CMOS-compatible fabrication of porous silicon gas sensors and their readout electronics on the same chip

In this work, integration on the same chip of porous silicon gas sensors along with their driving/readout electronic circuits by using an industrial microelectronic process is demonstrated. To ensure maximum compatibility, the porous silicon formation is performed after the integrated circuit fabrication flow is completed. The chip contains three CMOS operational amplifiers, a band-gap voltage reference, an integrated temperature sensor and several porous silicon-based NO 2 sensors. The simultaneous functionality of the electronics and the sensor is demonstrated by using various circuit blocks to implement a simple driving/readout electronic interface for the sensor