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

1. Dong Wu¹, 
2. Si-Zhu Wu¹, 
3. Shuai Zhao¹, 
4. Jia Yao¹, 
5. Jiang-Nan Wang¹, 
6. Qi-Dai Chen^1,*,
7. Hong-Bo Sun^1,2,*

Article first published online: 12 NOV 2012

DOI: 10.1002/smll.201201689

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 μm, which are controlled by the period of the microstructures from 2.5 to 4 μm, and 6 μm. Finally, the ‘mechanical hand’-like 4-cell arrays are integrated into 100 μm-width microfluidic channels prepared by ultraviolet photolithography, which shows that this technique is compatible with conventional microfabrication methods for on-chip applications.