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 actuato...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.展开更多
This review provides a comprehensive overview of the various three-dimensional printing techniques for area exposure additive manufacturing using the patterned control of optical devices.Additive manufacturing techniq...This review provides a comprehensive overview of the various three-dimensional printing techniques for area exposure additive manufacturing using the patterned control of optical devices.Additive manufacturing techniques can be broadly categorized into low-power exposure and high-power melting,both of which involve innovative patterning and light-sourcing methods.The working principles and accompanying auxiliary devices of core technologies including the digital micromirror device,liquid crystal display,liquid crystal on silicon mask,and optically addressable light valve are summarized.The discussed techniques and devices have played critical roles in advancing both vat photopolymerization and powder bed fusion additive manufacturing processes and can be applied to markedly enhance printing efficiency.The advances discussed in this review hold significant promise in fields such as biomedicine,robotics,and sensing.The associated challenges and opportunities faced by the considered techniques and devices are summarized accordingly.展开更多
The anisotropic setae structures of geckos demonstrate a natural anisotropic response to external forces,thereby enabling rapid and repeated attachment and detachment.Considering this biological mechanism,this study p...The anisotropic setae structures of geckos demonstrate a natural anisotropic response to external forces,thereby enabling rapid and repeated attachment and detachment.Considering this biological mechanism,this study proposes an innovative process that harnesses the overcuring of resins in digital light processing(DLP)3D printing to emulate setae structures.The proposed method facilitates the spontaneous fabrication of anisotropic shapes from isotropically modeled geometries.Furthermore,it reduces the number of hierarchical structures typically produced in conventional 3D printing and creates smooth surfaces,thereby enhancing the structural stability for directional adhesion and detachment.The anisotropic structures were processed into functional surfaces through a double-casting method,exhibiting an adhesive strength akin to that of gecko-setae structures while maintaining easy detachment capabilities.Finally,a simple mechanical module was fabricated to directly demonstrate the detachment effect.This study introduces a novel approach to DLP printing for fabricating enhanced anisotropic structures that can be seamlessly integrated with existing 3D printing techniques.By strategically utilizing overcuring,a phenomenon often perceived as a limitation,this study demonstrated its potential to expand the boundaries of next-generation 3D printing technologies.展开更多
Background:The shortage of donor corneas is a severe global issue,and hence the development of corneal alternatives is imperative and urgent.Although attempts to produce artificial cornea substitutes by tissue enginee...Background:The shortage of donor corneas is a severe global issue,and hence the development of corneal alternatives is imperative and urgent.Although attempts to produce artificial cornea substitutes by tissue engineering have made some positive progress,many problems remain that hamper their clinical application worldwide.For example,the curvature of tissue-engineered cornea substitutes cannot be designed to fit the bulbus oculi of patients.Objective:To overcome these limitations,in this paper,we present a novel integrated three-dimensional(3 D) bioprintingbased cornea substitute fabrication strategy to realize design,customized fabrication,and evaluation of multi-layer hollow structures with complicated surfaces.Methods:The key rationale for this method is to combine digital light processing(DLP) and extrusion bioprinting into an integrated 3 D cornea bioprinting system.A designable and personalized corneal substitute was designed based on mathematical modelling and a computer tomography scan of a natural cornea.The printed corneal substitute was evaluated based on biomechanical analysis,weight,structural integrity,and fit.Results:The results revealed that the fabrication of high water content and highly transparent curved films with geometric features designed according to the natural human cornea can be achieved using a rapid,simple,and low-cost manufacturing process with a high repetition rate and quality.Conclusions:This study demonstrated the feasibility of customized design,analysis,and fabrication of a corneal substitute.The programmability of this method opens up the possibility of producing substitutes for other cornea-like shell structures with different scale and geometry features,such as the glomerulus,atrium,and oophoron.展开更多
