The buckling-guided three-dimensional(3D)assembly method has arisen increasing attention for its advantages in forming complex 3D architectures with a rich diversity of geometric shapes in a broad spectrum of inorgani...The buckling-guided three-dimensional(3D)assembly method has arisen increasing attention for its advantages in forming complex 3D architectures with a rich diversity of geometric shapes in a broad spectrum of inorganic functional materials.Such an assembly method relies on the controlled lateral bucking of a 2D precursor structure integrated with a pre-stretched substrate at selective regions.In the assembly process,the preservation or break-ing of rotational symmetry is crucial for understanding the mechanism of 2D-to-3D geometric transformation.Here,we present a fundamental study on the rotational symmetry of 3D spoke double-ring structures formed through buckling-guided assembly.An energetic method is introduced to analyze the rotational symmetry and to understand the symmetry-breaking mechanism.Such symmetry-breaking phenomenon is validated by experi-ments and finite element analyses(FEA).Phase diagrams of the deformation mode are established to shed light on the influences of various geometric parameters(e.g.,initial rotational symmetry order,radius ratio,and lo-cation of bonding sites).This work offers new insights into the underlying mechanism of 2D-to-3D geometric transformation in ribbon-type structures formed by compressive buckling.展开更多
Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer ...Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer range）, but it does not always hold in nanoindentation experiments （indentation depths approaching the nanometer range）. Indenter tip radius effect has been proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao＇s relationship. We have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary dislocations. The comparison between numerical result and Feng and Nix＇s experimental data shows that the indenter tip radius effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.展开更多
The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micr...The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.展开更多
Plant leaves, insects and geckos are masters of adhesion or anti-adhesion by smartly designed refined surface structures with micro- and nano- ＇technologies＇. Understanding the basic principles in the design of the ...Plant leaves, insects and geckos are masters of adhesion or anti-adhesion by smartly designed refined surface structures with micro- and nano- ＇technologies＇. Understanding the basic principles in the design of the unique surface structures is of great importance in the manufacture or synthesis of micro- and nano- devices in MEMS or NEMS. This study is right inspired by this effort, focusing on the mechanics of wet adhesion between fibers having concave tips and a flat substrate via capillary forces. We show that the concave surface can effectively enhance the wet adhesion by reducing the effective contact angle of the fiber, firmly pinning the liquid bridge at its circumferential edge. A critical contact angle is identified below which the adhesion strength can achieve its maximum, being insensitive to the contact angle between the fiber and liquid. The analytical expression for the critical angle is derived. Then a tentative design for the profile of concave surfaces is proposed, considering the effects of chamfering size, deformation and buckling, etc. The effect of liquid volume on the wet adhesion of multiple-fiber system is also discussed.展开更多
Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish...Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish tasks in complex and time-varying environments through geometric reconfiguration induced by diverse external stimuli,such as heat,solvent,light,electric field,magnetic field,and mechanical field.Approaches to achieve reconfigurable mesostructures are essential to the design and fabrication of soft robots.Existing studies mainly focus on four key aspects:reconfiguration mechanisms,fabrication schemes,deformation control principles,and practical applications.This review presents a detailed survey of methodologies for morphable mesostructures triggered by a wide range of stimuli,with a number of impressive examples,demonstrating high degrees of deformation complexities and varied multi-functionalities.The latest progress based on the development of new materials and unique design concepts is highlighted.An outlook on the remaining challenges and open opportunities is provided.展开更多
Various methods have been developed to fabricate highly stretchable electronics. Recent studies show that over 100% two dimensional stretchability can be achieved by mesh structure of brittle functioning devices inter...Various methods have been developed to fabricate highly stretchable electronics. Recent studies show that over 100% two dimensional stretchability can be achieved by mesh structure of brittle functioning devices interconnected with serpentine bridges. Kim et al show that pressing down an inflated elastomeric thin film during transfer printing introduces two di- mensional prestrain, and therefore further improves the system stretchability. This paper gives a theoretical study of this process, through both analytical and numerical approaches. Simple analytical solutions are obtained for meridional and circumferential strains in the thin film, as well as the maximum strain in device islands, which all agree reasonably well with finite element analysis.展开更多
