Hard-magnetic soft materials exhibit significant shape morphing capabilities under non-contact magnetic actuation, yet their particulate composition tends to compromise material toughness. To quantify particle-matrix ...Hard-magnetic soft materials exhibit significant shape morphing capabilities under non-contact magnetic actuation, yet their particulate composition tends to compromise material toughness. To quantify particle-matrix interactions, we present a mechanics model describing the energy functional of planar magnetic composites. Through the Fourier series, the analytical solutions for stress distribution and interfacial peeling length of a single particle-polymer unit are derived with the Rayleigh-Ritz method under uniaxial tension. The calculated results of stress fields without the magnetic field agree well with those of the finite element method. The effects of external magnetic field strength and particle content on the stress distribution and peeling length are fully explored, and the enhanced analytical outcomes are obtained through numerical prediction.These insights can be used to validate the reliability of engineering designs, including adaptive structures, micro-electro-mechanical sensors, and soft robotic systems.展开更多
Soft materials,with the sensitivity to various external stimuli,exhibit high flexibility and stretchability.Accurate prediction of their mechanical behaviors requires advanced hyperelastic constitutive models incorpor...Soft materials,with the sensitivity to various external stimuli,exhibit high flexibility and stretchability.Accurate prediction of their mechanical behaviors requires advanced hyperelastic constitutive models incorporating multiple parameters.However,identifying multiple parameters under complex deformations remains a challenge,especially with limited observed data.In this study,we develop a physics-informed neural network(PINN)framework to identify material parameters and predict mechanical fields,focusing on compressible Neo-Hookean materials and hydrogels.To improve accuracy,we utilize scaling techniques to normalize network outputs and material parameters.This framework effectively solves forward and inverse problems,extrapolating continuous mechanical fields from sparse boundary data and identifying unknown mechanical properties.We explore different approaches for imposing boundary conditions(BCs)to assess their impacts on accuracy.To enhance efficiency and generalization,we propose a transfer learning enhanced PINN(TL-PINN),allowing pre-trained networks to quickly adapt to new scenarios.The TL-PINN significantly reduces computational costs while maintaining accuracy.This work holds promise in addressing practical challenges in soft material science,and provides insights into soft material mechanics with state-of-the-art experimental methods.展开更多
Taking three typical soft samples prepared respectively by loose packings of 77-,95-,and 109-μm copper grains as examples,we perform an experiment to investigate the energy-dependent laser-induced breakdown spectrosc...Taking three typical soft samples prepared respectively by loose packings of 77-,95-,and 109-μm copper grains as examples,we perform an experiment to investigate the energy-dependent laser-induced breakdown spectroscopy(LIBS)of soft materials.We discovered a reversal phenomenon in the trend of energy dependence of plasma emission intensity:increasing initially and then decreasing separated by a well-defined critical energy.The trend reversal is attributed to the laser-induced recoil pressure at the critical energy just matching the sample's yield strength.As a result,a one-to-one correspondence can be well established between the samples'yield stress and the critical energy that is easily obtainable from LIBS measurements.This allows us to propose an innovative method for estimating the yield stress of soft materials via LIBS with attractive advantages including in-situ remote detection,real-time data collection,and minimal destructive to sample.展开更多
Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the t...Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft materials.Considering a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.展开更多
In the current shift from conventional fossil-fuel-based materials to renewable energy,ecofriendly materials have attracted extensive research interest due to their sustainability and biodegradable properties.The inte...In the current shift from conventional fossil-fuel-based materials to renewable energy,ecofriendly materials have attracted extensive research interest due to their sustainability and biodegradable properties.The integration of sustainable materials in electronics provides industrial benefits from wasted bio-origin resources and preserves the environment.This review covers the use of sustainable materials as components in organic electronics,such as substrates,insulators,semiconductors,and conductors.We hope this review will stimulate interest in the potential and practical applications of sustainable materials for green and sustainable industry.展开更多
