Micromachined sol–gel carbon nanotube/SnO2 nanocomposite hydrogen sensor

A novel micromachined single wall carbon nanotube (SWCNT) reinforced nanocrystalline tin dioxide gas sensor has been developed. The presence of SWCNT in SnO₂ matrix was realized by a spin-on sol–gel process. The SWCNT/SnO₂ sensor's sensitivity for hydrogen detection has greatly increased by a factor of three, in comparison to that of pure SnO₂ sensor. The novel sensor also lowers the working temperature, response time and recovery time. The greatly improved performances are mainly attributed to the effective gas accessing nano passes through SWCNT plus the smaller distance between adjacent gas accessing boundaries formed by the distribution of tiny SWCNTs. Therefore, both the spatial requirement (D ≤ 2L, D is the distance between adjacent gas accessing boundaries and L is the space charge layer thickness) and surficial requirement (adequate gas activation area) are met and the maximum inherent sensitivity of SnO₂ is achieved.