Study Of A Microfluidic-based Method For Micro Particle Trapping And Displacement

With the fast development of modern technology, studies on application fields have stepped into micro scales and therefore micromanipulation techniques have received widespread attention. Micro particle trapping and displacement is a key technique in micromanipulation and is widely used in bioengineering, pharmaceuticals, micro-assembly, chemical analysis, and material performance evaluation.This work creatively proposed a microfluidic-based noncontact method for trapping and displacing micro particles. A pair of same microtubes is symmetrically placed on both sides of a particle, squirting fluid to produce a flow field. The particle is enveloped by a pressure surface which enables trapping and displacing the particles. In this work, with micron particles as examples, the mechanism of trapping and displacing was analyzed and the dynamics models were established. Proper flow field conditions for micro particle trapping and displacement as well as its dynamic process were discussed through simulation. Experiments were also conducted and the correctness of the simulation models and the feasibility of the method were demonstrated.Firstly, based on fluid dynamics, this paper analyzed the mechanism of trapping and displacement and discussed influences of particle parameters, microtube parameters and fluid parameters on manipulation performance to offer a reference for simulation and experiments; then we explained and described the formation of fluid flow. This paper also discussed the forces acting on a particle in the flow field and established its movement model, which laid a foundation for following simulations.Based on previous mechanism analysis, we used Finite Volume Method(FVM) and dynamic mesh technique to establish simulation models for particle trapping and displacement. We simulated the formation of the flow field, discussed influences of microtube distance, inner diameters, alignment and jetting velocity on the flow field performance, and explored conditions suitable for trapping and displacement; then we simulated the process of trapping and displacing and analyzed its manipulation performance. We also discussed trapping and displacing with unaligned microtubes as well as the feasibility of trapping and displacing particles which were not in the center and particles of different shapes and sizes.Finally, we established an experiment platform and conducted experiments including flow field visualization and micro particle trapping and displaceme nt. Experiment results showed that micro particles could be trapped and displaced by two aligned microtubes squirting fluid.Large experiments showed that this method could trap micro particles of different shapes and sizes and displace them in a certain d irection with certain distance, thus achieving position control of micro particles.