The authors carried out drop impact tests for several soft materials under a flat frontal impact condition in which a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. ...The authors carried out drop impact tests for several soft materials under a flat frontal impact condition in which a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. The experimental results indicated that the impact force waveforms of soft materials consisted of a thorn-shaped waveform and a subsequent mountain-shaped waveform. The thorn-shaped waveform was strongly affected by the strain rate. In the present study, the occurrence mechanism of this distinctive waveform was discussed from the viewpoint of the viscosity transient phenomenon. A standard linear solid (SLS) model in which the viscosity transient phenomenon was considered was applied to the simulation. Some features of the impact force waveform of soft materials could be explained by the SLS model. Furthermore, the thorn-shape waveform could also be observed in the impact force waveforms of human skin and free-falling hollow balls.展开更多
Soft material is becoming increasingly important to many industries, which leads to the demand for a better understanding of its mechanical properties under large deformation. In this paper, a technique of integrating...Soft material is becoming increasingly important to many industries, which leads to the demand for a better understanding of its mechanical properties under large deformation. In this paper, a technique of integrating the digital moire method and embedded-grating approach is presented for investigating mechanical behaviors of a vulcanized silicone rubber in contact with a wedge-shaped indenter. Two distinct deformation sectors are observed from the experimental result. A simple way of computing strain is also presented by analysing grid deformation within the framework of geometrical nonlinearity. Three regions were observed from strain distribution along the horizontal direction： the contact region, the sink-in region and the far-field region. Moreover, the extent of the sticky region and that of the slippy region within the contact interface are distinguished, which can provide realistic data for theoretical modelling. Based on the finite deformation elasticity theory, the distribution of contact pressure and shear stress over the contact interface are derived for prediction of possible cracks.展开更多
In this paper,the elastic wave band gap characteristics of two-dimensional hard-magnetic soft material phononic crystals(HmSM-PnCs)under the applied magnetic field are studied.Firstly,the relevant material parameters ...In this paper,the elastic wave band gap characteristics of two-dimensional hard-magnetic soft material phononic crystals(HmSM-PnCs)under the applied magnetic field are studied.Firstly,the relevant material parameters of hard-magnetic soft materials(HmSMs)are obtained by the experimental measurement.Then the finite element model of the programmable HmSM-PnCs is established to calculate its band structure under the applied magnetic field.The effects of some factors such as magnetic field,structure thickness,structure porosity,and magnetic anisotropy encoding mode on the band gap are given.The results show that the start and stop frequencies and band gap width can be tunable by changing the magnetic field.The magnetic anisotropy encoding mode has a remarkable effect on the number of band gaps and the critical magnetic field of band gaps.In addition,the effect of geometric size on PnC structure is also discussed.With the increase of the structure thickness,the start and stop frequencies of the band gap increase.展开更多
Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with...Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.展开更多
The concept of soft matter was first introduced by P. G. de Gennes in his acceptance speech for the No-bel Physics Prize in 1991. In mechanics community, however, people usually prefer using soft material in-stead of ...The concept of soft matter was first introduced by P. G. de Gennes in his acceptance speech for the No-bel Physics Prize in 1991. In mechanics community, however, people usually prefer using soft material in-stead of soft matter to describe the material whose en-ergy associated with thermal motion is comparative to the interaction energy. Unlike in the conventional con-densed matter, entropy plays an important and even de-terminative role in soft materials.展开更多
Due to the small size,active mobility,and intrinsic softness,miniature soft robots hold promising po-tentials in reaching the deep region inside living bodies otherwise inaccessible with compelling agility,adaptabilit...Due to the small size,active mobility,and intrinsic softness,miniature soft robots hold promising po-tentials in reaching the deep region inside living bodies otherwise inaccessible with compelling agility,adaptability and safety.Various materials and actuation strategies have been developed for creating soft robots,among which,ferromagnetic soft materials that self-actuate in response to external magnetic fields have attracted worldwide attention due to their remote controllability and excellent compatibil-ity with biological tissues.This review presents