Electromagnetic membrane-pump with an integrated magnetic yoke

Micro fluidics is a fast developing research area and is of interest to many scientific groups. Within microfluidic systems micro pumps transport the fluid to different functional areas of a so called Lab-on-a-chip. Up to now electro-magnetically actuated microfluidic pumps make no use of an essential part of electromagnetic systems: A highly permeable core which leads the magnetic flux and lowers the magnetic resistance. Utilizing the magnetic force which tends to minimize the reluctance of a magnetic system a magnetic actuator was achieved. Another common principle for directing laminar fluid flows, nozzle and diffuser geometries, was simulated and the optimal geometry for different Reynolds numbers was evaluated. The combination of these two improvements allows for a bubble resistive magnetic-reluctance micro-pump with an integrated membrane-like magnetic yoke, which was modeled, fabricated utilizing a simple single layer thin film technology, and tested. The realized device features high pumping forces to actuate viscous fluids, high pumping frequencies (565 Hz and multiples thereof) for a continuous flow and low power consumption. In our contribution we discuss the device design, the underlying theory and first experimental results.