Abhishek Kumar

During my master study in Nanotechnology at the University of Twente , I did a research project as part of my internship at the research group of Physics of complex fluids under the guidance of Prof. Frieder Mugele. The results from this project work were presented in the Fall 2005 MRS conference at Boston, USA. In the project I measured the electrowetting behavior of aqueous salt solutions. Electrowetting is a phenomenon allows for controlling the contact angle of partially wetting conductive liquids by applying a voltage between the liquid and insulator-covered electrodes on the substrate. By varying the conductivity and the frequency of the applied AC voltage we determined the range of the validity perfect conductor assumption of the standard electrowetting theory for the case of AC voltage. We show that the contact angle reduction is dramatically reduced at high frequency and low salt concentration due to Ohmic losses with the liquid. A simple RC-equivalent circuit model explains the observations. It is demonstrated that finite conductivity effects are more pronounced for sessile droplets than for droplets confined between to parallel plates.

A. Kumar, M. Pluntke, B. Cross, J.-C. Baret, and F. Mugele;

“Finite conductivity effects and apparent contact angle saturation in AC

electrowetting”; Proc. of the Materials Research Society Fall Meeting, Boston,

U.S.A., Nov. 2005

Mater.Res.Soc.Symp.Proc Vol. 899 E-N06-01.1

Weblink : http://pcf.tnw.utwente.nl/