Intelligent electro-optical sensor array and method for analyte detection

• US 6,649,416 B1
• Filed: 02/18/2000
• Issued: 11/18/2003
• Est. Priority Date: 02/18/2000
• Status: Expired due to Fees

• Current Assignee: Trustees of Tufts College
• Original Assignee: Trustees of Tufts College
• Inventors: White, Joel E., Kauer, John S.
• Primary Examiner(s): SNAY, JEFFREY R
• Application Number:
  US09/507,210
• Time in Patent Office: 1,369 Days
• Field of Search: 422/56, 422/82.06, 422/82.07, 422/82.08, 436/164, 436/172
• US Class Current: 436/164
• CPC Class Codes: G01N 2021/7786 Fluorescence
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids

Abstract

The invention relates to a chemical sensor, sensing system and sensing method which provides for a multi-sensor, cross-reactive, sensor array having a rapid response time, dynamic modulation of sampling parameters, and real-time feedback control of sampling and detection conditions. The device and method provide for smart detection and discrimination of analytes in fluids through intelligent sampling, detection, and control algorithms. The invention further provides for a sensor array having discrete sensor elements dispersed on fluid-permeable, high surface area, porous, textured substrates. The innovative device and method exhibit high sensitivity, discrimination and detection capability for target analytes at ppb and sub ppm concentrations.

Claims

1. An optical sensor for detecting target analytes in a fluid, said sensor comprising:

a fluid-permeable, signal enhancing, porous, textured substrate having a high surface area and high surface area to volume ratio, said substrate having a pore size distribution comprising substantially open pores; and

a sensor material dispersed on a plurality of internal and external surfaces within said substrate, said sensor material providing a characteristic optical response when subjected to excitation light energy in the presence of target analytes, said substrate open porosity and fluid permeability providing essentially free, unimpeded access for transport of analyte-containing fluids to said sensor material, said substrate providing enhanced responsivity, selectivity and discrimination of said sensor to said target analytes.

2. The sensor of claim 1 wherein said dye substrate is comprised of a fibrous material.

3. The sensor of claim 2 wherein said fibrous material is selected from the group consisting of papers, tissues, textiles, woven fabrics, felts, fibers, fiber bundles, composites, and laminates of the same.

4. The sensor of claim 1 wherein said dye substrate is comprised of a particulate material.

5. The sensor of claim 4 wherein said particulate is selected from the group consisting of glasses, silicas, aluminas, ceramics, polymers, plastics, metals, composites, sintered powders, and fritted assemblages of the same.

6. The sensor of claim 1 wherein said sensor material comprises a fluorescent dye.

7. The sensor of claim 6 wherein said sensor material further comprises a polymer.

8. The sensor of claim 6 wherein said fluorescent dye is a solvatochromic dye.

9. The sensor of claim 8 wherein said solvatochromic dye is selected from the group consisting of Nile Red, Prodan, 6-propionyl-2-(N,N-dimethylamino) napthalene, Acrylodan, and 6-acryloyl(dimethylamino) napthalene.

10. A cross-reactive sensor array for detecting target analytes in a fluid, said sensor array comprising:

a plurality of fluid-permeable, signal enhancing, porous, textured substrates having a high surface area and high surface area to volume ratio, said substrates having a pore size distribution comprising substantially open pores; and

a plurality of sensor materials, each one of said sensor materials dispersed on a plurality of internal and external surfaces within at least one of said substrates, each of said sensor materials providing a characteristic optical response when subjected to excitation light energy in the presence of target analytes, each combination of one of said substrates with one of said sensor materials forming a discrete sensor array element, each of said substrates providing essentially free, unimpeded access for transport of analyte-containing fluids to each of said dispersed sensor materials, each of said substrates providing enhanced responsivity, selectivity and discrimination of said sensor elements to said target analytes.

11. The sensor array of claim 10 wherein said dye substrates are comprised of a fibrous material.

12. The sensor array of claim 11 wherein said fibrous material is selected from the group consisting of papers, tissues, textiles, woven fabrics, felts, fibers, fiber bundles, composites, and laminates of the same.

13. The sensor array according to claim 11 further comprising an optical detector array comprised of a plurality of individual detectors, each detector being optically coupled to a single sensor element.

14. The sensor array of claim 13 wherein said detector array comprises an array of filtered photodiodes.

15. The sensor array of claim 10 wherein said dye substrates are comprised of a particulate material.

16. The sensor array of claim 15 wherein said particulate is selected from the group consisting of glasses, silicas, aluminas, ceramics, polymers, plastics, metals, composites, sintered powders, and fritted assemblages of the same.

