Encryption/decryption and microtarget capturing by pH-driven Janus microstructures fabricated by the same femtosecond laser printing parameters

Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus structure is a promising approach to achieve shape transformation based on its heterogeneous chemical or physical properties on opposite sides.However, the heterogeneity is generally realized by multi-step processing, different materials,and/or different processing parameters. Here, we present a simple and flexible method of producing p H-sensitive Janus microactuators from a single material, using the same laser printing parameters. These microactuators exhibit reversible structural deformations with large bending angles of ~31°and fast response(~0.2 s) by changing the p H value of the aqueous environment. Benefited from the high flexibility of the laser printing technique and the spatial arrangements, pillar heights, and bending directions of microactuators are readily controlled,enabling a variety of switchable ordered patterns and complex petal-like structures on flat surfaces and inside microchannels. Finally, we explore the potential applications of this method in information encryption/decryption and microtarget capturing.

A multi-photon(7×7)-focus 3D laser printer based on a 3D-printed diffractive optical element and a 3D-printed multi-lens array

One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/s.Here,we present a setup based on a 7×7 focus array(rather than 3×3 in our previous work)and using a focus velocity of about 1 m/s(rather than 0.5 m/s in our previous work)at the diffraction limit(40×/NA1.4 microscope objective lens).Combined,this advance leads to a ten times increased print speed of about 108 voxels/s.We demonstrate polymer printing of a chiral metamaterial containing more than 1.7×10^(12) voxels as well as millions of printed microparticles for potential pharmaceutical applications.The critical high-quality micro-optical components of the setup,namely a diffractive optical element generating the 7×7 beamlets and a 7×7 lens array,are manufactured by using a commercial two-photon grayscale 3D laser printer.

Towards in-situ diagnostics of multi-photon 3D laser printing using optical coherence tomography

In recent years,multi-photon 3D laser printing has become a widely used tool for the fabrication of micro-and nanostructures for a large variety of applications.Typically,thorough sample characterisation is key for an efficient optimisation of the printing process.To date,three-dimensional microscopic inspection has usually been carried out on finished 3D printed microstructures,that is,using ex-situ approaches.In contrast,in-situ 3D characterization tools are desirable for quickly assessing the quality and properties of 3D printed microstructures.Along these lines,we present and characterise a Fourier-domain optical coherence tomography(FD-OCT)system that can be readily integrated into an existing 3D laser lithography setup.We demonstrate its capabilities by examining different 3D printed polymer microstructures immersed in a liquid photoresist.In such samples,local reflectivity arises from the(refractive-index)contrasts between the polymerised and non-polymerised regions.Thus,the refractive index of the printed material can be extracted.Furthermore,we demonstrate that the reflectivity of polymer-monomer transitions exhibits time-dependent behaviour after printing.Supported by transfer-matrix calculations,we explain this effect in terms of the time-dependent graded-index transition originating from monomer diffusion into the polymer matrix.Finally,we show exemplary 3D reconstructions of printed structures that can be readily compared with 3D computer designs.

Formation Process and Mechanical Deformation Behavior of a Novel Laser-Printed Compression-Induced Twisting-Compliant Mechanism

A novel compression-induced twisting(CIT)-compliant mechanism was designed based on the freedom and constraint topology(FACT)method and manufactured by means of laser powder bed fusion(LPBF).The effects of LPBF printing parameters on the formability and compressive properties of the laserprinted CIT-compliant mechanism were studied.Within the range of optimized laser powers from 375 to 450 W and with the densification level of the samples maintained at above 98%,changes in the obtained relative densities of the LPBF-fabricated CIT-compliant mechanism with the applied laser powers were not apparent.Increased laser power led to the elimination of residual metallurgical pores within the inclined struts of the CIT mechanism.The highest dimensional accuracy of 0.2% and the lowest surface roughness of 20μm were achieved at a laser power of 450 W.The deformation behavior of the CIT-compliant mechanism fabricated by means of LPBF exhibited four typical stages:an elastic stage,a heterogeneous plastic deformation stage,a strength-destroying stage,and a deformation-destroying stage(or instable deformation stage).The accumulated compressive strain of the optimally printed CIT mechanism using a laser power of 450 W went up to 20% before fracturing,demonstrating a large deformation capacity.The twisting behavior and mechanical properties were investigated via a combination of finite-element simulation and experimental verification.An approximately linear relationship between the axial compressive strain and rotation angle was achieved before the strain reached 15% for the LPBF-processed CIT-compliant mechanism.

