Mechanism And Experimental Study Of Particle Proportional Collection Based On Thermal Buoyancy Fiow

With the rapid development of science and technology,microfluidic technology is more and more widely used in particle collection and precise control.Thermal actuation has been proved to be efficient and efficient in particle collection and manipulation,and thermal buoyancy flow is one of them.There are many ways to induce thermal buoyancy flow.Among them,the method of heating with microelectrodes has many advantages such as easy access to heat source,simple operation principle and so on.Moreover,in the aspect of particle proportional collection,the research and application of this method are few.Therefore,this paper studied the proportional collection mechanism of particles under the action of thermal buoyancy flow and carried out some experiments,which can provide a new solution for the rapid realization of multi-concentration experimental reagent.First,through analyzing thermal float flow model of heat transfer,this paper expounds the thermal buoyant flow model of heat transfer process,established the model of the temperature distribution equation of solid and fluid components,fluid force is analyzed,using stokes formula the equations of fluid velocity and fluid continuity equation and further expounds the formation of the thermal flow of floating and thermal buoyancy flow under the action of the three process of particle capture.In addition,through the force analysis of a single particle,Newton's second law is used to determine the kinematic equation of the particle at different capture stages,and through the analysis of the flux change of the particle in the fluid,the differential equation of particle swarm motion is established by using Euler method.Then,the structure of the thermal buoyancy flow microfluidic chip was designed.The structure parameters of the electrode were simulated by COMSOL Multiphysics software.The influence of different electrode structure parameters on the temperature and velocity distribution of the fluid was analyzed.Second,processing conditions in the laboratory,the process of chip is determined,for changing electrode structure on particle proportion of collection,processing and the electrode area proportion of microfluidic chip,a preliminary explore the effect of electrode area for particle collection speed,determine the different electrode area with the same thermal power and heat with different concentration,the convection in the impact velocity.Finally,through the simulation of multi-electrode coupling,the influence of electrode connection mode,electrode spacing,voltage on fluid temperature and velocity distribution was analyzed.At the end of this paper,a method of multielectrode particle proportional collection is proposed,which is to collect the particles on average before adjusting the voltage to migrate the particle swarm.COMSOL Multiphysics was used to simulate and verify the scheme.Through the simulation analysis of 1:1,1:2 and 1:3,the feasibility of the scheme was determined from the simulation level.