Gas Sensors – From conductance modulation via electrochemistry to potential readout, ceramics vs. Silicon

Abstract:
Variations in the design of gas sensing Microsystems yield a wide variety of device characteristics that can be exploited to fulfil heterogeneous application requirements. Gas sensors based on the conductance modulation of semi conducting metal oxides are characterised by very simple and robust constructions that allow the use even in harsh environments. Limits are in selectivity when several reactive gases are present. This may partly be overcome when electrochemistry is used to separate gases by their different redox enthalpies. The usage of the potential readout of gas sensing materials allows access to a wide variety of sensing materials that distinctly exceeds the limitations encountered within the metal oxide/catalytic systems. Besides the realisation of cheap room temperature sensors that are suitable for wireless networks this allows a chemical engineering approach to develop receptor materials that optimally fit to the target gases to be detected in a given application.