Sensor arrays for detecting analytes in fluids

• US 5,571,401 A
• Filed: 03/27/1995
• Issued: 11/05/1996
• Est. Priority Date: 03/27/1995
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Lewis, Nathan S., Freund, Michael S.
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/410,809
• Time in Patent Office: 589 Days
• Field of Search: 204/418, 204/415, 204/153.1, 204/406, 204/153.17, 204/153.2, 422/98, 422/69, 422/83, 422/68.1, 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
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode

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 array for detecting an analyte in a fluid comprising at least first and second chemically sensitive resistors electrically connected to an electrical measuring apparatus, each of said chemically sensitive resistors comprising:

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

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

a first electrical resistance when contacted with a first fluid comprising a chemical analyte at a first concentration, and

a second electrical resistance when contacted with a second fluid comprising said chemical analyte at a second different concentration,

wherein the difference between the first electrical resistance and the second electrical resistance of said first chemically sensitive resistor being different from the difference between the first electrical resistance and the second electrical resistance of said the second chemically sensitive resistor under the same conditions.

2. A sensor array according to claim 1, wherein said nonconductive organic polymer of said first chemically sensitive resistor is different from said nonconductive organic polymer of said second chemically sensitive resistor.

3. A sensor array according to claim 1, wherein said conductive material is an inorganic conductor.

4. A system for detecting an analyte in a fluid, said system comprising:

a sensor array comprising at least first and second chemically sensitive resistors, each chemically sensitive resistor comprising a mixture of nonconductive organic polymer and conductive material compositionally different than said nonconductive organic polymer, each resistor providing an electrical path through said mixture of nonconductive organic polymer and said conductive material, a first electrical resistance when contacted with a first fluid comprising a chemical analyte at a first concentration and a second different electrical resistance when contacted with a second fluid comprising said chemical analyte at a second different concentration, wherein the difference between the first electrical resistance and the second electrical resistance of said first chemically sensitive resistor being different from the difference between the first electrical resistance and the second electrical resistance of said second chemically sensitive resistor under the same conditions;

an electrical measuring device electrically connected to said sensor array; and

a computer comprising a resident algorithm;

said electrical measuring device detecting said first and said second electrical resistances in each of said chemically sensitive resistors and said computer assembling said resistances into a sensor array response profile.

5. A system according to claim 4, wherein said nonconductive organic polymer of said first chemically sensitive resistor is different from said nonconductive organic polymer of said second chemically sensitive resistor.

6. A system according to claim 4, wherein said conductive material is an inorganic conductor.

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

resistively sensing the presence of an analyte in a fluid with a sensor array comprising at least first and second chemically sensitive resistors each comprising a mixture of nonconductive organic polymer and a conductive material compositionally different than said nonconductive organic polymer, each resistor providing an electrical path through said mixture of nonconductive organic polymer and said conductive material, a first electrical resistance when contacted with a first fluid comprising a chemical analyte at a first concentration and a second different electrical resistance when contacted with a second fluid comprising said chemical analyte at a second different concentration.

8. A method according to claim 7, wherein said nonconductive organic polymer of said first chemically sensitive resistor is different from said nonconductive organic polymer of said second chemically sensitive resistor.

9. A method according to claim 7, wherein said conductive material is an inorganic conductor.

10. A method according to claim 7, said first and said second resistance each being a resistance over time.