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 res...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.展开更多
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 proc...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.展开更多
CONSPECTUS:Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymerbased additive manufacturing(AM),driven by the growing demand for multifunctional 3D-printi...CONSPECTUS:Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymerbased additive manufacturing(AM),driven by the growing demand for multifunctional 3D-printing.While several AM techniques have been adapted to process conductive composites,Digital Light Processing(DLP)stands out for its high-resolution and fast-curing capabilities.However,it poses a central limitation:the requirement for optical transparency in the printing resin,which is compromised by the incorporation of conventional conductive fillers.This Account highlights the advances in overcoming three fundamental challenges in the field:(i)How can conductive nanocomposites be printed by DLP without compromising resolution?(ii)How can high electrical conductivity be achieved at low filler content?(iii)What is the origin of anisotropic conductivity in printed objects,and how can it be mitigated?To address the first question,the authors introduced a strategy based on UV-transparent precursors,specifically monolayer graphene oxide(GO).GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol%,preserving the curing depth and optical clarity required for DLP.Postprinting thermal reduction of GO into reduced graphene oxide(rGO)yields nanocomposites with conductivities up to 10^(-2)S m^(-1)-comparable to conventional carbon nanotube(CNT)systems but achieved without high UV attenuation.To tackle the second question,the authors explored the use of single-walled carbon nanotubes(SWCNTs),which,due to their high aspect ratio and intrinsic conductivity,exhibit ultralow percolation thresholds(<0.01 vol%).At these concentrations,UV interference is negligible.However,the need for surfactant-assisted dispersion introduces contact resistance,limiting conductivity.To overcome this,this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive,enhancing internanotube contacts upon reduction.This approach achieves conductivities up to 0.3 S m^(-1),with a total filler content below 0.15 vol%,representing a significant leap in performance without sacrificing resolution.To resolve the third question regarding electrical anisotropy,the study employs polarized Raman spectroscopy,conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences.Instead,the anisotropy arises from interfacial contact resistance between printed layers,an intrinsic artifact of the layer-by-layer DLP process.Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.Beyond addressing these scientific questions,this Account highlights the practical impact of these materials.Notably,hybrid nanocomposites exhibited strong potential in microwave absorption,reaching broadband reflection losses below-10 dB at low filler loadings,due to combined ohmic and dielectric losses.These outcomes demonstrate that high-resolution,fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors,soft robotics,and electromagnetic shielding.By answering these key questions,the work establishes a foundation for the rational design of printable conductive nanocomposites,balancing optical compatibility,conductivity,and mechanical precision-paving the way for next-generation functional devices fabricated through vat photopolymerization.展开更多
Advancements in additive manufacturing(AM)are revolutionizing 3D part production,making 3D printing crucial for creating optical devices like lenses and waveguides.This study employs vat photopolymerization(VPP)to fab...Advancements in additive manufacturing(AM)are revolutionizing 3D part production,making 3D printing crucial for creating optical devices like lenses and waveguides.This study employs vat photopolymerization(VPP)to fabricate adaptive 4D printed smart Fresnel lenses with photochromic properties using digital light processing(DLP).These lenses are fabricated with precise optical performance and geometric dimensions.Photochromic powders enable dynamic color changes upon UV exposure.The lenses were optically evaluated in both inactive and active states,demonstrating excellent UV and blue light blocking when inactive.Upon UV activation,the lenses darken and absorb parts of the visible light spectrum,with the degree of absorption and color change dependent on the photochromic material and its concentration.The lenses show minimal focal length errors,maintaining high precision and UV responsiveness even at low concentrations.This research highlights the lenses’precision,UV responsiveness,blue light filtering capabilities,and stability after multiple UV exposure cycles.These findings underscore the potential of 4D printing in developing smart optical devices tailored for applications that demand dynamic light modulation and UV filtering,highlighting a combination of innovative manufacturing techniques and functional optics.展开更多
