A novel micromachined magnetic membrane microfluid pump

We present results on the design, fabrication, and testing of a new, micromachined magnetic pump for integrated microfluidic systems. Structurally, the pump consists of a magnetic microactuator and two polymer-based one-way diffuser valves. The microactuator is based on a thin membrane made of polydimethylsiloxane (PDMS), a soft silicone elastomer. Membrane displacement is caused by the interaction between ferromagnetic pieces (embedded within the thickness of the membrane) and an external magnet. This novel mechanism reduces fabrication and packaging complexity, and allows for remote operation of the micropump without any tether wires for power input. The operation is simple as no precise alignment is required between the external magnet and the pump. PDMS is biocompatible compared to silicon. One future application of this tetherless micropump is implanted biomedical microfluidic systems. We developed a novel micromachining process for embedding ferromagnetic materials within a thin, spin-cast PDMS membrane. Unique pump and diffuser mechanisms that allow for continuous pumping are also developed. Diffuser elements containing no moving parts are fabricated using polymer micromachining techniques. Micro Permalloy pieces are strategically positioned within a 2×2 mm², 40-μm-thick PDMS membrane. Dimensions and locations of the membrane and the Permalloy pieces are optimized for maximum membrane vertical displacement under a given magnetic field. Experimentally, we have demonstrated successful on-chip fluid pumping. In the presence of an oscillating 2.85×10⁵-A/m external magnetic field, a 1.2-μl/min flow rate was measured for an actuation frequency of 2.9-Hz. The flow rate can be easily varied by the frequency