Photonic crystals with three-dimensional dielectric structures were fabricated to control terahertz waves effectively by using micro-stereolithography of a CAD/CAM process. The photonic crystals with a diamond structu...Photonic crystals with three-dimensional dielectric structures were fabricated to control terahertz waves effectively by using micro-stereolithography of a CAD/CAM process. The photonic crystals with a diamond structure composed of acrylic lattice with nanosized alumina particles were fabricated. Dense alumina structures were obtained by successive dewaxing and sintering in an air atmosphere. The electromagnetic wave properties of these samples were measured by using a terahertz spectroscopy device. The micro periodic structures exhibited perfect band gaps in the terahertz range. To control terahertz waves, micrometer sized electromagnetic devices for cavities, filters, and antennas will be necessary.展开更多
Projection micro stereolithography(PμSL)has emerged as a powerful three-dimensional(3D)printing technique for manufacturing polymer structures with micron-scale high resolution at high printing speed,which enables th...Projection micro stereolithography(PμSL)has emerged as a powerful three-dimensional(3D)printing technique for manufacturing polymer structures with micron-scale high resolution at high printing speed,which enables the production of customized 3D microlattices with feature sizes down to several microns.However,the mechanical properties of as-printed polymers were not systemically studied at the relevant length scales,especially when the feature sizes step into micron/sub-micron level,limiting its reliable performance prediction in micro/nanolattice and other metamaterial applications.In this work,we demonstrate that PμSL-printed microfibers could become stronger and significantly more ductile with reduced size ranging from 20μm to 60μm,showing an obvious size-dependent mechanical behavior,in which the size decreases to 20μm with a fracture strain up to~100%and fracture strength up to~100 MPa.Such size effect enables the tailoring of the material strength and stiffness of PμSL-printed microlattices over a broad range,allowing to fabricate the microlattice metamaterials with desired/tunable mechanical properties for various structural and functional applications.展开更多
This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography （MSL） process. As a key enabler of high accuracy in this process, a comp...This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography （MSL） process. As a key enabler of high accuracy in this process, a compact desktop-size beam flexure-based nanopositioner was designed with millimeter range and nanometric motion quality. This beam flexure-based motion system is highly suitable for harsh operation conditions, as no assembly or maintenance is required during the operation. From a mechanism design viewpoint, a mirror-symmetric arrangement and appropriate redundant constraints are crucial to reduce undesired parasitic motion. Detailed finite element analysis （FEA） was conducted and showed satisfactory mechanical features. With the identified dynamic models of the nanopositioner, real-time control strategies were designed and implemented into the monolithically fabricated prototype system, demonstrating the enhanced tracking capability of the MSL process. The servo system has both a millimeter operating range and a root mean square （RMS） tracking error of about 80 nm for a circular traiectorv.展开更多
基金supported by the Priority Assistance for the Formation of Worldwide Renowned Centers of Research-The Global COE Program (Center of Excellence for Advanced Structural and Functional Materials Design) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan
文摘Photonic crystals with three-dimensional dielectric structures were fabricated to control terahertz waves effectively by using micro-stereolithography of a CAD/CAM process. The photonic crystals with a diamond structure composed of acrylic lattice with nanosized alumina particles were fabricated. Dense alumina structures were obtained by successive dewaxing and sintering in an air atmosphere. The electromagnetic wave properties of these samples were measured by using a terahertz spectroscopy device. The micro periodic structures exhibited perfect band gaps in the terahertz range. To control terahertz waves, micrometer sized electromagnetic devices for cavities, filters, and antennas will be necessary.
基金the financial support from Shenzhen Science and Technology Innovation Committee under the Grant Nos. JCYJ20170818103206501, Type C 202011033000145Changsha Municipal Science and Technology Bureau Project kh2201035supported by the City University of Hong Kong under the Grant No. 9667226
文摘Projection micro stereolithography(PμSL)has emerged as a powerful three-dimensional(3D)printing technique for manufacturing polymer structures with micron-scale high resolution at high printing speed,which enables the production of customized 3D microlattices with feature sizes down to several microns.However,the mechanical properties of as-printed polymers were not systemically studied at the relevant length scales,especially when the feature sizes step into micron/sub-micron level,limiting its reliable performance prediction in micro/nanolattice and other metamaterial applications.In this work,we demonstrate that PμSL-printed microfibers could become stronger and significantly more ductile with reduced size ranging from 20μm to 60μm,showing an obvious size-dependent mechanical behavior,in which the size decreases to 20μm with a fracture strain up to~100%and fracture strength up to~100 MPa.Such size effect enables the tailoring of the material strength and stiffness of PμSL-printed microlattices over a broad range,allowing to fabricate the microlattice metamaterials with desired/tunable mechanical properties for various structural and functional applications.
基金The authors would like to acknowledge support from the Open Foundation of the State Key Laboratory of Tribology ＆ Institute of Manufacturing Engineering （SKL2016B05）, and the National Natural Science Foundation of China （NSFC） （61327003）.
文摘This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography （MSL） process. As a key enabler of high accuracy in this process, a compact desktop-size beam flexure-based nanopositioner was designed with millimeter range and nanometric motion quality. This beam flexure-based motion system is highly suitable for harsh operation conditions, as no assembly or maintenance is required during the operation. From a mechanism design viewpoint, a mirror-symmetric arrangement and appropriate redundant constraints are crucial to reduce undesired parasitic motion. Detailed finite element analysis （FEA） was conducted and showed satisfactory mechanical features. With the identified dynamic models of the nanopositioner, real-time control strategies were designed and implemented into the monolithically fabricated prototype system, demonstrating the enhanced tracking capability of the MSL process. The servo system has both a millimeter operating range and a root mean square （RMS） tracking error of about 80 nm for a circular traiectorv.
