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Summary: Water, electricity, and between... On electrowetting and its applications
Romi Shamai,a
David Andelman,*b
Bruno Bergec
and Rob Hayesd
Received 1st October 2007, Accepted 29th October 2007
First published as an Advance Article on the web 14th November 2007
DOI: 10.1039/b714994h
Imagine a drop of water lying on a surface, pulled into a ball by surface tension. With electricity it
is possible to change the shape of the drop and cause it to flatten out. This is electrowetting, a
physical phenomenon which has aroused great interest in recent years as it has found new
applications. Here we will describe the phenomenon and two of its applications: variable-focus
liquid lenses and paper-thin, video-rate, reflective color displays.
The physics of wetting
Go into the kitchen and do a small experiment: place a drop of
water on a smooth, clean glass surface (a plate, for example),
and another drop on a Teflon frying pan or on greased baking
paper. You will be able to see the difference in the behavior of
the drops: on the glass the drop flattens out whereas on the
Teflon or the greased paper it turns into a ball. We say the
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