comprehensive and systematic research advancements in the design,fabrication,and applications of ferromagnetic soft materials for miniature robots,providing in-sights into their potential use in biomedical fields and beyond.The programming strategies of ferromag-netic soft materials are summarized and classified,including mold-assisted programming,3D printing-assisted programming,microassembly-assisted programming,and magnetization reprogramming.Each approach possesses unique advantages in manipulating the magnetic responsiveness of ferromagnetic soft materials to achieve outstanding actuation and deformation performances.We then discuss the biomedi-cal applications of ferromagnetic soft material-based soft robots(e.g.,minimally invasive surgery,targeted delivery,and tissue engineering),highlighting their potentials in revolutionizing biomedical technologies.This review also points out the current challenges and provides insights into future research directions,which we hope can serve as a useful reference for the development of next-generation adaptive miniature robots.展开更多
Seismic risk is one of the biggest challenges for tunnel safety,and several mitigation techniques have been proposed to enhance the seismic performance of existing tunnels.This paper aims to investigate the effectiven...Seismic risk is one of the biggest challenges for tunnel safety,and several mitigation techniques have been proposed to enhance the seismic performance of existing tunnels.This paper aims to investigate the effectiveness of an innovative approach for reducing the seismic risk of existing tunnels by using soft material walls(SMW)symmetrically installed in the surrounding soils.The investigation is performed with a two-dimensional numerical model and the effectiveness of SMW in mitigating the seismic-induced lining forces is quantitatively evaluated by reduction ratio.The influences of nonlinear properties of soil,SMW and tunnel lining on the isolation effectiveness are also discussed.The parametric studies show that the computed reduction ratio is strongly affected by the modulus ratio between the SMW and the soil,the wall geometric parameter,and the flexibility ratio.It is more effective for the thick and soft isolation walls that are inserted near a stiff tunnel in the soft soil.The tunnel seismic response can be reduced by up to 50%for the scenarios investigated.Notably,the parametric study identifies an optimum normalized depth of SMW and recommends a relation between the maximum isolation effect and the flexibility ratio.Finally,simple charts are suggested in this work for estimating the isolation effect in specific conditions of the soil and the tunnel.Along these lines,the results of this work may be used in the seismic retrofitting of an existing tunnel,aiding the preliminary design of the isolation walls.展开更多
Responsive soft materials capable of complex,reversible,and rapid geometric deformations under external stimuli hold significant potential for applications in minimally invasive medicine,wearable devices,and soft robo...Responsive soft materials capable of complex,reversible,and rapid geometric deformations under external stimuli hold significant potential for applications in minimally invasive medicine,wearable devices,and soft robotics.In this study,we present a novel approach for designing reconfigurable three dimensional(3D)deformable magnetic soft materials through photothermal programming.By embedding hard magnetic particles within a polymer matrix composed of fibrous polypyrrole(PPy)and semi-crystalline polymer,we develop magnetic composites that can be remotely controlled to achieve precise,programmable deformations under an external magnetic field.The key innovation lies in utilizing the photothermal effect of PPy,which temporarily alters the viscosity of the composite when irradiated with infrared light,allowing dynamic orientation of the magnetic particles.Upon cooling,the magnetic anisotropy is solidified,enabling rapid and reversible geometric changes.This method allows for intricate control over the magnetization distribution,leading to the development of multifunctional devices with various potential applications such as complex 3D deformations for soft robotics,multimodal electrical switches,rewritable quick response codes,and shape-adaptable grippers.Our study not only enhances the understanding of magnetic moment programming in soft materials but also opens new avenues for the design of adaptive and responsive materials for advanced technological applications.展开更多
Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to s...Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to stray from its intended path.Therefore,a cost-effective and straightforward solution is essential for reducing this deviation.In nature,the tail is often used to maintain balance and stability.Similarly,it has been used in robots to improve manoeuvrability and stability.Our aim is to reduce this deviation using a morphological computation approach,specifically by adding a tail.To test this hypothesis,we investigated four different tails(rigid plate,rigid gecko-shaped,soft plate,and soft gecko-shaped)and assessed the deviation of the robot with these tails on different slopes.Additionally,to evaluate the influence of different tail parameters,such as material,shape,and linkage,we investigated the locomotion performance in terms of the robot's climbing speed on slopes,its ability to turn at narrow corners,and the resistance of the tails to external disturbances.A new auto-reset joint was designed to ensure that a disturbed tail could be quickly reset.Our results demonstrate that the yaw deviation of the robot can be reduced by applying a tail.Among the four tails,the soft gecko-shaped tail was the most effective for most tasks.In summary,our findings demonstrate the functional role of the tail in reducing yaw deviation,improving climbing ability and stability and provide a reference for selecting the most suitable tail for geckoinspired robots.展开更多
Magneto-active soft materials,composed of hard-magnetic particles embedded in polymeric matrices,have found widespread applications in soft robotics,active metamaterials,and shape-morphing structures across various le...Magneto-active soft materials,composed of hard-magnetic particles embedded in polymeric matrices,have found widespread applications in soft robotics,active metamaterials,and shape-morphing structures across various length scales due to their ability to undergo reversible,untethered,and rapid deformation in response to magnetic actuation.At small scales,surface effects play a crucial role in the mechanical behavior of these soft materials.In this paper,we theoretically investigate the influence of surface effects on the buckling instability and large deformation of magneto-active soft beams under a uniform magnetic field.The theoretical model is derived according to the principle of minimum potential energy and numerically solved with the finite difference method.By employing the developed theoretical model,parametric studies are performed to explore how surface effects influence the buckling instability and large deformation of magneto-active soft cantilever beams with varying geometric parameters under different uniform magnetic fields.Our results reveal that the influence of surface effects on the mechanical behavior of magneto-active soft beams depends not only on the geometric parameters but also on the magnetic field strength.Specifically,when the magnetic field strength is relatively small,surface effects reduce the deformation of magneto-active soft beams,particularly for beams with smaller thicknesses and larger length-to-thickness ratios.However,when the magnetic field strength is sufficiently large,and the beam's deformation becomes saturated,surface effects have little influence on the deformation.This work uncovers the role of surface effects in the mechanical behavior of magnetoactive soft materials,which could provide guidelines for the design and optimization of small-scale magnetic-active soft material-based applications.展开更多
Characterizing the mechanical properties of soft materials and biological tissues is of great significance for understanding their deformation behaviors. In this paper, a regional stretching method is proposed to meas...Characterizing the mechanical properties of soft materials and biological tissues is of great significance for understanding their deformation behaviors. In this paper, a regional stretching method is proposed to measure the elastic and hyperelastic properties of a soft material with an adhesive surface or with the aid of glue. Theoretical and dimensional analyses are performed to investigate the regional stretch problem for soft materials that obey the neo-Hookean model, the Mooney-Rivlin model, or the Arruda-Boyce model. Finite element simulations are made to determine the expressions of the dimensionless functions that correlate the stretch response with the constitutive parameters. Thereby, an inverse approach is established to determine the elastic and hyperelastic properties of the tested materials. The regional stretch method is also compared to the indentation technique. Finally, experiments are performed to demonstrate the effectiveness of the proposed method.展开更多
Surface texturing is a smart strategy that is commonly used in nature or industry to improve the tribological properties of sliding surfaces.Herein,we focus on the recent research progress pertaining to the wet fricti...Surface texturing is a smart strategy that is commonly used in nature or industry to improve the tribological properties of sliding surfaces.Herein,we focus on the recent research progress pertaining to the wet friction modification of soft elastomers via texturing.To consider the pertinent physical mechanisms,we present and discuss the fundamentals of wet sliding on soft surfaces(including dewetting and wetting transitions in compliant contacts).Subsequently,we consider the methods in which the characteristic textures regulate and control wet sliding behaviors on soft surfaces;these textures range from conventional patterns of dimples to bioinspired architectures and can either positively or adversely impact the interfacial friction force.Furthermore,we briefly address the perspectives,potential applications,and challenges of texture design for modifying the friction characteristics of soft materials.展开更多
