Optical control of electroosmosis

Principal Investigator: Pál Ormos
This project is part of the EU-FP6 cooperation ATOM-3D

In the experiments, the excitation of the photoconductor is switched on and off periodically. The illumination of the photoactive layer results in an increased conductivity. This causes the electric field to be sqeezed out from the microchannel region. The lower electric field means lower electroosmotic driving force. This way the electroosmotic flow can be effectively modulated by light. The rate of flow could be reduced by a factor of over 5. The effect was simulated using the finite element method in the FEMLAB 3 multiphysics modeling environment. The simulations reproduce the behaviour of the experimental system.


The figure above shows the isosurfaces of the electric potential. The velocity field of the fluid flow is represented by arrows. The size of the arrows at any position is proportional to the local velocity.

Reference:
L. Oroszi, A. Dér, H. Kirei, V. Rakovics, and P. Ormos, Control of electroosmostic flow by light, Appl. Phys. Lett. 89 263508 (2006)