Electrowetting of liquid marbles

M I Newton, D L Herbertson, S J Elliott, N J Shirtcliffe, G McHale
2006 Journal of Physics D: Applied Physics  
Electrowetting of water drops on structured superhydrophobic surfaces are known to cause an irreversible change from a slippy (Cassie-Baxter) to sticky (Wenzel) regime. An alternative approach to using a water drop on a super-hydrophobic surface to obtain a non-wetting system is to use a liquid marble on a smooth solid substrate. A liquid marble is a droplet coated in hydrophobic grains, which therefore carries its own solid surface structure as a conformal coating. Such droplets can be
more » ... ed as perfect non-wetting systems having contact angles to smooth solid substrates of close to 180 o . In this work we report the electrowetting of liquid marbles made of water coated with hydrophobic Lycopodium grains and show that the electrowetting is completely reversible. Marbles are shown to return to their initial contact angle for both ac and dc electrowetting and without requiring a threshold voltage to be exceeded. Furthermore, we provide a proof-of-principle demonstration that controlled motion of marbles on a finger electrode structure is possible.
doi:10.1088/0022-3727/40/1/s04 fatcat:bhikmq3uyfdtvf2f33qu3iuhhu