| Microfluidic chip technology has been widely used in biomedical and chemical fields due to its advantages of miniaturization and integration.Immunomagnetic bead separation technology has the purpose of screening the target material by combining the magnetic bead with the target material and separating the target material from the biological sample through the magnetic field,so it has been widely used in the field of cell sorting.In this study,microfluidic technology and magnetometric separation technology are combined.A microfluid-controlled magnetometer separation chip with distributed structure is proposed based on the magnetic field force generated by integrated magnetometer in microchannel,the simulation analysis and experimental study of its magnetic field and flow field are carried out to improve the velocity of fluid under the condition of constant adsorption efficiency,thus the efficiency of the whole microfluidic analysis system is improved.Based on the theory of magnetostatics,fluid mechanics and Newton’s second law of motion,the equation of motion of magnetic bead in microflow passage is deduced,and the mathematical model of the change of velocity of single magnetic bead with magnetic field and flow field is established.Through the comparison of numerical simulation,the trajectory of magnetic beads in microchannel is analyzed,and the correctness of the mathematical model is verified.The magnetic field intensity gradient and magnetic field force near a single permanent magnet and an integrated magnetic conductor are compared.The two-dimensional numerical simulation of different structural size parameters of magnetic conducting body is carried out,and the movement rules of magnetic beads in microflow passage are analyzed,and the size parameters to improve the magnetic field gradient and the adsorption efficiency of magnetic beads are optimized.Through threedimensional numerical simulation,the magnetic field force,magnetic field gradient and dynamic characteristics of magnetic beads in the adsorption chamber are analyzed and compared when the magnetic conductivity is distributed as bars and lattice,and the optimal design of the spacing between lattice magnetic conductors is carried out to improve the magnetic field gradient and magnetic beads adsorption.This study presents a method for making magnetic conducting layer filled with magnetic conducting powder in grooves.Magnetic beads adsorption experiments were carried out for different structures and different size parameters of magnetic beads,including bar type magnetic beads and lattice magnetic beads of different sizes,and the degree of magnetic beads adsorption in the cavity was analyzed by image processing method.Compared with the numerical simulation,the results show that the law of change is consistent,which verifies the correctness of the numerical simulation.The influence of flow field structure on magnetic bead adsorption was studied by numerical simulation and experimental methods.The distribution uniformity of magnetic beads in the cavity is measured by variation coefficient,and the regularity of distribution uniformity of magnetic beads in the cavity caused by velocity change of flow field is analyzed. |
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