Voltage induced spreading and liquid optical devices

An experimental investigation has been carried out into Liquid dielectrophoresis (LDEP), in which dielectric forces are used to actuate bulk liquid spreading and to imprint a deformation pattern at a liquid air surface. Our basic conguration uses a set of co-planar stripe interdigital electrodes to create a non-uniform A.C. electric field that exponentially decays in amplitude and penetrates above the structure into a dielectric liquid droplet. Dielectric forces drive a voltage-induced spreading of the droplet into a low contact angle droplet/film, an effect which will be referred to here as "dielectrowetting". Further application of the A.C. voltage to the electrodes results in a static sinusoidal wrinkle forming at the oil-air interface on the spread film. Three main areas of investigations are reported, the first of which is a study of the statics and dynamics of the voltage induced spreading of a stripe of the material 1,2 propylene glycol. In the limit of thick droplets, a theoretical prediction has been derived that the cosine of the static equilibrium contact angle is proportional to the square of the amplitude of the voltage applied to the inter-digital electrodes. This relationship is analogous to that found for electrowetting-on-dielectric (EWOD). Experimental observations confirm this predicted dielectrowetting behavior for the advancing static contact angle of the voltage induced spreading of a stripe of the material 1,2 propylene glycol.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Nottingham Trent University

Year dc:date.issued

2013

Author dc:creator

• Sampara, N

Language dc:language

en