Soft pneumatic actuators by digital light processing combined with injection-assisted post-curing

The soft robotics display huge advantages over their rigid counterparts when interacting with living organisms and fragile objects.As one of the most efficient actuators toward soft robotics,the soft pneumatic actuator(SPA)can produce large,complex responses with utilizing pressure as the only input source.In this work,a new approach that combines digital light processing(DLP)and injection-assisted post-curing is proposed to create SPAs that can realize different functionalities.To enable this,we develop a new class of photo-cross linked elastomers with tunable mechanical properties,good stretchability,and rapid curing speed.By carefully designing the geometry of the cavities embedded in the actuators,the resulting actuators can realize contracting,expanding,flapping,and twisting motions.In addition,we successfully fabricate a soft self-sensing bending actuator by injecting conductive liquids into the three-dimensional(3D)printed actuator,demonstrating that the present method has the potential to be used to manufacture intelligent soft robotic systems.

DLP投影技术——Digital Light Procession

投影技术可能是最古老的现代显示技术之一，它发源于19世纪早期，并随着19世纪末20世纪初电影的发明和流行得以迅速推广。投影技术发展到今天，CRT投影技术主要面向高端领域：LCD和DLP瞄准家用市场，而且逐渐向高清方向发展；同时，光源技术和其他相关技术的进步也使得投影技术的发展如虎添翼。在《数字家庭》的创刊号（2005年11期）中，我们介绍了3LCD投影技术，现在，我们看看DLP投影技术。

High strength mullite-bond SiC porous ceramics fabricated by digital light processing

Fabricating SiC ceramics via the digital light processing(DLP)technology is of great challenge due to strong light absorption and high refractive index of deep-colored SiC powders,which highly differ from those of resin,and thus significantly affect the curing performance of the photosensitive SiC slurry.In this paper,a thin silicon oxide(SiO_(2))layer was in-situ formed on the surface of SiC powders by pre-oxidation treatment.This method was proven to effectively improve the curing ability of SiC slurry.The SiC photosensitive slurry was fabricated with solid content of 55 vol%and viscosity of 7.77 Pa·s(shear rate of 30 s^(−1)).The curing thickness was 50μm with exposure time of only 5 s.Then,a well-designed sintering additive was added to completely convert low-strength SiO_(2) into mullite reinforcement during sintering.Complexshaped mullite-bond SiC ceramics were successfully fabricated.The flexural strength of SiC ceramics sintered at 1550℃in air reached 97.6 MPa with porosity of 39.2 vol%,as high as those prepared by spark plasma sintering(SPS)techniques.

Fabrication and biological evaluation of 3D-printed calcium phosphate ceramic scaffolds with distinct macroporous geometries through digital light processing technology

Digital light processing(DLP)-based 3D printing technique holds promise in fabricating scaffolds with high precision.Here raw calcium phosphate(CaP)powders were modified by 5.5%monoalcohol ethoxylate phosphate(MAEP)to ensure high solid loading and low viscosity.The rheological tests found that photocurable slurries composed of 50wt%modified CaP powders and 2wt%toners were suitable for DLP printing.Based on geometric models designed by computer-aided design(CAD)system,three printed CaP ceramics with distinct macroporous structures were prepared,including simple cube,octet-truss and inverse face-centered cube(fcc),which presented the similar phase composition and microstructure,but the different macropore geometries.Inverse fcc group showed the highest porosity and compressive strength.The in vitro and in vivo biological evaluations were performed to compare the bioactivity of three printed CaP ceramics,and the traditional foamed ceramic was used as control.It suggested that all CaP ceramics exhibited good biocompatibility,as evidence by an even bone-like apatite layer formation on the surface,and the good cell proliferation and spreading.A mouse intramuscular implantation model found that all of CaP ceramics could induce ectopic bone formation,and foam group had the strongest osteoinduction,followed by inverse fcc,while cube and octet-truss had the weakest one.It indicated that macropore geometry was of great importance to affect the osteoinductivity of scaffolds,and spherical,concave macropores facilitated osteogenesis.These findings provide a strategy to design and fabricate high-performance orthopedic grafts with proper pore geometry and desired biological performance via DLP-based 3D printing technique.

