Single-Shot Microfabrication of Complex 3D Structures by Volumetric Multiphoton Lithography

Multi-photon lithography (MPL) is a technique for fabricating three-dimensional (3D) microstructures with submicron resolution. Arbitrarily complex forms are created by scanning a focal spot in a photoresist using a galvo scanner or a piezoelectric stage to locally induce multi-photon polymerization. The requirement for point-by-point scanning severely limits the throughput of MPL and hinders its industrial use. Methods for parallel exposure have been explored for improving the fabrication speed in MPL. Various approaches for 2D beam shaping have been used to pattern layers in parallel, but little is known of ways to achieve volumetric exposure, in which whole 3D sub-parts or complete 3D structures are patterned in a single exposure. We recently reported a method for high-throughput fabrication of complex 3D volumes using normal and superposed Bessel beams [1-7]. Complex structures were created in a single static exposure using one or a few laser pulses, including cylinders, needles, and spirals with tunable pitch. Importantly, the pitch distance can be designed to vary along the optical axis, creating “accelerating” or “decelerating” spirals with desired handedness. With complementary horizontal beam scanning, self-supporting matrices of spirals were fabricated in the photoresist SU-8 demonstrating the feasibility of large-scale fabrication. Volumetric exposure increases fabrication throughput by at least two orders of magnitude. This method paves the way for mass production of functional devices using MPL having applications in photonics, microfluidics, bioscaffolds, medicine, and more.<br/><br/>1. Cheng, H.; Xia, C.; Zhang, M.; Kuebler, S. M.; Yu, X., Fabrication of high-aspect-ratio structures using Bessel-beam-activated photopolymerization. <i>Applied Optics </i><b>2019,</b> <i>58</i> (13), D91-D97.<br/>2. Cheng, H.; Xia, C.; Sun, M.; Zhang, M.; Kuebler, S. M.; Yu, X., Micro-and nanofabrication using Bessel-beam activated photopolymerization. <i>Journal of Laser Applications </i><b>2020,</b> <i>32</i> (2), 022067.<br/>3. Cheng, H.; Xia, C.; Kuebler, S. M.; Yu, X., Aberration correction for SLM-generated Bessel beams propagating through tilted interfaces. <i>Optics Communications </i><b>2020,</b> <i>475</i>, 126213.<br/>4. Cheng, H.; Xia, C.; Kuebler, S. M.; Golvari, P.; Sun, M.; Zhang, M.; Yu, X., Generation of Bessel-beam arrays for parallel fabrication in two-photon polymerization. <i>Journal of Laser Applications </i><b>2021,</b> <i>33</i> (1), 012040.<br/>5. Cheng, H.; Golvari, P.; Xia, C.; Sun, M.; Zhang, M.; Kuebler, S. M.; Yu, X. In <i>Rapid microfabrication of helical structures for industrial applications</i>, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XV, SPIE: 2022; pp 22-29.<br/>6. Cheng, H.; Golvari, P.; Xia, C.; Sun, M.; Zhang, M.; Kuebler, S. M.; Yu, X. In <i>Volumetric microfabrication of helical structures for industrial applications</i>, Novel Patterning Technologies 2022, SPIE: 2022; pp 69-75.<br/>7. Cheng, H.; Golvari, P.; Xia, C.; Sun, M.; Zhang, M.; Kuebler, S. M.; Yu, X., High-throughput microfabrication of axially tunable helices. <i>Photonics Research </i><b>2022,</b> <i>10</i> (2), 303-315.