Chemical Warfare Agent Detection Using MEMS Microsensor Arrays
Douglas C. Meier, C J. Taylor, Richard E. Cavicchi, Edward White V, M W. Ellzy, K B. Sumpter, Stephen Semancik
Chemical sensors capable of accurate detection of trace quantities of chemical warfare (CW) agents would provide a potent tool for perimeter security, treaty verification, battlefield threat detection, and the protection of civilians in public places. Ideally, such sensors would be highly sensitive, selective, compact, and require low power. Since many CW agents are lethal at micromoles/mole (ppm) concentrations, reliable trace detection is the critical prerequisite to the employment of life-saving countermeasures. In an attempt to meet these goals, we have fabricated microsensors consisting of TiO2 and SnO2 sensing films prepared by chemical vapor deposition (CVD) on MEMS (micro-electromechanical systems) array platforms. Response measurements from these devices to the CW agents GA (tabun), GB (sarin), and HD (sulfur mustard) in dry air at concentrations between 5 and 200 nanomoles/mole (ppb), as well as to CW agent simulants CEES (chloroethyl ethyl sulfide) and DFP (diisopropyl fluorophosphate) between 250 and 3000 ppb, are reported. The microsensors yield both excellent signal-to-noise and good reproducibility for similar devices. The temperature of each sensor element is independently controlled by embedded microheaters that drive both the CVD process (375 C) and sensor operation at elevated temperatures (325 C to 475 C). The concentration-dependent analyte response magnitude is sensitive to conditions under which the sensing films are grown. Sensor stability studies carried out for 14 hours in GB exhibit 20% signal variation; similar studies in HD show little signal change. Use of pulsed (200 ms) temperature programmed sensing (TPS) over a broad temperature range (20 C to 480 C) enhances analyte selectivity, since the resulting signal trace patterns contain primarily kinetic information that is unique for each agent tested.
, Taylor, C.
, Cavicchi, R.
, White, E.
, Ellzy, M.
, Sumpter, K.
and Semancik, S.
Chemical Warfare Agent Detection Using MEMS Microsensor Arrays, IEEE Sensors Journal, [online], https://doi.org/10.1109/Jsen.2005.848139
(Accessed December 9, 2023)