The fabrication of pure copper microstructures with submicron resolution has found a host of applications,such as 5G communications and highly sensitive detection.The tiny and complex features of these structures can ...The fabrication of pure copper microstructures with submicron resolution has found a host of applications,such as 5G communications and highly sensitive detection.The tiny and complex features of these structures can enhance device performance during high-frequency operation.However,manufacturing pure copper microstructures remain challenging.In this paper,we present localized electrochemical deposition micro additive manufacturing(LECD-μAM).This method combines localized electrochemical deposition(LECD)and closed-loop control of atomic force servo technology,which can effectively print helical springs and hollow tubes.We further demonstrate an overall model based on pulsed microfluidics from a hollow cantilever LECD process and closed-loop control of an atomic force servo.The printing state of the micro-helical springs can be assessed by simultaneously detecting the Z-axis displacement and the deflection of the atomic force probe cantilever.The results showed that it took 361 s to print a helical spring with a wire length of 320.11μm at a deposition rate of 0.887μm s^(-1),which can be changed on the fly by simply tuning the extrusion pressure and the applied voltage.Moreover,the in situ nanoindenter was used to measure the compressive mechanical properties of the helical spring.The shear modulus of the helical spring material was about 60.8 GPa,much higher than that of bulk copper(~44.2 GPa).Additionally,the microscopic morphology and chemical composition of the spring were characterized.These results delineate a new way of fabricating terahertz transmitter components and micro-helical antennas with LECD-μAM technology.展开更多
The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressu...The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressure and sliding speed on the lubricant behaviour(i.e. evolutions of the coefficient of friction(COF) and the breakdown phenomenon) were experimentally studied. The evolutions of COF at elevated temperatures consisted of three distinct stages with different friction mechanisms. The first stage(stage Ⅰ) occurred with low friction when the boundary lubrication was present. The second stage(stage Ⅱ) was the transition process in which the COF rapidly increased as the lubricant film thickness decreased to a critical value. In the final plateau stage(stage Ⅲ), lubricant breakdown occurred and intimate contact at the interface led to high friction values. At the low friction stage(stage Ⅰ), the value of COF increased with increasing temperature. The increase in temperature, contact pressure and sliding speed as well as the decrease in initial lubricant volume accelerated the lubricant breakdown.展开更多
High-entropy(HE)ultra-high temperature ceramics have the chance to pave the way for future applications propelling technology advantages in the fields of energy conversion and extreme environmental shielding.Among oth...High-entropy(HE)ultra-high temperature ceramics have the chance to pave the way for future applications propelling technology advantages in the fields of energy conversion and extreme environmental shielding.Among others,HE diborides stand out owing to their intrinsic anisotropic layered structure and ability to withstand ultra-high temperatures.Herein,we employed in-situ high-resolution synchrotron diffraction over a plethora of multicomponent compositions,with four to seven transition metals,with the intent of understanding the thermal lattice expansion following different composition or synthesis process.As a result,we were able to control the average thermal expansion(TE)from 1.3×10^(−6)to 6.9×10^(−6)K^(−1)depending on the combination of metals,with a variation of in-plane to out-of-plane TE ratio ranging from 1.5 to 2.8.展开更多
As femtosecond(fs)laser machining advances from micro/nanoscale to macroscale,approaches capable of machining macroscale geometries that sustain micro/nanoscale precisions are in great demand.In this research,an fs la...As femtosecond(fs)laser machining advances from micro/nanoscale to macroscale,approaches capable of machining macroscale geometries that sustain micro/nanoscale precisions are in great demand.In this research,an fs laser sharp shaping approach was developed to address two key challenges in macroscale machining(i.e.defects on edges and tapered sidewalls).The evolution of edge sharpness(edge transition width)and sidewall tapers were systematically investigated through which the dilemma of simultaneously achieving sharp edges and vertical sidewalls were addressed.Through decreasing the angle of incidence(AOI)from 0◦to−5◦,the edge transition width could be reduced to below 10µm but at the cost of increased sidewall tapers.Furthermore,by analyzing lateral and vertical ablation behaviors,a parameter-compensation strategy was developed by gradually decreasing the scanning diameters along depth and using optimal laser powers to produce non-tapered sidewalls.The fs laser ablation behaviors were precisely controlled and coordinated to optimize the parameter compensations in general manufacturing applications.The AOI control together with the parameter compensation provides a versatile solution to simultaneously achieve vertical sidewalls as well as sharp edges of entrances and exits for geometries of different shapes and dimensions.Both mm-scale diameters and depths were realized with dimensional precisions below 10µm and surface roughness below 1µm.This research establishes a novel strategy to finely control the fs laser machining process,enabling the fs laser applications in macroscale machining with micro/nanoscale precisions.展开更多
Raman spectroscopy-based temperature sensing usually tracks the change of Raman wavenumber,linewidth and intensity,and has found very broad applications in characterizing the energy and charge transport in nanomateria...Raman spectroscopy-based temperature sensing usually tracks the change of Raman wavenumber,linewidth and intensity,and has found very broad applications in characterizing the energy and charge transport in nanomaterials over the last decade.The temperature coefficients of these Raman properties are highly material-dependent,and are subjected to local optical scattering influence.As a result,Raman-based temperature sensing usually suffers quite large uncertainties and has low sensitivity.Here,a novel method based on dual resonance Raman phenomenon is developed to precisely measure the absolute temperature rise of nanomaterial(nm WS_(2) film in this work)from 170 to 470 K.A 532 nm laser(2.33 eV photon energy)is used to conduct the Raman experiment.Its photon energy is very close to the excitonic transition energy of WS_(2) at temperatures close to room temperature.A parameter,termed resonance Raman ratio(R3)Ω=I_(A1g)/IE_(2g) is introduced to combine the temperature effects on resonance Raman scattering for the A_(1g) and E_(2g) modes.