Enhancement of H2-sensing Properties of F-doped SnO2 Sensor by Surface Modification with SiO2

Effects of surface chemical modification with sodium silicate on the gas-sensing properties of F-doped SnO2 gas sensor designed and fabricated employing micro-electro mechanical system (MEMS) technology were investigated. Gas sensing properties of the sensor were checked against combustible gases like H2, CO, CH4 and C3H8 at a heater voltage of 0.7 V. The H2 sensitivity of the surface modified F-doped SnO2 micro sensor markedly increased and reached S = 175 which was found to be about 40 times more than that of unmodified sensor (S = ~ 4.2). The increase in the sensitivity is discussed in terms of increased resistivity and reduced permeation of gaseous oxygen into the underlying sensing layer due to the surface modification of the sensor. The present micro-hydrogen sensor with enhanced sensitivity due to SiO2 incorporation is a low energy consuming portable sensor module that can be mass-produced using MEMS technology at low cost.