Piezoelectric Mems for Microparticles Detection

We present a thin film circular diaphragm for the implementation of micro electro-mechanical systems (MEMS) resonant mass sensors for detecting particles (e.g., PM10) in air. A piezoelectric resonating membrane with frequency of about 100kHz is used as high precision microbalance operated in flexural mode. The natural frequency shift is proportional to the extra mass added on its surface and can be related to the particle concentration in the sampled air-volume. The vibrational spectrum is recorded by means of a vibrometer and the mass sensitivity is then evaluated by measuring the frequency shift adding extra mass of calibrated PM5 particles (Silica beads) on the membrane surface. The feasibility study has experimentally showed real-time detection performance to standard silica micro-spheres. The sensor is promising in applications of personal portable air pollution monitoring and analysis.