Design of Micro Diaphragm Pumps With Active Valves

This paper deals with the theory, fabrication and characterization of micro diaphragm pumps with active valves. Three types of micropumps with piezoelectric actuation are presented. Special emphasis is given on the accordance of theory and experiment. The theory is based on a lumped-element approach that is reduced to its basics to enable a reasonable accuracy with a minimized set of conceptional parameters. The experimental results fit well to the theory. The fabrication technology of the micropumps comprises of a silicon bulk micromechanics process in combination with a back-end gluing process of piezoelectric PZT-disks (PZT lead-circonat-titanat) to the silicon diaphragms. The micropumps were developed for different applications. The three- and the four-diaphragm micropumps were designed as high performance drivers for an artificial sphincter prosthesis. They show a maximum flowrate of 4 ml/min and a maximum sustainable backpressure of up to 70 kPa. The two-diaphragm micropump was engineered for an implantable drug delivery device and features a pressure independent dosing for backpressures up to 20 kPa.