A Low-Cost Liquid-Based Capacitive Sensor for PM2.5 Monitoring

PM2.5 is one of the main sources of air pollution and could negatively affect the human health. The available commercial PM monitoring devices are often bulky and expensive and thus not useful for personal use. Toward the implementation of personal/wearable PM monitoring devices, this paper presents a low-cost, liquid-based capacitive monitoring device that uses in-house fabricated electrodes and a custom PCB with off-the-shelf components. The fabricated device is designed to detect concentration of particles in a liquid environment which enables integration of the capacitive detection with future electrochemical-based analysis of PM elemental composition. In this liquid-based detection scheme, a minimum detection level of 4.6 x 10(6) particles/mu L is achieved which corresponds to the particles sampled from an unhealthy level of PM2.5 in the air. The detection response shows a linearity of R-2 =0.9934 during the experiments.