Low-cost gas sensing: dynamic self-compensation of humidity in CNT based devices

Solid state gas sensors are a cost-effective and well-spread alternative to conventional gas sensing, em-ployable in most environments, ranging from homes and offices to harsh industrial scenarios. The emergence of Car-bon Nanotubes (CNTs) as sensing material in solid state gas sensors, paved the way to a new class of devices, which are semi-transparent, flexible and with a remarkably low environmental impact. These devices, however, lack of selec-tivity to other gases and concurring physical phenomena, such as temperature and pressure changes. In this contribu-tion we show how measuring the impedance of CNT-based gas sensors at different frequencies, it is possible to evaluate sensitivity coefficient for the immediate compensation of moisture content in the air, while still preserving in the considered ranges average sensitivities as high as 0.045, 0.112, 7.842·10-5 and 0.041 %Z/ppm for Ammonia, Carbon Dioxide, Carbon Monoxide and Ethanol gas respectively. With this simple approach, it will be possible to develop sim-ple sensor read-out systems, with reduced external electronic, simplifying the route to low-cost and low-power sensor nodes for the Internet of Things.     «

Solid state gas sensors are a cost-effective and well-spread alternative to conventional gas sensing, em-ployable in most environments, ranging from homes and offices to harsh industrial scenarios. The emergence of Car-bon Nanotubes (CNTs) as sensing material in solid state gas sensors, paved the way to a new class of devices, which are semi-transparent, flexible and with a remarkably low environmental impact. These devices, however, lack of selec-tivity to other gases and concurring physical ph...     »