Table of Contents
Journal of Experimental Physics
Volume 2015, Article ID 426435, 9 pages
Research Article

Effect of Interface Layer Capacitance on Polydimethylsiloxane in Electrowetting-on-Dielectric Actuation

1Department of Electrical and Electronics Engineering, National Institute of Technology (NIT) Sikkim, Sikkim 737139, India
2School of Medical Science and Technology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur 721302, India
3Department of Electrical Engineering, Indian Institute of Technology (IIT) Kharagpur, Kharagpur 721302, India

Received 18 September 2014; Revised 3 December 2014; Accepted 3 December 2014

Academic Editor: Ahmed Ibrahim

Copyright © 2015 Shiraz Sohail et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Electrowetting is an effective way to manipulate small volume of liquid in microfluidic applications. It has been sophisticatedly used in the fields of Lab-on-a-Chip (LoC) devices, optics, biomedical applications, and electronic paper (e-paper). Generally, Young-Lippmann (Y-L) equation is used to relate the mechanical and electrical force involved in electrowetting-on-dielectric (EWOD) based actuation. And the general trend is to neglect the effect of double layer capacitance formed at the metal-liquid interface considering the Debye-length to be in the order of nanometer. But, at electrode-electrolyte-insulator interface, the effect of interface layer capacitance becomes significant and often leads to the mismatch between the experimental observation and theoretical result. In this work, the surface behaviour of polydimethylsiloxane (PDMS) for EWOD application is studied experimentally and a term “” has been introduced in the Y-L equation to match the theoretical and experimental result. Effect of interface layer capacitance has been observed in contact angle versus applied voltage experiment with different pH buffer solution. The introduction of “” term takes care of the interface layer capacitance which can not be neglected and plays a vital role when the applied electric potential is high.