Evaluation of an Interdigitated Gate Electrode Field-Effect Transistor for Detecting Organophosphorus Compounds
AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
Pagination or Media Count:
This study used integrated circuit microsensors to detect organophosphorus compounds. Chemically-sensitive thin films, copper phthalocyanine, DFPase, succinyl chloride, succinylcholine chloride, 2- naphtholB, and L-histidine dihydrochloride,were deposited on interdigitated gate electrode IGE structures, with an average thickness of 2000A. Thin film electrical performance characteristics were measured for several parameters, including DC resistance, AC impedance, time-domain, and spectral responses from 10 Hz to 1 MHz. Each microsensor contained nine IGEs each IGE possessed an in situ field-effect transistor amplifier. After purging each sensor with filtered air, it was exposed to one or two of the following gases diisopropyl fluorophosphate DFP, diisopropyl methylphosphonate, and dimethyl methylphosphonate at concentrations spanning 100 ppb to 10 ppm at 90 relative humidity and 23 deg C. Testing was conducted with microsensors heated to 30, 50, and 70 degrees C. All six candidate films, demonstrated various degrees of sensitivity to the challenge gases at 30 degrees C. DFPase was especially sensitive to the challenge gases at 100 ppb. Only copper phthalocyanine and L- histidine dihydrochloride demonstrated sensitivity above 30 degrees C. In particular 2-naphtholB showed complete reversibility and succinyl chloride demonstrated partial reversibility at 30 deg C. Copper phthalocyanine was reversible only at 70 deg C. Succinylcholine chloride demonstrated a unique band-reject filter response to the presence of DFP in any challenge gas sample.
- Organic Chemistry
- Miscellaneous Detection and Detectors