The invention relates to a sheath-liquid-free particle three-dimensional focusing microfluid chip and a focusing method thereof, and belongs to the field of inertial microfluid chips. The microfluid chip is formed by bonding encapsulation of a flow channel layer and a base layer, and the flow channel layer includes a flow channel structure high in depth-to-width ratio and formed by periodic alternation and series connection of rectangular-section straight flow channels and curved flow channels. In a curve of each focusing period, under the action of inertial lift force and Dean drag force, particles are pushed and squeezed to the center of the section of the flow channel together, and the particles are gathered to the outer side of the flow channel; by means of inertial lift force in the straight flow channels in the next focusing period, cross-section distribution difference, obtained in the previous period, of the particles is subjected to induction and reorganization, so that distribution density difference between the two sides of each straight flow channel is further increased, and after multi-period focusing cumulative effect, sheath-liquid-free particle single-beam three-dimensional focusing arrangement is achieved. By means of the flow channel structure, the three-dimensional single-beam focusing arrangement of particle groups with the flow speed range of 50-2000 microliter/min and the particle size range of 1-30 microns can be achieved.
Tang, Fei, Yan Zhang, Xiaohao Wang