Liquid-state field-effect transistors using electrowetting

Abstract

The authors report the demonstration of transistor action in the liquid state. The control of current flow in a liquid field-effect transistor (LiquiFET) was achieved by electrowetting between competitive insulating/conducting fluids. The LiquiFET structure included dielectric/hydrophobic layers, source/drain regions, a gate electrode, and hydrophilic/hydrophobic grids to contain the liquids. For a 400μm long channel, turn-on occurs at 2.5–3V drain voltage. On/off current ratios >10000:1 were measured. Linear gate voltage control over drain current was obtained with a transconductance up to 40nS. A calculated channel mobility of ∼1cm2∕Vs indicates that electronic charge transport dominates transistor operation.