Development of a Semi-Nanoparticle Sensor Using an Optical Particle Counter for Application to Online Ambient Monitoring

Nanoparticles pose a significant health risk due to their ability to penetrate deep into the respiratory system. Despite the availability of numerous particle number concentration monitoring tools, there is a scarcity of cost-effective, accurate, and portable nanoparticle monitors, especially those utilizing light scattering. This study introduces a novel, low-cost, high-accuracy, and portable semi-nanoparticle sensor (SNS) designed for integration with Internet of Things networks. The SNS employs optical particle counter (OPC) technology for aerosol detection and hybrid inertial filter (HIF) technology for aerosol classification. We assessed the HIF’s performance, demonstrating a cutoff size of d_p50 ~0.2 µm and a steepness of ~2. The HIF exhibited a total pressure drop of ~5 kPa at a flow rate of 1.2 L min⁻¹. The SNS’s accuracy was validated by comparing its detected number concentration with that obtained by a Scanning Mobility Particle Sizer (SMPS), which provides reference number concentration and size information. The SNS estimates the true number concentration by applying a conversion factor derived from the detection rate, the HIF’s penetration efficiency, and the number concentration measured by SMPS.