Dielectrophoresis (DEP) and electrowetting (EWOD) as Anti-fouling processes for antibacterial surfaces

University essay from KTH/Mikro- och nanosystemteknik


Today the medical field is struggling to decrease bacteria biofilm formation which leads to infection. Also, biomedical devices sterilization has not changed over a long period of time which has resulted in high costs for hospitals healthcare managements. The objective of this project is to investigate electro-dynamic effects by surface energy manipulation as potential methods for preventing bacteria biofilm growing on medical devices.

Based on electrokinetic environments two different methods were tested: rejection bacteria dielectrophoretic forces feasibility by numerical simulations; and electrowetting-on -dielectric by the fabrication of golden interdigitated electrodes on silicon glass substrates covered by a Teflon layer.

In the first experiment, numerical simulations of gold electrodes in buffer solution and frequencies were carried out to determine the forces required to reject bacteria. In the second experiment, interdigitated gold electrodes coated with a dielectric Teflon layer, were characterized in terms of breakdown voltage, dielectric adhesion and contact angle in terms of applied voltage. Finally the effect of EWOD on bacterial adhesion was tested.

The project resulted in promising simulation results for bacteria rejection using dielectrophoresis due to the wide range of frequency that rejects the modelled bacteria. However, practical experiments such as electrowetting-on-dielectric must verify this at incubation times larger than 24 hours in spite of the Teflon non-adhesive properties.

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