Development of Laser Fusion Printing Machine for Ceramic Teeth Crown

Since former president Obama of America put forward the concept of 3D printing or additive manufacturing, it had been putting into use rapidly and getting acceptance widely. In particular, metal additive manufacturing machines had been successfully applied with pilot demonstration in industry. However, the present metal additive manufacturing machines cannot be directly used in medical fields such as dental restoration because of some different requirements between industry and medical fields. In this case, this paper is aimed for the development of laser fusion printing machine (LFP), also being called as selective laser melting (SLM), for ceramic teeth crown in dental restoration business. Through the reasonable design and development of key components such as machinery unit, optical unit, electrical controlling unit, and software unit, and the integration, debugging, and optimization of the entire system, the laser fusion printing apparatus for dental restoration has been successfully developed. Key technologies such as machine structure design, optical unit design, electrical controlling system design, system software and process software have been overcome, on the basis of which, a lot of process experiments of medical titanium alloy materials were deeply carried out. At last laser fusion printing technology of titanium alloy was mastered, and titanium dental crown by laser fusion printing with relative density up to 97.37% was realized. After post treatment with porcelain, it was found that the laser fusion printed porcelain teeth with titanium alloy has good metal-ceramic bonding strength, which is equivalent to the quality of traditional porcelain teeth, which showed that laser fusion printing can meet the requirements of dental restoration business and has a broad market outlook.

Laser Micro-Printing of Dye-Molecules on Polymeric Surfaces

We describe a technique for micro-patterning and immobilization of dyes on polymer substrates using a low-power visible laser for dye-excitation. Deposits from an aqueous medium containing the dye can be attached at any desired spot on the substrate simply by exposing the area to laser light. The area of the laser beam can control the spot-size of immobilized dye, in the range of 10 - 100 microns. The immobilization technique is characterized by micro-printing numerals, alphabets and patterns on polybutadiene substrates with Rhodamine (Rh6G) dye. Adsorption of laser-excited dye molecules within the polymer appears to be the mechanism for laser-printing technique.

Gyroid结构钛仿生骨支架修复下颌骨节段性缺损的生物力学性能

背景:三周期最小表面的多孔结构是最有前景的骨科生物结构之一,其中的Gyroid结构具有高比表面积、高渗透率、均曲率为零等特点。目的:通过有限元分析结合力学压缩实验测试,筛选出与下颌骨松质骨弹性模量范围相匹配的4 mm单胞Gyroid结构TC4仿生骨支架壁厚区间。方法:建立不同壁厚(0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8 mm)4 mm单胞Gyroid结构有限元模型,分析Gyroid结构的等效弹性模量,筛选出与下颌骨松质骨弹性模量范围相匹配的Gyroid结构壁厚区间,壁厚分别为0.2,0.3,0.4,0.5,0.6,0.7 mm。根据有限元分析筛选结果,以Ti6Al4V为原料,采用选择性激光熔融技术制备不同壁厚的3D打印Gyroid结构试件,进行大颗粒喷砂酸蚀处理,通过力学压缩实验测试试件的弹性模量与抗压强度。结果与结论:(1)有限元分析结果显示,随着壁厚的增加,Gyroid结构的等效弹性模量升高,其中壁厚为0.2-0.7 mm Gyroid结构的等效弹性模量在下颌骨松质骨弹性模量范围内(1.5-4.0 GPa),用于3D打印Gyroid结构试件;(2)力学压缩实验结果显示,随着壁厚的增加,Gyroid结构试件的弹性模量与抗压强度均升高,其中0.3-0.5 mm壁厚Gyroid结构试件的弹性模量在下颌骨松质骨弹性模量范围内,0.3-0.7 mm壁厚Gyroid结构试件的抗压强度符合下颌骨的力学性能;(3)结果显示0.3-0.5 mm壁厚Gyroid结构与下颌骨的弹性模量范围相适应。

Laser-induced forward transferred silver nanomembrane with controllable light absorption

