Dynamic control of DEP actuation and droplet dispensing

Abstract

Rapid dielectrophoretic (DEP) liquid actuation and dispensing of uniform aqueous droplets on a substrate are implemented for the first time in a silicon-based architecture. Using ⟨1 0 0⟩ Si wafers takes advantage of the high thermal conductivity and extensive semiconductor microfabrication capabilities of silicon. The structures employ a coplanar, three-electrode design to guarantee reproducible dispensing of multiple sessile droplets as small as ∼75 pl. A reduced-order dynamic model provides a predictive relation for the transient liquid motion, which is implemented in an open-loop dynamic control scheme to achieve repeatable production of anywhere from 1 to 23 droplets per structure by controlling voltage on-time.