Mechanism Analysis And Experimental Study On Cell Pose Adjustment Based On Dielectrophoresis

Cell micromanipulation is one of the key technologies of modern bioengineering. In most of the cell micromanipulation experiments, cell position and orientation(pose) should be adjusted before manipulation: Cell should be moved to the specified manipulating area first, and then be rotated to the desired orientation. At present, the cell pose adjustment task is usually performed manually, which is greatly affected by artificial factor resulting in low control precision, low efficiency, and low success rate. It has greatly prevented the development of modern biological micromanipulation technology. At the imminent demand of the cell micromanipulation technology, this paper conducted a study on the automatic adjustment method of cell pose, which is of great significance to the achievement of the automation of cell micromanipulation.Firstly, the commonly used methods of cell pose adjustment are reviewed, and the advantages and disadvantages of the different methods are compared. Based on that, a new strategy in which dielectrophoresis(DEP) and injection micropipette are used to achieve the cell position and 3D orientation control is proposed, which can effectively reduce the cell damage and improve the efficiency and precision of cell pose adjustment. In this method, cell is delivered to the operating area rapidly under the traveling wave dielectrophoresis(twDEP), and then be rotated to the desired orientation in the horizontal plane under the electrorotation(ROT). After that, cell orientation in the vertical plane will be adjusted by robotic cell rotation method based on the minimum rotation force.Secondly, the expression of conventional dielectrophoresis(cDEP) force, twDEP force and ROT torque are given on the basis of dielectric polarization theory. Then the factors which affect DEP force are analyzed in detail, as well as the force situation of cell and its movement. Meanwhile, a single-shell cell spherical DEP model is established on the basis of the biological dielectric model, which laid the foundation for the below simulation and experimental study of cell pose adjustment. After that, two factors caused by DEP which have negative effects on cell viability are analyzed, and the influences of DEP on cell viability in the cell pose adjusting strategy we proposed are evaluated according to the relevant researches from home and abroad.Thirdly, according to the adjusting method proposed in this paper, a cell pose adjusting chip based on DEP is designed. Then the electric field model and the particle motion model in the chip are established using COMSOL Multiphysics software, and the simulation analysis of electric potential distribution, force distribution and particle trajectory in the chip are carried out. According to the analysis of simulation results, the reasonable experimental parameters are obtained which provide the basis for further experimental study.Lastly, to verify the feasibility of this method, the cell pose adjusting experiments are performed. By experiment, the voltage, frequency of electric field, solution conductivity and presence of microcavity structure on the influence of the cell position and orientation are compared. According to the analysis of experimental data, the best range of parameters for experiment is obtained, and the cell pose adjustment is successfully achieved.