Electrowetting-based actuation of liquid droplets for microfluidic applications

TLDR

The study presents a microactuator designed for rapid manipulation of discrete microdroplets. The device uses direct electrical control of surface tension via two sets of opposing planar electrodes on glass, with a linear array of seven 1.5 mm‑pitch electrodes fabricated and tested. Droplets (0.7–1.0 µl) of 100 mM KCl were transferred between adjacent electrodes at 40–80 V, achieving repeatable transport at up to 20 Hz and average velocities of 30 mm/s—nearly a 100‑fold speed increase over prior electrical droplet‑transport methods.

Abstract

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 μl) 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.