Electrowetting-based actuation of liquid droplets for microfluidic applications

A microactuator for rapid manipulation of discrete microdroplets is presented. Microactuation is accomplished by direct electrical control of the surface tension through two sets of opposing planar electrodes fabricated on glass. A prototype device consisting of a linear array of seven electrodes at 1.5 mm pitch was fabricated and tested. Droplets (0.7-1.0 mu l) of 100 mM KCl solution were successfully transferred between adjacent electrodes at voltages of 40-80 V. Repeatable transport of droplets at electrode switching rates of up to 20 Hz and average velocities of 30 mm/s have been demonstrated. This speed represents a nearly 100-fold increase over previously demonstrated electrical methods for the transport of droplets on solid surfaces. (C) 2000 American Institute of Physics. [S0003-6951(00)01237-7].