| Microfluidic technology is a technology involving multidisciplinary research on mechanics,mechanics,chemistry,biology,medicine,etc.Its core is to control fluid flow at the microscale and process and analyze the substances in the microchannel.The microfluidic chip is the carrier of microfluidic technology.By introducing electrical,acoustic,optical,magnetic and other manipulation technologies into the microfluidic chip,the chip's ability to manipulate fluids and analyze and detect is improved.Because magnetic manipulation has the advantages of a wide range of force and no direct contact with the test object,magnetic manipulation technology is often applied to applications such as micro-separation in microfluidic chips.By combining magnetic materials and microspheres to prepare magnetic microparticles,combined with microfluidic and magnetic manipulation technology,the controllable movement of magnetic microparticles under the action of a magnetic field can be realized.Therefore,magnetic microparticles have broad application potential in drug transport,catalytic reactions,bacterial detection,information encoding,etc.The preparation of magnetic microparticles has always been a research hotspot.Based on simulation,this paper proposes a microfluidic chip design method for the preparation and separation of magnetic microparticles,and designs and manufactures related chips based on this method to realize the preparation and automatic screening of magnetic microparticles.main tasks as follows:Firstly,a cross-shaped micro-channel geometry model was constructed,and the factors affecting the size of droplets were analyzed.Based on the COMSOL numerical simulation platform,the influence of different inlet velocities and the size of the chip shear on the size of droplets was analyzed.The change rule of particle size when the micro-droplet method is used to prepare micro-particles is presented,which provides a numerical theoretical reference basis for subsequent experiments.Secondly,a flow channel separation area that can be used for a variety of microparticle screening is designed,and a movable permanent magnet device is used to adjust the intensity of the magnetic field,so that the particles in the flow channel deviate from different distances and flow out to complete the particle separation and screening operation.A joint simulation platform based on MATLAB and COMSOL was built to analyze in detail the influence of the flow rate,magnetism,and arrangement of magnets in the chip on the separation effect to determine the effectiveness of the separation function of the chip.Based on the joint simulation platform,the automatic numerical calculation of the batch chip model and the optimal result screening were carried out,and the screening parameters suitable for microparticles of different particle sizes and different magnetic properties were determined.And designed the simulation platform GUI interface to further realize the practicability of the co-simulation platform and reduce the complexity of computing operations.Finally,the chip size design was completed based on the aforementioned chip design method,and the microfluidic chip was made by the molding method,and the relevant experimental operation platform was built.The mixed solution of PEGDA(polyethylene glycol diacrylate)and magnetic fluid was selected,based on the microfluidic The droplet method realizes the preparation of magnetic microparticles.The formation process of the droplets and the influence of the flow rate on the size of the droplets were further analyzed,and the formation of stable magnetic microparticles was obtained by the method of curing the droplets by ultraviolet light.Then further explored the separation process of magnetic microparticles,measured the magnetic field distribution around the chip under different magnet combinations,analyzed the influence of the magnetic field distribution on the particle trajectory,and explored the magnet placement position on the magnetic particles.The law of influence of motion trajectory. |
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