A novel silicon micron amperometric gas sensor

The authors report on a silicon-based amperometric microelectrochemical gas sensor, based on an innovative design. This sensor shows a faster response (<0.5 s) to NO gas than other types of gas sensors, with good repeatability. Because the substrate is made porous only on the working electrode, the bulk of the substrate can be rather thick to support the very thin silicon porous membrane. The thin membrane allows a shorter and therefore quicker diffusion path to the electrode compared to, for example, thicker porous ceramic substrates which have tortuous path pores. Response and recovery times are therefore reduced over back-cell sensors based on porous ceramic sensors. A detection limit of 5 p.p.m. was achieved for the first generation of these sensors.<>