title: Laser printing hierarchical structures with the aid of controlled capillary-driven self-assembly.
abstract: Capillary force is often regarded as detrimental because it may cause undesired distortion or even destruction to micro/nanostructures during a fabrication process, and thus many efforts have been made to eliminate its negative effects. From a different perspective, capillary force can be artfully used to construct specific complex architectures. Here, we propose a laser printing capillary-assisted self-assembly strategy for fabricating regular periodic structures. Microscale pillars are first produced by localized femtosecond laser polymerization and are subsequently assembled into periodic hierarchical architectures with the assistance of controlled capillary forces in an evaporating liquid. Spatial arrangements, pillar heights, and evaporation processes are readily tuned to achieve designable ordered assemblies with various geometries. Reversibility of the assembly is also revealed by breaking the balance between the intermolecular force and the elastic standing force. We further demonstrate the functionality of the hierarchical structures as a nontrivial tool for the selective trapping and releasing of microparticles, opening up a potential for the development of in situ transportation systems for microobjects.
authors.affiliation: Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China; Centre for Micro-Photonics and Centre for Ultrahigh-Bandwidth Devices for Optical Systems (CUDOS), Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia;
authors.forename: Yanlei
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China;
authors.forename: Zhaoxin
authors.initials: Z
authors.lastname: Lao
authors.affiliation: Centre for Micro-Photonics and Centre for Ultrahigh-Bandwidth Devices for Optical Systems (CUDOS), Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia;
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Cumming
authors.affiliation: Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China;
authors.forename: Dong
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China;
authors.forename: Jiawen
authors.initials: J
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Mechanical Behavior and Design of Materials, and Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027, China.
authors.forename: Haiyi
authors.initials: H
authors.lastname: Liang
authors.affiliation: Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China; jrchu@ustc.edu.cn mgu@swin.edu.au.
authors.forename: Jiaru
authors.initials: J
authors.lastname: Chu
authors.affiliation: Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China;
authors.forename: Wenhao
authors.initials: W
authors.lastname: Huang
authors.affiliation: Centre for Micro-Photonics and Centre for Ultrahigh-Bandwidth Devices for Optical Systems (CUDOS), Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; jrchu@ustc.edu.cn mgu@swin.edu.au.
authors.forename: Min
authors.initials: M
authors.lastname: Gu
keywords: capillary force; hierarchical structures; laser printing; microobject trapping; self-assembly