Effects of light size and intensity on photoconductive effect-based optically-induced dielectrophoresis for three-dimensional manipulation

This study aims to study the effect of light size and intensity on photoconductive effect-based optically-induced dielectrophoresis (ODEP) for three-dimensional manipulation of cells. HL-7702 cells and SMMC-7721 cells in sucrose solution were manipulated three-dimensionally by ODEP. We found that the ODEP force generated by the three-dimensional non-uniform electric field will form a three-dimensional space, and the positive ODEP force will attract the cells near the space into it. When the number of cells is large, the three-dimensional stacking phenomenon will occur, that is, the three-dimensional assembly of cells. When the size of the light spot is similar to that of the cell, the projector with weak light intensity can only manipulate a single cell, while the laser with higher light intensity can carry out cell three-dimensional assembly. When the light intensity is similar, the larger size of light can produce larger a three-dimensional assembly space. So the cell three-dimensional manipulation by ODEP is achieved only when the photoconductive effect induced by the light pattern reaches the required intensity. The three-dimensional manipulation of cells by ODEP is from plane to stereo, and its realization is related to the light size and the photoconductive layer resistance determined by light intensity. And the three-dimensional space of assembling cells is related to the light size and intensity, and the larger and stronger the light, the larger the space.