Ultra-low-power chemiresistive microsensor array in a back-end CMOS process towards selective volatile compounds detection and IoT applications

We describe an ultra-low-power volatile compounds microsensor array towards increased selectivity and sensitivity. The chemiresistive transducers are 100 nm-thick interdigitated gold microelectrodes coated with polypyrrole based polymer. Two sensors arrays were implemented with respectively 3 x 3 and 2 x 2 pixels², showing a surface per pixel down to 400 x 200 μm². The fabrication is fully CMOS compatible and the polymer coating is performed at wafer level by electropolymerization, using a differential pulse method from 1.1 to 1.5 V. The polymer film thickness varies from 1.2 to 1.5 μm. Looking at ammonia detection, a sensitivity up to 80 % at 5 ppm in nitrogen is achieved, while consuming below 20 μW continuously. Finally, temperature and humidity effects are analyzed at 25 and 45 °C, from 45 to 95 % RH. Such devices are very promising for remote environmental monitoring applications requiring low-cost low-power sensors associated with dedicated electronics

Sub-ppm detection of H2S with CuO-loaded SnO2 hollow nanospheres deposited on interdigitated electrodes

Hydrogen sulfide is a toxic, highly corrosive and pollutant gas, but also a key-biomarker in disease diagnosis trough breath analysis. Its detection at very low level is therefore relevant and can be achieved with chemiresistors. The present work proposes a solution consisting in a facile synthesis of CuO- loaded SnO2 hollow nanospheres deposited on interdigitated electrodes (IDEs). Synthesis, chemical and electrical character- ization, deposit process of the sensing layer and gas sensing capabilities of the sensing platform are presented. CuO loaded SnO2 sensing platforms achieved a successful sub-ppm detection at an operating temperature of 100 degrees Celsius