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在对细胞进行显微注射时,细胞姿态对注射后细胞的成活率有重要影响。基于PDMS微流控技术设计了一种在注射之前可调节细胞位置和姿态的显微注射芯片,芯片是由含微流道的PDMS和表面有微电极的石英基片键合而成,显微注射针固定在微流道中直径为500μm的圆柱形区域底面圆心处。利用从微流道喷射出的微流体使细胞单侧受力而旋转进而达到调节其姿态的目的;通过控制电极上施加的交流电信号来控制细胞所受介电泳力的大小和方向,进而控制细胞运动,使细胞被显微注射针刺入从而完成显微注射操作。分析了芯片内微流体流动状态以及细胞在不同电导率溶液中CM因子随频率变化的特征。最后用COMSOL Multiphysics软件对芯片内微流体的速度和压力分布、电极在流道中产生的传统介电泳力和行波介电泳力大小及分布进行仿真。分析得出芯片内流体流态为层流,能够保证细胞在流道内随流体平稳移动;使细胞上升至悬浮状态的最佳频率是10~3~10~5 Hz,使细胞竖直向下运动的最佳频率是10~7~10~8 Hz。分析和仿真结果显示该芯片能将细胞调节到适合显微注射的位置和姿态并对细胞进行显微注射。
When the cells are microinjected, the cell pose has an important influence on the survival rate of the cells after injection. Based on the PDMS microfluidic technology, a microinjection chip was designed to regulate cell position and attitude before injection. The chip was formed by bonding PDMS with microchannels and a quartz substrate with microelectrodes on the surface. The injection needle is fixed at the center of the bottom surface of a cylindrical area having a diameter of 500 μm in the microchannel. Using the microfluid ejected from the microchannels to unilaterally rotate the cell to regulate the posture of the cell; controlling the size and direction of the dielectrophoretic force by controlling the AC signal applied on the electrode, and then controlling The cells move so that the cells are penetrated by the microinjection needle to complete the microinjection procedure. The flow characteristics of microfluid in microchip and the variation of CM factor with frequency in different conductivity solutions were analyzed. Finally, COMSOL Multiphysics software was used to simulate the velocity and pressure distribution of microfluidic chip, the traditional dielectrophoretic force and traveling wave dielectrophoretic force in the flow channel. The results show that the fluid flow in the chip is laminar, which can ensure the smooth movement of the cells in the flow channel with the fluid. The optimal frequency for the cells to rise to the suspension state is 10 ~ 3 ~ 10 ~ 5 Hz, and the cells are moved vertically downward The best frequency is 10 ~ 7 ~ 10 ~ 8 Hz. Analysis and simulation results show that the chip can be adjusted to the appropriate micro-injection of the location and posture and micro-injection of cells.