Large membrane deflection via capillary force actuation

Experimental results from six prototype devices demonstrate that pressure changes induced in a liquid bridge via electrowetting can generate large deflections (20-75 mu m) of an elastomeric membrane similar to those used in lab-on-a-chip microfluidic devices. In all cases deflections are obtained with a low voltage (20 V) and very small power consumption (< 1 mu W). The effects of variations in the bridge size and membrane dimensions on measured displacements are examined. Theoretical predictions are in good agreement with the measured displacements in those cases where the liquid contact angles could be measured within the devices during electrowetting. Contact angle hysteresis and charge injection into the dielectric layers limited the repeatability of deflection behavior during repeated cycling. Approaches for achieving greater deflections and improved repeatability are discussed.