CONDUCTIVE POLYMER-FILMS AS ULTRASENSITIVE CHEMICAL SENSORS FOR HYDRAZINE AND MONOMETHYLHYDRAZINE VAPOR

Thin films of the electrically conductive polymer poly(3-hexylthiophen e) were investigated as ultrasensitive chemical sensors for hydrazine and monomethylhydrazine vapor. The threshold limit value for these hig hly toxic species, which are used extensively as rocket fuels, has rec ently been lowered to 10 ppb for 8-h exposure, necessitating the devel opment of instrumentation with improved sensitivity, The present study describes the fabrication, calibration, and testing of simple, rugged , polymer-based sensors for detection of hydrazines in both ambient an d vacuum environments, For reasonable choices of film thickness, initi al resistance, and integration time, it is demonstrated that concentra tions in the 0.1-100 ppb range can be monitored with an accuracy of +/ -20%. The sensor can be utilized for both dosimetric and real-time det ection, Reproducible fabrication was achieved using standard spin-coat ing techniques, The polymer sensors exhibit good specificity to hydraz ines in the presence of NH3, amines, and ambient H2O and have a shelf- life of several years when stored in cold, dry conditions.