微纳电子技术

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10³~10⁵ Hz,使细胞竖直向下运动的最佳频率是10⁷~10⁸ 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。

The orientation of the cell has a significant impact on the survival rate of the cell during the process of the cell microinjection.A novel microinjection chip with the function of adjusting the position and orientation of the cell before injection was designed based on the PDMS microfluidic technology.The chip was fabricated by bonding of the PDMS containing microchannels and the quartz substrate with microelectrodes on its surface.The injection microneedle was fixed on the bottom center of a cylindrical area with a diameter of 500μm in the microchannel.The microfluid ejected from the microchannel was employed to exert a force on the cell from one side and drive the cell to rotate,thus the orientation of the cell was adjusted.By controlling the alternating current signal applied on the electrode,the size and direction of the dielectrophoresis force were controlled.Therefore the motion of the cell was controlled,and the cell was pierced by the microneedle,then the microinjection was completed.The flow state of the microfluid in the chip was analyzed,and the variations of the CM factor of cells with the frequency in different conductivity solutions were also analyzed.Finally,with the COMSOL Multiphysics software,the velocity and pressure distributions of the microfluid flow in the chip were simulated,the size and distribution of the traditional dielectrophoresis force and traveling wave dielectrophoresis force generated by the electrode in the flow channel were also simulated.The analysis shows that the flow state in the chip is laminar flow,which can ensure that the cells move smoothly and steady in the microchannels.The optimal frequency range to raise the cells to the suspension state is10³-10⁵ Hz,and the optimal frequency range of vertical downward movement of the cells is10⁷-10⁸ Hz.The results of analysis and simulation show that the appropriate position and orientation of the cell for the microinjection are adjusted by the chip,and the cell microinjection is carried out.