Ω has a change of more than two orders of magnitude from 177 to 477 K,and such change is independent of film thickness and local optical scattering.It is shown that when Ω is varied by 1%,the temperature probing sensitivity is 0.42 K and 1.16 K at low and high temperatures,respectively.Based on Ω,the in-plane thermal conductivity(k)of a∼25 nm-thick suspended WS_(2) film is measured using our energy transport state-resolved Raman(ET-Raman).k is found decreasing from 50.0 to 20.0 Wm^(−1) K^(−1) when temperature increases from 170 to 470 K.This agrees with previous experimental and theoretical results and the measurement data using our FET-Raman.The R3 technique provides a very robust and high-sensitivity method for temperature probing of nanomaterials and will have broad applications in nanoscale thermal transport characterization,non-destructive evaluation,and manufacturing monitoring.展开更多
High entropy alloys(HEAs)with multi-component solid solution microstructures have the potential for large-scale industrial applications due to their excellent mechanical and functional properties.However,the mechanica...High entropy alloys(HEAs)with multi-component solid solution microstructures have the potential for large-scale industrial applications due to their excellent mechanical and functional properties.However,the mechanical properties of HEAs limit the selection of processing technologies.Additive manufacturing technology possesses strong processing adaptability,making itthe best candidate method to overcome this issue.This comprehensive review examines the current state of selective laser melting(SLM)of HEAs.Introducing SLM to HEAs processing is motivated by its high quality for dimensional accuracy,geometric complexity,surface roughness,and microstructure.This review focuses on analyzing the current developments and challenges in SLM of HEAs,including defects,microstructures,and properties,as well as strengthing prediction models of fabricated HEAs.This review also offers directions for future studies to address existing challenges and promote technological advancement.展开更多
Liquid metal(LM) has potential applications in flexible electronics due to its high electrical conductivity and high flexibility. However, common methods of printing LM circuits on soft substrates lack controllability...Liquid metal(LM) has potential applications in flexible electronics due to its high electrical conductivity and high flexibility. However, common methods of printing LM circuits on soft substrates lack controllability, precision, and the ability to repair a damaged circuit. In this paper, we propose a method that uses a magnetic field to guide a magnetic LM(MLM) droplet to print and repair a flexible LM circuit on a femtosecond(fs) laser-patterned silicone surface.After mixing magnetic iron(Fe) particles into LM, the movement of the resultant MLM droplet could be controlled by a magnetic field. A patterned structure composed of the untreated flat domain and the LM-repellent rough microstructure produced by fs laser ablation was prepared on the silicone substrate. As an MLM droplet was guided onto the designed pattern, a soft LM circuit with smooth, uniform, and high-precision LM lines was obtained. Interestingly, the MLM droplet could also be guided to repair the circuit broken LM lines, and the repaired circuit maintained its original electrical properties. A flexible tensile sensor was prepared based on the printed LM circuit, which detected the bending degree of a finger.展开更多
Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus str...Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus structure is a promising approach to achieve shape transformation based on its heterogeneous chemical or physical properties on opposite sides.However, the heterogeneity is generally realized by multi-step processing, different materials,and/or different processing parameters. Here, we present a simple and flexible method of producing p H-sensitive Janus microactuators from a single material, using the same laser printing parameters. These microactuators exhibit reversible structural deformations with large bending angles of ~31°and fast response(~0.2 s) by changing the p H value of the aqueous environment. Benefited from the high flexibility of the laser printing technique and the spatial arrangements, pillar heights, and bending directions of microactuators are readily controlled,enabling a variety of switchable ordered patterns and complex petal-like structures on flat surfaces and inside microchannels. Finally, we explore the potential applications of this method in information encryption/decryption and microtarget capturing.展开更多
In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changin...In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.展开更多
Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing.The laser interferometer is one of the most important measurement tools inv...Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing.The laser interferometer is one of the most important measurement tools invented in the 20th century.Today,it is commonly used in ultraprecision machining and manufacturing,ultraprecision positioning control,and many noncontact optical sensing technologies.So far,the state-of-the-art laser interferometers are the ground-based gravitational-wave detectors,e.g.the Laser Interferometer Gravitational-wave Observatory(LIGO).The LIGO has reached the measurement quantum limit,and some quantum technologies with squeezed light are currently being tested in order to further decompress the noise level.In this paper,we focus on the laser interferometry developed for space-based gravitational-wave detection.The basic working principle and the current status of the key technologies of intersatellite laser interferometry are introduced and discussed in detail.The launch and operation of these large-scale,gravitational-wave detectors based on space-based laser interferometry is proposed for the 2030s.展开更多