A novel mullite anti-gyroid/SiC gyroid ceramic metastructure based on digital light processing 3D printing with enhanced electromagnetic wave absorption and mechanical properties

Sic-based composites are widely used as electromagnetic wave absorbers due to their excellent dielectric properties.However,the constraints associated with structural design and the intricacies of the preparation process hinder their broader application.In this study,novel mullite anti-gyroid/SiC gyroid metastructures are designed to integrate the mechanical and electromagnetic wave(EMW)absorption properties of composite materials.Mullite anti-gyroid/SiC gyroid composites are fabricated utilizing a combination of digital light processing(DLP)three-dimensional(3D)printing and precursor infiltration and pyrolysis(PiP)processes.Through the modulation of structural units,the electromagnetic parameters can be effectively regulated,thus improving the impedance matching characteristics of the composites.The structural composites show outstanding EMW absorption properties,with a minimum reflection loss of-54 dB at a thickness of 1.9 mm and an effective absorption bandwidth of 3.20 GHz at a thickness of 2.2 mm.Furthermore,the PIP process significantly enhances the mechanical properties of the composites;compared with those of the mullite/SiC ceramics,the flexural strength of the composites is improved by 3.69-5.85 times(13.28±1.15 MPa vs.(49.05±1.07)-(77.78±3.72)MPa),and the compressive strength is improved by 4.59-13.58 times(8.55±0.90 MPa vs.(39.02±1.63)-(116.13±2.58)MPa).This approach offers a novel and effective method for fabricating structural composites with an expanded range of higher electromagnetic wave absorption properties and improved mechanical properties.

Demonstration of a Polymer-Based Single Step Waveguide by 3D Printing Digital Light Processing Technology for Isopropanol Alcohol-Concentration Sensor

A polymer based horizontal single step waveguide fbr the sensing of alcohol is developed and analyzed.The waveguide is fabricated by 3-dimensional(3D)printing digital light processing(DLP)technology using monocure 3D rapid ultraviolet(UV)clear resin with a refractive index of n=1.50.The fabricated waveguide is a one-piece tower shaped ridge structure.It is designed to achieve the maximum light confinement at the core by reducing the effective refractive index around the cladding region.With the surface roughness generated from the 3D printing DLP technology,various waveguides with different gap sizes are printed.Comparison is done fbr the different gap waveguides to achieve the minimum feature gap size utilizing the light re-coupling principle and polymer swelling effect.This effect occurs due to the polymer-alcohol interaction that results in the diffusion of alcohol molecules inside the core of the waveguide,thus changing the waveguide from the leaky type(without alcohol)to the guided type(with alcohol).Using this principle,the analysis of alcohol concentration performing as a larger increase in the transmitted light in tensity can be measured.In this work,the sensitivity of the system is also compared and analyzed fbr different waveguide gap sizes with different concentrations of isopropanol alcohol(IPA).A waveguide gap size of 300 jim gives the highest in crease in the transmitted optical power of 65%when tested with 10μL(500ppm)concentration of IPA.Compared with all other gaps,it also displays faster response time(/=5seconds)fbr the optical power to change right after depositing IPA in the chamber.The measured limit of detection(LOD)achieved fbr 300μm is 0.366 yL.In addition,the fabricated waveguide gap of 300μm successfully demonstrates the sen sing limit of IPA concentration below 400μpm which is considered as an exposure limit by"National Institute for Occupational Safety and Health".All the mechanical mount and the alignments are done by 3D printing fused deposition method(FDM).

