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Electrowetting is the modification of the wetting properties of a surface (which is typically hydrophobic) with an applied electric field. == History == The electrowetting behavior of mercury and other liquids on variably charged surfaces was probably first explained by Gabriel Lippmann in 1875〔M.G. Lippmann,"Relation entre les phénomènes électriques et capillaires." Ann. Chim. Phys, 5:494, 1875〕 and was certainly observed much earlier. A.N. Frumkin used surface charge to change the shape of water drops in 1936.〔A. Frumkin, Об явлениях смачивания и прилипания пузырьков, I (On the phenomena of wetting and adhesion of the bubbles, I). Zhurnal Fizicheskoi Khimii (J Phys Chem USSR),12: 337- 345 (1938).〕 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.〔G. Beni and S. Hackwood, Appl. Phys. Lett. 38, 4, pp.207-209, 1981〕 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.〔()〕 Electrowetting using an insulating layer on top of the bare electrodes was later studied by Bruno Berge in 1993.〔B. Berge, "Électrocapillarité et mouillage de films isolants par l'eau", C.R. Acad. Sci. Paris, t. 317, Série II, p. 157-163, 1993.〕 Electrowetting on this dielectric-coated surface is called electrowetting-on-dielectric (EWOD)〔J. Lee, "Microactuation by Continuous Electrowetting and Electrowetting: Theory, Fabrication, and Demonstration," PhD Thesis, University of California, Los Angeles, 2000〕 to distinguish it from the conventional electrowetting on the bare electrode. Microfluidic manipulation of liquids by electrowetting was demonstrated first with mercury droplets in water〔J. Lee and C.-J. Kim, "Liquid Micromotor Driven by Continuous Electrowetting", Proc. IEEE Micro Electro Mechanical Systems Workshop, Heidelberg, Germany, Jan. 1998, pp. 538-543〕 and later with water in air〔 and water in oil.〔M.G. Pollack, R.B. Fair and A.D. Shenderov, "Electrowetting-based actuation of liquid droplets for microfluidic applications", Applied Physics Letters, vol. 77 (11), 2000〕 Manipulation of droplets on a two-dimensional path was demonstrated later.〔S.-K. Fan, P.-P. de Guzman, and C.-J. Kim, "EWOD Driving of Droplet on NxM Grid Using Single-Layer Electrode Patterns, Tech. Dig., Solid-State Sensor, Actuator, and Microsystems Workshop, Hilton Head Island, SC, June 2002, pp. 134-137〕〔J. Gong and C.-J. Kim, "Two-Dimensional Digital Microfluidic System by Multi-Layer Printed Circuit Board", Proc. IEEE Conf. MEMS, Orlando, FL, Jan. 2005, pp. 726-729〕 If the liquid is discretized and programmably manipulated, the approach is called "Digital Microfluidic Circuits"〔C.-J. Kim, "Integrated Digital Microfluidic Circuits Operated by Electrowetting-on-Dielectrics (EWOD) Principle", granted in 2000 by Defense Advanced Research Projects Agency (DARPA), award number N66001-0130-3664〕〔C.-J. Kim, "Micropumping by Electrowetting", Proceedings of the ASME International Mechanical Engineering Congress and Exposition, November 2001, New York, NY, IMECE2001/HTD-24200.〕 or "Digital Microfluidics".〔M.G. Pollack, Electrowetting-Based Microactuation Of Droplets For Digital Microfluidics, PhD Thesis, Duke University, 2001.〕 Discretization by electrowetting-on-dielectric (EWOD) was first demonstrated by Cho, Moon and Kim,〔S. K. Cho, H. Moon, and C.-J Kim, "Creating, Transporting, Cutting, and Merging Liquid Droplets by Electrowetting-Based Actuation for Digital Microfluidic Circuits", J. Microelectromechanical Systems, Vol. 12, 2003, pp. 70-80〕 completing the four basic digital microfluidic functions of creating, transporting, dividing and merging droplets on chip by electrowetting Since then, a large number of applications based on electrowetting have been demonstrated. Currently five companies are at the forefront in commercializing electrowetting-based applications based on Cytonix〔()〕 and Berge's later research: Clinical diagnostics by Advanced Liquid Logic〔(Advanced Liquid Logic )〕 which was spun out of Duke University, electronic paper by both Gamma Dynamics,〔(Gamma Dynamics )〕 which was spun out of the University of Cincinnati, and Liquavista〔(LiquaVista )〕 which was spun out of Philips Research, liquid lenses by (Varioptic ),〔(Varioptic )〕 and Digital PCR by Life Technologies and Sequenom. In some of these applications, electrowetting allows large numbers of droplets to be independently manipulated under direct electrical control without the use of external pumps, valves or even fixed channels. In e-paper and liquid lenses, droplets are manipulated in-place whereas in clinical diagnostics applications, droplets are moved around on the platform. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electrowetting」の詳細全文を読む スポンサード リンク
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