Chemiresistive Sensor Array Based on Semiconducting Metal Oxides for Environmental Monitoring

We present gas sensing performance based on <TEX>$2{\times}2$</TEX> sensor array with four different elements (<TEX>$TiO_2$</TEX>, <TEX>$SnO_2$</TEX>, <TEX>$WO_3$</TEX> and <TEX>$In_2O_3$</TEX> thin films) fabricated by rf sputter. Each thin film was deposited onto the selected <TEX>$SiO_2$</TEX>/Si substrate with Pt interdigitated electrodes (IDEs) of <TEX>$5{\mu}m$</TEX> spacing which were fabricated on a <TEX>$SiO_2$</TEX>/Si substrate using photolithography and dry etching. For 5 ppm <TEX>$NO_2$</TEX> and 50 ppm CO, each thin film sensor has a different response to offers the distinguishable response pattern for different gas molecules. Compared with the conventional micro-fabrication technology, <TEX>$2{\times}2$</TEX> sensor array with such remarkable response pattern will be open a new foundation for monolithic integration of high-performance chemoresistive sensors with simplicity in fabrication, low cost, high reliablity, and multifunctional smart sensors for environmental monitoring.