Tunable Liquid Microlens Utilizing Electrowetting

Procedure for electrochemical control of shape of HDT drop. The solution could be translated so that the microscope objective focused on the drop or the image focused by the drop. (Source Gorman, C.B., H.A. Biebuyck, and G.M. Whitesides. 1995. Langmuir, 11(6), 2242-2246. With permission.) 

They had different refractive indices with the same density so that gravity did not deform the liquid-liquid interface that remained spherical no matter what the cell orientation was. 

Krupenkin et al. reported a planar electrode system for electrowetting based liquid lens [18]. They did not impregnate the substrate surface with a lubricant. Instead, they attempted to separate the droplet from the substrate 

To provide an electrical connection to the droplet without distorting its shape, a hole was made in the dielectric material so that the center of the droplet was 

Tunable liquid microlens, (a) Electrode design. Black lines indicate etched areas on indium tin oxide (ITO). Applied voltages are indicated as Vq through V4. Lightly shaded area represents approximate droplet position, (b) Device cross section. Voltage applied to ground electrode is indicated as V5 (Source Krupenkin, T, S. Yang, and P. Mach. 2003. Applied Physics Letters, 82(3), 316-318. With permission.) 

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