Mathematical Simulation Study of Digital Signal Processing of the ESPART Analyzer for the Nanoparticle Size Range

摘要

ESPART (Electronic Single Particle Relaxation Time) analyzer is an instrument that has been used in many applications to determine both size and charge of micrometer sized particles in an aerosol flow in real time. By applying an electric field onto particles passing through a Laser Doppler Velocimeter (LDV) apparatus and measuring relative motion of the particle in the electric field, particle aerodynamic diameter and charge can be calculated. The current development of the ESPART analyzer is in measuring nanoparticles, which requires measuring signals with a low SNR (Signal-to-Noise Ratio). The purpose of this study is to develop a simulation model and to investigate the effects of the algorithm of digital signal processing, low signal strength, and noise in the signal detection circuits on the measurement resolution of an ESPART analyzer. A general purpose model was developed for an ESPART analyzer in Matlab/Simulink. Simulation was performed to investigate the resolution over nanoparticle size ranges for signals with different signal/noise ratios and different algorithms of digital signal processing. Results were compared for accuracy and percent error of the system.