The finite element method for the conventional theory of mechanism-based strain gradient plasticity is used to study the indentation size effect. For small indenters （e.g., radii on the order of 10μm）, the maximum ...The finite element method for the conventional theory of mechanism-based strain gradient plasticity is used to study the indentation size effect. For small indenters （e.g., radii on the order of 10μm）, the maximum allowable geometrically necessary dislocation （GND） density is introduced to cap the GND density such that the latter does not become unrealistically high. The numerical results agree well with the indentation hardness data of iridium. The GND density is much larger than the density of statistically stored dislocations （SSD） underneath the indenter, but this trend reverses away from the indenter. As the indentation depth （or equivalently, contact radius） increases, the GND density decreases but the SSD density increases.展开更多
Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate...Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. By considering a circular thin film/substrate system subject to non-uniform, but axisymmetric misfit strain distributions in the thin film, we derived relations between the film stresses and the misfit strain, and between the plate system＇s curvatures and the misfit strain. These relations feature a “local” part which involves a direct dependence of the stress or curvature components on the misfit strain at the same point, and a “non-local” part which reflects the effect of misfit strain of other points on the location of scrutiny. Most notably, we also derived relations between the polar components of the film stress and those of system curvatures which allow for the experimental inference of such stresses from full-field curvature measurements in the presence of arbitrary radial non-uniformities. These relations also feature a “non-local” dependence on curvatures making a full-field measurement a necessity. Finally, it is shown that the interfacial shear tractions between the film and the substrate are proportional to the radial gradients of the first curvature invariant and can also be inferred experimentally.展开更多
Objective and Impact Statement.Real-time monitoring of the temperatures of regional tissue microenvironments can serve as the diagnostic basis for treating various health conditions and diseases.Introduction.Tradition...Objective and Impact Statement.Real-time monitoring of the temperatures of regional tissue microenvironments can serve as the diagnostic basis for treating various health conditions and diseases.Introduction.Traditional thermal sensors allow measurements at surfaces or at near-surface regions of the skin or of certain body cavities.Evaluations at depth require implanted devices connected to external readout electronics via physical interfaces that lead to risks for infection and movement constraints for the patient.Also,surgical extraction procedures after a period of need can introduce additional risks and costs.Methods.Here,we report a wireless,bioresorbable class of temperature sensor that exploits multilayer photonic cavities,for continuous optical measurements of regional,deep-tissue microenvironments over a timeframe of interest followed by complete clearance via natural body processes.Results.The designs decouple the influence of detection angle from temperature on the reflection spectra,to enable high accuracy in sensing,as supported by in vitro experiments and optical simulations.Studies with devices implanted into subcutaneous tissues of both awake,freely moving and asleep animal models illustrate the applicability of this technology for in vivo measurements.Conclusion.The results demonstrate the use of bioresorbable materials in advanced photonic structures with unique capabilities in tracking of thermal signatures of tissue microenvironments,with potential relevance to human healthcare.展开更多
Pressure ulcers remain a persistent challenge in healthcare,particularly for individuals with limited mobility or compromised sensation.Early detection is critical to prevent ischemic damage leading to necrosis,infect...Pressure ulcers remain a persistent challenge in healthcare,particularly for individuals with limited mobility or compromised sensation.Early detection is critical to prevent ischemic damage leading to necrosis,infections,and prolonged hospital stays.Conventional sensing technologies that integrate into the mattress,while effective in gathering data on pressure distributions,are restricted to stationary environments,and they can miss significant periods when patients leave their beds or shift positions.Furthermore,these systems do not offer consistent information on the specific spatial distribution of pressure across the body,because the sensors integrate with the mattress and not the body.Recent research establishes capabilities in soft,skin-interfaced wireless alternatives,but in designs that require specialized processes and materials that might not scale effectively for practical production and use.Here,we present a wireless,skin-integrated pressure monitoring system that mounts on the skin,in anatomically matched forms and with soft mechanical interfaces,for continuous data collection.This platform,built on manufacturable components and designs,features an array of soft,elastomer-encapsulated pressure sensors that minimize discomfort,with wireless communications and an independent power management system to enable operation across diverse healthcare settings,including homes,outpatient facilities,and operating rooms,all without physical tethers.Additionally,an external alarm satellite device delivers vibratory and visual alerts if predefined pressure thresholds are exceeded,guiding caregivers or patients to take timely action.Experimental and finite element analysis support the design principles,and deployments on patients in hospital settings illustrate modes for practical use.展开更多
Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original ar...Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.展开更多
Recent research establishes methods of controlled mechanical assembly as versatile routes to three-dimensional(3D)mesostructures from patterned 2D films,with demonstrated applicability to a broad range of materials(e....Recent research establishes methods of controlled mechanical assembly as versatile routes to three-dimensional(3D)mesostructures from patterned 2D films,with demonstrated applicability to a broad range of materials(e.g.,semiconductors,polymers,metals,and their combinations)and length scales(e.g.,from sub-microscale to centimeter scale).Previously reported schemes use pre-stretched elastomeric substrates as assembly platforms to induce compressive buckling of 2D precursor structures,thereby enabling their controlled transformation into 3D architectures.Here,we introduce tensile buckling as a different,complementary strategy that bypasses the need for a pre-stretched platform,thereby simplifying the assembly process and opening routes to additional classes of 3D geometries unobtainable with compressive buckling.A few basic principles in mechanics serve as guidelines for the design of 2D precursor structures that achieve large out-of-plane motions and associated 3D transformations due to tensile buckling.Experimental and computational studies of nearly 20 examples demonstrate the utility of this approach in the assembly of complex 3D mesostructures with characteristic dimensions from micron to millimeter scales.The results also establish the use of nonlinear mechanics modeling as a mechanism for designing systems that yield desired 3D geometries.A strain sensor that offers visible readout and large detectable strain range through a collection of mechanically triggered electrical switches and LEDs serves as an application example.展开更多
Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications...Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications that cannot be addressed by wearable hardware that is commercially available today.A primary challenge is power supply;the physical bulk,large mass and high mechanical modulus associated with conventional battery technologies can hinder efforts to achieve epidermal characteristics,and near-field power transfer schemes offer only a limited operating distance.Here we introduce an epidermal,farfield radio frequency(RF)power harvester built using a modularized collection of ultrathin antennas,rectifiers and voltage doublers.These components,separately fabricated and tested,can be integrated together via methods involving soft contact lamination.Systematic studies of the individual components and the overall performance in various dielectric environments highlight the key operational features of these systems and strategies for their optimization.The results suggest robust capabilities for battery-free RF power,with relevance to many emerging epidermal technologies.展开更多
The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sen...Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sensors with important capabilities in this context,rendered in soft,ultrathin,‘skin-like’formats with numerous advantages over alternative technologies,including the ability to establish intimate,conformal contact without applied pressure,and to provide spatiotemporally resolved data on both electrical and thermal transport properties from sensitive regions of the skin.Systematic in vitro studies and computational models establish the underlying measurement principles and associated approaches for determination of temperature,thermal conductivity,thermal diffusivity,volumetric heat capacity,and electrical impedance using simple analysis algorithms.Clinical studies on 20 patients subjected to a variety of external stimuli validate the device operation and allow quantitative comparisons of measurement capabilities to those of existing state-of-the-art tools.展开更多
Recent developments in the fields of materials science and engineering technology(mechanical,electrical,biomedical)lay the foundation to design flexible bioelec-tronics with dynamic interfaces,widely used in biomedica...Recent developments in the fields of materials science and engineering technology(mechanical,electrical,biomedical)lay the foundation to design flexible bioelec-tronics with dynamic interfaces,widely used in biomedical/clinical monitoring,stimulation,and characterization.Examples of this technology include body motion and physiological signal monitoring through soft wearable devices,mechanical characterization of biological tissues,skin stimulation using dynamic actuators,and energy harvesting in biomedical implants.Typically,these bioelectronic systems feature thin form factors for enhanced flexibility and soft elastomeric encapsula-tions that provide skin‐compliant mechanics for seamless integration with biological tissues.This review examines the rapid and continuous progress of bioelectronics in the context of design strategies including materials,mechanics,and structure to achieve high performance dynamic interfaces in biomedicine.It concludes with a concise summary and insights into the ongoing opportunities and challenges facing developments of bioelectronics with dynamic interfaces for future applications.展开更多
