Abstract
Abstract This study investigated the electro-rotation of cells using optical dielectrophoresis (o-DEP) for the first time. The electro-rotation is the phenomenon that a rotating electric field drives particles/cells rotating. Analyzing the electric field in the o-DEP system, it is possible to produce a rotating electric field in o-DEP system. Moreover, the concept of the equivalent circuit and fundamental theory could show that a rotating electric field exists in o-DEP system. To precisely simulate the electric field, the relaxation method for electrostatic problems is applied. Above three methods can derives that there is a rotating electric field in o-DEP system. Since simulation takes a lot of time, two models for estimating the rotation speed are proposed. One is developed for vast illuminated region in o-DEP; another is developed for locally illuminated region in o-DEP. However the first model could only used to estimate the order of the rotation speed the trends of rotation speed. Thus, it could be applied to determine whether particles/cells are able to rotate under a certain illuminated condition. The second one can depict the trend of the rotation speed after some modification but the magnitude of the rotation speed could not be estimated precisely using this model. Actually the control of rotation speed is easy in practice because it depends on the magnitude square of the electric field. These two models are able to help us estimate the rotation effect before experiment or application. The electro-rotation using o-DEP can make both yeast cells and 3T3 cells rotating. The rotation speed of the yeast cells could reach 3rps under voltage of 4V and 10 kHz, but the rotation speed of the 3T3 cells is less than 1rps under voltage 5V and 50kHz. The rotation speed of both two kinds gets greater as yeast cells getting closer to the illuminated region and stop rotating when they are in the inner of the illuminated region. Keyword: dielectrophoresis, electro-rotation