A plastic micropump constructed with conventional techniques and materials

A plastic micropump which can be produced using conventional production techniques and materials is presented. By applying well-known techniques and materials, economic fabrication of micropumps for various applications is feasible even at low production volumes. The micropump is capable of pumping both liquid and gas at a considerable high pump rate and is self-priming, which means that it can start pumping gas in a dry state and automatically fills with liquid. Pump rates, at actuation frequencies between 2 and 500 Hz, were around 2 ml/min for water and up to 50 ml/min for air. A differential pressure of 1.25×104 Pa (125 cm water column) was reached. Basically, the micropump consists of two parts, a flat valve assembly with two passive membrane valves and an actuator placed on top. The valves were made by sandwiching a punched thin polymer film between two plastic valve parts containing the valve seats. The latter parts are made by reactive injection molding of an epoxy resin. Two types of actuators have been applied to drive the pump; an electromagnetic actuator consisting of a magnet placed in a coil and secondly a disk. The first actuator, when combined with a flexible polymer pump membrane, showed a very large pump rate for gas, up to 40 ml/min at the resonant frequency of the actuator system. A disadvantage of the electromagnetic actuator was the relatively large volume occupied by the coil giving the micropump final dimensions of 10×10×8 mm3. Application of the piezoelectric actuator reduced these dimensions down to 12×12×2 mm3 with comparable performance.