Fluidtransport an Grenzflächen durch pneumatisch angesteuerte strukturierte Oberflächen mit zilienähnlichen Strukturen

• Fluid transport on interfaces by pneumatically actuated structured surfaces with cilia like structures

Rockenbach, Alexander Benjamin; Schnakenberg, Uwe (Thesis advisor); Brücker, Christoph (Thesis advisor)

Aachen (2017)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2017

Abstract

In this work a device was simulated, developed and characterized. The device allows the transport of liquids at interfaces. The biomimetic transport mechanism was recreated from the beat of the ctenophore. A production process based on softlithography was developed. The three-dimensional device was made from polydimethylsiloxane (PDMS), which was produced by a new production method. Based on a process with two molds adjusted to each other and a forming process for PDMS. The new device consists of 20 elongated channels, which are covert by elastic membranes. On all membranes a flap is eccentrically positioned. Each membrane can be activated individually by over and under pressure, by this a corresponding flap movement was gained. The application of a metachronal wave leads to a directed fluid transport. The flow profile was like a profile of a wall jet. In this work the dependence between transport, inclination angle and frequency were shown. An inclination angle of 20° showed no transport, whereas smaller inclination angles facilitate negative and antiplectic transport. Higher inclination angles showed positive and symplectic transport. The highest measured velocity of 1500 µm/s was found without inclination angle and with an antiplectic wave type at a beating frequency of 10 Hz. For the acquisition of flow velocities, a camera system was built, which measured the velocity field with particle image velocimetry (PIV). A method to analyze the flow profile close to the surface, by superimposing 500 pictures. Camera movements in direction of the flap length allow the study of the complete flow field. Additionally, extensive numerical simulations based on finite element method were carried out. In mechanical simulations the optimal position for the flaps on the membrane and the asymmetric movement was analyzed. For the first time a coupled finite volume simulation with ANSYS and Fluent showed the fluid transport in the microsystem. All calculations showed good accordance to the experimental results. The developed simulations allow optimization of flap based systems or forecasts of flows close to walls.

Institutions

• Chair of Materials in Electrical Engineering I and Institute of Materials in Electrical Engineering [611510]