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 tha...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.展开更多
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...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.展开更多
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...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.展开更多
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 surfac...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.展开更多
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 ...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).展开更多
4D-printable shape memory polymers(SMPs)hold great promise for fabricating shape morphing biomedical devices,but most existing printed polymers either require harsh activation conditions or lack sufficient mechanical ...4D-printable shape memory polymers(SMPs)hold great promise for fabricating shape morphing biomedical devices,but most existing printed polymers either require harsh activation conditions or lack sufficient mechanical strength for vascular implantation.Here,we report a dual-stimuli-responsive shape memory polymer system enhanced by acrylated Pluronic F127(PF127-DA)micelles,which can be fabricated using digital light processing(DLP)based 3D printing.The PF127-DA based nanoscale micelles,which are formed via self-assembly in the hydrogel ink for 3D printing,act as crosslinkers to improve mechanical strength,fatigue resistance and elastic recovery.After drying the printed hydrogel,the obtained SMPs exhibit excellent shape recovery behaviour under mild physiological conditions—specifically body temperature(37℃)and aqueous swelling—resulting in recovery stress up to about 150?k Pa.This swelling-assisted actuation enables effective radial support,making the printed constructs suitable for vascular use.In vitro cytocompatibility assays with NIH/3T3 fibroblasts confirmed the suitable biocompatibility.Furthermore,the self-expanding behavior of the printed stents was validated in an occluded vessel model under physiological conditions.These results demonstrate the feasibility of 4D printed micelle-enhanced SMP for patient-specific,minimally invasive vascular stents and other soft implantable devices requiring high recovery force under physiological stimulation.展开更多
In bone tissue engineering,scaffolds with excellent mechanical and bioactive properties play prominent roles in space maintaining and bone regeneration,attracting increasingly interests in clinical practice.In this st...In bone tissue engineering,scaffolds with excellent mechanical and bioactive properties play prominent roles in space maintaining and bone regeneration,attracting increasingly interests in clinical practice.In this study,strontium-incorporatedβ-tricalcium phosphate(β-TCP),named Sr-TCP,bioceramic triply periodic minimal surface(TPMS)structured scaffolds were successfully fabricated by digital light processing(DLP)-based 3D printing technique,achieving high porosity,enhanced strength,and excellent bioactivity.The Sr-TCP scaffolds were first characterized by element distribution,macrostructure and microstructure,and mechanical properties.Notably,the compressive strength of the scaffolds reached 1.44 MPa with porosity of 80%,bringing a great mechanical breakthrough to porous scaffolds.Furthermore,the Sr-TCP scaffolds also facilitated osteogenic differentiation of mouse osteoblastic cell line(MC3T3-E1)cells in both gene and protein aspects,verified by alkaline phosphatase(ALP)activity and polymerase chain reaction(PCR)assays.Overall,the 3D-printed Sr-TCP bioceramic TPMS structured scaffolds obtained high porosity,boosted strength,and superior bioactivity at the same time,serving as a promising approach for bone regeneration.展开更多
Additive manufacturing(AM),which is also known as three-dimensional(3D)printing,uses computer-aided design to build objects layer by layer.Here,we focus on the recent progress in the development of techniques for 3D p...Additive manufacturing(AM),which is also known as three-dimensional(3D)printing,uses computer-aided design to build objects layer by layer.Here,we focus on the recent progress in the development of techniques for 3D printing of glass,an important optoelectronic material,including fused deposition modeling,selective laser sintering/melting,stereolithography(SLA)and direct ink writing.We compare these 3D printing methods and analyze their benefits and problems for the manufacturing of functional glass objects.In addition,we discuss the technological principles of 3D glass printing and applications of 3D printed glass objects.This review is finalized by a summary of the current achievements and perspectives for the future development of the 3D glass printing technique.展开更多
基金the National Natural Science Foundation of China(Nos.11572002 and 12002032)the China Postdoctoral Science Foundation(Nos.BX20200056 and 2020M670149)。
文摘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.
