Autonomous monitoring method and system using sensors of different sensitivities

• US 7,477,994 B2
• Filed: 04/22/2005
• Issued: 01/13/2009
• Est. Priority Date: 04/22/2004
• Status: Active Grant

• Current Assignee: Smiths Detection (Smiths Group International Holdings Ltd.)
• Original Assignee: Smiths Detection (Smiths Group International Holdings Ltd.)
• Inventors: Sunshine, Steven A., Burch, Timothy E.
• Primary Examiner(s): Bui; Bryan
• Application Number:
  US11/111,960
• Publication Number:
  US 20060282225A1
• Time in Patent Office: 1,362 Days
• Field of Search: 702/32, 702/22, 702/23, 702/82, 702/83, 422/58
• US Class Current: 702/32
• CPC Class Codes: G01N 33/0032 using two or more different physical functioning modes
• CPC Class Codes: G01N 33/0075 for multiple spatially distributed sensors, e.g. for environmental monitoring transmission systems for measured values G08C
• CPC Class Codes: G16B 99/00 Subject matter not provided for in other groups of this subclass

Abstract

A method and system of monitoring for chemical or other toxic agents includes operating a plurality of first type sensors having a first level of sensitivity to an agent in a monitored area. Concurrently a second type sensor is operated having a second level of sensitivity to the agent in the monitored area, where the second level of sensitivity is at least ten times more sensitive than the first level of sensitivity. Input from the plurality of first type sensors and the second type sensor is received and analyzed, at a central location, in order to determine the presence of the agent in the monitored area.

Claims

1. A method of monitoring for chemical or other toxic agents, comprising:

operating a plurality of first type sensors having a first level of sensitivity to an agent in a monitored area;

concurrently operating a second type sensor having a second level of sensitivity to the agent in the monitored area, wherein the second level of sensitivity is at least ten times more sensitive than the first level of sensitivity; and

receiving and analyzing, at a central location, input from the plurality of first type sensors and the second type sensor in order to determine the presence of the agent in the monitored area.

2. The method according to claim 1, wherein the second level of sensitivity is at least one hundred times more sensitive than the first level of sensitivity.

3. The method according to claim 1, wherein both the plurality of first type sensors and the second type sensor are operated continuously.

4. The method according to claim 1, wherein both the first type sensors and the second type sensors comprise chemiresistor based sensor arrays

5. The method according to claim 4, wherein the chemiresistor based sensor arrays comprise conductive polymer composite vapor sensors.

6. The method according to claim 4, wherein the chemiresistor sensor arrays comprise orthogonal sensing technologies on a single sensor array.

7. The method according to claim 1, further comprising providing a preconcentrator with the second type sensor.

8. The method according to claim 1, wherein the agents comprise one or more from the group consisting of chemical warfare agents and toxic industrial chemicals.

9. The method according to claim 1, wherein the first level of sensitivity is the IDLH (Immediately Dangerous to Life or Health) level and the second level of sensitivity is the PEL (Permissible Exposure Level) level.

10. The method according to claim 1, further comprising activating an alarm only when data analyzed from both a first type sensor and the second type sensor indicate presence of a particular agent.

11. The method according to claim 1, further comprising activating an alarm only when two separate analytical models applied to data from either a first type sensor or a second type sensor indicate the presence of a particular agent.

12. The method according to claim 11, wherein the analytical model includes assigning different weights to different sensors based on the type or location of the sensor or the density of sensors at a location.

13. The method according to claim 11, wherein activating the alarm is determined based on a model configured such that the results from the two separate analytical models indicate a false alarm percentage of less than 0.01% and the false positive percentage of less than 5% for all agents tested at the IDLH level of concentration.

14. The method according to claim 1, further comprising:

determining an optimum layout and number of first and second type sensors in the monitored area by modeling to meet specified performance standards and minimizing costs.

15. A system for monitoring for chemical or other toxic agents, comprising:

a plurality of first type sensors, having a first level of sensitivity to an agent, arranged in a monitored area;

a second type sensor, having a second level of sensitivity to the agent, arranged in the monitored area, wherein the second type of sensor is configured to operate concurrently with the plurality of first type sensors, wherein the second level of sensitivity is at least ten times more sensitive than the first level of sensitivity, and

a central analysis unit connected to the plurality of first type sensors and the second type sensor, wherein the central analysis unit analyzes data from the plurality of first type sensors and the second type sensor in order to determine the presence of the agent in the monitored area.

16. The system according to claim 15, wherein the first type sensors and the second type sensors comprise chemiresistor based sensor arrays.

17. The system according to claim 16, wherein the chemiresistor based sensor arrays comprise conductive polymer based vapor sensors.

18. The system according to claim 15, wherein the second type sensor further comprises a preconcentrator.

19. The system according to claim 15, wherein the central analysis unit is configured to activate an alarm only when input from both a first type sensor and the second type sensor indicate the presence of a particular agent.

20. The system according to claim 15, wherein the central analysis unit is configured to activate an alarm only when two separate analytical models each indicate the presence of a particular agent when provided with input from either a first type sensor or a second type sensor.