A normally closed microvalve and a micropump are fabricated on a silicon wafer by micro-machining techniques. The normally closed microvalve has a movable silicon diaphragm and a small piezoactuator to drive it. The controllable gas flow rate is from 0.1 ml/min to 85 ml/min at a gas pressure of 0.75 kgf/cm2. The micropump is a diaphragm-type pump, which consists of two polysilicon one-way valves and a diaphragm driven by a small piezoactuator. The maximum pumping flow rate and pressure are 20 μ/min and 780 mmH2O respectively.
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