文摘This review provides a comprehensive overview of the various three-dimensional printing techniques for area exposure additive manufacturing using the patterned control of optical devices.Additive manufacturing techniques can be broadly categorized into low-power exposure and high-power melting,both of which involve innovative patterning and light-sourcing methods.The working principles and accompanying auxiliary devices of core technologies including the digital micromirror device,liquid crystal display,liquid crystal on silicon mask,and optically addressable light valve are summarized.The discussed techniques and devices have played critical roles in advancing both vat photopolymerization and powder bed fusion additive manufacturing processes and can be applied to markedly enhance printing efficiency.The advances discussed in this review hold significant promise in fields such as biomedicine,robotics,and sensing.The associated challenges and opportunities faced by the considered techniques and devices are summarized accordingly.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2023-00260527).
文摘The anisotropic setae structures of geckos demonstrate a natural anisotropic response to external forces,thereby enabling rapid and repeated attachment and detachment.Considering this biological mechanism,this study proposes an innovative process that harnesses the overcuring of resins in digital light processing(DLP)3D printing to emulate setae structures.The proposed method facilitates the spontaneous fabrication of anisotropic shapes from isotropically modeled geometries.Furthermore,it reduces the number of hierarchical structures typically produced in conventional 3D printing and creates smooth surfaces,thereby enhancing the structural stability for directional adhesion and detachment.The anisotropic structures were processed into functional surfaces through a double-casting method,exhibiting an adhesive strength akin to that of gecko-setae structures while maintaining easy detachment capabilities.Finally,a simple mechanical module was fabricated to directly demonstrate the detachment effect.This study introduces a novel approach to DLP printing for fabricating enhanced anisotropic structures that can be seamlessly integrated with existing 3D printing techniques.By strategically utilizing overcuring,a phenomenon often perceived as a limitation,this study demonstrated its potential to expand the boundaries of next-generation 3D printing technologies.
基金Project supported by the National Natural Science Foundation of China(Nos.51875518 and 51475419)the Key Research and Development Projects of Zhejiang Province(Nos.2017C01054 and2018C03062)the Fundamental Research Funds for the Central Universities(No.2019FZA4002),China
文摘Background:The shortage of donor corneas is a severe global issue,and hence the development of corneal alternatives is imperative and urgent.Although attempts to produce artificial cornea substitutes by tissue engineering have made some positive progress,many problems remain that hamper their clinical application worldwide.For example,the curvature of tissue-engineered cornea substitutes cannot be designed to fit the bulbus oculi of patients.Objective:To overcome these limitations,in this paper,we present a novel integrated three-dimensional(3 D) bioprintingbased cornea substitute fabrication strategy to realize design,customized fabrication,and evaluation of multi-layer hollow structures with complicated surfaces.Methods:The key rationale for this method is to combine digital light processing(DLP) and extrusion bioprinting into an integrated 3 D cornea bioprinting system.A designable and personalized corneal substitute was designed based on mathematical modelling and a computer tomography scan of a natural cornea.The printed corneal substitute was evaluated based on biomechanical analysis,weight,structural integrity,and fit.Results:The results revealed that the fabrication of high water content and highly transparent curved films with geometric features designed according to the natural human cornea can be achieved using a rapid,simple,and low-cost manufacturing process with a high repetition rate and quality.Conclusions:This study demonstrated the feasibility of customized design,analysis,and fabrication of a corneal substitute.The programmability of this method opens up the possibility of producing substitutes for other cornea-like shell structures with different scale and geometry features,such as the glomerulus,atrium,and oophoron.
基金supported by Shandong University−MSEA International Institute for Materials Genome Joint Innovation Center for Advanced Ceramics,and the Key Research and Development Projects of Shaanxi Province(Nos.2018ZDCXLGY-09-06 and 2021ZDLGY14-06).
文摘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.
基金The authors gratefully acknowledged the financial support provided by the National Key R&D Program of China(No.2021YFB3701500)the Program of Shanghai Academic/Technology Research Leader(No.22XD1404000).
文摘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.