17. The sensor array of claim 10 wherein at least one of said sensor materials comprises a fluorescent dye.

18. The sensor array of claim 17 wherein at least one of said sensor materials further comprises a polymer.

19. The sensor array of claim 17 wherein said fluorescent dye is a solvatochromic dye selected from the group consisting of Nile Red, Prodan, 6-propionyl-2-(N,N-dimethylamino)napthalene, Acrylodan, and 6-acryloyl(dimethylamino) napthalene.

20. The sensor array according to claim 10 further comprising an excitation light source array comprised of a plurality of individual light sources, each light source being optically coupled to a single sensor element.

21. The sensor array of claim 20 wherein said light source array comprises an array of filtered light emitting diodes.

22. A method for detecting target analytes in a fluid comprising the steps of:

contacting said sample with a cross-reactive sensor array comprised of

a plurality of fluid-permeable, signal enhancing, porous, textured substrates having a high surface area and high surface area to volume ratio, said substrates having a pore size distribution comprising substantially open pores; and

a plurality of sensor materials, each one of said sensor materials dispersed on a plurality of internal and external surfaces within at least one of said substrates, each of said sensor materials providing a characteristic optical response when subjected to excitation light energy in the presence of target analytes, each combination of at least one of said substrates with at least one of said sensor materials forming a discrete sensor array element, each of said substrates providing essentially free, unimpeded access for transport of analyte-containing fluids to each of said dispersed sensor materials, each of said substrates providing enhanced responsivity, selectivity and discrimination of said sensor elements to said target analytes; and

detecting the presence or absence of said target analytes from a plurality of characteristic optical response signals produced by a plurality of said sensor elements.

23. The method of claim 22 wherein said contacting further comprises drawing said fluid into a sample chamber and exposing said array to said fluid for no more than five seconds.

24. The method of claim 22 wherein said detecting further comprises:

illuminating said sensors with an array of individual excitation light sources, each light source being optically coupled to a single sensor element; and

measuring an optical response produced by said sensors due to the presence of said analyte with a detector means.

25. The method of claim 24 further comprising identifying said analyte by

employing a pattern-matching algorithm;

and

comparing said optical response of said sensor with said characteristic optical response.

26. The method of claim 24 further comprising identifying said analyte by

providing spatio-temporal response patterns of said optical response;

and

recognizing said patterns through a method selected from the group consisting of a template matching, neural networks, delay line neural networks, or statistical analysis.

27. A method for detecting target analytes in a fluid comprising the steps of:

providing a cross-reactive sensor array comprising,

a plurality of fluid-permeable, signal enhancing, porous, textured substrates having a high surface area and high surface area to volume ratio, said substrates having a pore size distribution comprising substantially open pores; and

a plurality of sensor materials, each one of said sensor materials dispersed on a plurality of internal and external surfaces within at least one of said substrates, each of said sensor materials providing a characteristic optical response when subjected to excitation light energy in the presence of target analytes, each combination of at least one of said substrates with at least one of said sensor materials forming a discrete sensor array element, each of said substrates providing essentially free, unimpeded access for transport of analyte-containing fluids to each of said dispersed sensor materials, each of said substrates providing enhanced responsivity, selectivity and discrimination of said sensor elements to said target analytes;

setting primary sampling parameters for said sensor array;

contacting said fluid with said array;

detecting a first plurality of optical responses produced by interaction of said fluid with said array sensors;

comparing said first plurality of responses to a first stored spatio-temporal response for said primary parameters for said analytes;

setting secondary sampling parameters for said array wherein at least one sampling parameter is changed;

detecting a second plurality of optical responses produced by interaction of said fluid with said sensor elements;

comparing said second plurality of responses to a second stored spatio-temporal response for said secondary parameters for said analytes; and

detecting the presence or absence of said analytes.

28. The method of claim 27 wherein said setting primary sampling parameters comprises:

adjusting an excitation light source to a non-zero minimum intensity;

setting a fluid sampling time to a non-zero minimum time;

adjusting said fluid flow to a non-zero minimum flow rate;

setting a number of sampling time points to a non-zero minimum; and

setting a number of sniff samples to a maximum.

