Sensors for detecting analytes in fluids

• US 5,788,833 A
• Filed: 08/14/1996
• Issued: 08/04/1998
• Est. Priority Date: 03/27/1995
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Severin, Erik, Lewis, Nathan S.
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/696,128
• Time in Patent Office: 720 Days
• Field of Search: 205/787, 205/782.5, 205/775, 204/406, 204/415, 204/418, 422/68.1, 422/69, 422/82.01, 422/82.02, 436/150
• US Class Current: 205/787
• CPC Class Codes: G01N 27/126 comprising organic polymers
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array

Abstract

Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

Claims

1. A sensor for detecting the presence of a chemical analyte in a fluid, said sensor comprising a chemically sensitive resistor electrically connected to an electrical measuring apparatus and being in thermal communication with a temperature control apparatus, said chemically sensitive resistor comprising:

a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer, wherein said resistor provides

an electrical path through said mixture of nonconductive organic polymer and said conductive material, and

an electrical resistance R_m at temperature T_m when contacted with a fluid comprising said chemical analyte, where m is an integer greater than 1.

2. The sensor according to claim 1 wherein said conductive material is an inorganic conductor.

3. The sensor according to claim 1 wherein said conductive material is an organic conductor.

4. The sensor according to claim 1 wherein said sensor comprises an array of two or more of said chemically sensitive resistors, wherein each of said chemically sensitive resistors is electrically connected to an electrical measuring apparatus and is in thermal communication with a temperature control apparatus.

5. The sensor according to claim 4 wherein said nonconductive organic polymer in one of said chemically sensitive resistors in said array is different from said nonconductive organic polymer in at least one other chemically sensitive resistor in said array.

6. The sensor according to claim 4 wherein said conductive material in one chemically sensitive resistor in said array is different from said conductive material in at least one other chemically sensitive resistor in said array.

7. The sensor according to claim 4 wherein each of said chemically sensitive resistors in said array are compositionally the same.

8. A sensor for detecting the presence of a chemical analyte in a fluid, said sensor comprising a chemically sensitive resistor electrically connected to an electrical measuring apparatus, said chemically sensitive resistor comprising:

a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer, wherein said resistor provides

an electrical path through said mixture of nonconductive organic polymer and said conductive material, and

an electrical impedance Z_m at frequency ω

_m when contacted with a fluid comprising said chemical analyte, where m is an integer greater than 1 and ω

_m does not equal 0.

9. The sensor according to claim 8 wherein said conductive material is an inorganic conductor.

10. The sensor according to claim 8 wherein said conductive material is an organic conductor.

11. The sensor according to claim 8 wherein said sensor comprises an array of two or more of said chemically sensitive resistors, wherein each of said chemically sensitive resistors is electrically connected to an electrical measuring apparatus.

12. The sensor according to claim 11 wherein said nonconductive organic polymer in one of said chemically sensitive resistors in said array is different from said nonconductive organic polymer in at least one other chemically sensitive resistor in said array.

13. The sensor according to claim 11 wherein said conductive material in one chemically sensitive resistor in said array is different from said conductive material in at least one other chemically sensitive resistor in said array.

14. The sensor according to claim 11 wherein each of said chemically sensitive resistors in said array are compositionally the same.

15. A sensor for detecting the presence of a chemical analyte in a fluid, said sensor comprising a chemically sensitive resistor electrically connected to an electrical measuring apparatus and being in thermal communication with a temperature control apparatus, said chemically sensitive resistor comprising:

a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer, wherein said resistor provides

an electrical path through said mixture of nonconductive organic polymer and said conductive material, and

an electrical impedance Z_m,n at frequency ω

_m and temperature T_n when contacted with a fluid comprising said chemical analyte, where m and/or n is an integer greater than 1.

16. The sensor according to claim 15, wherein m and n are integers greater than 1.

17. The sensor according to claim 15 wherein said conductive material is an inorganic conductor.

18. The sensor according to claim 15 wherein said conductive material is an organic conductor.

19. The sensor according to claim 15 wherein said sensor comprises an array of two or more of said chemically sensitive resistors, wherein each of said chemically sensitive resistors is electrically connected to an electrical measuring apparatus and is in thermal communication with a temperature control apparatus.

20. The sensor according to claim 19 wherein said nonconductive organic polymer in one of said chemically sensitive resistor in said array is different from said nonconductive organic polymer in at least one other chemically sensitive resistor in said array.

21. The sensor according to claim 19 wherein said conductive material in one chemically sensitive resistor in said array is different from said conductive material in at least one other chemically sensitive resistor in said array.

22. The sensor according to claim 19 wherein each of said chemically sensitive resistors in said array are compositionally the same.

23. A method for detecting the presence of a chemical analyte in a fluid, said method comprising:

contacting a sensor with a fluid comprising said chemical analyte, said sensor comprising a chemically sensitive resistor electrically connected to an electrical measuring apparatus and being in thermal communication with a temperature control apparatus, wherein said chemically sensitive resistor comprises a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer and provides an electrical path through said mixture of nonconductive organic polymer and said conductive material, and

measuring the electrical resistance R_m at temperature T_m, where m is an integer greater than 1,

wherein said electrical resistance R_m at temperature T_m is indicative of the presence or absence of said chemical analyte in said fluid.

24. A method for detecting the presence of a chemical analyte in a fluid, said method comprising:

contacting a sensor with a fluid comprising said chemical analyte, said sensor comprising a chemically sensitive resistor electrically connected to an electrical measuring apparatus, wherein said chemically sensitive resistor comprises a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer and provides an electrical path through said mixture of nonconductive organic polymer and said conductive material, and

measuring the electrical impedance Z_m at frequency ω

_m, where m is an integer greater than 1 and ω

_m does not equal 0,

wherein said electrical impedance Z_m at frequency ω

_m is indicative of the presence or absence of said chemical analyte in said fluid.

25. A method for detecting the presence of a chemical analyte in a fluid, said method comprising:

contacting a sensor with a fluid comprising said chemical analyte, said sensor comprising a chemically sensitive resistor electrically connected to an electrical measuring apparatus and being in thermal communication with a temperature control apparatus, wherein said chemically sensitive resistor comprises a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer and provides an electrical path through said mixture of nonconductive organic polymer and said conductive material, and

measuring the electrical impedance Z_m,n at frequency ω

_m and temperature T_n, where m and/or n is an integer greater than 1,

wherein said electrical impedance Z_m,n at frequency ω

_m and at temperature T_n is indicative of the presence or absence of said chemical analyte in said fluid.