Flowrate control in flexible bioelectronics with targeted drug delivery capabilities is essential to ensure timely and safe delivery.For neuroscience and pharmacogenetics studies in small animals,these flexible bioele...Flowrate control in flexible bioelectronics with targeted drug delivery capabilities is essential to ensure timely and safe delivery.For neuroscience and pharmacogenetics studies in small animals,these flexible bioelectronic systems can be tailored to deliver small drug volumes on a controlled fashion without damaging surrounding tissues from stresses induced by excessively high flowrates.The drug delivery process is realized by an electrochemical reaction that pressurizes the internal bioelectronic chambers to deform a flexible polymer membrane that pumps the drug through a network of microchannels implanted in the small animal.The flowrate temporal profile and global maximum are governed and can be modeled by the ideal gas law.Here,we obtain an analytical solution that groups the relevant mechanical,fluidic,environmental,and electrochemical terms involved in the drug delivery process into a set of three nondimensional parameters.The unique combinations of these three nondimensional parameters(related to the initial pressure,initial gas volume,and microfluidic resistance)can be used to model the flowrate and scale up the flexible bioelectronic design for experiments in medium and large animal models.The analytical solution is divided into(1)a fast variable that controls the maximum flowrate and(2)a slow variable that models the temporal profile.Together,the two variables detail the complete drug delivery process and control using the three nondimensional parameters.Comparison of the analytical model with alternative numerical models shows excellent agreement and validates the analytic modeling approach.These findings serve as a theoretical framework to design and optimize future flexible bioelectronic systems used in biomedical research,or related medical fields,and analytically control the flowrate and its global maximum for successful drug delivery.展开更多
Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sour...Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sources Citation Index(ESCI)on June 27,2023,after being indexed by Inspec,Scopus,DOAJ,Dimensions,and some other databases.We would like to take this opportunity,on behalf of the IJMSD Editorial Board,to extend our gratitude and sincere appreciation for your significant contributions and support to IJMSD.展开更多
Dear Readers,Authors,Reviewers,Editorial Board Members,Editorial Office Members,We are pleased and honored to inform you that,according to the 2024 Journal Citation Reports(JCR)from Clarivate released on June 20,2024,...Dear Readers,Authors,Reviewers,Editorial Board Members,Editorial Office Members,We are pleased and honored to inform you that,according to the 2024 Journal Citation Reports(JCR)from Clarivate released on June 20,2024,the International Journal of Mechanical System Dynamics(IJMSD)received its first Journal Impact Factor of 3.4(2023).IJMSD ranks 42nd out of 180 journals in the Engineering,Mechanical category(Q1,top 23.1%),and 39th out of 170 journals in the Mechanics category(Q1,top 22.6%).展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12225206,11921002,and 12202233)the New Cornerstone Science Foundation through the XPLORER PRIZE,the Tsinghua National Laboratory for Information Science and Technology,a grant from the Institute for Guo Qiang,Tsinghua University(Grant No.2021GQG1009)。
文摘The buckling-guided three-dimensional(3D)assembly method has arisen increasing attention for its advantages in forming complex 3D architectures with a rich diversity of geometric shapes in a broad spectrum of inorganic functional materials.Such an assembly method relies on the controlled lateral bucking of a 2D precursor structure integrated with a pre-stretched substrate at selective regions.In the assembly process,the preservation or break-ing of rotational symmetry is crucial for understanding the mechanism of 2D-to-3D geometric transformation.Here,we present a fundamental study on the rotational symmetry of 3D spoke double-ring structures formed through buckling-guided assembly.An energetic method is introduced to analyze the rotational symmetry and to understand the symmetry-breaking mechanism.Such symmetry-breaking phenomenon is validated by experi-ments and finite element analyses(FEA).Phase diagrams of the deformation mode are established to shed light on the influences of various geometric parameters(e.g.,initial rotational symmetry order,radius ratio,and lo-cation of bonding sites).This work offers new insights into the underlying mechanism of 2D-to-3D geometric transformation in ribbon-type structures formed by compressive buckling.