Surface defects introduced by conventional mechanical processing methods can induce irreversible damage and reduce the service life of optics applied in high-power lasers.Compared to mechanical processing,laser polish...Surface defects introduced by conventional mechanical processing methods can induce irreversible damage and reduce the service life of optics applied in high-power lasers.Compared to mechanical processing,laser polishing with moving beam spot is a noncontact processing method,which is able to form a defect-free surface.This work aims to explore the mechanism of forming a smooth,defect-free fused silica surface by high-power density laser polishing with coupled multiple beams.The underlying mechanisms of laser polishing was revealed by numerical simulations and the theoretical results were verified by experiments.The simulated polishing depth and machined surface morphology were in close agreement with the experimental results.To obtain the optimized polishing quality,the effects of laser polishing parameters(e.g.overlap rate,pulse width and polishing times)on the polishing quality were experimentally investigated.It was found that the processing efficiency of fused silica materials by carbon dioxide(CO2)laser polishing could reach 8.68 mm2 s−1,and the surface roughness(Ra)was better than 25 nm.Besides,the cracks on pristine fused silica surfaces introduced by initial grinding process were completely removed by laser polishing to achieve a defect-free surface.The maximum laser polishing rate can reach 3.88μm s−1,much higher than that of the traditional mechanical polishing methods.The rapid CO2 laser polishing can effectively achieve smooth,defect-free surface,which is of great significance to improve the surface quality of fused silica optics applied in high-power laser facilities.展开更多
Anisotropy is one central influencing factor on achievable ultimate machined surface integrity of metallic materials.Specifically,grain boundary has a strong impact on the deformation behaviour of polycrystalline mate...Anisotropy is one central influencing factor on achievable ultimate machined surface integrity of metallic materials.Specifically,grain boundary has a strong impact on the deformation behaviour of polycrystalline materials and correlated material removal at the microscale.In the present work,we perform molecular dynamics simulations and experiments to elucidate the underlying grain boundaryassociated mechanisms and their correlations with machining results of a bi-crystal Cu under nanocutting using a Berkovich tool.Specifically,crystallographic orientations of simulated bi-crystal Cu with a misorientation angle of 44.1°are derived from electron backscatter diffraction characterization of utilized polycrystalline copper specimen.Simulation results reveal that blocking of dislocation motion at grain boundaries,absorption of dislocations by grain boundaries and dislocation nucleation from grain boundaries are operating deformation modes in nanocutting of the bi-crystal Cu.Furthermore,heterogeneous grain boundary-associated mechanisms in neighbouring grains lead to strong anisotropic machining behaviour in the vicinity of the grain boundary.Simulated machined surface morphology and machining force evolution in the vicinity of grain boundary qualitatively agree well with experimental results.It is also found that the geometry of Berkovich tool has a strong impact on grain boundary-associated mechanisms and resultant ploughing-induced surface pile-up phenomenon.展开更多
The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high-performance ...The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high-performance electrochemical energy devices.In this paper,a one-step,easy processing and cost-effective technique for generating composite materials with heterojunctions was successfully developed.The composite containing Ni_(3)S_(4),NiS,and N-doped amorphous carbon(abbreviated as Ni_(3)S_(4)/NiS/NC)with multiple heterojunction nanosheets are synthesized via the space-confined effect of molten salt interface of recrystallized NaCl.Several lattice matching forms of Ni_(3)S_(4)with cubic structure and NiS with hexagonal structure are confirmed by the detailed characterization of heterogeneous interfaces.The C–S bonds are the key factor in realizing the chemical coupling between nickel sulfide and NC and constructing the stable heterojunction.Density functional theory calculations further revealed that the electronic interaction on the heterogeneous interface of Ni_(3)S_(4)/NiS can contribute to high electronic conductivity.The heterogeneous interfaces are identified to be the good electroactive region with excellent electrochemical performance.The synergistic effect of abundant active sites,the enhanced kinetic process and valid interface charge transfer channels of Ni_(3)S_(4)/NiS/NC multiple heterojunction can guarantee high reversible redox activity and high structural stability,resulting in both high specific capacitance and energy/power densities when it is used as the electrode for supercapacitors.This work offers a new avenue for the rational design of the heterojunction materials with improved electrochemical performance through space-confined effect of NaCl.展开更多
Textile electronics have become an indispensable part of wearable applications because of their large flexibility,light-weight,comfort and electronic functionality upon the merge of textiles and microelectronics.As a ...Textile electronics have become an indispensable part of wearable applications because of their large flexibility,light-weight,comfort and electronic functionality upon the merge of textiles and microelectronics.As a result,the fabrication of functional fibrous materials and the integration of textile electronic devices have attracted increasing interest in the wearable electronic community.Challenges are encountered in the development of textile electronics in a way that is electrically reliable and durable,without compromising on the deformability and comfort of a garment,including processing multiple materials with great mismatches in mechanical,thermal,and electrical properties and assembling various structures with the disparity in dimensional scales and surface roughness.Equal challenges lie in high-quality and cost-effective processes facilitated by high-level digital technology enabled design and manufacturing methods.This work reviews the manufacturing of textile-shaped electronics via the processing of functional fibrous materials from the perspective of hierarchical architectures,and discusses the heterogeneous integration of microelectronics into normal textiles upon the fabric circuit board and adapted electrical connections,broadly covering both conventional and advanced textile electronic production processes.We summarize the applications and obstacles of textile electronics explored so far in sensors,actuators,thermal management,energy fields,and displays.Finally,the main conclusions and outlook are provided while the remaining challenges of the fabrication and application of textile electronics are emphasized.展开更多
Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such ...Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such as electrocatalysis, rechargeable batteries, and supercapacitors. Here we report a novel hybrid laser-assisted micro/nanopatterning and sulfurization method for rapid manufacturing of hierarchically architectured molybdenum disulfide (MoS2) layers directly on molybdenum sheets. This laser surface structuring not only provides the ability to design specific micro/nanostructured patterns but also significantly enhances the crystal growth kinetics. Micro and nanoscale characterization methods are employed to study the morphological, structural, and atomistic characteristics of the formed crystals at various laser processing and crystal growth conditions. To compare the performance characteristics of the laser-structured and unstructured samples, Li-ion battery cells are fabricated and their energy storage capacity is measured. The hierarchically architectured MoS2 crystals show higher performance with specific capacities of about 10 mAh cm-2, at a current rate of 0.1 mA cm-2. This rapid laser patterning and growth of 2D materials directly on conductive sheets may enable the future large-scale and roll-to-roll manufacturing of energy and sensing devices.展开更多
Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these...Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.展开更多
We report novel results on top-down percussion drilling in different glasses with femtosecond laser GHz-bursts.Thanks to this particular regime of light–matter interaction,combining non-linear absorption and thermal ...We report novel results on top-down percussion drilling in different glasses with femtosecond laser GHz-bursts.Thanks to this particular regime of light–matter interaction,combining non-linear absorption and thermal cumulative effects,we obtained crack-free holes of aspect ratios exceeding 30 in sodalime and 70 in fused silica.The results are discussed in terms of inner wall morphology,aspect ratio and drilling speed.展开更多
Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catal...Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization,fast migration of charge carriers,efficient surface redox reactions and good electrical conductivity.In this review,we summarize the fabrication methods of CDs and corresponding CD nanocomposites,including the strategies of surface modification and heteroatom doping.The properties of CDs that concerned to the photo-and electro-catalysis are highlighted and detailed corresponding applications are listed.More importantly,as new non-contact detection technologies,transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics,which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts.The development and application of the techniques are reviewed.Finally,we discuss and outline the major challenges and opportunities for future CD-based catalysts,and the needs and expectations for the development of novel characterization technologies.展开更多
Neuromorphic computing systems,which mimic the operation of neurons and synapses in the human brain,are seen as an appealing next-generation computing method due to their strong and efficient computing abilities.Two-d...Neuromorphic computing systems,which mimic the operation of neurons and synapses in the human brain,are seen as an appealing next-generation computing method due to their strong and efficient computing abilities.Two-dimensional (2D) materials with dangling bond-free surfaces and atomic-level thicknesses have emerged as promising candidates for neuromorphic computing hardware.As a result,2D neuromorphic devices may provide an ideal platform for developing multifunctional neuromorphic applications.Here,we review the recent neuromorphic devices based on 2D material and their multifunctional applications.The synthesis and next micro–nano fabrication methods of 2D materials and their heterostructures are first introduced.The recent advances of neuromorphic 2D devices are discussed in detail using different operating principles.More importantly,we present a review of emerging multifunctional neuromorphic applications,including neuromorphic visual,auditory,tactile,and nociceptive systems based on 2D devices.In the end,we discuss the problems and methods for 2D neuromorphic device developments in the future.This paper will give insights into designing 2D neuromorphic devices and applying them to the future neuromorphic systems.展开更多
The introduction of living cells to manufacturing process has enabled the engineering of complex biological tissues in vitro.The recent advances in biofabrication with extremely high resolution(e.g.at single cell leve...The introduction of living cells to manufacturing process has enabled the engineering of complex biological tissues in vitro.The recent advances in biofabrication with extremely high resolution(e.g.at single cell level)have greatly enhanced this capacity and opened new avenues for tissue engineering.In this review,we comprehensively overview the current biofabrication strategies with single-cell resolution and categorize them based on the dimension of the single-cell building blocks,i.e.zero-dimensional single-cell droplets,one-dimensional single-cell filaments and two-dimensional single-cell sheets.We provide an informative introduction to the most recent advances in these approaches(e.g.cell trapping,bioprinting,electrospinning,microfluidics and cell sheets)and further illustrated how they can be used in in vitro tissue modelling and regenerative medicine.We highlight the significance of single-cell-level biofabrication and discuss the challenges and opportunities in the field.展开更多
基金supported by the National Natural Science Foundation of China under Grant U19A20103the Fund for Jilin Province Scientific and Technological Development Program under No.Z20190101005JH。
文摘The fabrication of pure copper microstructures with submicron resolution has found a host of applications,such as 5G communications and highly sensitive detection.The tiny and complex features of these structures can enhance device performance during high-frequency operation.However,manufacturing pure copper microstructures remain challenging.In this paper,we present localized electrochemical deposition micro additive manufacturing(LECD-μAM).This method combines localized electrochemical deposition(LECD)and closed-loop control of atomic force servo technology,which can effectively print helical springs and hollow tubes.We further demonstrate an overall model based on pulsed microfluidics from a hollow cantilever LECD process and closed-loop control of an atomic force servo.The printing state of the micro-helical springs can be assessed by simultaneously detecting the Z-axis displacement and the deflection of the atomic force probe cantilever.The results showed that it took 361 s to print a helical spring with a wire length of 320.11μm at a deposition rate of 0.887μm s^(-1),which can be changed on the fly by simply tuning the extrusion pressure and the applied voltage.Moreover,the in situ nanoindenter was used to measure the compressive mechanical properties of the helical spring.The shear modulus of the helical spring material was about 60.8 GPa,much higher than that of bulk copper(~44.2 GPa).Additionally,the microscopic morphology and chemical composition of the spring were characterized.These results delineate a new way of fabricating terahertz transmitter components and micro-helical antennas with LECD-μAM technology.
