Steve Semancik, NIST "The Use of Micro Machined Array Platforms for Tuning Oxide-Based Gas Sensing Materials"

This presentation will describe research efforts at NIST aimed at developing a new generation of low power, tunable gas microsensors. The work is based on "microhotplate" platforms (single elements and arrays) which are produced by surface-micromachining silicon. Each ~ 100 µm x 100 µm microhotplate element is individually-addressable, and includes functionality for localized heating (20 °C to 800 °C), temperature measurement, and electrical characterization of films deposited on it. Self-lithographic methods used to incorporate conductometric sensing films (semiconducting oxides such as SnO2 and ZnO, low coverage catalytic metals, and polymers, which undergo gas-induced changes in electrical conductivity) onto the tiny sensing devices will be discussed, as will the use of rapid (~ 10 ms) temperature programming to amplify the information content of response signals. The presentation will also emphasize how arrays of microhotplates, being developed for analyzing gas mixtures, are employed as microtools in high efficiency processing/property/performance studies of sensing materials. Sensing data will be correlated to film composition, the presence of surface-dispersed catalytic additives, film microstructure, and temperature.

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