基于动态多焦点双光子聚合的微螺旋结构制备  

Fabrication of Micro-Helix Structures via Two-Photon Polymerization Based on Dynamic Multi-Focus Holograms

作　　者：谢辰 孙世贤 贾而穑 胡明列 Xie Chen;Sun Shixian;Jia Erse;Hu Minglie(Ultrafast Laser Laboratory,Key Laboratory of Opto-Electronic Information Science and Technology Ministry of Education,College of Precision Instruments and OptoElectronics Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学精密仪器与光电子工程学院超快激光研究室&光电信息技术教育部重点实验室,天津300072

出　　处：《中国激光》2023年第24期200-207,共8页Chinese Journal of Lasers

基　　金：国家自然科学基金(62275191,61605142,61827821);天津市杰出青年基金(17JCJQJC43500)。

摘　　要：微螺旋结构在微机器人、手性超材料中有重要应用,不同的应用对螺旋结构有着不一样的要求。基于飞秒激光双光子聚合技术可以直写任意三维微结构,然而,单焦点逐点直写的效率较低。基于结构光场的单步曝光方案能够实现高效制备,但目前受限于复杂而专业的光场调控技术,仅能制备较有限的微螺旋结构。针对微尺度多螺旋结构,本文提出了一种基于动态多焦点的制备方案。该方案将光斑的螺旋运动轨迹分解为由动态全息图控制的圆周运动和由z轴位移台控制的线性扫描,最终成功制备了直径、螺线数、螺距与手性等特征灵活可控的多重微螺旋结构。所提微螺旋结构制备方案兼具经济性及高效灵活的优势,对于微机器人、手性超材料和生物工程等领域的相关研究具有较大的参考价值。Objective Micro-helices are applied in microrobots and chiral metamaterials and require various features for structure fabrication in diverse applications.The femtosecond laser direct writing(FsLDW) technology can fabricate three dimensional(3D) microstructures based on two-photon polymerization(2PP) with sub-diffraction-limited resolution.This technology is used to fabricate micro-helix structures using the widely used point-by-point writing scheme with a single focus.However,this is relatively inefficient because of the repetitive scans along many helical trajectories in the fabrication process.Recently,one-step exposure with structured light has allowed the rapid fabrication of micro-helices,wherein helical beams are specially designed with vortex phases.However,state-of-theart schemes can only produce microstructures with limited patterns owing to the complex and professional light manipulation techniques.To efficiently fabricate micro-helix structures with flexible features such as diameter,thread number,pitch,and chirality,we propose a scheme based on dynamic multi-focus patterns to fabricate multiple helical microstructures.Methods Micro-helix structures were fabricated by piling up the multi-focal voxels along helical trajectories.The helical motion of the voxels was divided into two components:a circular motion manipulated by dynamic holograms loaded on the spatial light modulator(SLM),and a linear motion controlled by a z-axis translation stage(Fig.3).Based on our in-house fabrication system,we adapted the Gerchberg-Saxton(G-S) algorithm to compute dynamic multi-focus holograms on the SLM iteratively.Subsequently,the tightly focused femtosecond multi-focal beam patterns induced polymerization of the photoresist(SU-8).In this method,the diameter and thread number of the micro-helices were determined by the parameters of the hologram alone under fixed exposure conditions.The dynamic holograms with the z-axis translation stage allowed flexible control of the pitch and chirality.Results and Discussions The

关 键 词：激光技术 微螺旋 双光子聚合 多焦点 空间光调制器 

分 类 号：O436[机械工程—光学工程]