基金supported by the China Scholarship Council (Grant CSC No. 201706230235): a nonprofit institution that enables talented Chinese students to participate in overseas Ph D programs。
文摘The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressure and sliding speed on the lubricant behaviour(i.e. evolutions of the coefficient of friction(COF) and the breakdown phenomenon) were experimentally studied. The evolutions of COF at elevated temperatures consisted of three distinct stages with different friction mechanisms. The first stage(stage Ⅰ) occurred with low friction when the boundary lubrication was present. The second stage(stage Ⅱ) was the transition process in which the COF rapidly increased as the lubricant film thickness decreased to a critical value. In the final plateau stage(stage Ⅲ), lubricant breakdown occurred and intimate contact at the interface led to high friction values. At the low friction stage(stage Ⅰ), the value of COF increased with increasing temperature. The increase in temperature, contact pressure and sliding speed as well as the decrease in initial lubricant volume accelerated the lubricant breakdown.
基金financial support for the XRPD experiments (proposals nr. 20200101 and 20210215)supported by the U.S. National Science Foundation through Grant CMMI-1902069
文摘High-entropy(HE)ultra-high temperature ceramics have the chance to pave the way for future applications propelling technology advantages in the fields of energy conversion and extreme environmental shielding.Among others,HE diborides stand out owing to their intrinsic anisotropic layered structure and ability to withstand ultra-high temperatures.Herein,we employed in-situ high-resolution synchrotron diffraction over a plethora of multicomponent compositions,with four to seven transition metals,with the intent of understanding the thermal lattice expansion following different composition or synthesis process.As a result,we were able to control the average thermal expansion(TE)from 1.3×10^(−6)to 6.9×10^(−6)K^(−1)depending on the combination of metals,with a variation of in-plane to out-of-plane TE ratio ranging from 1.5 to 2.8.
基金This study was supported by the National Science Foundation(CMMI 1826392)and the Nebraska Center for Energy Sci-ences Research(NCESR)The research was performed in part in the Nebraska Nanoscale Facility:National Nanotechnology Coordinated Infrastructure and the Nebraska Center for Mater-ials and Nanoscience,which are supported by the National Sci-ence Foundation under Award ECCS:1542182,and the Neb-raska Research Initiative.
文摘As femtosecond(fs)laser machining advances from micro/nanoscale to macroscale,approaches capable of machining macroscale geometries that sustain micro/nanoscale precisions are in great demand.In this research,an fs laser sharp shaping approach was developed to address two key challenges in macroscale machining(i.e.defects on edges and tapered sidewalls).The evolution of edge sharpness(edge transition width)and sidewall tapers were systematically investigated through which the dilemma of simultaneously achieving sharp edges and vertical sidewalls were addressed.Through decreasing the angle of incidence(AOI)from 0◦to−5◦,the edge transition width could be reduced to below 10µm but at the cost of increased sidewall tapers.Furthermore,by analyzing lateral and vertical ablation behaviors,a parameter-compensation strategy was developed by gradually decreasing the scanning diameters along depth and using optimal laser powers to produce non-tapered sidewalls.The fs laser ablation behaviors were precisely controlled and coordinated to optimize the parameter compensations in general manufacturing applications.The AOI control together with the parameter compensation provides a versatile solution to simultaneously achieve vertical sidewalls as well as sharp edges of entrances and exits for geometries of different shapes and dimensions.Both mm-scale diameters and depths were realized with dimensional precisions below 10µm and surface roughness below 1µm.This research establishes a novel strategy to finely control the fs laser machining process,enabling the fs laser applications in macroscale machining with micro/nanoscale precisions.
基金Support of this work by National Science Foundation(CBET1930866 and CMMI2032464 for X W)National Natural Science Foundation of China(No.52106220 for S X and No.51906161 for Y X)。
文摘Raman spectroscopy-based temperature sensing usually tracks the change of Raman wavenumber,linewidth and intensity,and has found very broad applications in characterizing the energy and charge transport in nanomaterials over the last decade.The temperature coefficients of these Raman properties are highly material-dependent,and are subjected to local optical scattering influence.As a result,Raman-based temperature sensing usually suffers quite large uncertainties and has low sensitivity.Here,a novel method based on dual resonance Raman phenomenon is developed to precisely measure the absolute temperature rise of nanomaterial(nm WS_(2) film in this work)from 170 to 470 K.A 532 nm laser(2.33 eV photon energy)is used to conduct the Raman experiment.Its photon energy is very close to the excitonic transition energy of WS_(2) at temperatures close to room temperature.A parameter,termed resonance Raman ratio(R3)Ω=I_(A1g)/IE_(2g) is introduced to combine the temperature effects on resonance Raman scattering for the A_(1g) and E_(2g) modes.Ω has a change of more than two orders of magnitude from 177 to 477 K,and such change is independent of film thickness and local optical scattering.It is shown that when Ω is varied by 1%,the temperature probing sensitivity is 0.42 K and 1.16 K at low and high temperatures,respectively.Based on Ω,the in-plane thermal conductivity(k)of a∼25 nm-thick suspended WS_(2) film is measured using our energy transport state-resolved Raman(ET-Raman).k is found decreasing from 50.0 to 20.0 Wm^(−1) K^(−1) when temperature increases from 170 to 470 K.This agrees with previous experimental and theoretical results and the measurement data using our FET-Raman.The R3 technique provides a very robust and high-sensitivity method for temperature probing of nanomaterials and will have broad applications in nanoscale thermal transport characterization,non-destructive evaluation,and manufacturing monitoring.