基金the AID(Agence Innovation Défense)and the Nouvelle Aquitaine Region。
文摘CONSPECTUS:Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymerbased additive manufacturing(AM),driven by the growing demand for multifunctional 3D-printing.While several AM techniques have been adapted to process conductive composites,Digital Light Processing(DLP)stands out for its high-resolution and fast-curing capabilities.However,it poses a central limitation:the requirement for optical transparency in the printing resin,which is compromised by the incorporation of conventional conductive fillers.This Account highlights the advances in overcoming three fundamental challenges in the field:(i)How can conductive nanocomposites be printed by DLP without compromising resolution?(ii)How can high electrical conductivity be achieved at low filler content?(iii)What is the origin of anisotropic conductivity in printed objects,and how can it be mitigated?To address the first question,the authors introduced a strategy based on UV-transparent precursors,specifically monolayer graphene oxide(GO).GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol%,preserving the curing depth and optical clarity required for DLP.Postprinting thermal reduction of GO into reduced graphene oxide(rGO)yields nanocomposites with conductivities up to 10^(-2)S m^(-1)-comparable to conventional carbon nanotube(CNT)systems but achieved without high UV attenuation.To tackle the second question,the authors explored the use of single-walled carbon nanotubes(SWCNTs),which,due to their high aspect ratio and intrinsic conductivity,exhibit ultralow percolation thresholds(<0.01 vol%).At these concentrations,UV interference is negligible.However,the need for surfactant-assisted dispersion introduces contact resistance,limiting conductivity.To overcome this,this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive,enhancing internanotube contacts upon reduction.This approach achieves conductivities up to 0.3 S m^(-1),with a total filler content below 0.15 vol%,representing a significant leap in performance without sacrificing resolution.To resolve the third question regarding electrical anisotropy,the study employs polarized Raman spectroscopy,conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences.Instead,the anisotropy arises from interfacial contact resistance between printed layers,an intrinsic artifact of the layer-by-layer DLP process.Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.Beyond addressing these scientific questions,this Account highlights the practical impact of these materials.Notably,hybrid nanocomposites exhibited strong potential in microwave absorption,reaching broadband reflection losses below-10 dB at low filler loadings,due to combined ohmic and dielectric losses.These outcomes demonstrate that high-resolution,fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors,soft robotics,and electromagnetic shielding.By answering these key questions,the work establishes a foundation for the rational design of printable conductive nanocomposites,balancing optical compatibility,conductivity,and mechanical precision-paving the way for next-generation functional devices fabricated through vat photopolymerization.
基金We acknowledge Khalifa University for the research funding,in the form of Advanced Digital&Additive Manufacturing(ADAM)Group(Award No.RCII-2019-003),in support of this research.
文摘Advancements in additive manufacturing(AM)are revolutionizing 3D part production,making 3D printing crucial for creating optical devices like lenses and waveguides.This study employs vat photopolymerization(VPP)to fabricate adaptive 4D printed smart Fresnel lenses with photochromic properties using digital light processing(DLP).These lenses are fabricated with precise optical performance and geometric dimensions.Photochromic powders enable dynamic color changes upon UV exposure.The lenses were optically evaluated in both inactive and active states,demonstrating excellent UV and blue light blocking when inactive.Upon UV activation,the lenses darken and absorb parts of the visible light spectrum,with the degree of absorption and color change dependent on the photochromic material and its concentration.The lenses show minimal focal length errors,maintaining high precision and UV responsiveness even at low concentrations.This research highlights the lenses’precision,UV responsiveness,blue light filtering capabilities,and stability after multiple UV exposure cycles.These findings underscore the potential of 4D printing in developing smart optical devices tailored for applications that demand dynamic light modulation and UV filtering,highlighting a combination of innovative manufacturing techniques and functional optics.
基金the National Key R&D Program of China(2017YFB1103500,2017YFB1103502).
文摘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.
基金sponsored by the National Key Research and Development Program of China(2017YFB0702600)National Natural Science Foundation of China(31971283,31670985)Sichuan Science and Technology Programs(2019JDTD0008,2021YFS0032).
文摘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.
基金supported by grants from the Key Project Fund for Science and Technology Development of Guangdong Province (2020B090924003)the National Natural Science Foundation of China (51975230)Major Special Projects of Technological Innovation in Hubei Province (2019AAA002).
文摘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.
