Abstract: Trapping and displacement of micro particles is extensively used in bioengineering, pharmaceuticals, micro-assembly, chemical analysis, and material performance evaluation. A microfluidic-based method for trapping and displacement of micro particles is presented. With this method, two identical microtubes are symmetrically aligned on both sides of a particle, which squirt inside fluid to produce a flow field. The particle is enveloped by a pressure surface which enables trapping and clamping the particle. This method is valid for micron-sized particles of arbitrary shapes and sizes. With micron-scale particles as examples, the mechanism of trapping and displacement is analyzed in detail, suitable fluid conditions of trapping and clamping particles are discussed through simulation, and dynamic process of trapping and displacement is analyzed. In addition, the feasibility of this method is verified by experiments. The results show that using a pair of aligned microtubes squirting fluid can trap and move micro particles. According to the particle size and fluid viscosity, micro particles of arbitrary sizes can be trapped and fixed with proper flow field parameters. This method is also capable of displacing the particle to some distance in a certain direction with the microtubes, thereby enabling noncontact position control of micro particles.

Key words: micro particle trapping and displacement, microfluidics, micromanipulation, noncontact