Sensor array for toxic gas detection

• US 4,670,405 A
• Filed: 03/02/1984
• Issued: 06/02/1987
• Est. Priority Date: 03/02/1984
• Status: Expired due to Fees

• Current Assignee: ARCH Development Corporation (University of Chicago)
• Original Assignee: United States Department of Energy (Government of the United States of America)
• Inventors: Stetter, Joseph R., Zaromb, Solomon, Penrose, William R.
• Primary Examiner(s): Richman, Barry S.
• Assistant Examiner(s): Gzybowski, Michael S.
• Application Number:
  US06/585,699
• Time in Patent Office: 1,187 Days
• Field of Search: 73/23, 204/411, 204/412, 338/34, 340/634, 422/83, 422/93, 422/94, 422/95, 422/98, 436/151, 436/152
• US Class Current: 436/151
• CPC Class Codes: G01N 2030/8881 Modular construction, specially adapted therefor
• CPC Class Codes: G01N 30/78 using more than one detector
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array

Abstract

A portable instrument for use in the field in detecting and identifying a hazardous component in air or other gas including an array of small sensors which upon exposure to the gas from a pattern of electrical responses, a source of standard response patterns characteristic of various components, and microprocessor means for comparing the sensor-formed response pattern with one or more standard patterns to thereby identify the component on a display. The number of responses may be increased beyond the number of sensors by changing the operating voltage, temperature or other condition associated with one or more sensors to provide a plurality of responses from each of one or more of the sensors. In one embodiment, the instrument is capable of identifying anyone of over 50-100 hazardous components.

Claims

1. A method for identifying at least one component in a gas sample, comprising the steps of:

introducing a gas sample suspected of containing at least one component to an array of sensors for exposure of said component or a derivative thereof to said sensors,

said array including plural sensors having differing electrical responses to said at least one component of said derivative thereof dependent on the chemical interaction of said at least one component or said derivative thereof with each of said sensors and also dependent on an operational condition of at least one of said plurality of sensors;

changing said operational condition during the exposure of said sensors to the gas sample to provide a plurality of different responses from said at least one sensor,

forming a response pattern from the responses of said sensors, and

comparing the formed response pattern with a set of previously established response patterns to identify said at least one component.

2. The method of claim 1 wherein the step of forming the response pattern includes the step of converting a first response pattern to a second response pattern.

3. The method of claim 1 wherein the step of comparing includes comparing the formed response pattern with a plurality of previously established response patterns, and further includes the step of first eliminating at least one of said plurality of previously established response patterns by comparing an insignificant response of said at least one sensor for one condition with said at least one previously established response pattern having a significant response for said at least one sensor for the same operational condition.

4. The method of claim 1, wherein the changing of the operational condition is carried out to provide a plurality of responses greater in number than the number of said sensors and not smaller than the number of components to be identified in said gas.

5. The method of claim 1 wherein the step of forming said response pattern results in at least one response pattern identifiable with a concentration of said at least one component and said step of comparing response patterns provides a comparison of said at least one response pattern with a previously established response pattern for determining said concentration.

6. The method of claim 1 including the step of providing a portable device including said array of sensors and wherein the formation and comparison of the response pattern are carried out with the device in the field.

7. The method of claim 1, wherein the total number of components that can be detected is greater than the product of the number of sensors times the number of different operational conditions.

8. An instrument for indeifying at least one hazardous component in a gas sample, comprising

sensing means including an array of sensors,

means for introducing to said sensing means a gas sample suspected of containing at least one hazardous component,

said array including plural sensors having differing electrical responses to said at least one component or a derivative thereof dependent on the chemical interaction of asid at least one component or a derivative thereof with each of said sensors and also dependent on an operational condition of at least one of said plurality of sensors,

means for changing said operational condition during the exposure of said sensors to the gas sample to provide a plurality of different responses from said at least one sensor,

means for forming a response pattern from said sensing means upon exposure to said sample,

means for providing a plurality of previously established response patterns including a previously established response pattern for identifying said at least one component, and

means for comparing the formed response pattern with at least one previously established response pattern to identify said at least one component.

9. The instrument of claim 8 wherein said array includes a heating filament in addition to said sensors, said heating filament being capable of forming a derivative of said at least one component.

10. The instrument of claim 8 wherein said array includes four sensors, each of said four sensors having electrical responses differing from those of the others of said four sensors.

11. The instrument of claim 8 having means for providing electrical power of up to about 2 watts.

12. The instrument of claim 8 wherein said sensing means includes two different heating filaments and four different electrochemical sensors.

13. The instrument of claim 8 wherein said forming means includes means for converting a first response pattern to a second response pattern prior to the comparison of patterns.

14. The instrument of claim 8 wherein said comparing means incudes means for comparing an insignificant response of said at least one sensor for one operational condition with a previously established response pattern having a significant response for said at least one sensor for the same operational condition.

15. The instrument of claim 8 wherein said changing means comprises means for diverting said sample past a chemically selective filter.

16. The instrument of claim 8 including programming means for selectively identifying an unknown component or monitoring the concentration of a known component of the gas.

17. The instrument of claim 16 wherein said programming means includes means for mathematically modifying the responses for sensor calibration and background noise.

18. The instrument of claim 8 including a carrying case including electrical power means, said array of sensors, said means for forming said response pattern, memory means for storing said previously established response patterns, and said comparison means.

19. The instrument of claim 18, wherein said power means includes at least one electrical battery.

20. The instrument of claim 8 wherein said changing means enables said at least one sensor to provide more than one response.

21. The instrument of claim 20 wherein said sensors include at least one semiconductor sensor.

22. The instrument of claim 20 wherein said changing means comprises at least one heating filament disposed upstream from said array of sensors.

23. The instrument of claim 22 wherein said array is arranged with the sensors having the higher responses downstream from the other sensors.

24. The instrument of claim 20 wherein said changing means enables each of a plurality of said sensors to provide more than one response with the number responses for said array of sensors being greater than the number of said sensors.

25. The instrument of claim 24 wherein said array of sensors is arranged in a space less than about 8 cm by 15 cm by 8 cm.

26. The instrument of claim 24 wherein said sensors include a plurality of electrochemical sensors.

27. An instrument for identifying and estimating the concentrations of a plurality of components in a gas sample, comprising:

sensing means including an array of differently selective sensors,

means for introducing to said sensing means a gas sample suspected of containing one or more components of a predetermined number of components that are detectable by said array, the number of said sensors being greater than one and fewer than said predetermined number of components,

means for forming a multi-channel response pattern from said sensing means upon exposure to said sample,

means fo comparing said formed pattern with a set of previously established patterns,

said comparing means including means for eliminating those of said previously established response patterns which call for significant signals in those channels in which said formed pattern has no significant signal,

and means for processing the remaining ones of said previously established response patterns so as to identify and estimate the concentration of each of said one or more components in said sample.

28. The instrument of claim 27, and further including means for changing an operational condition of said array to provide a plurality of different responses from each of said sensors, said predetermined number of components being greater than the product of the number of sensors times the number of different operational conditions.