MEMS gas sensor based on Cr/Cd–In2O3 composite for H2S detection: quick response and fast recovery

Purpose This study aims to develop a microelectromechanical systems (MEMS)-based hydrogen sulfide (H2S) gas sensor using Cr/Cd–In2O3 composite material for highly sensitive and fast-responsive detection of H2S gas. Design/methodology/approach The Cr/Cd–In2O3 composite material was synthesized, and its structural, compositional and morphological characteristics were analyzed using X-ray diffractometer, X-ray photoelectron spectroscopy, scanning electron microscope, high-resolution transmission electron microscopy and Ultraviolet Photoelectron Spectroscopy. The material was coated onto a MEMS micro-hotplate, and sensor performance was evaluated in terms of sensitivity, response and selectivity. Findings The sensor exhibited a sensitivity of 0.00449 mA/ppm (20–100 ppm) and 0.0038 mA/ppm (4–15 ppm) at 93.3 °C, with a strong linear relationship (R2 = 0.99436 for 20–100 ppm H2S; R2 = 0.95106 for 4–15 ppm H2S). Response and recovery times were 3.5 s and 1.3 s, respectively, with excellent selectivity and repeatability, even with interfering gases. Originality/value This study presents a MEMS-based H2S sensor with Cr/Cd–In2O3 composite material, offering high sensitivity and fast response. It holds great potential for applications in environmental monitoring, industrial safety and public health.