Development of an optical particle counter

Abstract

The environment and public health are at risk due to vehicle emissions, which constitute a significant source of airborne particulate matter. The creation of a small, inexpensive optical particle counter (OPC) that uses Mie scattering theory to measure the size and distribution of particles in vehicle exhaust is presented in this research. A laser-illuminated flow cell is surrounded by eleven photodiodes positioned at particular scattering angles, and an ESP32 microprocessor records analog intensity signals in real time. Numerical interpolation is used to estimate particle sizes by normalizing these signals and comparing them to a precomputed Mie scattering matrix. Aerosolized Brilliant Green dye was used to verify the accuracy of the technique, and the findings closely matched known particle size distributions. The system offers real-time data visualization through its integration with Excel using PLX-DAQ. The OPC, which was constructed for less than LKR 9,000, presents a viable option for monitoring urban air quality, tracking emissions, and supporting sustainable development projects. Future integration with IoT platforms and diagnostic systems for a wider environmental impact is made possible by the modular design.