creating a mechanical bond between said terminals and said film.

18. The method of claim 12, further comprising:

placing a chemical binding agent between said terminals and said film.

19. The method of claim 12, further comprising:

oven curing said film after said film is placed on said second control surface.

20. The method of claim 12, further comprising:

placing said terminals in electrical contact with a sensor circuit having a diode to prevent bypass leakage from negatively affecting the performance of said sensor probe.

21. A chemiresistor sensor for detecting the presence of analytes comprising:

a probe body having a first control surface;

a second control surface recessed within said first control surface;

a sensor film deposited on said second control surface, said film having a thickness that is equal to a distance that said second control surface is recessed within said first control surface;

a control unit in receipt of an output from said probe body, said output indicative of the presence or absence of said analytes; and

a user interface for providing an alert indicating the presence of said analytes, said user interface in receipt of a signal from said control unit, said signal indicative of the presence or absence of said analytes.

22. The chemiresistor sensor of claim 21, further comprising a plurality of conductive materials disposed within said sensor film, said conductive materials becoming more dispersed within said film as said film swells upon absorbing said materials, thus increasing a resistance of said film as measured by said terminals.

23. The chemiresistor sensor of claim 21, wherein said film is a crosslinked, polymeric matrix.

24. The chemiresistor sensor of claim 21, further comprising:

a conductive plate in electrical contact with said sensor film, said conductive plate providing a mechanical bond between said sensor film and said terminals.

25. The chemiresistor sensor of claim 21, further comprising:

a conductive mesh plate in electrical contact with said sensor film, said conductive mesh plate providing a mechanical bond between said sensor film and said terminals.

26. The chemiresistor sensor of claim 21, further comprising:

a chemical binding agent deposited between said terminals and said film to form a chemical bond between said terminals and said film.

27. The chemiresistor sensor of claim 21, wherein said film is first applied to said second control surface in excess with a portion of said film extending beyond said first control surface being subsequently removed such that said film has a thickness equal to said distance that said second control surface is recessed within said first control surface.

28. The chemiresistor sensor of claim 21, further comprising:

a sensor circuit coupled with said probe body, said sensor circuit to prevent bypass leakage from negatively affecting performance of said sensor.

29. A chemiresistor sensor probe for detecting the presence of one or more analytes comprising:

a probe body;

a sensing surface located on said probe body;

a sensor film located on said sensing surface; and

a pair of terminals having a conductive plate in electrical contact with said sensor film, said conductive plate providing a mechanical bond between said sensor film and said terminals.

30. The chemiresistor sensor probe of claim 29, further comprising a control surface recessed within said sensing surface, said sensor film having a thickness that is equal to a distance between said sensing surface and said control surface.

31. The chemiresistor sensor probe of claim 29, wherein said conductive plate is a mesh plate.

32. The chemiresistor sensor probe of claim 29, further comprising a chemical bond between said conductive plate and said sensor film.

33. The chemiresistor sensor probe of claim 29, further comprising at least one aperture within each of said terminals for receipt of a positioning rod for positioning said terminals within said probe body during manufacturing.

34. The chemiresistor sensor probe of claim 29, wherein said probe body is comprised of a molded polymer.

35. The chemiresistor sensor probe of claim 29, further comprising a protective cap placed atop said sensing surface.

36. The chemiresistor sensor probe of claim 29, wherein said sensor film is a crosslinked, polymeric matrix.

37. The chemiresistor sensor probe of claim 29, further comprising a sensor circuit, said sensor circuit having a diode to prevent bypass leakage from negatively affecting performance of said sensor probe.

38. A chemiresistor sensor probe for detecting the presence of one or more analytes comprising:

a probe body;

a sensor film comprising a polymeric matrix located on an exterior of said probe body, said sensor film having a predetermined and controlled thickness;

a plurality of current conducting terminals, each of said terminals being in electrical contact with said sensor film, at least one of said terminals comprising means for mechanically interlocking said at least one terminal with said sensor film.

39. The chemiresistor sensor probe of claim 38, further comprising a sensor circuit, said sensor circuit having a diode to prevent bypass leakage from negatively affecting performance of said sensor probe.