基金This work was supported by the financial support from the Major Special Projects of Technological Innovation in Hubei Province(2019AAA002)the National Key R&D Program of China(2018YFB1105503)Fundamental Research Funds for the Central Universities(2019kfyXMPY020,2020kfyFPZX003,2018KFYYXJJ030,and 2019kfyXKJC011).
文摘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.
文摘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).
基金Natural Science Basic Research Program of Shaanxi(No.2025JC-YBMS-358)the Fundamental Research Funds for the Central Universities(No.D5000250307)。
文摘4D-printable shape memory polymers(SMPs)hold great promise for fabricating shape morphing biomedical devices,but most existing printed polymers either require harsh activation conditions or lack sufficient mechanical strength for vascular implantation.Here,we report a dual-stimuli-responsive shape memory polymer system enhanced by acrylated Pluronic F127(PF127-DA)micelles,which can be fabricated using digital light processing(DLP)based 3D printing.The PF127-DA based nanoscale micelles,which are formed via self-assembly in the hydrogel ink for 3D printing,act as crosslinkers to improve mechanical strength,fatigue resistance and elastic recovery.After drying the printed hydrogel,the obtained SMPs exhibit excellent shape recovery behaviour under mild physiological conditions—specifically body temperature(37℃)and aqueous swelling—resulting in recovery stress up to about 150?k Pa.This swelling-assisted actuation enables effective radial support,making the printed constructs suitable for vascular use.In vitro cytocompatibility assays with NIH/3T3 fibroblasts confirmed the suitable biocompatibility.Furthermore,the self-expanding behavior of the printed stents was validated in an occluded vessel model under physiological conditions.These results demonstrate the feasibility of 4D printed micelle-enhanced SMP for patient-specific,minimally invasive vascular stents and other soft implantable devices requiring high recovery force under physiological stimulation.
基金supported by the National Natural Science Foundation of China(Nos.51972339 and 51802350).
文摘In bone tissue engineering,scaffolds with excellent mechanical and bioactive properties play prominent roles in space maintaining and bone regeneration,attracting increasingly interests in clinical practice.In this study,strontium-incorporatedβ-tricalcium phosphate(β-TCP),named Sr-TCP,bioceramic triply periodic minimal surface(TPMS)structured scaffolds were successfully fabricated by digital light processing(DLP)-based 3D printing technique,achieving high porosity,enhanced strength,and excellent bioactivity.The Sr-TCP scaffolds were first characterized by element distribution,macrostructure and microstructure,and mechanical properties.Notably,the compressive strength of the scaffolds reached 1.44 MPa with porosity of 80%,bringing a great mechanical breakthrough to porous scaffolds.Furthermore,the Sr-TCP scaffolds also facilitated osteogenic differentiation of mouse osteoblastic cell line(MC3T3-E1)cells in both gene and protein aspects,verified by alkaline phosphatase(ALP)activity and polymerase chain reaction(PCR)assays.Overall,the 3D-printed Sr-TCP bioceramic TPMS structured scaffolds obtained high porosity,boosted strength,and superior bioactivity at the same time,serving as a promising approach for bone regeneration.
基金This work was financially supported by the National Key R&D Program of China(No.2018YFB1107200)the National Natural Science Foundation of China(Grant No.51772270)+1 种基金the Open Project Program of Wuhan National Laboratory for Optoelectronics(No.2018-WNLOKF005)State Key Laboratory of High Field Laser Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences.
文摘Additive manufacturing(AM),which is also known as three-dimensional(3D)printing,uses computer-aided design to build objects layer by layer.Here,we focus on the recent progress in the development of techniques for 3D printing of glass,an important optoelectronic material,including fused deposition modeling,selective laser sintering/melting,stereolithography(SLA)and direct ink writing.We compare these 3D printing methods and analyze their benefits and problems for the manufacturing of functional glass objects.In addition,we discuss the technological principles of 3D glass printing and applications of 3D printed glass objects.This review is finalized by a summary of the current achievements and perspectives for the future development of the 3D glass printing technique.
