Sensors for detecting analytes in fluids

• US 6,093,308 A
• Filed: 02/26/1999
• Issued: 07/25/2000
• 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:
  US09/258,713
• Time in Patent Office: 515 Days
• Field of Search: 205/787, 205/782.5, 205/775, 204/406, 204/415, 204/418, 422/82.12, 422/82.02, 422/98, 436/150, 73/23.2, 73/23.31, 73/23.34, 73/335.05, 324/691, 324/693, 338/7, 338/13, 338/14
• 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 electrochemical electrode arrays G01N27/27

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 method for detecting an analyte in a fluid, said method comprising:

contacting a sensor array with a fluid comprising said analyte, said sensor array comprising a first and a second sensor electrically connected to an electrical measuring apparatus, wherein said first sensor comprises a region of nonconducting organic material and a region of conducting material compositionally different than said nonconducting organic material; and

an electrical path through said regions of nonconducting organic material and said conducting material, thereby detecting said analyte in said fluid.

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

3. The method according to claim 2, wherein said inorganic conductor is a member selected from the group consisting of Ag, Au, Cu, Pt and AuCu.

4. The method according to claim 3, wherein said inorganic conductor is Au.

5. The method according to claim 1, wherein said first sensor comprises a chemically sensitive resistor.

6. The method according to claim 1, wherein said conductive material is an organic conductor.

7. The method according to claim 6, wherein said organic conductor is a polymer.

8. The method according to claim 6, wherein said organic conductor is carbon black.

9. An array of sensors for detecting an analyte in a fluid, said sensor array comprising a first and a second sensor electrically connected to an electrical measuring apparatus, wherein said first sensor comprises a region of nonconducting organic material and a region of conducting material compositionally different than said nonconducting organic material;

and an electrical path through said regions of nonconducting organic material and said conducting material.

10. The array of sensors according to claim 9, wherein said conductive material is an inorganic conductor.

11. The array of sensors according to claim 10, wherein said inorganic conductor is a member selected from the group consisting of Ag, Au, Cu, Pt and AuCu.

12. The array of sensors according to claim 11, wherein said inorganic conductor is Au.

13. The array of sensors according to claim 9, wherein said first sensor comprises a chemically sensitive resistor.

14. The array of sensors according to claim 9, wherein said conductive material is an organic conductor.

15. The array of sensors according to claim 14, wherein said organic conductor is a polymer.

16. The array of sensors according to claim 14, wherein said organic conductor is carbon black.

17. The array of sensors according to claim 9, further comprising a temperature control apparatus in thermal communication with said electrical measuring apparatus, wherein said first sensor provides an electrical resistance R_m at temperature T_m when contacted with a fluid comprising said analyte, wherein m is an integer greater than 1;

and R_m in at least one resistor is different from R_m in at least one other resistor.

18. The array of sensors according to claim 9, wherein said first sensor provides an electrical resistance and an electrical impedance Z_m at frequency ω

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

_m does not equal 0.