Rapid, Controllable Fabrication of Regular Complex Microarchitectures by Capillary Assembly of Micropillars and Their Application in Selectively Trapping/Releasing Microparticles

A simple strategy to realize new controllable 3D microstructures and a novel method to reversibly trapping and releasing microparticles are reported. This technique controls the height, shape, width, and arrangement of pillar arrays and realizes a series of special microstructures from 2-pillar-cell to 12 cell arrays, S-shape, chain-shape and triangle 3-cell arrays by a combined top down/bottom up method: laser interference lithography and capillary force-induced assembly. Due to the inherent features of this method, the whole time is less than 3 min and the fabricated area determined by the size of the laser beam can reach as much as 1 cm2, which shows this method is very simple, rapid, and high-throughput. It is further demonstrated that the mechanical hand'-like 4-cell arrays could be used to selectively trap/release microparticles with different sizes, e.g., 1.5, 2, or 3.5 m, which are controlled by the period of the microstructures from 2.5 to 4 m, and 6 m. Finally, the mechanical hand'-like 4-cell arrays are integrated into 100 m-width microfluidic channels prepared by ultraviolet photolithography, which shows that this technique is compatible with conventional microfabrication methods for on-chip applications.