Monolithic surface micromachined fluidic devices for dielectrophoretic preconcentration and routing of particles

We describe a batch fabrication process for producing encapsulated monolithic microfluidic structures. The process relies on sacrificial layers of silicon oxide to produce surface micromachined fluid channels. Bulk micromachined interconnects provide an interface between the microchannels and meso-scale fluidics. The full integration of the fabrication processing significantly increases device reproducibility and reduces long-term costs. The design and fabrication of dielectrophoresis (DEP) gating structures configured in both batch-flow and continuous-flow modes are detailed. Highly efficient microparticle preconcentration (up to similar to 100 x in 100 s) and valving (97% particle routing efficiency) are demonstrated using ac DEP and an accompanying phase separation. The low aspect-ratio fluid channels with integrated microelectrodes are well suited for mu m and sub-mu m particle manipulation with electric fields.