基金The project supported by the National Natural Science Foundation of China (10121202)the Ministry of Education of China (20020003023)
文摘Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer range）, but it does not always hold in nanoindentation experiments （indentation depths approaching the nanometer range）. Indenter tip radius effect has been proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao＇s relationship. We have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary dislocations. The comparison between numerical result and Feng and Nix＇s experimental data shows that the indenter tip radius effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.
基金X.G. and Z.X. contributed equally to this work. Y.Z. acknowledges the support from the National Natural Science Foundation of China （Grant Nos. 11502129 and 11722217） and the Tsinghua National Laboratory for Information Science and Technology. Y.H. acknowledges the support from the NSF （Grant Nos. CMMI1400169, CMMI1534120 and CMMI1635443）. X.G. acknowledges the support from the National Natural Science Foundation of China （Grant Nos. 11702155）.
文摘The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.
基金supported by the National Natural Science Foundation of China through Grant Nos 10628205,10732050 and10872115National Basic Research Program of China through Grant No 2007CB936803,and SRF-SEM for ROCS
文摘Plant leaves, insects and geckos are masters of adhesion or anti-adhesion by smartly designed refined surface structures with micro- and nano- ＇technologies＇. Understanding the basic principles in the design of the unique surface structures is of great importance in the manufacture or synthesis of micro- and nano- devices in MEMS or NEMS. This study is right inspired by this effort, focusing on the mechanics of wet adhesion between fibers having concave tips and a flat substrate via capillary forces. We show that the concave surface can effectively enhance the wet adhesion by reducing the effective contact angle of the fiber, firmly pinning the liquid bridge at its circumferential edge. A critical contact angle is identified below which the adhesion strength can achieve its maximum, being insensitive to the contact angle between the fiber and liquid. The analytical expression for the critical angle is derived. Then a tentative design for the profile of concave surfaces is proposed, considering the effects of chamfering size, deformation and buckling, etc. The effect of liquid volume on the wet adhesion of multiple-fiber system is also discussed.
文摘Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish tasks in complex and time-varying environments through geometric reconfiguration induced by diverse external stimuli,such as heat,solvent,light,electric field,magnetic field,and mechanical field.Approaches to achieve reconfigurable mesostructures are essential to the design and fabrication of soft robots.Existing studies mainly focus on four key aspects:reconfiguration mechanisms,fabrication schemes,deformation control principles,and practical applications.This review presents a detailed survey of methodologies for morphable mesostructures triggered by a wide range of stimuli,with a number of impressive examples,demonstrating high degrees of deformation complexities and varied multi-functionalities.The latest progress based on the development of new materials and unique design concepts is highlighted.An outlook on the remaining challenges and open opportunities is provided.
基金Project supported by the NSF (Nos.DMI-0328162 and ECCS-0824129)the support from NSFCthe support from China Scholarship Council
文摘Various methods have been developed to fabricate highly stretchable electronics. Recent studies show that over 100% two dimensional stretchability can be achieved by mesh structure of brittle functioning devices interconnected with serpentine bridges. Kim et al show that pressing down an inflated elastomeric thin film during transfer printing introduces two di- mensional prestrain, and therefore further improves the system stretchability. This paper gives a theoretical study of this process, through both analytical and numerical approaches. Simple analytical solutions are obtained for meridional and circumferential strains in the thin film, as well as the maximum strain in device islands, which all agree reasonably well with finite element analysis.
基金Project supported by the National Science Foundation （No. CMS-0084980） ONR （No. N00014-01-1-0205, program officer Dr. Y.D.S. Rajapakse）, by the Foundation for the Author of National Excellent Doctoral Dissertation of China （FANEDD） （No. 2007B30）.
文摘The finite element method for the conventional theory of mechanism-based strain gradient plasticity is used to study the indentation size effect. For small indenters （e.g., radii on the order of 10μm）, the maximum allowable geometrically necessary dislocation （GND） density is introduced to cap the GND density such that the latter does not become unrealistically high. The numerical results agree well with the indentation hardness data of iridium. The GND density is much larger than the density of statistically stored dislocations （SSD） underneath the indenter, but this trend reverses away from the indenter. As the indentation depth （or equivalently, contact radius） increases, the GND density decreases but the SSD density increases.
