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.

Microfluidic bubble-generator enables digital light processing 3D printing of porous structures

Three-dimensional(3D)printing is an emerging technique that has shown promising success in engineering human tissues in recent years.Further development of vatphotopolymerization printing modalities has significantly enhanced the complexity level for 3D printing of various functional structures and components.Similarly,the development of microfluidic chip systems is an emerging research sector with promising medical applications.This work demonstrates the coupling of a digital light processing(DLP)printing procedure with a microfluidic chip system to produce size-tunable,3D-printable porosities with narrow pore size distributions within a gelatin methacryloyl(GelMA)hydrogel matrix.It is found that the generation of size-tunable gas bubbles trapped within an aqueous GelMA hydrogel-precursor can be controlled with high precision.Furthermore,the porosities are printed in two-dimensional(2D)as well as in 3D using the DLP printer.In addition,the cytocompatibility of the printed porous scaffolds is investigated using fibroblasts,where high cell viabilities as well as cell proliferation,spreading,and migration are confirmed.It is anticipated that the strategy is widely applicable in a range of application areas such as tissue engineering and regenerative medicine,among others.

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.

基于熔模铸造的DLP光固化增材制造装备的研制

文章将DLP光固化成型技术与熔模铸造工艺相结合,研制了适用于陶瓷浆料打印的光固化增材制造装备。以实现DLP光固化成型工艺参数:曝光时间、曝光层厚及曝光强度等为设计出发点,合理设计光固化打印机的选型及零部件布置,验证最佳工艺参数,确定了设备最佳曝光时间为30~35 s;最佳打印曝光层厚为0.1 mm。

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。

DLP大灯设计与应用研究

车灯是汽车核心零部件,集驾驶安全、场景应用、信息交互功能于一身,正朝智能化和功能化方向发展。数字投影技术的应用为汽车大灯带来革命级别的技术创新,诞生更加智能和更多功能的数字投影大灯。由于数字投影大灯具有亮度高、分辨率高、应用场景多及安全性强等诸多优势,正成为汽车大灯的未来趋势。基于很高的基础研究价值和应用前景,该文系统地研究基于数字微镜的数字投影大灯的设计原理以及应用场景。

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.

Fabrication of Ceramic-Polymer Piezo-Composites with Triply Periodic Minimal Interfaces via Digital Light Processing

The geometry of the phase interface in co-continuous piezoelectric composites is critical in improving their piezo-electric properties.However,conventional co-continuous piezoelectric composites are mostly simple structures such as wood stacks or honeycombs,which are prone to stress concentrations at the joints,thus reducing the fatigue service performance and force-electric conversion efficiency of piezoelectric composites.Such simple structures limit further improvements in the overall performance of co-continuous piezoelectric composites.In this study,based on the digital light processing 3D printing method,we investigated the influence of three dif-ferent structures-the gyroid,diamond,and woodpile interfaces-on the piezoelectric and mechanical properties of co-continuous ceramic/polymer piezoelectric composites.These findings demonstrate that the gyroid and di-amond interfaces outperformed the ceramic skeleton of the woodpile interface in terms of both mechanical and electrical properties.When the ceramic volume percentage was 50%,the piezo-composite of the gyroid surface exhibited the greatest hydrostatic figure of merit(HFOM),reaching 4.23×10^(−12) Pa^(−1),and its piezoelectric coeffi-cient(d_(33))and relative dielectric constant(εr)reached 115 pC/N and 748,respectively.The research results lay the foundation for the application of co-continuous piezoelectric composites in underwater communication and detection.

Tough PEG-only hydrogels with complex 3D structure enabled by digital light processing of“all-PEG”resins

Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP.Instead of using aqueous solutions of photo-crosslinkable monomers,PEG macromonomer melts werefirst printed in the absence of water,resulting in bulk PEG networks.Then,post-printing swelling of the printed networks was achieved in water,producing high-fidelity 3D hydrogels with complex structures.By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator,“all-PEG”hydrogel constructs were pro-duced with compressive toughness up to 1.3 MJ m^(-3).By this approach,porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated,and the scaf-fold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells.This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication,which may accelerate the development of 3D tissue-like constructs for regenerative medicine.

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。

增材制造钛酸钡压电陶瓷的高温烧结与极化工艺研究

为提高增材制造BaTiO_(3)压电陶瓷的综合性能,本文研究了BaTiO_(3)压电陶瓷的浆料剪切变稀特性及数字光处理(DLP)成型特性,揭示了DLP成型BaTiO_(3)压电陶瓷坯体在不同烧结温度条件下的致密化机制,探索了极化方向对DLP成型BaTiO_(3)陶瓷压电性能的影响规律。结果表明,调节高温烧结与极化工艺,可以在一定程度上改善DLP增材制造BaTiO_(3)压电陶瓷的电学性能。当烧结温度为1420℃、保温时间为2 h时,压电系数d_(33)最大,为163.4 pC/N,样品层间结合紧密,晶粒尺寸均匀。当Z轴与极化方向夹角由0°变为90°时,相对介电常数εr和d_(33)分别提高了29.37%和27.01%。当固含量为80%(质量分数)、烧结温度为1420℃、Z轴与极化方向夹角为90°时,样品d_(33)最大,达到182.4 pC/N。

Additive manufacturing of hydroxyapatite bioceramic scaffolds: Dispersion, digital light processing, sintering, mechanical properties, and biocompatibility

Hydroxyapatite(HA)bioceramic scaffolds were fabricated by using digital light processing(DLP)based additive manufacturing.Key issues on the HA bioceramic scaffolds,including dispersion,DLP fabrication,sintering,mechanical properties,and biocompatibility were discussed in detail.Firstly,the ffects of dispersant dosage,solid loading,and sintering temperature were studied.The optimal dispersant dosage,solid loading,and sintering temperature were 2wt%,50vol%,and 1250℃,respectively.Then,the mechanical properties and biocompatibility of the HA bioceramic scaffolds were investigated.The DLP-prepared porous HA bioceramic scaffold was found to exhibit excellent mechanical properties and degradation behavior.From this study,DLP technique shows good potential for manufacturing HA bioceramic scaffolds.

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.

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.

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.

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).

数字化光处理技术在陶瓷3D打印领域的应用进展

陶瓷材料因其优异的机械性能、耐高温性和化学稳定性,在众多领域得到广泛应用。然而传统陶瓷加工工艺复杂且成本高昂,限制了其应用的发展。与传统材料加工成型工艺相比,增材制造擅长解决个性化、复杂化、特殊化和高难度的异型精密部件加工问题。本文探讨了数字化光处理(DLP)技术在陶瓷3D打印领域的应用进展,介绍DLP的基本原理与发展历程,分析氧化铝、氧化锆和氮化硅等典型陶瓷材料在DLP打印中的配方体系、烧结制度、力学性能测试及应用案例。通过改进光敏树脂的配方、优化打印工艺和后处理技术,可进一步提升陶瓷材料的打印质量和性能,为其在更多高性能应用领域的推广提供技术支持。