1-4244-0551-3/06/$20.00 ©2006 IEEE 489 ISSE 2006 St. Marienthal, Germnay Examining the effects of polymer binder in Fe 2 O 3 /ZnO thick film sensors on the response to propanol vapour K.I Arshak 1) , M. Nicholson 2) , A. Arshak 2) , E. G. Moore 1) , I. Gaidan 1) , C. Cunniffe 1) 1) Electronic and Computer Engineering Department, University of Limerick, Ireland 2) Physics Department, University of Limerick, Ireland Khalil.Arshak@ul.ie Abstract: Investigations have been carried out on the role of the binder in screen printed Fe 2 O 3 /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 Fe 2 O 3 /ZnO mixture which has been previously fired at 1250°C. 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. 1. INTRODUCTION As concern for environmental safety rises, so too does the need for fast, accurate low powered gas sensors. Interest has grown in the use of metal oxide gas and vapour sensing devices for applications such as air quality control, remote sensing of toxic environmental pollutants and industrial environmental control [1-3]. The sensitivity, selectivity and stability of these materials make them ideal candidates for gas sensing applications. Previous work has explored the use of oxide materials such as ZnO, TiO 2 , WO 3 , Fe 2 O 3 and In 2 O 3 in gas sensing devices. Multi-component oxides like NiFe 2 O 4 , SrFe 2 O 3 and ZnFe 2 O 4 have also been successfully used in gas sensing applications [4, 5]. These studies have concentrated on using the chemical make up of the oxide material, its structural defects and grain size to describe the degree of sensitivity of the material to a particular gas. However an inherent disadvantage to metal oxide sensors is their operation at elevated temperatures which requires the printing of a heating element on the back on the sensor. This contributes to an increase in power consumption, fabrication costs as well as complexity in sensor design [6]. However recent studies have shown that mixing the oxides with a polymer binder allows for room temperature operation [4]. Various approaches have been used to produce oxide gas sensors including thin film techniques, thermal deposition, sputtering and solgels and thick film techniques, screen-printing and drop coating. This study focuses on the use of screen-printing to produce the oxide sensors. Screen printing is a thick film technology that uses a squeegee to force a paste through the apertures of a stencil screen to form a pattern on the substrate. Paste preparation involves the mixing of oxide particles with a polymer binder and suitable solvent. Generally the role of the polymer binder in the response mechanism of the sensor is ignored and the sensitivity is explained with reference to the oxide interaction with the vapour. This study investigates the role of the polymer binder in the sensor response mechanism and determines whether it can be used as a means to alter the sensitivity and selectivity of the sensor.