A study of CO sensors with oscillatory response

In this paper, oscillatory changes in the conductance of catalyst-doped SnO2 semiconductor materials in the presence of CO gas are investigated. The sensors with various transducing structures of ceramic tubes (Taguchi structure), co-axial Pt coils and substrates with deposited interdigital electrodes are compared. The results show that catalysts in the sensing materials and the sensor's operating temperature play a key role in generating an oscillatory response. A unique oscillatory response is observed when a bare Pt coil is exposed to CO gas. The relationship between the oscillation waveforms, gas concentration, operating conditions and gas flow rates for the Pt coils are preliminarily tested and discussed.