Study on a micro-gas sensor with SnO2-NiO sensitive film for indoor formaldehyde detection

A micro-gas sensor is fabricated based on a micro-hotplate (MHP) with micromachining technology. The SnO2-NiO nanometer polycrystalline composite synthesized by a chemical co-precipitation method is coated onto a micro-hotplate as a sensitive film. The response and recovery time of the micro-gas sensor decrease rapidly with increasing the formaldehyde (HCHO) concentration at relatively low concentrations. The micro-gas sensor shows good stability, low power consumption of 180 mW at the MHP operation temperature of 300 degrees C, and high selectivity in the presence of interference gases such as alcohol, toluene, alpha-pinene and acetone. The micro-gas sensor can detect 0.06 ppm HCHO, which is the indoor exposure limit for HCHO referring to Chinese environmental protection agency (EPA). (C) 2008 Elsevier B.V. All rights reserved.