文摘Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. By considering a circular thin film/substrate system subject to non-uniform, but axisymmetric misfit strain distributions in the thin film, we derived relations between the film stresses and the misfit strain, and between the plate system＇s curvatures and the misfit strain. These relations feature a “local” part which involves a direct dependence of the stress or curvature components on the misfit strain at the same point, and a “non-local” part which reflects the effect of misfit strain of other points on the location of scrutiny. Most notably, we also derived relations between the polar components of the film stress and those of system curvatures which allow for the experimental inference of such stresses from full-field curvature measurements in the presence of arbitrary radial non-uniformities. These relations also feature a “non-local” dependence on curvatures making a full-field measurement a necessity. Finally, it is shown that the interfacial shear tractions between the film and the substrate are proportional to the radial gradients of the first curvature invariant and can also be inferred experimentally.
基金This work utilized Northwestern University Micro/Nano Fabrication Facility(NUFAB)which is partially supported by Soft and Hybrid Nanotechnology Experimental(SHyNE)Resource(NSF ECCS-1542205)+3 种基金the Materials Research Science and Engineering Center(DMR-1720139)the State of Illinois,and Northwestern University.Y.H.acknowledges the support from the National Science Foundation,USA(grant no.CMMI1635443)supported by Querrey Simpson Institute for Bioelectronicssupported by Cancer Center Support Grant P30 CA060553 from the National Cancer Institute awarded to the Robert H.Lurie Comprehensive Cancer Center.
文摘Objective and Impact Statement.Real-time monitoring of the temperatures of regional tissue microenvironments can serve as the diagnostic basis for treating various health conditions and diseases.Introduction.Traditional thermal sensors allow measurements at surfaces or at near-surface regions of the skin or of certain body cavities.Evaluations at depth require implanted devices connected to external readout electronics via physical interfaces that lead to risks for infection and movement constraints for the patient.Also,surgical extraction procedures after a period of need can introduce additional risks and costs.Methods.Here,we report a wireless,bioresorbable class of temperature sensor that exploits multilayer photonic cavities,for continuous optical measurements of regional,deep-tissue microenvironments over a timeframe of interest followed by complete clearance via natural body processes.Results.The designs decouple the influence of detection angle from temperature on the reflection spectra,to enable high accuracy in sensing,as supported by in vitro experiments and optical simulations.Studies with devices implanted into subcutaneous tissues of both awake,freely moving and asleep animal models illustrate the applicability of this technology for in vivo measurements.Conclusion.The results demonstrate the use of bioresorbable materials in advanced photonic structures with unique capabilities in tracking of thermal signatures of tissue microenvironments,with potential relevance to human healthcare.
基金supported by the Querrey Simpson Institute for Bioelectronics at Northwestern University.S.Y.acknowledges support from the National Research Foundation of Korea(NRF)grant(No.RS-2025-23525124)funded by the Korea government(MSIT)+4 种基金the BK21 FOUR program(Digital Anti-aging Convergence Research Group,Inje University)support from the National NaturalScience Foundation of China(12202241)support from the National Research Foundation of Korea(NRF)grant(Nos.RS-2022-NR072054 and RS-2020-NR049568)the Institute of Information&Communications Technology Planning&Evaluation(IITP)under the Graduate School of Artificial Intelligence Semiconductor(IITP-2025-RS-2023-00256472)grantfunded by the Korea government(MSIT),and the BK21 FOUR program(Connected AI Education&Research Program for Industry and Society Innovation,KAIST EE,No.4120200113769).