基金This research is financially supported by the National Key Research and Development Program of China(Grant Nos.2017YFB1103900 and 2018YFB1107701)the Fundamental Research Funds for the Central Universities(Grant No.2042019kf0015)+1 种基金the Key R&D projects of Sichuan Province(Grant No.2020YFSY0054)the National Natural Science Foundation of China(Grant No.51605343).
文摘High entropy alloys(HEAs)with multi-component solid solution microstructures have the potential for large-scale industrial applications due to their excellent mechanical and functional properties.However,the mechanical properties of HEAs limit the selection of processing technologies.Additive manufacturing technology possesses strong processing adaptability,making itthe best candidate method to overcome this issue.This comprehensive review examines the current state of selective laser melting(SLM)of HEAs.Introducing SLM to HEAs processing is motivated by its high quality for dimensional accuracy,geometric complexity,surface roughness,and microstructure.This review focuses on analyzing the current developments and challenges in SLM of HEAs,including defects,microstructures,and properties,as well as strengthing prediction models of fabricated HEAs.This review also offers directions for future studies to address existing challenges and promote technological advancement.
基金supported by the National Science Foundation of China under the Grant No. 61875158the National Key Research and Development Program of China under the Grant No. 2017YFB1104700+1 种基金the International Joint Research Laboratory for Micro/Nano Manufacturing and Measurement Technologiesthe Fundamental Research Funds for the Central Universities。
文摘Liquid metal(LM) has potential applications in flexible electronics due to its high electrical conductivity and high flexibility. However, common methods of printing LM circuits on soft substrates lack controllability, precision, and the ability to repair a damaged circuit. In this paper, we propose a method that uses a magnetic field to guide a magnetic LM(MLM) droplet to print and repair a flexible LM circuit on a femtosecond(fs) laser-patterned silicone surface.After mixing magnetic iron(Fe) particles into LM, the movement of the resultant MLM droplet could be controlled by a magnetic field. A patterned structure composed of the untreated flat domain and the LM-repellent rough microstructure produced by fs laser ablation was prepared on the silicone substrate. As an MLM droplet was guided onto the designed pattern, a soft LM circuit with smooth, uniform, and high-precision LM lines was obtained. Interestingly, the MLM droplet could also be guided to repair the circuit broken LM lines, and the repaired circuit maintained its original electrical properties. A flexible tensile sensor was prepared based on the printed LM circuit, which detected the bending degree of a finger.
基金the Hong Kong Scholar Program (XJ2018035) for their financial supportsupported by Research Grants Council of Hong Kong (No. JLFS/E-402/18)National Natural Science Foundation of China (No. 51805509)。
文摘Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus structure is a promising approach to achieve shape transformation based on its heterogeneous chemical or physical properties on opposite sides.However, the heterogeneity is generally realized by multi-step processing, different materials,and/or different processing parameters. Here, we present a simple and flexible method of producing p H-sensitive Janus microactuators from a single material, using the same laser printing parameters. These microactuators exhibit reversible structural deformations with large bending angles of ~31°and fast response(~0.2 s) by changing the p H value of the aqueous environment. Benefited from the high flexibility of the laser printing technique and the spatial arrangements, pillar heights, and bending directions of microactuators are readily controlled,enabling a variety of switchable ordered patterns and complex petal-like structures on flat surfaces and inside microchannels. Finally, we explore the potential applications of this method in information encryption/decryption and microtarget capturing.
文摘In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.
基金the National Natural Science Foundation of China(Grant Nos.11655001,11654004,91836104).
文摘Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing.The laser interferometer is one of the most important measurement tools invented in the 20th century.Today,it is commonly used in ultraprecision machining and manufacturing,ultraprecision positioning control,and many noncontact optical sensing technologies.So far,the state-of-the-art laser interferometers are the ground-based gravitational-wave detectors,e.g.the Laser Interferometer Gravitational-wave Observatory(LIGO).The LIGO has reached the measurement quantum limit,and some quantum technologies with squeezed light are currently being tested in order to further decompress the noise level.In this paper,we focus on the laser interferometry developed for space-based gravitational-wave detection.The basic working principle and the current status of the key technologies of intersatellite laser interferometry are introduced and discussed in detail.The launch and operation of these large-scale,gravitational-wave detectors based on space-based laser interferometry is proposed for the 2030s.
基金supported by the National Natural Science Foundation of China(Grant Nos.51775147,51705105)Science Challenge Project(Grant No.TZ2016006-0503-01)+3 种基金Young Elite Scientists Sponsorship Program by CAST(Grant No.2018QNRC001)China Postdoctoral Science Foundation funded project(Grant Nos.2018T110288,2017M621260)Self-Planned Task(Grant Nos.SKLRS201718A,SKLRS201803B)of State Key Laboratory of Robotics and System(HIT)Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.2019053).
