PNNL

Abstract

A sensor aray for analyzing hydrogen and ammonia gas mixtures in humid air has been developed, built into a rugged system, and calibrated for laboratory testing. The sensor array is comprised of four chemically sensitive field-effect transistors (CHEMFETs). Chemically sensitive layers for the sensors were developed and tested using a Kelvin probe. A combination of catalytic and noncatalytic thin layers (palladium and polyaniline) was selected for the four-sensor array. The work function responses of the monia, and humid air were measured. Chemometric multivariate methods, linear and nonlinear partial least squares, were used for the calibration of the sensor array using gas mixtures in the concentration range from 0 to 10,000 ppm hydrogen and ammonia showed good sensitivity, selectivity, response time, and stability and is recommended for field development. In contrast, the sensor array for hydrogen, though highly sensitive to hydorgen, demonstrated inadequate stability, requiring further development before deployment is recommended.