Electrowetting-on-Dielectric (EWOD) Microfluidic Devices
Sang Kug Chung, Yuejun Zhao and Sung Kwon Cho
from: Lab-on-a-Chip Technology (Vol. 1): Fabrication and Microfluidics (Edited by: Keith E. Herold and Avraham Rasooly). Caister Academic Press, U.K. (2009)
Since the emergence of microfabrication technology, microfluidics has bloomed, bringing a revolutionary concept: lab on a chip which is currently having tremendous impact in biomedical applications. In particular, droplet-based digital microfluidics, in which fluids are handled in a droplet form rather than continuous streams in microchannels, has developed as a new paradigm and is growing in popularity alongside conventional microchannel-based microfluidics. Electrowetting on dielectric (EWOD), which enables efficient manipulation of droplets, is greatly contributing to the development, maturation, and realization of digital microfluidics. This chapter begins with a brief description and discussion on EWOD principle and background. Then, detailed design and fabrication technology of simplified EWOD testing chips with dual plane driving scheme are described with emphasis on hands-on microfabrication process. In addition, as fundamental operations of droplets and bubbles, it is demonstrated how to manipulate (transport and split) droplets and bubbles using the testing chips. Finally, it is shown that transportation of droplets and bubbles is immediately applied to collection and manipulation of microparticles, respectively. It is expected that the present EWOD configuration would serve as a template that can be easily adopted for the real-world lab-on-a-chip applications read more ...