Rotation speed control of Janus particles by dielectrophoresis in a microfluidic channel

In this work, Janus particles (Au/fluorescent polystyrene) are fabricated and their flip/flop rotational effect is studied in a microfluidic channel thanks to dielectrophoresis, providing a new type of local light switch. A method for producing large amounts (more than 106 particles/ml) of Janus particles is first presented. Those particles were then injected in an electromicrofluidic chip and stabilized in the fluid by a dielectrophoretic trap. The spanning frequency of this trap allowed performing a “flip-flop” effect of the Janus particles by recording their fluorescent intensities. Flip (Au top side) and flop (PS top side) frequencies are identified. Finally, experiments were performed on the time triggered commutations between flip and flop frequencies to define the capability of each Janus particle to sustain speed control of their flip-flop.