Laser processing provides highly-controlled modification and on-demand fabrication of plasmon metal nanostructures for light absorption and photothermal convention.We present the laser-induced forward tansfer(LIFT)fabrication of silver nanomembranes in control of light absorption.By varying the hatch distance,different morphologies of randomly distributed plasmon silver nanostructures were produced,leading to well-controlled light absorption levels from 11%to 81%over broadband.The anti-reflection features were maintained below 17%.Equilibrated and plain absorptions were obtained throughout all absorption levels with a maximum intensity fluctuation of±8.5%for the 225μJ cases.The 45μJ pulse energy can offer a highly equilibrated absorption at a 60%absorption level with an intensity fluctuation of±1%.Pattern transfer was also achieved on a thin tape surface.The laser-transferred characters and patterns demonstrate a localized temperature rise.A rapid temperature rising of roughly 15℃can be achieved within 1 s.The LIFT process is highly efficiently fabricated with a typical speed value of 10^(3)to 10^(5)cm^(2)/h.The results indicated that LIFT is a well-controlled and efficient method for the production of optical films with specific absorption levels.

Preparation of a Novel Cationic Photosensitive Resin(3D-SLR01) for Stereolithography 3D Printing and Determination of Its Some Properties

A novel cationic photosensitive resin(3 DSLR-01) for stereolithography 3 D printing was prepared with 3,4-epoxycyclohexylmethyl-3’,4’-epoxycyclohexane carboxylate(2021 P),1,4-cyclohexanedimethanol glycidyl ether(JX-026), diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate(S-186), polycaprolactone polyol(Polyol-0305), novolac epoxy resin(F-51), bis(3-ethyl-3-oxetanylmethyl) ether(S-221) and a mixture of triarylsulfonium hexafluoroantimonate salts solution(UVI-6976). The properties of the photosensitive resin and its UV-cured films were investigated by some instruments and equipment.The experimental results show that the critical exposure(Ec) of the photosensitive resin is 16.3 mJ/cm^2, the penetration depth(Dp) is 0.14 mm, and the optical property of the photosensitive resin is excellent. Rectangle plates were printed by using a stereolithography apparatus(HRPL-150 A) with the photosensitive resin as the manufacturing material, and the shrinkage rates of the plates were less than 0.60%, which showed that the accuracy of the manufactured plates was very high.

Preparation of A Novel Hybrid Type Photosensitive Resin for Stereolithography in 3D Printing and Testing on the Accuracy of the Fabricated Parts

A novel hybrid type photosensitive resin for stereolithography in 3D printing was prepared with bisphenol A type epoxy diacrylate （EA-612）, tripropylene glycol diacrylate （TPGDA）,ethoxylated trimethyolpropane triacrylate（EO3TMPTA）, cycloaliphatic diepoxide（ERL-4221）,polycaprolactonepolyol（Polyol-0301）,1-hydroxy-cyclohphenyl ketone（Irgacure184）, and a mixture of triarylsulfonium hexafluoroantimonate salts （Ar3SSbF6）. The novel hybrid type photosensitive resin was the photosensitive resin of an epoxy-acrylate hybrid system, which proceeded free radical polymerization and cationic polymerization in ultraviolet （UV） laser. Cuboid parts and double-cantilever parts were fabricated by using a stereolithography apparatus with the novel hybrid type photosensitive resin as the processing material,and the dimension shrinkage factor and the curl factor were tested. The shrinkage factor was less than 2.00%,and the curl factor was less than 8.00%, which showed that the accuracy of the fabricated parts was high with the photosensitive resin for stereolithography in 3D printing.

Application of Bis[2-(3,4-epoxycyclohexyl)ethyl]octamethyltetrasiloxane in the Preparation of a Photosensitive Resin for Stereolithography 3D Printing

Bis[2-(3,4-epoxycyclohexyl)ethyl]octamethyltetrasiloxane is also called diepoxycyclohexylethyl octamethyltetrasiloxane. In the present paper, diepoxycyclohexylethyl octamethyltetrasiloxane was synthesized, and the synthesized product was characterized by FTIR and 1 HMR. The synthesized product was compounded with some acrylates and an expoxide as well as photoinitiators to obtain a 3D printing stereolithography resin(3DSLR111). The properties of 3DSLR111 and its UV-cured samples were investigated by some instruments and equipments. The experimental results show that the critical exposure(Ec) of 3DSLR111 is 10.1 mJ/cm^2, its penetration depth(Dp) is 0.15 mm, and its viscosity at 30 ℃ is 319 mPa·s. Some samples were printed with 3DSLR111, and their linear shrinkage and warping factor were evaluated. The linear shrinkage and the curl distortion factor are less than 0.80% and 7.30%, respectively, which indicates that the sample printed with 3DSLR111 has high accuracy, and that the synthesized diepoxycyclohexylethyl octamethyltetrasiloxane can be well applied to the preparation of the photosensitive resin for stereolithography 3D printing.

