Design, simulation and fabrication of doped TiO2-coated surface acoustic wave oxygen sensor

This paper reports on the design, simulation and fabrication of Surface Acoustic Wave (SAW) devices using lithium niobate (LiNbO3) as a substrate. Sol-gel prepared doped TiO2 thin films have been deposited onto the SAW devices by spin-coating. Modelling and simulation has been performed to predict the performance of a SAW oxygen sensor using a high frequency electronics computer software package (HP-EEsof(TM)). Experimental work has been carried out for the purpose of evaluating the accuracy of the simulated results. Resistivity of doped TiO2 thin films has been found to decrease 47 fold when the oxygen concentration is decreased from 1% to 1 ppm at a working temperature of 200 degrees C. The SAW oxygen sensor registered a 180 kHz frequency shift for the same changes in oxygen concentration. Our preliminary experiments highlighted that the doped TiO2-coated SAW sensors can detect oxygen in the concentration range of 1 ppm-1%.