Electrostatic actuation of liquid droplets for micro-reactor applications

A device for the electrostatic transport and manipulation of liquid droplets on a solid surface is described. Arrays of microelectrodes are fabricated on a substrate, which is covered by a hydrophobic layer. Water droplets, typically a microliter in volume, take spherical shape on the surface and are caused to move by switching the voltage applied to the electrode array. The transport of droplets, deflection of a droplet in either of the bifurcating paths, and the mixing of two droplets by coalescence are experimentally demonstrated. The device can be used for microchemical reactors where transport, sorting and mixing of reagents constitute basic unit operation.