文摘Pressure ulcers remain a persistent challenge in healthcare,particularly for individuals with limited mobility or compromised sensation.Early detection is critical to prevent ischemic damage leading to necrosis,infections,and prolonged hospital stays.Conventional sensing technologies that integrate into the mattress,while effective in gathering data on pressure distributions,are restricted to stationary environments,and they can miss significant periods when patients leave their beds or shift positions.Furthermore,these systems do not offer consistent information on the specific spatial distribution of pressure across the body,because the sensors integrate with the mattress and not the body.Recent research establishes capabilities in soft,skin-interfaced wireless alternatives,but in designs that require specialized processes and materials that might not scale effectively for practical production and use.Here,we present a wireless,skin-integrated pressure monitoring system that mounts on the skin,in anatomically matched forms and with soft mechanical interfaces,for continuous data collection.This platform,built on manufacturable components and designs,features an array of soft,elastomer-encapsulated pressure sensors that minimize discomfort,with wireless communications and an independent power management system to enable operation across diverse healthcare settings,including homes,outpatient facilities,and operating rooms,all without physical tethers.Additionally,an external alarm satellite device delivers vibratory and visual alerts if predefined pressure thresholds are exceeded,guiding caregivers or patients to take timely action.Experimental and finite element analysis support the design principles,and deployments on patients in hospital settings illustrate modes for practical use.
文摘Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.
基金Y.Z.acknowledges support from the National Natural Science Foundation of China(#11672152 and#11722217)the Thousand Young Talents Program of China,and the Tsinghua National Laboratory for Information Science and TechnologyY.H.acknowledges the support from the NSF(#CMMI1400169,#CMMI1534120,and#CMMI1635443).
文摘Recent research establishes methods of controlled mechanical assembly as versatile routes to three-dimensional(3D)mesostructures from patterned 2D films,with demonstrated applicability to a broad range of materials(e.g.,semiconductors,polymers,metals,and their combinations)and length scales(e.g.,from sub-microscale to centimeter scale).Previously reported schemes use pre-stretched elastomeric substrates as assembly platforms to induce compressive buckling of 2D precursor structures,thereby enabling their controlled transformation into 3D architectures.Here,we introduce tensile buckling as a different,complementary strategy that bypasses the need for a pre-stretched platform,thereby simplifying the assembly process and opening routes to additional classes of 3D geometries unobtainable with compressive buckling.A few basic principles in mechanics serve as guidelines for the design of 2D precursor structures that achieve large out-of-plane motions and associated 3D transformations due to tensile buckling.Experimental and computational studies of nearly 20 examples demonstrate the utility of this approach in the assembly of complex 3D mesostructures with characteristic dimensions from micron to millimeter scales.The results also establish the use of nonlinear mechanics modeling as a mechanism for designing systems that yield desired 3D geometries.A strain sensor that offers visible readout and large detectable strain range through a collection of mechanically triggered electrical switches and LEDs serves as an application example.
基金XF and YM acknowledge the support from the National Basic Research Program of China(Grant No.2015CB351900)the National Natural Science Foundation of China(Grant Nos.11402135 and 11320101001).
文摘Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications that cannot be addressed by wearable hardware that is commercially available today.A primary challenge is power supply;the physical bulk,large mass and high mechanical modulus associated with conventional battery technologies can hinder efforts to achieve epidermal characteristics,and near-field power transfer schemes offer only a limited operating distance.Here we introduce an epidermal,farfield radio frequency(RF)power harvester built using a modularized collection of ultrathin antennas,rectifiers and voltage doublers.These components,separately fabricated and tested,can be integrated together via methods involving soft contact lamination.Systematic studies of the individual components and the overall performance in various dielectric environments highlight the key operational features of these systems and strategies for their optimization.The results suggest robust capabilities for battery-free RF power,with relevance to many emerging epidermal technologies.
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
基金YM and XF acknowledge the support from the National Basic Research Program of China(Grant No.2015CB351900)National Natural Science Foundation of China(Grant Nos.11402135,11320101001)+2 种基金YH acknowledges the support from NSF(Grant Nos.DMR1121262,CMMI1300846,CMMI1400169,and CMMI1534120)the NIH(Grant No.R01EB019337)RCW acknowledges support from the National Science Foundation under grant no.DGE-1144245.
