Medical models, or ＂phantoms,＂ have been widely used for medical training and for doctor-patient interactions. They are increasingly used for surgical planning, medical computational models, algorithm verification a...Medical models, or ＂phantoms,＂ have been widely used for medical training and for doctor-patient interactions. They are increasingly used for surgical planning, medical computational models, algorithm verification and validation, and medical devices development. Such new applications demand high-fidelity, patient-specific, tissue-mimicking medical phantoms that can not only closely emulate the geometric structures of human organs, but also possess the properties and functions of the organ structure. With the rapid advancement of three-dimensional （3D） printing and 3D bioprinting technologies, many researchers have explored the use of these additive manufacturing techniques to fabricate functional medical phantoms for various applications. This paper reviews the applications of these 3D printing and 3D bioprinting technologies for the fabrication of functional medical phantoms and bio-structures. This review specifically discusses the state of the art along with new developments and trends in 3D printed functional medical phantoms （i.e., tissue-mimicking medical phantoms, radiologically relevant medical phantoms, and physiological medical phantoms） and 3D bio-printed structures （i.e., hybrid scaffolding materials, convertible scaffolds, and integrated sensors） for regenerated tissues and organs.展开更多
Due to their high hardness and high strength,VC reinforced hard materials such as high vanadium high-speed steel(HVHSS)are not suitable for machining to obtain complex shape with low cost.Therefore,3D gel printing(3DG...Due to their high hardness and high strength,VC reinforced hard materials such as high vanadium high-speed steel(HVHSS)are not suitable for machining to obtain complex shape with low cost.Therefore,3D gel printing(3DGP)was employed to print HVHSS parts,using highly loaded slurry with 60%solid content as printing slurry.After printing parameters optimization,the printing sample had good surface quality,and obvious printing lines were observed.The extruded filament was in-situ cured,thus enough to maintain the designed shape.Uniform sintering shrinkage with a shrinkage rate of about 15%was obtained in the as-sintered sample with relative density of 99%.The surface roughness decreased from 6.5μm to 3.8μm.Fine carbides(<1μm)and dense microstructure were achieved.Besides,the as-sintered sample had comprehensive performance of HRC60 in hardness,3000 MPa in bend strength,and 20−26 J in impact energy.This study proposed one promising method to directly manufacture complex-shaped hard materials without subsequent machining.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
Vascular networks inside organs provide the means for metabolic exchange and adequate nutrition.Similarly,vascular or nutrient networks are needed when building tissue constructs>500μm in vitro due to the hydrogel...Vascular networks inside organs provide the means for metabolic exchange and adequate nutrition.Similarly,vascular or nutrient networks are needed when building tissue constructs>500μm in vitro due to the hydrogel compact pore size of bioinks.As the hydrogel used in bioinks is rather soft,it is a great challenge to reconstruct effective vascular networks.Recently,coaxial 3 D bioprinting was developed to print tissue constructs directly using hollow hydrogel fibers,which can be treated as built-in microchannels for nutrient delivery.Furthermore,vascular networks could be printed directly through coaxial 3 D bioprinting.This review summarizes recent advances in coaxial bioprinting for the fabrication of complex vascularized tissue constructs including methods,the effectiveness of varying strategies,and the use of sacrificial bioink.The limitations and challenges of coaxial 3 D bioprinting are also summarized.展开更多
文摘Medical models, or ＂phantoms,＂ have been widely used for medical training and for doctor-patient interactions. They are increasingly used for surgical planning, medical computational models, algorithm verification and validation, and medical devices development. Such new applications demand high-fidelity, patient-specific, tissue-mimicking medical phantoms that can not only closely emulate the geometric structures of human organs, but also possess the properties and functions of the organ structure. With the rapid advancement of three-dimensional （3D） printing and 3D bioprinting technologies, many researchers have explored the use of these additive manufacturing techniques to fabricate functional medical phantoms for various applications. This paper reviews the applications of these 3D printing and 3D bioprinting technologies for the fabrication of functional medical phantoms and bio-structures. This review specifically discusses the state of the art along with new developments and trends in 3D printed functional medical phantoms （i.e., tissue-mimicking medical phantoms, radiologically relevant medical phantoms, and physiological medical phantoms） and 3D bio-printed structures （i.e., hybrid scaffolding materials, convertible scaffolds, and integrated sensors） for regenerated tissues and organs.
基金Projects(2019-ZD08,2020-Z17)supported by the State Key Lab of Advanced Metals and Materials,ChinaProject(52004027)supported by the National Natural Science Foundation of China+2 种基金Project(GDOE[2019]A16)supported by the Guangdong MEPP Fund,ChinaProject(311020012)supported by the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),ChinaProject(FRF-GF-20-05A)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Due to their high hardness and high strength,VC reinforced hard materials such as high vanadium high-speed steel(HVHSS)are not suitable for machining to obtain complex shape with low cost.Therefore,3D gel printing(3DGP)was employed to print HVHSS parts,using highly loaded slurry with 60%solid content as printing slurry.After printing parameters optimization,the printing sample had good surface quality,and obvious printing lines were observed.The extruded filament was in-situ cured,thus enough to maintain the designed shape.Uniform sintering shrinkage with a shrinkage rate of about 15%was obtained in the as-sintered sample with relative density of 99%.The surface roughness decreased from 6.5μm to 3.8μm.Fine carbides(<1μm)and dense microstructure were achieved.Besides,the as-sintered sample had comprehensive performance of HRC60 in hardness,3000 MPa in bend strength,and 20−26 J in impact energy.This study proposed one promising method to directly manufacture complex-shaped hard materials without subsequent machining.
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the National Key Research and Development Program of China(No.2018YFA0703000)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.51521064)。
文摘Vascular networks inside organs provide the means for metabolic exchange and adequate nutrition.Similarly,vascular or nutrient networks are needed when building tissue constructs>500μm in vitro due to the hydrogel compact pore size of bioinks.As the hydrogel used in bioinks is rather soft,it is a great challenge to reconstruct effective vascular networks.Recently,coaxial 3 D bioprinting was developed to print tissue constructs directly using hollow hydrogel fibers,which can be treated as built-in microchannels for nutrient delivery.Furthermore,vascular networks could be printed directly through coaxial 3 D bioprinting.This review summarizes recent advances in coaxial bioprinting for the fabrication of complex vascularized tissue constructs including methods,the effectiveness of varying strategies,and the use of sacrificial bioink.The limitations and challenges of coaxial 3 D bioprinting are also summarized.
