Method of resolving analytes in a fluid

• US 6,571,603 B1
• Filed: 05/26/1999
• Issued: 06/03/2003
• Est. Priority Date: 05/27/1998
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Severin, Erik J., Lewis, Nathan S., Doleman, Brett J.
• Primary Examiner(s): Larkin, Daniel S.
• Assistant Examiner(s): Politzer, Jay L
• Application Number:
  US09/318,900
• Time in Patent Office: 1,469 Days
• Field of Search: 73/233.4, 364/497, 359/561, 382/225, 205/787, 702/19, 706/25
• US Class Current: 73/23.34
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array
• CPC Class Codes: G01N 33/0034 comprising neural networks or related mathematical techniques
• CPC Class Codes: G06F 18/2132 based on discrimination criteria, e.g. discriminant analysis

Abstract

A statistical metric, based on the magnitude and standard deviations along linear projections of clustered array response data, is utilized to facilitate an evaluation of the performance of detector arrays in various vapor classification tasks. This approach allows quantification of the ability of arrays of different types including carbon black-insulating polymer composite chemiresistor sensors, tin oxide sensors and bulk conducting organic polymer sensors to distinguish between analytes. The evaluation of questions such as the optimal number of detectors required for a specific task, whether improved performance is obtained by increasing the number of detectors in a detector array, and how to assess statistically the diversity of a collection of detectors in order to understand more fully which properties are underrepresented in a particular set of array elements, are addressed.

Claims

1. A method of resolving different odors, said method comprising

exposing an array of odor sensors to a plurality of odors, each odor sensor having an electrical response to at least one of said odors;

determining the maximum relative electrical response for each odor and sensor, the maximum relative electrical response comprising the maximum electrical response to an odor beyond the background electrical response;

determining the average maximum relative electrical response for the maximum relative electrical responses determined for each odor;

determining the standard deviation for the average maximum relative electrical response for the maximum relative electrical responses determined for each odor; and

computing the optimum resolution factor by the Fisher linear discriminant for each pair of odors.

2. The method of claim 1 wherein the optimum resolution factor-equals $\frac{d_{\stackrel{\_}{w}}}{\sqrt{{\sigma }_{}^{}}}$

a,w_2+σ

b,w_2

where w and {overscore (w)} are identical and w is a projection vector in a d-dimensional space, d corresponding to the number of odor sensors in the array, σ

_a,w is the standard deviation for the average maximum relative response for odor a along vector w, σ

_b,w is the standard deviation for the average maximum relative response for the odor b along vector w, and d_w is the distance between the average maximum responses for odors a and b along vector w.

3. The method of claim 1 wherein said array of odor sensors includes at least four sensors.

4. The method of claim 1 wherein said array of odor sensors includes at least eight sensors.

5. The method of claim 1 further comprising disposing said sensors on a single substrate.

6. The method of claim 5 wherein said substrate comprises semiconductor material.

7. The method of claim 5 wherein said sensors comprise carbon black-polymer composite sensors.

8. The method of claim 5 wherein said sensors comprise tin oxide sensors.

9. The method of claim 5 wherein said sensors comprise bulk organic conducting polymer sensors.

10. The method of claim 7 wherein said sensors sense odor by a change in resistance responsive to exposure to said odor.

11. The method of claim 1 wherein said exposing of an array comprises disposing a plurality of different types of sensors in an array.

12. The method of claim 11 wherein said disposing step further comprises selecting at least one type of sensor from the group comprising surface acoustic wave devices, tin oxide detectors, conducting organic polymers, dye-impregnated polymer films on fiber optic detectors, polymer-coated micromirrors, quartz crystal microbalances, electrochemical gas detectors, chemically sensitive field-effect transistors, carbon black-polymer composite chemiresistors, micro-electro-mechanical system devices, and micro-opto-electro-mechanical system devices.

13. The method of claim 12 wherein at least one type of sensor comprises carbon black-polymer composite sensors.

14. The method of claim 12 wherein at least one type of sensor comprises tin oxide sensors.

15. The method of claim 14 wherein at least one type of sensor comprises bulk organic conducting polymer sensors.

16. The method of claim 15 wherein a second type of sensor comprises carbon black-polymer composite sensors.