Z. Shi, J. Sun, S. Jia, P. Zhang
Xi'an Jiaotong University,
Keywords: microfluidic, magnetic bioseparation, soft-magnetic element
Summary:The separation of magnetically-labeled bioparticles in a microfluidic system is dependent on the characteristics of the particles and the carrier fluid as well as the external magnetic field. To discuss the influence of these factors, a microfluidic design is proposed for implementing greatly enhanced capture efficiency using two arrays of soft-magnetic elements. One array of the elements are integrated into the bottom of the microfluidic separation chamber, while the other array of elements are encapsulated above the chamber. The combination of these two arrays of the soft-magnetic elements, which are magnetized using an external permanent magnet, greatly enhances the capture efficiency as compared with the conventional system wherein only one array of elements is used. The magnetic field provided by these two arrays of elements is reciprocal to each other, which enables the Kelvin force with the same complementarity. This novel peculiarity narrows the chamber size as well as enhances separation. The enhanced capture efficiency is analyzed using a computational model that takes the particle-fluid momentum transfers into account. Besides, a closed-form magnetic analysis, which is more efficiency and accurate than other numerical methods in calculating Kelvin force, is adopted to describe the spatial distribution of the magnetic field. Furthermore, the influence of the flow rate and the volume fraction of the particles on the capture efficiency is also discussed.