A MEMS electrostatic particle transportation system

We demonstrate here an electrostatic MEMS system capable of transporting particles 5-10 /spl mu/m in diameter in air. This system consists of 3-phase electrode arrays covered by insulators. Extensive testing of this system has been done using a variety of insulation materials (silicon nitride, photoresist, and Teflon), thickness (0-12 /spl mu/m), particle sizes (1-10 /spl mu/m), particle materials (metal, glass, polystyrene, spores, etc.), waveforms, frequencies, and voltages. Although previous literature claimed it impractical to electrostatically transport particles with sizes 5-10 /spl mu/m due to complex surface forces, this effort actually shows it feasible (as high as 90% efficiency) with the optimal combination of insulation thickness, electrode geometry, and insulation material. Moreover, we suggest a qualitative theory for our particle transportation system which is consistent with our data and finite-element electrostatic simulations.