MEMS H₂S Gas Sensor Using Ni–WO₃/TiO₂ Composite Material: Investigation of Rapid Response Characteristics

This article introduces a new micro-electromechanical systems (MEMS)-based hydrogen sulfide (H2S) gas sensor. Using a combination of sol-gel and high-temperature solid-state approaches, a sheet-structured Ni-WO3/TiO2 composite was developed. Its features, inclu- ding crystallography, elemental makeup, and surface morphology, were investigated with tools such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and SEM. XRD and XPS analyses indicate successful synthesis of Ni-WO3/TiO2 material, and SEM results reveal that the surface of the sensitive material has dense pores and is uniformly coated on the MEMS device. This material is applied to a MEMS microhotplate, showing high sensitivity and selectivity. The tests demonstrated that the sensor achieves a sensitivity rate of 0.00872 mA/ppm, characterized by strong linearity (0.91301) and swift operation, with response and recovery durations of 7 and 8 s, respectively. This gas sensor possesses high sensitivity, strong selectivity, good linear response, excellent stability, and repeatability, with a broad application potential, supporting the development of future low-cost, efficient H2S monitoring technologies.