Rapid prototyping of microfluidic components

Microfluidic devices are receiving considerable attention in the fabrication of micro-electro-mechanical systems for biotechnological applications (e.g. BioMEMS). Microscale total analysis systems can reduce cost and increase speed of analysis, especially through reduced use of reagents and reduced system size. A key factor in developing new microfluidic applications is the development of prototyping technologies for fabricating and testing new system designs that incorporate fluidic networks, microreactors, separation, and detection systems. One technique for fabricating microfluidic networks is based on replica molding of microchannels with poly(dimethyl siloxane) (PDMS). Microchannel networks with feature size down to 5 mum have been demonstrated with PDMS replica molding. PDMS replica molding can fabricate microchannel networks with a turnaround period of hours to days using inexpensive, benchtop equipment. However, valves and pump technologies are still macro-scale (e.g. external syringe pumps, peristaltic pumps, or power supplies for electro-osmotic pumps). We present a rapid prototyping technique for fabrication of microfluidic networks and active components (e.g. valves) based on PDMS replica molding combined with magnetic actuation. This technique allows embedding of magnetically actuated, mechanically active polymers within the PDMS microchannel network. By activating the microchannels, the channels may be closed or opened (e.g. valving action). Multiple valves and reservoirs may be actuated in order to create pumping via peristaltic action. Magnetic actuation may be achieved by incorporating a magnetically active material into the PDMS (whether permanent magnet, or high permeability material), and applying an external magnetic field from a printed circuit board. Both valves and pumps have been demonstrated, Using inexpensive benchtop equipment, we can fabricate actual devices with sizes on the order of a few millimeters, with channel sizes on the order of a few hundred micrometers. We have demonstrated active valves that close leak-tight, and withstand back pressures on the order of 1.5 kPa.