Investigations on Structured Polyamide for Laser Sintered Body Armor

Stab resistance body armor（SRBA）is essential in protecting people from knife injuries.The protective parts of traditional SRBA are made of multi-layered ultra-high molecular weight polyethylene（UHMWPE）,which causes heavy heat stress for people wearing it.The protective parts of SRBA manufactured using laser sintering（LS）3D printing technology provide high manufacturing flexibility and low weight.Two different structures,plain plate and pyramid-structured plate,were investigated.The pyramid structure showed much higher stab resistance property then the plain plate,because of the angle and thickness effects.This is the first effort applying the LS technology and polyamide（PA）material（PA3200）on SRBA.By applying the pyramid structure on the protective layer of the SRBA,the total weight could reduce 30%-40%.

金属增材制造工艺、材料及成形机理的研究与应用

作为一种快速、精密、自由制造的关键成形工艺,3D打印在推动工业化和产业发展方面发挥了重要作用。通过介绍金属3D打印技术,主要围绕选择性激光、电化学和电子束增材制造技术等工艺原理和关键技术,深入探讨了增材制造技术制备金属材料零部件的特性及其应用,同时详细阐述了它们的成形机理并探讨了金属3D打印技术所面临的主要问题和挑战。最后,对金属增材制造技术领域未来的发展趋势和研究重点进行了展望。

基于Kano-FAST的瓦楞纸激光印刷设备设计研究

目的推动印刷行业朝更高效的方向迈进,提高印刷设备的易操作性和视觉识别性。方法将Kano和FAST(Function Analysis System Technique)模型引入瓦楞纸激光打印设备设计的前期应用需求分析中,通过问卷的方法获取用户的基本要求,并划分为几个子类型,进而建立Kano的二维功能属性模型。采用FAST法建立功能树,辅助使用Kano模型,从而更精准地分析用户需求,并更好地根据其需求进行优化设计。结果综合运用设计原理,针对性地挖掘瓦楞纸激光印刷设备在造型识别性、操作易用性、生产安全性上存在的问题,进而输出更优解。结论该设计方法的引入有助于为同类型的印刷设备设计提供参考,并引起更多相关厂家的重视,推动印刷行业向更积极的方向发展。

融合自注意力与残差神经网络的3D打印激光在机测量误差修正方法

激光测量能够实现高效地非接触实时测量,被广泛应用于3D打印领域,但激光测量容易受测量条件、外部环境等多种因素的干扰,这些因素错综复杂,难以量化分析。为此,结合直射式激光三角测量原理,在分析测量精度影响因素的基础上,提出了一种基于融合自注意力和残差神经网络的3D打印在机测量误差修正方法。首先,将影响测量精度的因素作为输入变量,采集激光测量值,得到样本数据集;然后利用残差网络提取出样本数据的深层次特征,并引入自注意力机制建立影响因素之间的联系,得到带权重的提取特征;再通过全连接网络对带权重特征进行学习,得到测量误差的预测值,基于该预测值完成对测量误差的修正。自主搭建了一套激光在机测量系统,采用红、绿、紫3种同材质彩色卡纸进行实验验证。结果表明,所提的方法与卷积神经网络和自注意力神经网络相比,均方误差、均方根误差和平均绝对误差均最小,稳定性最好,修正结果最接近真实值;对激光测量结果进行校正后,使其误差由原来的±28μm减小到±9μm以下,显著提高了3D打印激光在机测量的精度和稳定性。

