Optoelectrofluidic control of colloidal assembly in an optically induced electric field.

This letter reports a method for controlling the organization of colloidal particles using optoelectrofluidic mechanisms. This optoelectrofluidic colloidal assembly (OCA) can be an efficient and simple way of preparing 2D colloidal crystals. Here, we present the first investigation of 2D colloidal assembly due to the electrohydrodynamic flows in an optoelectrofluidic device. The normalized distance among the assembled particles and the assembly rate according to the applied ac signal were analyzed. This OCA allows the control of both the colloidal crystal pattern over a large area and the distance between the assembled particles by adjusting the projected light pattern and the applied ac signal.