An investigation of electrowetting-based microactuation

Abstract

Electrical control of the interfacial tension between a liquid and solid ("e1ectrowetting") has been studied as a means of actuation in the microdomain (characteristic dimensions 1 fim-l mm). Electrowetting provides a means of direct fluid pumping with no moving mechanical parts, which may prove useful in a number of application areas, most notably the liquid cooling of high-density microelectronic devices. A detailed model of a test device for the study of e1ectrowetting is presented. The model describes liquid flow in a small channel, as governed as the Navier-Stokes equations, Young's equation, and Lippmann's equation (for the effect of an applied potential on interfacial tension). Simulation results are presented. Preliminary results indicate that electrowetting is a viable approach to microactuation: in a 10 fim radius channel, it may be used to generate pressures on the order of 0.01 MPa, comparable to pressures generated by existing micropump designs, which are orders of magnitude larger in size.

Microfluidics: Fluid physics at the nanoliter scale

“…͑22͒ until some critical voltage V c , at which point electrowetting saturates. ͓Recently, however, Krupenkin et al ͑2004͒ demonstrated that a superhydrophobic nanostructured surface becomes completely wet with only 22 V.͔ More generally, the saturation mechanism remains unknown ͑Quilliet and Berge, 2001;Moon et al, 2002͒, although Mach et al, 2002;Acharya et al, 2003;Hsieh et al, 2003͒. Specific microfluidic examples include electrowettingbased micropumps ͑Colgate and Matsumoto, 1990;Jun and Kim, 1998;Yun et al, 2002͒, creation, manipulation, and metering of fluid droplets ͑Lee and Pollack et al, 2000;Lee, Moon, et al, 2002;Cho, Moon, and Kim, 2003;Kuo et al, 2003;Ren et al, 2004͒, and chemical …”

Activation and control of microlens liquid arrays on functionalized polar electric crystal substrates by electro-wetting effect and temperature

“…where γ sl0 corresponds to zero charge condition and c is the capacitance per unit area assuming that the charge layer can be modelled as a symmetric Helmholtz capacitor [12]. To best characterize the microlens array we positioned the hotplate with the sample in a Digital Holographic Microscope as it's drawn in Fig.3.…”

“…The hydrostatic pressure is responsible for changing the focal power of the microfluidic lens. Electro-wetting or more in general studies on wettability and de-wettability [11][12][13][14][15][16][17][18][19][20][21][22] of surfaces have been studied and investigated since long time with the aim to pattern liquids on surfaces. An interesting overview about scope, methods and results is given in ref.…”

Wettability of Sodium Chloride Aqueous Solutions on SUS304 Stainless Steel with Current Flow

“…1,2) The change in the wettability of the fluid has been confirmed to be reversible at low voltages, for example, for a droplet of liquid metal (mercury) 2) or a droplet of 10 À2 M KNO 3 electrolyte 3) on various dielectric films. By using this technique, many applications have been recently achieved in micro-actuation, 2,4,5) micro-fluidic transport and mixing, 6,7) switchable devices, 8,9) liquid lens profile control [10][11][12] and self-assembled particle arrays.…”