@inproceedings{ff712ed45e794cc7adfac637d7eded75,
title = "Three-dimensional printing and deformation behavior of low-density target structures by two-photon polymerization",
abstract = "Two-photon polymerization (2PP), a 3D nano to microscale additive manufacturing process, is being used for the first time to fabricate small custom experimental packages ({"}targets{"}) to support laser-driven high-energy-density (HED) physics research. Of particular interest is the use of 2PP to deterministically print low-density, low atomic-number (CHO) polymer matrices ({"}foams{"}) at millimeter scale with sub-micrometer resolution. Deformation during development and drying of the foam structures remains a challenge when using certain commercial photo-resins; here we compare use of acrylic resins IP-S and IP-Dip. The mechanical strength of polymeric beam and foam structures is examined particularly the degree of deformation that occurs during the development and drying processes. The magnitude of the shrinkage in the two resins in quantified by printing sample structures and by use of FEA to simulate the deformation. Capillary drying forces are shown to be small and likely below the elastic limit of the core foam structure. In contrast the substantial shrinkage in IP-Dip (∼5-10%) cause large shear stresses and associated plastic deformation particularly near constrained boundaries such as the substrate and locations with sharp density variation. The inherent weakness of stitching boundaries is also evident and in certain cases can lead to delamination. Use of IP-S shows marked reduction in deformation with a minor loss of print resolution.",
keywords = "2-photon polymerization, Laser targets, Low-density structures, Structure deformation",
author = "Ying Liu and Ori Stein and Campbell, {John H.} and Lijia Jiang and Nicole Petta and Yongfeng Lu",
note = "Funding Information: The authors gratefully acknowledge the financial support of the U.S. Dept. of Energy under contract #DE-NA0001385. We greatly appreciate the technical support of our many colleagues at the University of Nebraska-Lincoln Laser Assisted Nano-Engineering Laboratory and at Schafer Livermore Laboratory. Publisher Copyright: {\textcopyright} 2017 SPIE.; Nanoengineering: Fabrication, Properties, Optics, and Devices XIV 2017 ; Conference date: 09-08-2017 Through 10-08-2017",
year = "2017",
doi = "10.1117/12.2274193",
language = "English (US)",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
publisher = "SPIE",
editor = "Campo, {Eva M.} and Eldada, {Louay A.} and Dobisz, {Elizabeth A.}",
booktitle = "Nanoengineering",
}