基于DLP 3D打印的高给药效率微针制备工艺

载药微针可以实现一次性快速药物递送,无需二次药物涂敷与输送过程,但其不佳的载药量与刺入率造成了给药效率差的问题。研发了一种基于数字光处理(DLP)3D打印技术的高给药效率微针(HDMN)制备工艺。通过在载药微针上构建锯齿状针体结构与阶梯状载药结构来提高载药微针的刺入率与载药量,进而提高给药效率。实验结果表明使用环氧丙烯酸酯(EA)打印微针时,当曝光时间为700 ms、打印层厚为30μm时,打印出的微针实际尺寸与理论尺寸平均误差最小为9.2%。利用旋涂法在微针表面交联聚乙二醇二丙烯酸酯(PEGDA)以改善微针生物相容性。显微镜观察发现,当交联层数为1层时,PEGDA均匀地覆盖在微针表面。石蜡膜穿刺实验结果表明,HDMN穿透了2层石蜡膜,而相同实验条件下的传统载药微针仅穿透了1层。药物释放实验结果表明,HDMN相对于传统载药微针在猪皮内留下的模拟药物浓度提升了61%。该研究为后续通过改善微针结构来优化微针性能研究提供了有益借鉴。

基于DLP投影光刻方法的PDMS柔性磁轴编码驱动器

传统的聚二甲基硅氧烷(PDMS)磁轴编码的方法依赖于固定模具单向磁化、喷墨3D打印和重编码等方法,存在编码自由度不足、编码稳定性差等问题。本文报告了一种基于数字光处理(DLP)投影光刻的紫外(UV)光固化方法,利用光敏PDMS将磁性颗粒的重定向与图案化分块UV曝光相结合,实现对PDMS材料的快速、图案化、多自由度的磁性编程。本文对该方法加工的PDMS磁轴编码驱动器的进行了性能测试,并展示了该方法在柔性变形装置与软体机器人领域的应用。

High performance hydroxyapatite ceramics and a triply periodic minimum surface structure fabricated by digital light processing 3D printing

High performance hydroxyapatite(HA)ceramics with excellent densification and mechanical properties were successfully fabricated by digital light processing(DLP)three-dimensional(3D)printing technology.It was found that the sintering atmosphere of wet C02 can dramatically improve the densification process and thus lead to better mechanical properties.HA ceramics with a relative density of 97.12%and a three-point bending strength of 92.4 MPa can be achieved at a sintering temperature of 1300℃,which makes a solid foundation for application in bone engineering.Furthermore,a relatively high compressive strength of 4.09 MPa can be also achieved for a DLP-printed p-cell triply periodic minimum surface(TPMS)structure with a porosity of 74%,which meets the requirement of cancellous bone substitutes.A further cell proliferation test demonstrated that the sintering atmosphere of wet CO2 led to improve cell vitality after 7 days of cell culture Moreover,with the possible benefit from the bio-inspired structure,the 3D-printed TPMS structure significantly improved the cell vitality,which is crucial for early osteogenesis and osteointegration.

Influence of high-temperature oxidation of SiC powders on curing properties of SiC slurry for digital light processing

Fabrication of silicon carbide(SiC)ceramics by digital light processing(DLP)technology is difficult owing to high refractive index and high ultraviolet(UV)absorptivity of SiC powders.The surface of the SiC powders can be coated with silicon oxide(SiO_(2))with low refractive index and low UV absorptivity via high-temperature oxidation,reducing the loss of UV energy in the DLP process and realizing the DLP preparation of the SiC ceramics.However,it is necessary to explore a high-temperature modification process to obtain a better modification effect of the SiC powders.Therefore,the high-temperature modification behavior of the SiC powders is thoroughly investigated in this paper.The results show that nano-scale oxide film is formed on the surface of the SiC powders by short-time high-temperature oxidation,effectively reducing the UV absorptivity and the surface refractive index(nʹ)of the SiC powders.When the oxidation temperature is 1300℃,compared with that of unoxidized SiC powders,the UV absorptivity of oxidized SiC powders decreases from 0.5065 to 0.4654,and a curing depth of SiC slurry increases from 22±4 to 59±4μm.Finally,SiC green bodies are successfully prepared by the DLP with the the oxidized powders,and flexural strength of SiC sintered parts reaches 47.9±2.3 MPa after 3 h of atmospheric sintering at 2000℃without any sintering aid.