The hard-magnetic soft materials which can sustain high residual magnetic flux density gradually attract the attention of researchers because of potential applications in soft robotics and biomedical fields.In this wo...The hard-magnetic soft materials which can sustain high residual magnetic flux density gradually attract the attention of researchers because of potential applications in soft robotics and biomedical fields.In this work,we focus on the dynamic response of hardmagnetic soft materials.The dynamic motion equations are derived by the Euler-Lagrange equation.The effects of the aspect radio on the nonlinear vibration of the hard-magnetic soft cuboid under the force and applied magnetic fields in different directions are investigated.The amplitude-frequency curves demonstrate that the aspect ratio also has an influence on the frequency and amplitude of the primary resonance.Moreover,to eliminate undesired vibration responses,the PID controller is applied to the vibration of the hardmagnetic soft materials,and the desired results can be obtained.展开更多
Integrated printing of magnetic soft robots with complex structures using recyclable materials to achieve sustainability of the soft robots remains a persistent challenge.Here,we propose a kind of ferromagnetic fibers...Integrated printing of magnetic soft robots with complex structures using recyclable materials to achieve sustainability of the soft robots remains a persistent challenge.Here,we propose a kind of ferromagnetic fibers that can be used to print soft robots with complex structures.These ferromagnetic fibers are recyclable and can make soft robots sustainable.The ferromagnetic fibers based on thermoplastic polyurethane(TPU)/NdFeB hybrid particles are extruded by an extruder.We use a desktop three-dimensional(3D)printer to demonstrate the feasibility of printing two-dimensional(2D)and complex 3D soft robots.These printed soft robots can be recycled and reprinted into new robots once their tasks are completed.Moreover,these robots show almost no difference in actuation capability compared to prior versions and have new functions.Successful applications include lifting,grasping,and moving objects,and these functions can be operated untethered wirelessly.In addition,the locomotion of the magnetic soft robot in a human stomach model shows the prospect of medical applications.Overall,these fully recyclable ferromagnetic fibers pave the way for printing and reprinting sustainable soft robots while also effectively reducing e-waste and robotics waste materials,which is important for resource conservation and environmental protection.展开更多
A touch sensor is an essential component in meeting the growing demand for human-machine interfaces.These sensors have been developed in wearable,attachable,and even implantable forms to acquire a wide range of inform...A touch sensor is an essential component in meeting the growing demand for human-machine interfaces.These sensors have been developed in wearable,attachable,and even implantable forms to acquire a wide range of information from humans.To be applied to the human body,sensors are required to be biocompatible and not restrict the natural movement of the body.Ionic materials are a promising candidate for soft touch sensors due to their outstanding properties,which include high stretchability,transparency,ionic conductivity,and biocompatibility.Here,this review discusses the unique features of soft ionic touch point sensors,focusing on the ionic material and its key role in the sensor.The touch sensing mechanisms include piezocapacitive,piezoresistive,surface capacitive,piezoelectric,and triboelectric and triboresistive sensing.This review analyzes the implementation hurdles and future research directions of the soft ionic touch sensors for their transformative potential.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 11972375 and12211530028)the Special Funds for the Basic Scientific Research Expenses of Central Government Universities of China (No. 2472022X03006A)
文摘Hard-magnetic soft materials exhibit significant shape morphing capabilities under non-contact magnetic actuation, yet their particulate composition tends to compromise material toughness. To quantify particle-matrix interactions, we present a mechanics model describing the energy functional of planar magnetic composites. Through the Fourier series, the analytical solutions for stress distribution and interfacial peeling length of a single particle-polymer unit are derived with the Rayleigh-Ritz method under uniaxial tension. The calculated results of stress fields without the magnetic field agree well with those of the finite element method. The effects of external magnetic field strength and particle content on the stress distribution and peeling length are fully explored, and the enhanced analytical outcomes are obtained through numerical prediction.These insights can be used to validate the reliability of engineering designs, including adaptive structures, micro-electro-mechanical sensors, and soft robotic systems.
