Microelectromechanical gas sensor of resistive type for detection of hydrogen sulphide low concentrations

This article proposes a technology for manufacturing a microelectromechanical (MEMS) resistive gas sensor for detecting low concentrations of analytes and demonstrates the main technological characteristics of the device. MEMS  contains a silicon substrate with nickel comb electrodes that act as a microheater. The distance between the teeth on the comb is about 300 microns, and the width of the heater tracks is 100 microns. As a sensitive layer, a thin (100nm) gas-sensitive layer of nickel oxide (NiO) is applied on top of the microheaters. The operating temperature of the sensitive layer in measurement mode is 130–205 °C. All applied meters are made on a silicon membrane of  about 50 microns. The proposed work shows the effect of introducing H₂S into a gas mixture from 1 to 100 ppm on the conductivity of a gas sensor. The effective operating temperature of the heating elements was determined, at  which the greatest response to the presence of hydrogen sulfide in the gas mixture is observed.