29. The method of claim 27 wherein said setting secondary sampling parameters comprises:

incrementing said number of sniff samples by at least one;

selecting said at least one parameter setting from the group consisting of amplifier gain, fluid sampling time, fluid flow rate, number of sampling time points, sample sniff rate, amplifier high pass filtering, excitation light source intensity, and exhale velocity; and

modifying said at least one parameter setting from an initial setting value.

30. A sensing system for detecting and identifying analytes in a fluid comprising:

a cross-reactive sensor array comprised of

a plurality of fluid-permeable, signal enhancing, porous, textured substrates having a high surface area and high surface area to volume ratio, said substrates having a pore size distribution comprising substantially open pores; and

a plurality of sensor materials, each one of said sensor materials dispersed on a plurality of internal and external surfaces within at least one of said substrates, each of said sensor materials providing a characteristic optical response when subjected to excitation light energy in the presence of target analytes, each combination of at least one of said substrates with at least one of said sensor materials forming a discrete sensor array element, each of said substrates providing essentially free, unimpeded access for transport of analyte-containing fluids to each of said dispersed sensor materials, each of said substrates providing enhanced responsivity, selectivity and discrimination of said sensor elements to said target analytes;

an excitation light source array comprising a plurality of individual light sources, each light source being optically coupled to one sensor element;

an optical detector array comprising a plurality of individual detectors, each detector being optically coupled to one sensor element;

a sample chamber for housing said sensor array, said light source array and said detector array;

a sampling means enclosed in said chamber for drawing said fluid into said chamber for contact with said sensor array for a controlled exposure time;

a controller means in electrical communication with said light sources, said detectors, and said sampling means, said controller means electrically coordinating and switching said sampling means with said light sources and said detectors for sampling said fluid, measuring optical responses of said sensor elements to said fluid, and detecting said analytes; and

an analyte identification algorithm for comparing said measured sensor optical responses to characteristic optical responses of said sensor elements to target analytes and identifying said analytes in said fluid.

31. The sensing system of claim 30 wherein said light source array comprises an array of filtered light emitting diodes and said detector array comprises an array of filtered photodiodes.

32. A smart sensing system for intelligent detecting and identifying analytes in a fluid comprising:

a cross-reactive sensor array comprised of

a plurality of fluid-permeable, signal enhancing, porous, textured substrates having a high surface area and high surface area to volume ratio, said substrates having a pore size distribution comprising substantially open pores; and

a plurality of sensor materials, each one of said sensor materials dispersed on a plurality of internal and external surfaces within at least one of said substrates, each of said sensor materials providing a characteristic optical response when subjected to excitation light energy in the presence of target analytes, each combination of at least one of said substrates with at least one of said sensor materials forming a discrete sensor array element, each of said substrates providing essentially free, unimpeded access for transport of analyte-containing fluids to each of said dispersed sensor materials, each of said substrates providing enhanced responsivity, selectivity and discrimination of said sensor elements to said target analytes;

an excitation light source array comprising a plurality of individual light sources, each light source being optically coupled to one sensor element;

an optical detector array comprising a plurality of individual detectors, each detector being optically coupled to one sensor element;

a sampling chamber for housing said sensor array, said light source array and said detector array;

a sampling means enclosed in said chamber for drawing said fluid into said chamber for contact with said sensor array for a controlled exposure time;

a microcontroller in electrical communication with said sampling means, said light source array and said detector array, said controller means electrically coordinating and switching said sampling means, said light source array and said detector array for sampling said fluid, for measuring responses of said sensor elements to said fluid, for detecting said analytes and for reporting analyte detection results;

an intelligent sampling algorithm for directing said microcontroller, said sampling algorithm selecting sensors, light sources and detectors, said sampling algorithm coordinating said microcontroller electrical communication for said switching, said sampling, said measuring, said detecting and said reporting, said sampling algorithm setting first and second sampling parameters; and

an analyte identification algorithm in communication with said sampling algorithm and said microcontroller, said identification algorithm comparing said measured sensor optical responses to characteristic responses of said sensor elements to target analytes and identifying said analytes in said sample.

33. The sensing system of claim 32 wherein said light source array comprises an array of filtered light emitting diodes and said detector array comprises an array of filtered photodiodes.

34. The sensing system of claim 32 wherein said identification algorithm comprises a response report comparing a spatio-temporal pattern of said measured optical responses to a spatio-temporal pattern of said characteristic responses;

and

an identification report selected from the group consisting of a pattern match, a delay line neural network match, and a neuronal network match.