SBIR-STTR Award

This Phase I Small Business Technology Transfer project aims to develop a novel microsensor for the in-situ, real-time detection of toxic organic chemicals. The proposed microsensor will be capable of operating under field conditions, with sufficient sensitivity to permit high detection rates, and with sufficient selectivity to prevent high false alarm rates. The proposed sensor is based on a combination of gravimetric sensing and the determination of the unique photothermal spectrum of an analyte and utilizes a wavelength dispersive device and a thermal infrared detector array. This sensing technique is capable of detecting the presence of minute amounts of organic analytes with increased sensitivity and selectivity. During the detection process the sample is allowed to interact/adsorb onto the coated surface of femto-joule sensitive thermal detector. The surface of the detector will be coated with an appropriate chemical layer which preferentially adsorbs/reacts with a category of chemicals similar to the target analytes. As molecules adsorb on the thermal detector surface, various physical changes can take place such as changes in the electrical resistance when a microbolometer is used or changes in the bending due to adsorption induced stress when a microcantilever thermal detector is used. This step provides the chemical detection sensitivity comparable to recent chemical detection technologies in addition to providing the required selectivity. In order to determine the specific identity of the adsorbed molecule, a photothermal spectrum is obtained by scanning a broadband wavelength region of the detector array with the aid of a wavelength dispersive device. For the wavelengths at which the adsorbed analyte absorbs photons, the temperature of those particular detector pixels will rise proportional to the amount of analyte deposited and heat absorbed. Since different pixels will be exposed to different wavelengths, an extremely sensitive and unique photothermal signature response can be determined. The chemical detector surface can be regenerated by ohmic heating of the detector element. Miniature toxic organic sensors offer both extremely high sensitivity and are easily miniaturized, and could be readily mass produced using standard IC fabrication technology for use in high volume commercial applications, including industrial process monitoring, air and water pollution control, air quality monitoring, as well as vehicle emission monitoring.

This Small Business Technology Transfer Research (STTR) Phase II project has as the primary focus the development and commercialization of a novel microsensor for the in-situ, real-time detection of toxic organic chemicals. The proposed microsensor will be capable of operating under field conditions, with sufficient sensitivity to permit high detection rates, and with sufficient selectivity to prevent high false alarm rates. Using a revolutionary photo-thermal concept, the detector will operate with both high chemical selectivity and a less than parts per billion sensitivity. The technological concept of the proposed detector (CalSpec) won the 1998 R&D 100 award. The chemical sensitivity can be substantially enhanced to a less than parts per trillion level by simply operating in an integrating chemical detection mode. The objective of this research is to demonstrate highly specific, sensitive and selective detection of organic chemical compounds and to develop a multichemical detector which can detect toxic organics with concentrations varying from a few parts per thousand to a few parts per trillion. Sensitive monitoring and detection is an area of continuing importance to EPA, DOD, DOE and other federal agencies. The CalSpec detector could be used in a variety of applications, including process monitoring and control, environmental compliance (including emissions monitoring), ambient air monitoring, airport security, personal dosimeters for toxic gases or metal vapor, and smoke and fire constituent detection.