Ambient Temperature Carbon Nanotube Ammonia Sensor on CMOS Platform

We report here the development of a resistive single wall carbon nanotubes (SWCNTs) sensor, based on a CMOS substrate that responds at ambient temperature to ppm levels of ammonia. The power efficient CMOS micro-hotplate is a thin membrane structure and comprises metal heater with an interdigitated electrode. The SWCNTs film was prepared first by treatment with aqua regia solution, followed by washing with distilled water, and then treated with ascorbic acid at 95 °C. The film was deposited by simply dipping the chip into the solution. The SWCNTs showed good response to ammonia in a humid nitrogen atmosphere.