Research Of Dielectric Microfluidic Chip With Inertial Focusing Structure For Continuous Particles Separation

With the development of micro-manufacturing technology,the application of biology integrated fluid,electric field and optical components of the chip is developing rapidly.These chips make full use of different techniques for sample preparation and analysis.In the preparation of samples,one of the most important technology is cell separation,in which the electrophoresis is a kind of no need to mark the particles,no damage to the cells can be simultaneously on the multi-cell operation,but also can be combined with other techniques or methods to improve the separation efficiency.The traditional method of separation use dielectrophoresis is carried out by intermittent separation method.The particles are adsorbed on the surface of the electrode according to the positive and negative dielectrophoresis of the particles,and the unadsorbed particles are washed away by the flow of the fluid to realize the separation of the two kinds of particles.It takes a long time until the particles are adsorbed completely before carrying out.Secondly,in order to improve the efficiency of separation,it need to set a higher electric field,which in turn causes the generation of electric heat flux to avoid the target particles were washed away.Therefore,this paper designs a particle continuous separation microfluidic chip with inertial focusing structure,which combines the inertial focusing technique with the dielectrophoretic separation technology to realize the continuous and rapid separation of particles.In this paper,the principle of inertial focusing and dielectrophoretic are studied.The influence factors of particle focusing and the influence factors of the size of the particles were analyzed by the force of particles in the channel.The frequency response characteristics of polystyrene microspheres,yeast cells and NB4 cells were analyzed to determine the force of different particles in the chip.Secondly,according to the principle of particle focusing and separation,the structure of the integrated inertial focusing particles is designed.The trapezoidal structure is provided at the inlet side of the channel so that the passing particles are focused by the action of the inertial force.The bottom of the channel is photographed by a group of interdigitating electrodes to produce a non-uniform electric field,and the different particles are generated by the combination of the dielectrophoretic force and the fluid drag force so that different angles of the deflection into different channels,in order to achieve separation.The electric field of the chip were simulated by Comsol Multiphysis software,and the size of each part of the chip was optimized and determined.The microfluidic chip was fabricated on the surface of ITO glass,and the microchannel with focusing structure was fabricated by PDMS.The chip was subjected by oxygen plasma bonding.Finally,the experimental platform was established and the continuous separation experiment was carried out.Firstly,the critical frequencies of polystyrene microspheres and yeast cells were measured,and the separation frequencies of the two groups were determined.Secondly,the polystyrene microspheres and yeast cells were continuous separated by using the designed electrode.The effects of flow rate and voltage on the separation of polystyrene microspheres and yeast cells were studied.The separation conditions were optimized.Finally,the yeast cells and NB4 cells were isolated,and the separation efficiency and the purity were statistical analysis.