Preparation and properties of T-ZnO_(w) enhanced BCP scaffolds with double-layer structure by digital light processing

Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair.In this work,T-ZnO_(w) enhanced biphasic calcium phosphate(BCP)scaffolds with triply periodic minimal surface(TPMS)-based double-layer porous structure were fabricated by digital light processing(DLP)with high precision.Property of suspension was first discussed to obtain better printing quality.After sintering,T-ZnO_(w) reacts with b-tricalcium phosphate(β-TCP)to form Ca_(19)Zn_(2)(PO_(4))14,and inhibits the phase transition toα-TCP.With the content of T-ZnO_(w) increasing from 0 to 2 wt%,the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress,and have the effect of pulling out as well as fracture toughening.However,excessive whiskers will reduce the cure depth,and cause more printing defects,thus reducing the mechanical strength.Besides,T-ZnO_(w) accelerates the deposition of apatite,and the sample with 2 wt%T-ZnO_(w) shows the fastest mineralization rate.The good biocompatibility has been proved by cell proliferation test.Results confirmed that doping T-ZnO_(w) can improve the mechanical strength of BCP scaffolds,and keep good biological property,which provides a new strategy for better bone repair.

DLP光固化3D打印含能药柱及延期性能

以光固化液态树脂、镁粉、高氯酸铵和燃速调节剂为主要成分,设计一种含能浆料配方,利用数字光处理(DLP)光固化3D打印技术打印了具有延期功能的含能药柱,测试了含能药柱的燃烧过程、延期性能、药柱均匀性和相容性,分析了延期时间的影响因素。研究结果表明:用于DLP光固化3D打印的含能浆料最佳配方质量分数为:燃速调节剂7.53%、高氯酸铵(AP)62.37%、Mg 3.22%、光固化树脂26.88%。浆料性能测试结果为黏度325 mPa·s,固化时间3.2s,固化硬度2H,收缩率4.98%。成功打印的含能药柱为圆柱形,尺寸为Φ6 mm×11.5 mm,平均密度为1.507 g·cm^(-3),各组分均匀分布,相容性好,燃烧稳定,发出明亮的黄色火焰,燃烧残渣率为4.98%,无黑烟产生,平均延期时间为12.43 s,延期时间的标准偏差为0.0158 s,平均燃速为0.805 mm·s^(-1),燃速标准差为0.0012 mm·s^(-1),延期时间满足长秒量延期药标准,延期精度可满足秒级延期药要求。延期时间的影响主次为AP>光固化液态树脂>燃速调节剂>Mg,调整含能浆料各组分含量可控制含能药柱的延期时间,实现不同延期目的。

DLP投影显示系统的优势及发展前景

基于DLP技术的新投影系统已被开发出来,该系统的核心是DMD器件。采用二进制脉宽调制技术精确控制光的灰度等级,在大屏幕上可得到高亮度、高对比度、高分辨率的优质彩色投射图像。本文介绍DLP系统及DMD的基本工作原理,讨论DLP显示系统在技术上的优势,分析DLP显示的市场前景和技术发展趋势,

基于DLP投影的智能像素前照灯研究

本文介绍一种基于DLP投影的智能像素前照灯系统,其以LED作为光源,DMD芯片作为核心器件,基于数字光处理(DLP)技术,结合智能识别控制算法,实现全数字化操控,可扩展性好,控制精度高达百万像素级别。

DLP高精度3D打印系统搭建及其在细胞打印中的应用

细胞的三维培养是目前的研究热点,其主要依赖于微尺寸下水凝胶细胞支架的制备。常规的3D打印是常用的细胞支架制备技术,但其无法同时满足打印范围和打印精度的需求,且存在打印速度慢的局限性,这限制了高精度、较大范围细胞3D打印技术的发展。基于数字光处理(DLP)技术,搭建了一个成本低、打印范围较大、精度在微米级的细胞打印平台。该平台包括数字动态掩膜投影光学系统、实时检焦光学系统和高精度运动系统三个部分。通过聚乙二醇双丙烯酸酯(PEGDA)水凝胶微结构的紫外固化实验,证明该平台实际打印精度可达25μm。该平台可通过精确控制高精度位移平台的移动,实现较大范围打印。为验证细胞打印的可行性,使用搭建的平台完成了甲基丙烯酸化水凝胶(GelMA)生物细胞支架的打印,并完成了人肝细胞系HL7702细胞的三维培养。该平台未来可用于组织和器官打印与高通量药物筛选领域。

