磁珠分离式样品提取微流控芯片的磁珠运动速度建模及特性研究

为提高磁珠分离式生物医学样品的提取效率，采用永磁和软磁体相结合的磁场设计结构，提出一种新型磁珠分离式样品提取微流控芯片。利用静磁学和流体力学基本原理推导出流场中磁珠运动的速度模型，通过多物理场耦合仿真软件对流场中磁珠运动规律进行瞬态仿真，分析软磁体的结构和分布对微流道内磁珠的水平分速度以及竖直分速度的影响关系，计算不同设计结构所允许的磁珠完全吸附时微流道中最大允许流量。结果表明，增大软磁体的厚度可以快速减小磁珠水平运动的速度，并减小其在垂直方向上的波动，且在双软磁体作用时，软磁体的间距越大，水平方向和垂直方向的速度波动越大；间距越小，磁珠粒子速度稳定的时间越短。

Modeling and Characteristics of Magnetic Bead Velocity in Microfluidic Chip for Sample Extraction with Magnetic Separation

In order to improve the separation efficiency of the biomedical samples using magnetic beads, a new magnetic separation microfluidic chip is proposed, which uses the combination of permanent magnet and soft magnet for the structure design of magnetic field. The velocity model for the motion of magnetic beads in the flow field is derived by the basic principles of magnetostatics and fluid mechanics. The motion of magnetic beads in the flow field is simulated transiently by a multiphysics-coupling simulation software. The relationship between the structure and position of soft magnetic elements on the horizontal velocity and vertical velocity of magnetic beads in microchannels is analyzed. The maximum allowable flow rate in the microchannel is calculated when the magnetic beads are completely adsorbed by different design structures. The results show that the thickness increasing of the soft magnet can rapidly reduce the horizontal speed of the magnetic bead, and reduce its fluctuation in the vertical direction. In addition, the larger the distance between the two soft magnets, the bigger the fluctuation in the horizontal and vertical directions. The smaller the distance, the shorter the time required for the magnetic bead particles to stabilize.