An experimental study on micro-gas sensors with strip shape tin oxide thin films

Micro-cracks in tin oxide thin film may cause bad stability to the micro-hotplate (MHP) gas sensor, especially at high operation temperature or in moisture ambience. In order to reduce micro-cracks, tin oxide thin films on a 2 × 2 MHP gas sensor array are patterned as narrow strips. It is proved by SEM that micro-cracks induced by thermal stress can be greatly restrained in narrow strip shape films comparing with the traditional rectangle board film. Stability of the MHP sensors with narrow strip films was characterized by testing their resistance in air for 60 h, and their responses respectively to methane and carbon monoxide for 300 h. The results show that the strip shape SnO2 films are really helpful to enhance stability of the MHP gas sensors.