文摘Surface defects introduced by conventional mechanical processing methods can induce irreversible damage and reduce the service life of optics applied in high-power lasers.Compared to mechanical processing,laser polishing with moving beam spot is a noncontact processing method,which is able to form a defect-free surface.This work aims to explore the mechanism of forming a smooth,defect-free fused silica surface by high-power density laser polishing with coupled multiple beams.The underlying mechanisms of laser polishing was revealed by numerical simulations and the theoretical results were verified by experiments.The simulated polishing depth and machined surface morphology were in close agreement with the experimental results.To obtain the optimized polishing quality,the effects of laser polishing parameters(e.g.overlap rate,pulse width and polishing times)on the polishing quality were experimentally investigated.It was found that the processing efficiency of fused silica materials by carbon dioxide(CO2)laser polishing could reach 8.68 mm2 s−1,and the surface roughness(Ra)was better than 25 nm.Besides,the cracks on pristine fused silica surfaces introduced by initial grinding process were completely removed by laser polishing to achieve a defect-free surface.The maximum laser polishing rate can reach 3.88μm s−1,much higher than that of the traditional mechanical polishing methods.The rapid CO2 laser polishing can effectively achieve smooth,defect-free surface,which is of great significance to improve the surface quality of fused silica optics applied in high-power laser facilities.
基金The authors greatly acknowledge support from the Science Challenge Project(Nos.TZ2018006-0201-02 and TZ2018006-0205-02)the Fundamental Research Funds for the Central Universities.
文摘Anisotropy is one central influencing factor on achievable ultimate machined surface integrity of metallic materials.Specifically,grain boundary has a strong impact on the deformation behaviour of polycrystalline materials and correlated material removal at the microscale.In the present work,we perform molecular dynamics simulations and experiments to elucidate the underlying grain boundaryassociated mechanisms and their correlations with machining results of a bi-crystal Cu under nanocutting using a Berkovich tool.Specifically,crystallographic orientations of simulated bi-crystal Cu with a misorientation angle of 44.1°are derived from electron backscatter diffraction characterization of utilized polycrystalline copper specimen.Simulation results reveal that blocking of dislocation motion at grain boundaries,absorption of dislocations by grain boundaries and dislocation nucleation from grain boundaries are operating deformation modes in nanocutting of the bi-crystal Cu.Furthermore,heterogeneous grain boundary-associated mechanisms in neighbouring grains lead to strong anisotropic machining behaviour in the vicinity of the grain boundary.Simulated machined surface morphology and machining force evolution in the vicinity of grain boundary qualitatively agree well with experimental results.It is also found that the geometry of Berkovich tool has a strong impact on grain boundary-associated mechanisms and resultant ploughing-induced surface pile-up phenomenon.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1804126,U21A2077 and U1804129)the Support Program of Science and Technology Innovation Leading Talent of Zhongyuan(Grant 204200510014)PhD program of Shanghai University and Program for Interdisciplinary Direction Team in Zhongyuan University of Technology.
文摘The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high-performance electrochemical energy devices.In this paper,a one-step,easy processing and cost-effective technique for generating composite materials with heterojunctions was successfully developed.The composite containing Ni_(3)S_(4),NiS,and N-doped amorphous carbon(abbreviated as Ni_(3)S_(4)/NiS/NC)with multiple heterojunction nanosheets are synthesized via the space-confined effect of molten salt interface of recrystallized NaCl.Several lattice matching forms of Ni_(3)S_(4)with cubic structure and NiS with hexagonal structure are confirmed by the detailed characterization of heterogeneous interfaces.The C–S bonds are the key factor in realizing the chemical coupling between nickel sulfide and NC and constructing the stable heterojunction.Density functional theory calculations further revealed that the electronic interaction on the heterogeneous interface of Ni_(3)S_(4)/NiS can contribute to high electronic conductivity.The heterogeneous interfaces are identified to be the good electroactive region with excellent electrochemical performance.The synergistic effect of abundant active sites,the enhanced kinetic process and valid interface charge transfer channels of Ni_(3)S_(4)/NiS/NC multiple heterojunction can guarantee high reversible redox activity and high structural stability,resulting in both high specific capacitance and energy/power densities when it is used as the electrode for supercapacitors.This work offers a new avenue for the rational design of the heterojunction materials with improved electrochemical performance through space-confined effect of NaCl.
基金funding support from Research Grants Council, Hong Kong (Nos. 15201922E, 15203421E, 15202020E, 15201419E)Innovation and Technology Commission (ITC) of Hong Kong SAR Government (No. ITP/031/21TP)+2 种基金postgraduate scholarships from the same sourcessupported by the Distinguished Postdoctoral Fellowship from Hong Kong Polytechnic Universitysupported by ITC’s Postdoctoral Fellowship
文摘Textile electronics have become an indispensable part of wearable applications because of their large flexibility,light-weight,comfort and electronic functionality upon the merge of textiles and microelectronics.As a result,the fabrication of functional fibrous materials and the integration of textile electronic devices have attracted increasing interest in the wearable electronic community.Challenges are encountered in the development of textile electronics in a way that is electrically reliable and durable,without compromising on the deformability and comfort of a garment,including processing multiple materials with great mismatches in mechanical,thermal,and electrical properties and assembling various structures with the disparity in dimensional scales and surface roughness.Equal challenges lie in high-quality and cost-effective processes facilitated by high-level digital technology enabled design and manufacturing methods.This work reviews the manufacturing of textile-shaped electronics via the processing of functional fibrous materials from the perspective of hierarchical architectures,and discusses the heterogeneous integration of microelectronics into normal textiles upon the fabric circuit board and adapted electrical connections,broadly covering both conventional and advanced textile electronic production processes.We summarize the applications and obstacles of textile electronics explored so far in sensors,actuators,thermal management,energy fields,and displays.Finally,the main conclusions and outlook are provided while the remaining challenges of the fabrication and application of textile electronics are emphasized.
