CMOS-Compatible Hot-Wire CO2 Sensors (SNIFFER)

Themes: Smart Ultrasound

In the project, we have developed carbon dioxide (CO2) sensors that measure the CO2-dependent thermal conductivity of ambient air using a hot-wire transducer and an associated integrated readout circuit. A single resistive transducer, realized in the VIA layer of a standard CMOS process, is used both as a heater and as a temperature sensor, thus greatly simplifying the fabrication process compared to prior MEMS-based thermal CO2 sensors. We have developed various energy-efficient readout circuits to extract the small CO2-dependent signal, including a readout circuit employing a high-resolution dual-mode delta-sigma ADC, and a readout circuit based on a novel phase-domain delta-sigma ADC.