Publications

Surface micromachined microfluidics - Example microsystems, challenges and opportunities

Galambos, Paul; James, Conrad D.

A variety of fabrication techniques have been used to make microfluidic microsystems: bulk etching in silicon and glass, plastic molding and machining, and PDMS (silicone) casting. Surprisingly the most widely used method of integrated circuit (IC) fabrication (surface micromachining - SMM) has not been extensively utilized in microfluidics despite its wide use in MEMS. There are economic reasons that SMM is not often used in microfluidics; high infrastructure and start-up costs and relatively long fabrication times: and there are technical reasons; packaging difficulties, dominance of surface forces, and fluid volume scaling issues. However, there are also important technical and economic advantages for SMM microfluidics relating to large-scale batch, no-assembly fabrication, and intimate integration of mechanical, electrical, microfluidic, and nano-scale sub-systems on one chip. In our work at Sandia National Laboratories MDL (Microelectronics Development Lab) we have built on the existing MEMS SMM infrastructure to produce a variety of microfluidic microsystems. These example microsystems illustrate the challenges and opportunities associated with SMM microfluidics. In this paper we briefly discuss two SMM microfluidic microsystems (made in the SUMMiT™ and SwIFT™ processes - www.mdl.sandia.gov/micromachine ) in terms of technical challenges and unique SMM microfluidics opportunities. The two example microsystems are a DEP (dielectrophoretic) trap, and a drop ejector patterning system. Copyright © 2005 by ASME.