大幅面DLP型3D打印机错位均摊接缝消除方法研究

针对面曝光模式的数字光处理(Digital light processing,DLP)型3D打印机成型幅面较小问题,提出一种移动拼接与错位均摊消除接缝痕迹相结合的大幅面技术方案.该方案首先对三维模型进行均匀切片形成N层切面,再对切面位图进行错位切分,使得相邻层的拼接位置错开,每张切面位图形成M张单元位图,构成3D打印的数据源;其次根据错位参数沿着X轴移动投影仪到达对应曝光位,每层成型M张单元位图,拼接构成一层切面薄片,切面薄片的拼接位置逐层错开,叠加生成三维模型实体.实际打印结果表明,该方案能够以较小的附加成本扩大成型尺寸,提高模型整体质量.

基于TI DLP技术的投影机驱动电路设计和实现

DLP是由美国德州仪器公司研制的一种全数字投影技术,在投影机上已经得到广泛的应用。但是,面对LCD和LCOS投影机的竞争,如何在保持投影机的良好性能基础上尽可能地降低成本,成为每个DLP投影机生产厂商必须考虑的问题。设计了以TI DDP2230芯片为核心的DLP投影机驱动电路,利用了"极致色彩"技术实现完美的投影效果。该电路性能优良,具有设计简单、功能强大、成本低等优点;有极高的应用价值和市场前景。

基于侧面DLP的3D打印技术制作微流控芯片

微流控芯片的关键技术是内部封闭管道的制备,其中一步打印出微流控芯片及接口尤为重要。基于数字光处理(DLP)技术提出了一种新型的侧面曝光打印技术,并利用4F光路以及运动系统完成平台搭建。该3D打印系统的投影图像分辨率为12.5μm,靶面约为16 mm×10 mm。相比常用的上曝光或下曝光3D打印技术,其容易消除气泡且装置简单。通过对封闭管道打印机制分析及实验优化,可实现直径400μm的圆形或边长400μm的方形等封闭管道打印。为验证侧面曝光打印平台打印微流控芯片的可行性,设计具有一体化封闭管道和接口的模型进行打印测试,40 min可以打印一个6 mm厚的微流控芯片,管道打通率为100%。结果表明该平台可用于快速制作微流控芯片,未来可用于微流控及微纳制造领域。

DLP型3D打印机参数对树脂影响的研究

以本团队所研发的光敏树脂为打印材料,基于数字光处理(DLP)3D打印光固化技术制备了拉伸样条,研究了基础固化时间、首层固化时间对拉伸样条的表观、拉伸强度、断裂伸长率、硬度等的影响。后续研究了打印后处理对固化成型树脂的影响。结果表明,当基础固化时间高于10 s,首层固化时间高于35 s时,拉伸样条打印完整,随着打印时间的增加,对固化成型树脂的性能并没有太大影响,如果时间更长,反而影响其性能。因此,综合考虑时间成本及打印的效果,首层固化时间约为12 s、基础固化时间约为40 s时为最佳。此外,通过研究对比发现,树脂的清洗适合几秒的喷洗而不是长时间的浸泡。与在阴凉的环境下相比,在阳光下后固化的更快更好。

多光源连续生产的DLP型3D打印机研制

针对当前DLP技术成型幅面较小导致的其在生产型3D打印设备中难以使用的问题,提出一种多光源连续生产的DLP型3D打印机设计方案。利用多个DLP光机扩大成型幅面,设计出一种具有多沟槽的托板及梳状铲刀,以此实现成型后的零件自动从托板上取下并放到接料槽中,并配合集中供液系统实现打印机内树脂的自动补充。借助计算机网络技术,每次打印完后通知云端服务器,服务器自动下发下一个生产任务给打印机,解决了DLP型3D打印机幅面过小及无法连续生产的难题,对3D打印技术从原型制造到小批量生产的升级有着积极的意义。