Abstract. We present a microelectromechanical system (MEMS)-based condensation particle counter (CPC) for sensitive and precise monitoring of airborne ultrafine particles (UFPs) at a point of interest that is portable, inexpensive, and accurate. The proposed system consists of two main parts: a MEMS-based condensation chip that grows UFPs to micro-sized droplets and a miniature optical particle counter (OPC) that singly counts grown droplets with the light scattering method. A conventional conductive cooling–type CPC is miniaturized through MEMS technology and the 3D printing technique, and the essential elements for growing droplets are integrated on a single glass slide. The proposed system is much more compact (75 mm × 130 mm × 50 mm), lightweight (205 g), and power-efficient (2.7 W) than commercial CPCs. In quantitative experiments, the results indicated that the proposed system can detect UFPs as small as 13.4 nm by growing them to micro-sized (3.16 µm) droplets. The proposed system measured the UFP number concentration with high accuracy (deviation within 4.1 %), and its detectable concentration range of 7.99–7200 N cm−3. Thus, the proposed system can potentially be used for UFP monitoring in both low-concentration (e.g., air filtration system, high-precision industries utilizing cleanrooms) and high-concentration (e.g., indoor/outdoor atmospheres) environments.
Supplementary material to "MEMS-based condensation particle counter for real-time monitoring
of airborne ultrafine particles at a point of interest"
