Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Poster: Wetting, Micro and nanofluidics
CPP 21.15: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
Electrowetting on 3-dimensional structures: A method to control the transport of liquid plugs through hydrophobic sieves — •Markus Wink1,2, Thomas Palberg1, Karin Potje-Kamloth2, and Michael Baßler2 — 1Johannes Gutenberg University Mainz, Germany — 2Institut für Mikrotechnik Mainz, Germany
In the last two decades electrowetting has made its way into new applications, e. g., "lab-on-a-chip" systems, display technologies and microlenses. Recently, Lifton et al. have shown the use of electrowetting in microbatteries by introducing a micropourous structure, which is actively switched to the wetting state [1]. Here, we apply electrowetting to a microfluidic system and show tunable wetting and subsequent dewetting of a sieve representing a fundamental 3-dimensional structure. The pressure curve for transport of a liquid plug through a sieve is analytically described for a square mesh. The liquid entry pressure (LEP), which is the pressure required to fully wet the pores, depends on the size and shape of the pores, the interfacial tension of the liquid and the contact angle of the liquid on the solid surface. To enable electrowetting the square mesh is coated with a dielectric layer for electrical isolation and the surface is functionalized with a hydrophobic layer. The apparent contact angle of droplets on the sieve is investigated as a function of voltage. In addition, the LEP as a function of voltage is determined to test our hypothesis of a reduced LEP under electrowetting conditions.
[1] V.A. Lifton et al., Appl. Phys. Lett. 93, Issue 4 (2008) 043112