基金supported by the National Natural Science Foundation of China(Nos.12172273 and 11820101001)。
文摘Soft materials,with the sensitivity to various external stimuli,exhibit high flexibility and stretchability.Accurate prediction of their mechanical behaviors requires advanced hyperelastic constitutive models incorporating multiple parameters.However,identifying multiple parameters under complex deformations remains a challenge,especially with limited observed data.In this study,we develop a physics-informed neural network(PINN)framework to identify material parameters and predict mechanical fields,focusing on compressible Neo-Hookean materials and hydrogels.To improve accuracy,we utilize scaling techniques to normalize network outputs and material parameters.This framework effectively solves forward and inverse problems,extrapolating continuous mechanical fields from sparse boundary data and identifying unknown mechanical properties.We explore different approaches for imposing boundary conditions(BCs)to assess their impacts on accuracy.To enhance efficiency and generalization,we propose a transfer learning enhanced PINN(TL-PINN),allowing pre-trained networks to quickly adapt to new scenarios.The TL-PINN significantly reduces computational costs while maintaining accuracy.This work holds promise in addressing practical challenges in soft material science,and provides insights into soft material mechanics with state-of-the-art experimental methods.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0402300)the National Natural Science Foundation of China(Grant Nos.U2241288 and 11974359).
文摘Taking three typical soft samples prepared respectively by loose packings of 77-,95-,and 109-μm copper grains as examples,we perform an experiment to investigate the energy-dependent laser-induced breakdown spectroscopy(LIBS)of soft materials.We discovered a reversal phenomenon in the trend of energy dependence of plasma emission intensity:increasing initially and then decreasing separated by a well-defined critical energy.The trend reversal is attributed to the laser-induced recoil pressure at the critical energy just matching the sample's yield strength.As a result,a one-to-one correspondence can be well established between the samples'yield stress and the critical energy that is easily obtainable from LIBS measurements.This allows us to propose an innovative method for estimating the yield stress of soft materials via LIBS with attractive advantages including in-situ remote detection,real-time data collection,and minimal destructive to sample.
基金supported by the National Natural Science Foundation of China (Grants 51528501, 11532009)the Fundamental Research Funds for Central Universities (Grant 2014qngz12)supported by China Scholarship Council as a visiting scholar to Harvard University
文摘Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft materials.Considering a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.
基金This work was supported by a grant from the National Research Foundation(NRF)funded by the Korean Government(MSIT,2017R1E1A1A01072798 and 2019K1A3A1A14065772).
文摘In the current shift from conventional fossil-fuel-based materials to renewable energy,ecofriendly materials have attracted extensive research interest due to their sustainability and biodegradable properties.The integration of sustainable materials in electronics provides industrial benefits from wasted bio-origin resources and preserves the environment.This review covers the use of sustainable materials as components in organic electronics,such as substrates,insulators,semiconductors,and conductors.We hope this review will stimulate interest in the potential and practical applications of sustainable materials for green and sustainable industry.
文摘The authors carried out drop impact tests for several soft materials under a flat frontal impact condition in which a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. The experimental results indicated that the impact force waveforms of soft materials consisted of a thorn-shaped waveform and a subsequent mountain-shaped waveform. The thorn-shaped waveform was strongly affected by the strain rate. In the present study, the occurrence mechanism of this distinctive waveform was discussed from the viewpoint of the viscosity transient phenomenon. A standard linear solid (SLS) model in which the viscosity transient phenomenon was considered was applied to the simulation. Some features of the impact force waveform of soft materials could be explained by the SLS model. Furthermore, the thorn-shape waveform could also be observed in the impact force waveforms of human skin and free-falling hollow balls.
基金Project supported by the National Natural Science Foundation of China(Nos.11127202 and 11227202)
文摘Soft material is becoming increasingly important to many industries, which leads to the demand for a better understanding of its mechanical properties under large deformation. In this paper, a technique of integrating the digital moire method and embedded-grating approach is presented for investigating mechanical behaviors of a vulcanized silicone rubber in contact with a wedge-shaped indenter. Two distinct deformation sectors are observed from the experimental result. A simple way of computing strain is also presented by analysing grid deformation within the framework of geometrical nonlinearity. Three regions were observed from strain distribution along the horizontal direction： the contact region, the sink-in region and the far-field region. Moreover, the extent of the sticky region and that of the slippy region within the contact interface are distinguished, which can provide realistic data for theoretical modelling. Based on the finite deformation elasticity theory, the distribution of contact pressure and shear stress over the contact interface are derived for prediction of possible cracks.