文摘Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sensors with important capabilities in this context,rendered in soft,ultrathin,‘skin-like’formats with numerous advantages over alternative technologies,including the ability to establish intimate,conformal contact without applied pressure,and to provide spatiotemporally resolved data on both electrical and thermal transport properties from sensitive regions of the skin.Systematic in vitro studies and computational models establish the underlying measurement principles and associated approaches for determination of temperature,thermal conductivity,thermal diffusivity,volumetric heat capacity,and electrical impedance using simple analysis algorithms.Clinical studies on 20 patients subjected to a variety of external stimuli validate the device operation and allow quantitative comparisons of measurement capabilities to those of existing state-of-the-art tools.
基金National Natural Science Foundation of China,Grant/Award Number:12072057Liaoning Revitalization Talents Program,Grant/Award Number:XLYC2007196+2 种基金Fundamental Research Funds for the Central Universities,Grant/Award Number:DUT20RC(3)032National Science Foundation,Grant/Award Number:CMMI1635443National Science Foundation Graduate Research Fellowship,Grant/Award Number:1842165。
文摘Recent developments in the fields of materials science and engineering technology(mechanical,electrical,biomedical)lay the foundation to design flexible bioelec-tronics with dynamic interfaces,widely used in biomedical/clinical monitoring,stimulation,and characterization.Examples of this technology include body motion and physiological signal monitoring through soft wearable devices,mechanical characterization of biological tissues,skin stimulation using dynamic actuators,and energy harvesting in biomedical implants.Typically,these bioelectronic systems feature thin form factors for enhanced flexibility and soft elastomeric encapsula-tions that provide skin‐compliant mechanics for seamless integration with biological tissues.This review examines the rapid and continuous progress of bioelectronics in the context of design strategies including materials,mechanics,and structure to achieve high performance dynamic interfaces in biomedicine.It concludes with a concise summary and insights into the ongoing opportunities and challenges facing developments of bioelectronics with dynamic interfaces for future applications.
基金R.A.acknowledges support from the National Science Foundation Graduate Research Fellowship(NSF grant number DGE-1842165)and from the Ford Foundation Predoctoral Fellowship。
文摘Flowrate control in flexible bioelectronics with targeted drug delivery capabilities is essential to ensure timely and safe delivery.For neuroscience and pharmacogenetics studies in small animals,these flexible bioelectronic systems can be tailored to deliver small drug volumes on a controlled fashion without damaging surrounding tissues from stresses induced by excessively high flowrates.The drug delivery process is realized by an electrochemical reaction that pressurizes the internal bioelectronic chambers to deform a flexible polymer membrane that pumps the drug through a network of microchannels implanted in the small animal.The flowrate temporal profile and global maximum are governed and can be modeled by the ideal gas law.Here,we obtain an analytical solution that groups the relevant mechanical,fluidic,environmental,and electrochemical terms involved in the drug delivery process into a set of three nondimensional parameters.The unique combinations of these three nondimensional parameters(related to the initial pressure,initial gas volume,and microfluidic resistance)can be used to model the flowrate and scale up the flexible bioelectronic design for experiments in medium and large animal models.The analytical solution is divided into(1)a fast variable that controls the maximum flowrate and(2)a slow variable that models the temporal profile.Together,the two variables detail the complete drug delivery process and control using the three nondimensional parameters.Comparison of the analytical model with alternative numerical models shows excellent agreement and validates the analytic modeling approach.These findings serve as a theoretical framework to design and optimize future flexible bioelectronic systems used in biomedical research,or related medical fields,and analytically control the flowrate and its global maximum for successful drug delivery.
文摘Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sources Citation Index(ESCI)on June 27,2023,after being indexed by Inspec,Scopus,DOAJ,Dimensions,and some other databases.We would like to take this opportunity,on behalf of the IJMSD Editorial Board,to extend our gratitude and sincere appreciation for your significant contributions and support to IJMSD.
文摘Dear Readers,Authors,Reviewers,Editorial Board Members,Editorial Office Members,We are pleased and honored to inform you that,according to the 2024 Journal Citation Reports(JCR)from Clarivate released on June 20,2024,the International Journal of Mechanical System Dynamics(IJMSD)received its first Journal Impact Factor of 3.4(2023).IJMSD ranks 42nd out of 180 journals in the Engineering,Mechanical category(Q1,top 23.1%),and 39th out of 170 journals in the Mechanics category(Q1,top 22.6%).
