Study Of The Related Problems Of Rotary-drive-type Magnetic Bead-droplet Transportation And Agitation

The micro fluidic chip system has the characteristics of less reagent consumption,short reaction time,high-throughput parallel large-scale response,online testing,low cost,more reliable test results and higher degree of automation,which has a wide range of biological application.Under the situation of microcale and nanoscale,microfluidic chip drive system is on the basis of microfluidic drive.The traditional microfluidic chip system is drived by micro-pumps and micro-valves,which is difficult to be integrated.It has a larger size and the drive efficiency is not very high.Based on mature micro immunomagnetic bead technique and electromagnetic MEMS processing technology,the discrete-droplet-drive microfluidic system could be more precise to control microfluidic and control reaction sample volume,such a microfluidic chip system is a research focus at home and abroad.The principles and applications of magnetic bead technology are introduced,and a research status of microfluidic drive approach is summarized in this paper.And then,a rotary-drive-type microfluidic chip is identified as an object of study.Then,the structure of the rotary-drive-type micro fluidic chip and the principles of magnetic droplet manipulation are introduced,and the mathematical principles of the separation,integration,collection,transportation,and mixing of magnetic bead droplet of the chip are researched.The related issues of electromagnetic drive components of the chip are researched as an emphasis.The magnetic bead droplet of this chip system is manipulated by the coupling magnetic field generated by the multi-layer flat coil and permanent magnet.The coupling magnetic field distribution is critical to manipulate magnetic bead and optimize chip parameters is based on the coupled magnetic field analysis.Firstly,based on the law of Biot-Safar and integral equation method,the numerical calculation of three dimension magnetic field distribution of single-layer planar micro-coil is proposed,and the magnetic field of the planar micro coil distribution and its characteristics are simulated with numerical computational tool Matlab;Secondly,open-domain magnetic field distribution of single layer planar micro coil model is established using the finite element tool Ansys,and then imposition the boundary conditions of the parallel magnetic field lines and the same current load with numerical simulation,the calculation results obtained by the Ansys are consistent with numerical methods,which proved the feasibility of this finite element analysis;Then,based on single-layer planar micro-coil finite element analysis method,the finite element model of multi-layer planar micro-coil and permanent magnet are established,which derived analysis method of the coupled magnetic field;Finally,a calculation method of the magnetic bead manipulation feasibility is proposed using Matlab and Ansys.The magnetic field strength and gradient values of the coupling magnetic field are derived by Ansys powerful post-processing functions,and then magnetic bead carrier response parameters are thought about,finally,the magnetic force and viscous resistance can be calculated by Matlab in order to determine the magnetic bead manipulation feasibility.This method can be used to guide the design of planar micro-coil parameters.As the planar micro coil is a complex irregular geometry,there will be some problems during mesh grid,such as the degradation and irregular grid.On the basis of comprehensive considering the heat transfer affect factors,such as the heat conduction,convection,the simplified finite element model of a planar micro coil is proposed,which is equivalent to a regular hexahedron.Based on it,the finite element model of the mixing device is established.And then,the temperature distribution of the magnetic bead droplets are simulated and calculated under different loading conditions and the results are consistent with the experimental results of the existing literature,which verify the correctness of the analysis method in this article.The chip thickness,the thickness of the glass substrate and the drive current carrying size have impact on temperature field distribution and the influence can be analyzed based on this finite element simulation method.