A high sensitive dust particle detector using MEMS based silicon cantilever

Abstract

The silicon based high sensitive cantilever sensors have been fabricated by standard micro electro mechanical system (MEMS) for monitoring the amount and size of dust particles in atmosphere. Dust particles are attached at the electrode surface formed on the cantilever due to electrostatic force. The cantilever is excited by a piezo that is mounted under the cantilever. The cantilever resonance frequency change and the deflection due to the dust particles attached on the cantilever are detected by optical fiber interferometer developed for atomic force microscopy. A phase-locked loop detects the resonance frequency change of the cantilever due to dust particles and minimizes the phase shift contribution to the cantilever deflection measurement. We investigated the density and the size distribution of dust particles in the air and compared these results to those measured by conventional methods, commonly the β-ray absorption method or the mass-concentration measurement, which cannot detect the number or mass of particles except the mass-concentration per unit area.