Electroosmotic flow assisted rotation of self-assembled microparticle chains using optoelectronic tweezers

A method integrating electrorotation(ER) and electroosmotic (EO) effect for the formation and motion control of microparticle chains is experimentally demonstrated. In this method, the rotating electric field and EO fluid roll are both created around the border between light and dark area of the fluidic chamber in an optoelectronic tweezers (OET) device. The experimental results show that the particle chains can self-rotate in their pitch axes under the rotating electric field produced due to the different impedances of photoconductor layer at light and dark areas; the orbital movement of entire particle chain around the center of EO fluid roll can be achieved below 550 kHz. The strength of EO flow can be adjusted by changing the frequency of AC voltage. This non-contact method has the potential for spatially regulating the posture, orientation and position of microparticle chains.