Light-induced electro-rotation: Microspheres spin in micro-manipulation using light-induced dielectrophoresis

Abstract

According to the equivalent circuit model (ECM), finite element model (FEM) and physical experiment, the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark regions on the photoconductive layer was demonstrated. Besides, the phenomenon of the light-induced electro-rotation (LIER) caused by the light-induced rotating electric field was confirmed numerically and experimentally for the first time. It may be helpful to go out of the dilemma that only the dipole moment model, based on the effect of light-induced partial potentials, can be used for LIDEP theoretical calculation currently. Through the FEM simulation and the electro-rotating experiment of yeast cells, it was found that the direction of yeast’s LIER is relevant to the distance between its location and the edge of optical electrode, and the spin velocity of LIER is inversely proportional to that distance. Nevertheless, the LIER torques in the three-electrode mode show a non-uniform distribution where the LIDEP forces are harmful for a particle spinning stably around a fixed axis. Moreover, a four-electrode double-layer mode was proposed for the first time and the finite element simulation results agreed with the expected design, suggesting a new way for the dielectric spectrum measurement based on LIER.