Low-Cost and Point-of-Use Sensing Device Based on 2D Diffusion-Controlled Colorimetric Sensing Array for Continuous and Multiplexed Air Pollution Monitoring

The development of a low-cost and point-of-use sensing device capable of continuously and simultaneously detecting various air pollutants is essential for enhancing air pollution monitoring in communities and workplaces. This technology would enable real-time monitoring, facilitating prompt interventions to mitigate the impact of air pollution on human health and the environment. Colorimetric gas sensors are often used to detect different air pollutants owing to their high selectivity and sensitivity, low cost, and compact size. Nevertheless, continuous and multiplexed detection of gas with a colorimetric sensor often requires lifetime-extension methods and an expensive, space-demanding, and power-hungry optical imaging system as the signal transducer. To address these challenges, we introduce a fully integrated portable gas sensing device that uses cheap, miniaturized, and power-efficient electronic and sensing components. This device enables continuous and multiplexed monitoring of air pollutants through a two-dimensional (2D) diffusion-controlled colorimetric sensor array. By selecting sensing probes with specific colorimetric chemical reactions for different gas analytes, the 2D sensor array ensures specificity across a range of analytes. The test results demonstrate that our 2D diffusion-based colorimetric sensing device can be used for sensitive, selective, and multiplexed monitoring of different air pollutants (ammonia, carbon monoxide, carbon dioxide, and nitrogen dioxide) in a continuous manner. This device has proven effective in monitoring pollutants released from car exhaust. Our innovative chemical sensing approach has facilitated the creation of a compact, cost-effective, and easily deployable sensing device. This device offers continuous and multiplexed sensing capabilities, making it ideal for air pollution monitoring in communities and workplaces to provide evidence-based environmental data for effective air pollution management strategies.