A phase-change type micropump with aluminum flap valves

In this paper, a phase-change type micropump is presented. This micropump consists of a pair of aluminum flap valves and a phase-change type actuator. The actuator is composed of a heater, a silicone rubber diaphragm and a working fluid chamber. The diaphragm is actuated by the vaporization and the condensation of the working fluid. The micropump is fabricated by the anisotropic etching, the boron diffusion and the metal evaporation. The dimension of the micropump is 8.5 mm × 5 mm × 1.7 mm. The forward and the backward flow characteristics of the flap valve illustrate the appropriateness as a check valve. The flow rate of the micropump is measured for various voltages, frequencies and duty cycles of the square-wave input. When the square-wave input voltage of 10 V is applied to the heater, the maximum flow rate of the micropump is 6.1 μl min −1 at 0.5 Hz and the duty ratio of 60% for zero pressure difference. The maximum backward pressure when the flow rate is zero is 10 mm H 2 O.