Ultra Responsive NO2 silicon nanowires gas sensor

Nitrogen dioxide (NO2) is a hazardous gas emitted primarily from burning fossil fuels. When inhaled, it can have severe health implications, particularly for individuals with respiratory conditions such as asthma. It contributes to ground-level ozone formation, which can cause reduced lung function and increased susceptibility to respiratory infections. When in contact with water moisture in the air, NO2 is easily oxidized into nitric acid (HNO3), causing acid rain. Detection of NO2 levels is therefore important for monitoring air quality and protecting public health. Among the possible technical solutions for gas sensing, silicon nanowires (SiNWs) have proven to be a promising candidate, partly due to their high sensitivity, low manufacturing cost, and ability to perform in various air qualities. This paper presents using SiNWs, fabricated by metal-assisted chemical etching, as a fast, accurate, sensitive, robust, and cost-effective NO2 gas sensor. Our SiNWs gas sensor can experimentally detect 20 parts per billion (ppb) of NO2 under a wide range of relative humidity. Our sensor shows ultra-high sensitivity with fast response and recovery time. [Display omitted] •Our silicon nanowires gas sensor can operate with high cross-sensitivity of NO2 gas and in a wide range of humidity concentrations (20%–80% r.h.).•This allows our sensors to be applicable in many real-life situations, without any negative effects on the sensing mechanism.•Our gas sensor has high reproducibility and sensitivity allowing for NO2 gas to be detected in concentrations as low as 20 ppb experimentally.