激光技术在塑料加工中的应用与案例

激光技术在工业中应用得到了很大的发展,尤其在塑料加工中应用逐步取代传统的加工方式,这对塑料加工质量和加工效率等都有较好地成效。本文就激光原理、特点与类型作些介绍,围绕了激光技术在塑料加工中应用作了描述,结合对3D打印、切割(打孔)、焊接、表面打标、表面处理、表面清洗等原理和应用案例进行详细分享,并对激光在塑料加工中应用趋势作些预料。

基于医学CT与SLM技术的踝关节骨骼逆向建模与制备

基于医学CT与3D打印技术实现了骨骼重建与制造。通过对病人踝关节骨骼原始CT数据的采集,运用医学逆向工程软件Mimics及Geomagic软件对骨骼分别进行三维模型重建和骨骼曲面修复、优化,得到了骨面较为光滑平整的踝关节模型。通过对骨骼模型进行静力学分析,说明在人体结构生物力学条件下,所建立的踝关节三维模型满足力学要求。通过实验获得了TC4钛合金激光选区熔化(SLM)技术的优化工艺参数为激光功率240 W,扫描速度800 mm/s,扫描间距为0.12 mm,铺粉厚度为0.05 mm。采用该工艺参数和所建立的踝关节模型,实现了TC4钛合金踝关节3D打印逆向制造,所得制品的形状与组织成分优,满足医学使用要求。

颗粒级配对选区激光烧结打印结合常压固相烧结制备碳化硅陶瓷性能的影响

SiC陶瓷因其独特的热学、电学性能及优异的力学性能,被广泛应用于航空航天、核能、化工、半导体等国防与工业重大领域,但是传统的成型方法无法满足大尺寸复杂构件的制备需求。选区激光烧结(SLS)打印具有无需支撑、材料利用率高、加工效率高等优势,能高效成型复杂陶瓷结构零部件。本研究采用颗粒级配SiC的方法,系统研究了冷等静压(CIP)、前驱体浸渍热解(PIP)、CIP结合PIP后常压固相烧结等工艺对级配和中位径82μm未级配体系SiC陶瓷的影响。研究发现,级配粉末成型坯体的体积密度和抗弯强度比未级配坯体均提升了20%以上,级配体系CIP后常压固相烧结体的相对致密度达到了90%以上,实现了致密化烧结,而未级配体系烧结体的相对致密度仅为89%,这是由颗粒级配后坯体的堆积密度提升所致,且级配烧结体的抗弯强度(136.8 MPa)比未级配(99.4 MPa)提升了37%以上。采用多次重复PIP结合常压固相烧结的方法制备高致密的SiC陶瓷,发现SLS打印成型的坯体经四次PIP后致密度可达到CIP堆积致密的效果,但四次PIP后常压固相烧结体的体积密度仅为2.29 g/cm^(3),抗弯强度为59.6 MPa。

3D打印-激光烧结制备导体和介质厚膜的显微结构与性能

为拓展3D打印技术在厚膜混合集成电路制备领域的应用,提高厚膜浆料烧结效率,采用3D直写+激光烧结制备三种导体浆料厚膜和一种介质浆料厚膜,并与常规的丝网印刷+高温炉烧结厚膜进行显微结构与性能的对比研究。结果表明,常规丝网印刷+高温炉烧结的导体及介质厚膜具有良好的显微结构与性能。相比而言,3D直写+激光烧结制备的导体厚膜平整连续、厚度均匀,焊接性能良好,但结构不够致密,部分导体厚膜存在膜层附着力不足,方阻偏大的问题;介质厚膜激光烧结后的致密性较导体厚膜更低,绝缘性能不满足要求。3D直写制备导体或介质浆料厚膜具有可行性,但激光烧结工艺参数有待优化,以实现厚膜的烧结致密化,提高厚膜与基板的结合强度。

结构对SLS砂型次级烧结区的影响及其控制工艺研究

设计了一种包含多种常见结构的精度测试件,用于探究结构对SLS打印的砂型成形精度的影响。通过打印和尺寸测量发现,纵向椭圆结构和圆孔的次级烧结相对其他结构更加严重,且存在方向性差异。采用低密度多道次的扫描方法,相较于常规扫描方法,在0.1 J·mm·s^(-2)的总能量密度下可以将国标鼓形件的精度等级从无评级提高至5级,筋板的尺寸偏差降低到0.072 mm,显著改善了砂型的尺寸精度。