A plastic micropump constructed with conventional techniques and materials

A plastic micropump which can be produced using conventional production tec hniques and materials is presented. By applying well-known techniques and m aterials, economic fabrication of micropumps for various applications is fe asible 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, w hich means that it can start pumping gas in a dry state and automatically f ills 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 differentia l pressure of 1.25 x 10(4) Pa (125 cm water column) was reached. Basically, the micropump consists of two parts, a flat valve assembly with two passiv e membrane valves and an actuator placed on top. The valves were made by sa ndwiching a punched thin polymer film between two plastic valve parts conta ining the valve seats. The latter parts are made by reactive injection mold ing of an epoxy resin. Two types of actuators have been applied to drive th e pump; an electromagnetic actuator consisting of a magnet placed in a coil and secondly a disk. The first actuator, when combined with a flexible pol ymer 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 ele ctromagnetic actuator was the relatively large volume occupied by the coil giving the micropump final dimensions of 10 x 10 x 8 mm(3). Application of the piezoelectric actuator reduced these dimensions down to 12 x 12 x 2 mm( 3) with comparable performance. (C) 1999 Elsevier Science S.A. All rights r eserved.