Self-Resonant Flow Sensor using Resonance Frequency Shift by Flow-Induced Vibration

A self-resonant flow sensor using resonance frequency shift by the flow-induced vibration is presented. All of MEMS-based flow sensors have measured thermal flux, mechanical strain, capacitance, and so on. In this paper, we used self-resonant vibration induced by a fluid flow and resonant frequency shift by a surface stress on the cantilever beam due to fluid drag force in order to measure mass flow. Vibration induced by air flow was measured by the piezoelectric material of PZT on the silicon cantilever beam. Theoretical resonant frequency of the cantilever beam (610 mum times 300 mum times 3.3 mum) was 12,416 Hz. For the air flow velocities of 2.8 m/sec and 9.7 m/sec, shifted resonant frequencies were 12,810 Hz and 15,602 Hz, respectively. Sensitivity of the present self-resonant flow sensor was approximately 384 Hz/(m/sec).