Examining the effects of polymer binder in Fe2O3/ZnO thick film sensors on the response to propanol vapour

Investigations have been carried out on the role of the binder in screen printed Fe₂O₃/ZnO thick film sensors for gas and vapour analysis. These sensors were prepared by mixing a polymer binder and carbon black with a 50:50 Fe₂O₃/ZnO mixture which has been previously fired at 1250degC. The advantages of these sensors include room temperature operation, straight forward circuitry and low power consumption. Previous work in the literature has concentrated on varying the composition of the oxides in the sensing layer to improve their sensitivity to vapours. The aim of this study is to evaluate the contribution of the polymer binder to the sensor response and selectivity. The polymer binders investigated were Ethyl Cellulose (EC) and polyvinyl butyral (PVB). Sensors were prepared using each binder and exposed to propanol at concentrations ranging from 500-14000 ppm in an automated dynamic flow system. Drop coated PVB and EC sensors containing carbon black (CB) were also fabricated in order to compare their responses with the thick film oxide sensors. Correlations were found between both sensor types suggesting that the polymer binder plays a significant role in the response mechanism of room temperature oxide sensors.