Development of a new Nano-particle sizer equipped with a 12 channel multi-port differential mobility analyzer and multi-condensation particle counters

Abstract. Measuring particle size distributions precisely is an important concern in addressing environmental and human health-related issues. To measure particle size distribution, a scanning mobility particle sizer (SMPS) is often used. However, it is difficult to analyze particle size distribution under fast-changing concentration conditions because the SMPS cannot respond fast enough to reflect current conditions due to the time necessary for voltage scanning. In this research, we developed a new Nano-particle sizer (NPS), which consists of a multi-port differential mobility analyzer (MP-DMA) with 12 sampling ports and multi-condensation particle counters (M-CPCs) that simultaneously measure concentrations of particles classified by the sampling ports. The M-CPC can completely condense particles larger than 10 nm, and the total particle concentrations measured by each homemade CPC in the M-CPCs and an electrometer were in agreement up to 20,000 # cm−3. For particle classification tests on the MP-DMA, geometric standard deviations of the size distributions of classified particles were estimated in the range of 1.035–1.066. We conducted size distribution measurements under steady-state conditions using an aerosol generator and under unsteady conditions by switching the aerosol supply on/off. The data obtained by the NPS corresponded closely with the SMPS measurement data for the steady-state particle concentration case. In addition, the NPS could successfully capture the changes in particle size distribution under fast-changing particle concentration conditions. For the last, we presented the NPS measurement results of size distributions in common situation (cooking) as an exemplary real-world application.