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DY: Fachverband Dynamik und Statistische Physik

DY 45: Microfluidics (joint session DY/CPP)

DY 45.2: Vortrag

Mittwoch, 18. März 2020, 17:15–17:30, ZEU 147

Theoretical and numerical investigation of an EWOD-driven micro pump — •Sebastian Bohm and Erich Runge — Technische Universität Ilmenau, Theoretische Physik 1, Weimarer Straße 25, 98693 Ilmenau

We show how the EWOD (electrowetting-on-dielectric) effect can be used to realize a micro pump that uses no moveable components at all, see patent [1]. The flow is generated due to the periodic movement of liquid-vapor interfaces in a large number (≈ 10⁶) of microcavities (Δ V≈ 1 pl per cavity). The total flow resulting from all microcavities adds up to a few hundred nanolitres per cycle. Tesla-Diodes are used as valves to completely forgo on moving parts. They must be optimized to generate a reasonable valve action even at the small Reynolds numbers that are typical for micro pumps.
The theoretical description of the pumping mechanism is a challenge due to the coupling of the fluid- and electrodynamics and the intrinsic multi-scale character of the system. In each microcavity, the flow can be modelled as multiphase flow with time-dependent wetting properties as boundary conditions. It is implemented via a boundary element method. Additionally, an approximation is presented that allows the fast calculation of the stationary shape of liquid/vapor interfaces in electrical fields. Topological optimization methods for the optimization of the Tesla-Diodes are presented, in which the complete micro pump system is considered as well.
[1] Hoffmann, M., Dittrich, L., Bertko, M.; German patent DE11 2011 104 467 (2012)