Integration of MEMS with Nanostructured Metal-oxide Materials for Improved Sensors for Volatile Organic Compounds

The primary aim of the present work is to lower the operating temperature of the metal-oxide based sensors for detection of volatile organic compounds (VOCs) without compromising the sensitivity of the device. For this purpose, nanostructured oxides of ITO, Cu and Zn have been explored. The oxides of Cu and Zn have been synthesized by a novel process of thermal oxidation of the respective metal layers in air ambient without using any seed or catalyst layer. On the other hand, nanostructured ITO was obtained by RF magnetron sputtering process. For the heating of the sensing layer, a Ni microheater has been integrated on the sensor chip. Micro-electro-mechanical Systems (MEMS) technology has been adopted for the fabrication of the complete sensor for achieving the desired operating temperature at reduced power level. The sensor was extensively tested for a variety of VOCs such as acetone, methanol, ethanol and IPA. The issues involved in integrating nanostructured oxides with MEMS technology are also addressed.