Correlation of Chemisorption and Electronic Effects for Metal/Oxide Interfaces: Transducing Principles for Temperature-Programmed Gas Microsensors

Abstract

This Final Report describes efforts and results for a 3-year DoE/OST-EMSP project centered at NIST. The multidisciplinary project investigated scientific and technical concepts critical for developing tunable, MEMS-based, gas and vapor microsensors that could be applied for monitoring the types of multiple analytes (and differing backgrounds) encountered at DoE waste sites. Micromachined ''microhotplate'' arrays were used as platforms for fabricating conductometric sensor prototypes, and as microscale research tools. Efficient microarray techniques were developed for locally depositing and then performance evaluating thin oxide films, in order to correlate gas sensing characteristics with properties including composition, microstructure, thickness and surface modification. This approach produced temperature-dependent databases on the sensitivities of sensing materials to varied analytes (in air) which enable application-specific tuning of microsensor arrays. Mechanistic studies on adsorb ate transient phenomena were conducted to better understand the ways in which rapid temperature programming schedules can be used to produce unique response signatures and increase information density in microsensor signals. Chemometric and neural network analyses were also employed in our studies for recognition and quantification of target analytes.