AC Dielectrophoresis 

(Prof.Dr. Levent Trabzon, Prof.Dr. Ali Beşkök, Doç.Dr. Hüseyin Kızıl, Emre Altınağaç, Yavuz Genç)


In this study, a lab-on-a-chip (LOC) device, which has a Ti interdigitated electrode layer on a glass substrate and a PDMS chamber is fabricated to investigate the effective regions of each transport mechanism. The standart photolithograpy techniques and lift off processes are used for fabrication.
Fluorescent polystyrene microparticles are added to DI water and suspension conductivity is adjusted by adding NaCl. Inverted signals between 1kHz - 5 MHz are applied for the observation of the transport mechanism behaviour under the ranging frequencies and conductivies. Pictures are taken at the steady state.
The experimental results demonstrates that at low frequencies particles are more polarizable than the medium and undergoes positive DEP (pDEP) whereas at high frequencies particles are less polarizable than the medium and experience negative DEP (nDEP) as found in literature. At a given combinations of frequency, medium conductivity and applied voltage, the DEP force can dominate over hydrodynamic forces.



                        Figure: AC DEP