Electrowetting

Electrowetting is the modification of the wetting properties of a surface (which is typically hydrophobic) with an applied electric field.

==History== The electrowetting of mercury and other liquids on variably charged surfaces was probably first explained by Gabriel Lippmann in 1875 and was certainly observed much earlier. A. N. Frumkin used surface charge to change the shape of water drops in 1936. The term electrowetting was first introduced in 1981 by G. Beni and S. Hackwood to describe an effect proposed for designing a new type of display device for which they received a patent. The use of a "fluid transistor" in microfluidic circuits for manipulating chemical and biological fluids was first investigated by J. Brown in 1980 and later funded in 1984–1988 under NSF Grants 8760730 & 8822197, employing insulating dielectric and hydrophobic layer(s) (EWOD), immiscible fluids, DC or RF power; and mass arrays of miniature interleaved (saw tooth) electrodes with large or matching indium tin oxide (ITO) electrodes to digitally relocate nano droplets in linear, circular, and directed paths, pump or mix fluids, fill reservoirs, and control fluid flow electronically or optically. Later, in collaboration with J. Silver at the NIH, EWOD-based electrowetting was disclosed for single and immiscible fluids to move, separate, hold, and seal arrays of digital PCR sub-samples.