Fabrication of suspended electrokinetic microchannels from directly written sacrificial polymer fibers

Freely suspended microchannels with diameters ranging from4 to 100 lmwere fabricated by utilizing directly written PMMA fibers as sacrificial structures. These precisely oriented fibers served as scaffolds aroundwhich thin cylinders of glass were deposited (via sputtering), followed by a conformal coating of Parylene to augment the mechanical integrity of the structures. After coating, the PMMA fibers were dissolved to yield suspended, hollow conduits that were hydrophilic and robust. The freely suspended channels were loaded with a buffer solution containing charged particles, which were subsequently electrokinetically manipulated and velocities quantified using microparticle image velocimetry (μPIV). Mobilities within 1.3 % of those observed in conventional, planar microchannels were recorded.