Effect of gold nanoparticles on resistive type nickel oxide based MEMS gas sensor properties

The technology to produce hydrogen sulphide sensor with a sensitive layer based on nickel oxide on a silicon chip is presented. Response of the sensor to H2S in concentrations from 1 to 70 ppm at 190 °C operating temperature is investigated. Modification of NiO film with gold nanoparticles (GNPs) significantly improves sensitivity level. The sensing layer made of NiO embedded with GNPs shows five times higher response and improved response time compared to pure nickel oxide one. The response time under 70 ppm H2S in Ar exposure is ∼5 s and the recovery time is ∼28 min. The enhanced sensitivity of NiO embedded with GNPs is attributed to (i) the increased crystallinity of NiO grown over the gold nanoparticles and (ii) the spillover effect of GNPs in NiO. MEMS technology used to produce the sensor chip with thin active layers makes it possible to drastically reduce the energy consumption of the sensor.