A slim type microvalve driven by PZT films

A slim type microvalve actuated by PZT films was developed. Three different sizes of microvalves having a thickness of 528 μm were designed. Each one has 120 cantilevers arrayed circularly. In designing them, tip deflections of PZT cantilevers were calculated, and compared with those obtained by FEM simulations. Leakage and flow rate were calculated. Fabrication process and the PZT film deposition process are explained. The microvalve structure with PZT films was fabricated on a SiO2 layer over a supporting silicon on insulator (SOI) wafer. The ferroelectric properties of PZT films were studied with polarization-voltage (P-V) and dielectric constant, dielectric loss-voltage measurement. Tip deflections were measured on the fabricated array, applied with different voltages. Tip displacement of 12 μm (Φ = 10 mm-type) was obtained with the applied voltage of 5 V. When the microvalve was closed, the air leakage was 15 μl/s. The air-flow rate of 122 μl/s (Φ = 10 mm-type) was measured with the pressure difference of 1000 Pa in the opened position at 15 V.