Orthogonal Sensors for Trace Detection

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Project Description

A small footprint, thermodynamic gas sensor capable of detecting trace levels of explosives in the vapor phase is being developed at the University of Rhode Island. A number of analytes of great interest to the Department of Homeland Security, including TATP, DADP, 2,6-DNT and ammonium nitrate, have been successfully detected at the ppm level or lower using our sensor platform. The thermodynamic sensor can reliably detect both nitrogen and non-nitrogen based explosives at trace levels and is ideally suited for continuously monitoring a confined vapor space for threat molecules, especially those explosive compounds that exhibit a finite vapor pressure. Our thermodynamic sensor measures the heat effect associated with the interaction of specific target molecules with a metal oxide catalyst. The heat effect is measured using a digital control system and a microheater coated with a catalyst, which is thermally scanned over a selected temperature range and the electrical power difference due to catalytic activity is measured. The explosive molecule of interest is decomposed in the presence of a responsive metal oxide catalyst at a specific temperature, to yield the desired sensitivity and selectivity. In addition to the thermodynamic sensor platform, a conductometric platform has been integrated into the same sensor package to monitor electrical conductivity changes in the same metal oxide catalyst when exposed to the analyte. The additional sensor signatures can provide a certain redundancy and help mitigate false positives and negatives. Current efforts are focused on a MEMS based sensor platform that has the potential to screen a wide range of threat molecules using arrays of catalyst-coated microheaters on a single substrate measuring a few mm by a few mm. This, combined with advanced thermal isolation techniques made possible with the MEMS platform, will enable the implementation of a hand held detection device with superior reliability, sensitivity and response.

Project Leader
  • Otto J. Gregory
    URI Center for Sensor and Instrumentation Research

Faculty and Staff Currently Involved in Project
  • Alan Davis
    Industry Researcher
    Naval Undersea Welfare Center

Students Currently Involved in Project
  • Yun Chu
  • Daniel Mallin
  • Mitch Champlin
  • Elizabeth Shokunbi
  • Jimmy Chan
  • Ben Jacques