Analysis of the Influence of the Cell Geometry and Cell Proximity Effects on the Single-cell Trapping using Light-induced Dielectrophoresis

In order to better design the virtual microelectrode patterns and enhance the efficiency and the controllability of single-cell manipulation using light-induced dielectrophoresis, we attempt to systematically investigate how the scaling of the dielectrophoresis, cell geometry and cell proximity effects influence the operating performance with a quantitative analysis. Firstly, based on the equivalent circuit model for manipulation using light-induced dielectrophoresis, the optimum operating frequency of the device is obtained, which is around 105 Hz. Then, the mathematical model of light-induced dielectrophorestic trapping is developed to calculate the distribution of electric field by solving Laplace's equation with appropriate boundary conditions. At last, after careful comparison of the DEP force in light-induced dielectrophoresis based on the Pohl model, the effective-multipole-moment model and the Maxwell stress tensor (MST) approach, the results show that when the cell radius is comparable to the effective trapping radius, the accuracy of Pohl model is unsatisfactory, and in the proximity of the electrodes, the higher-order multipolar contribution to the DEP force must be considered to approximate the actual DEP force. The study of the interaction force between two cells shows that the dipole approximation is accurate for the normalized spacing D/R>6.