Eco-Friendly Disposable WS Paper Sensor for Sub-ppm NO Detection at Room Temperature.

We developed inexpensive and disposable gas sensors with a low environmental footprint. This approach is based on a biodegradable substrate, paper, and features safe and nontoxic electronic materials. We show that abrasion-induced deposited WS nanoplatelets on paper can be employed as a successful sensing layer to develop high-sensitivity and selective sensors, which operate even at room temperature. Its performance is investigated, at room temperature, against NO exposure, finding that the electrical resistance of the device drops dramatically upon NO adsorption, decreasing by 42% (31% half a year later) for 0.8 ppm concentration, and establishing a detection limit around2 ppb (3 ppb half a year later). The sensor is highly selective towards NO gas with respect to the interferents NH and CO, whose responses were only 1.8% (obtained for 30 ppm) and 1.5% (obtained for 8 ppm), respectively. Interestingly, an improved response of the developed sensor under humid conditions was observed (tested for 25% relative humidity at 23 °C). The high-performance, in conjunction with its small dimensions, low cost, operation at room temperature, and the possibility of using it as a portable system, makes this sensor a promising candidate for continuous monitoring of NO on-site.