基金partially funded by the U.S.National Science Foundation(NSF)under Grant No.1923363.
文摘Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such as electrocatalysis, rechargeable batteries, and supercapacitors. Here we report a novel hybrid laser-assisted micro/nanopatterning and sulfurization method for rapid manufacturing of hierarchically architectured molybdenum disulfide (MoS2) layers directly on molybdenum sheets. This laser surface structuring not only provides the ability to design specific micro/nanostructured patterns but also significantly enhances the crystal growth kinetics. Micro and nanoscale characterization methods are employed to study the morphological, structural, and atomistic characteristics of the formed crystals at various laser processing and crystal growth conditions. To compare the performance characteristics of the laser-structured and unstructured samples, Li-ion battery cells are fabricated and their energy storage capacity is measured. The hierarchically architectured MoS2 crystals show higher performance with specific capacities of about 10 mAh cm-2, at a current rate of 0.1 mA cm-2. This rapid laser patterning and growth of 2D materials directly on conductive sheets may enable the future large-scale and roll-to-roll manufacturing of energy and sensing devices.
基金supported by the National Natural Science Foundation of China(NSFC)(62122057,62075136,62175165)Natural Science Foundation of Guangdong Province(2022B1515120061,2019B1515120042)Science and Technology Innovation Commission of Shenzhen(RCYX20200714114524139,JCYJ20200109114001806).
文摘Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.
文摘We report novel results on top-down percussion drilling in different glasses with femtosecond laser GHz-bursts.Thanks to this particular regime of light–matter interaction,combining non-linear absorption and thermal cumulative effects,we obtained crack-free holes of aspect ratios exceeding 30 in sodalime and 70 in fused silica.The results are discussed in terms of inner wall morphology,aspect ratio and drilling speed.
基金supported by National MCF Energy R&D Program of China(2018YFE0306105)National Key R&D Program of China(2020YFA0406104,2020YFA0406101)+6 种基金Innovative Research Group Project of the National Natural Science Foundation of China(51821002)National Natural Science Foundation of China(51725204,21771132,51972216,52041202,51902217)Natural Science Foundation of Jiangsu Province(BK20190041)Key-Area Research and Development Program of GuangDong Province(2019B010933001)Collaborative Innovation Center of Suzhou Nano Science and Technologythe 111 ProjectSuzhou Key Laboratory of Functional Nano and Soft Materials。
文摘Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization,fast migration of charge carriers,efficient surface redox reactions and good electrical conductivity.In this review,we summarize the fabrication methods of CDs and corresponding CD nanocomposites,including the strategies of surface modification and heteroatom doping.The properties of CDs that concerned to the photo-and electro-catalysis are highlighted and detailed corresponding applications are listed.More importantly,as new non-contact detection technologies,transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics,which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts.The development and application of the techniques are reviewed.Finally,we discuss and outline the major challenges and opportunities for future CD-based catalysts,and the needs and expectations for the development of novel characterization technologies.
基金supported by the Hunan Science Fund for Distinguished Young Scholars (2023JJ10069)the National Natural Science Foundation of China (52172169)。
文摘Neuromorphic computing systems,which mimic the operation of neurons and synapses in the human brain,are seen as an appealing next-generation computing method due to their strong and efficient computing abilities.Two-dimensional (2D) materials with dangling bond-free surfaces and atomic-level thicknesses have emerged as promising candidates for neuromorphic computing hardware.As a result,2D neuromorphic devices may provide an ideal platform for developing multifunctional neuromorphic applications.Here,we review the recent neuromorphic devices based on 2D material and their multifunctional applications.The synthesis and next micro–nano fabrication methods of 2D materials and their heterostructures are first introduced.The recent advances of neuromorphic 2D devices are discussed in detail using different operating principles.More importantly,we present a review of emerging multifunctional neuromorphic applications,including neuromorphic visual,auditory,tactile,and nociceptive systems based on 2D devices.In the end,we discuss the problems and methods for 2D neuromorphic device developments in the future.This paper will give insights into designing 2D neuromorphic devices and applying them to the future neuromorphic systems.
基金support from the National Natural Science Foundation of China(No.52105306,32211530075)New Faculty Start-up Funding provided by Tsinghua University(012-53330200421).
文摘The introduction of living cells to manufacturing process has enabled the engineering of complex biological tissues in vitro.The recent advances in biofabrication with extremely high resolution(e.g.at single cell level)have greatly enhanced this capacity and opened new avenues for tissue engineering.In this review,we comprehensively overview the current biofabrication strategies with single-cell resolution and categorize them based on the dimension of the single-cell building blocks,i.e.zero-dimensional single-cell droplets,one-dimensional single-cell filaments and two-dimensional single-cell sheets.We provide an informative introduction to the most recent advances in these approaches(e.g.cell trapping,bioprinting,electrospinning,microfluidics and cell sheets)and further illustrated how they can be used in in vitro tissue modelling and regenerative medicine.We highlight the significance of single-cell-level biofabrication and discuss the challenges and opportunities in the field.