Pushing the limit of the silicon technology by using porous silicon: a CMOS gas sensing chip

Air monitoring is a challenging objective both for city safeguard and human health. However, in order to get information on the real population exposure with the necessary spatial and temporal resolution a high density monitoring network would be needed. To this aim, small, reliable, low cost, integrated silicon-based sensors would be required. Among the different materials proposed in literature for gas sensor integration, porous silicon (PS) is one of the most promising because of its intrinsic compatibility with the silicon technology. In this work, the design and fabrication of a gas sensing chip, containing an array of PS gas sensors integrated along with several electronic basic blocks, by using an industrial CMOS process is reported, along with its electrical characterization. Finally, to demonstrate the functionality of the sensing chip, a simple readout electronic interface connected to one of the sensors is used to implement an integrated current-voltage converter.