基金funded by the National Natural Science Foundation of China(11872143).
文摘In this paper,the elastic wave band gap characteristics of two-dimensional hard-magnetic soft material phononic crystals(HmSM-PnCs)under the applied magnetic field are studied.Firstly,the relevant material parameters of hard-magnetic soft materials(HmSMs)are obtained by the experimental measurement.Then the finite element model of the programmable HmSM-PnCs is established to calculate its band structure under the applied magnetic field.The effects of some factors such as magnetic field,structure thickness,structure porosity,and magnetic anisotropy encoding mode on the band gap are given.The results show that the start and stop frequencies and band gap width can be tunable by changing the magnetic field.The magnetic anisotropy encoding mode has a remarkable effect on the number of band gaps and the critical magnetic field of band gaps.In addition,the effect of geometric size on PnC structure is also discussed.With the increase of the structure thickness,the start and stop frequencies of the band gap increase.
基金supported by the National "111 Project" Foundation of China(B06024)the National Natural Science Foundation of China(11372243)+3 种基金"Zhi Gu" Innovation Program of Southern Chinathe Major InternationalJoint Research Program of China(11120101002)International Science and Technology Cooperation Program of China(2013DFG02930)partially supported by the Fundamental Research Funds for the Central Universities(NCET-12-0437)
文摘Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.
文摘The concept of soft matter was first introduced by P. G. de Gennes in his acceptance speech for the No-bel Physics Prize in 1991. In mechanics community, however, people usually prefer using soft material in-stead of soft matter to describe the material whose en-ergy associated with thermal motion is comparative to the interaction energy. Unlike in the conventional con-densed matter, entropy plays an important and even de-terminative role in soft materials.
基金the National Key R&D Program of China(No.2023YFE0208700)National Natural Sci-ence Foundation of China(No.92163109 and 52072095)+7 种基金Shenzhen Science and Technology Program(No.RCJC20231211090000001,GXWD20231129101105001)the National Natural Science Foundation of China(No.52205590)the Natural Science Foundation of Jiangsu Province(No.BK20220834)the Start-up Research Fund of Southeast University(No.RF1028623098)the State Key Laboratory of Robotics and Systems(HIT)(No.SKLRS-2024-KF-11)National Natural Science Foundation of China(No.52202348)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011491)Shenzhen Science and Technology Program(Nos.GXWD20220818224716001,KJZD20231023100302006).
文摘Due to the small size,active mobility,and intrinsic softness,miniature soft robots hold promising po-tentials in reaching the deep region inside living bodies otherwise inaccessible with compelling agility,adaptability and safety.Various materials and actuation strategies have been developed for creating soft robots,among which,ferromagnetic soft materials that self-actuate in response to external magnetic fields have attracted worldwide attention due to their remote controllability and excellent compatibil-ity with biological tissues.This review presents comprehensive and systematic research advancements in the design,fabrication,and applications of ferromagnetic soft materials for miniature robots,providing in-sights into their potential use in biomedical fields and beyond.The programming strategies of ferromag-netic soft materials are summarized and classified,including mold-assisted programming,3D printing-assisted programming,microassembly-assisted programming,and magnetization reprogramming.Each approach possesses unique advantages in manipulating the magnetic responsiveness of ferromagnetic soft materials to achieve outstanding actuation and deformation performances.We then discuss the biomedi-cal applications of ferromagnetic soft material-based soft robots(e.g.,minimally invasive surgery,targeted delivery,and tissue engineering),highlighting their potentials in revolutionizing biomedical technologies.This review also points out the current challenges and provides insights into future research directions,which we hope can serve as a useful reference for the development of next-generation adaptive miniature robots.
基金financially supported by the Chunhui Program of the Natural Science Foundation of Hebei Province(Grant No.E2022201021)the Research Fund for Talented Scholars of Hebei University(Grant No.521100221063).
文摘Seismic risk is one of the biggest challenges for tunnel safety,and several mitigation techniques have been proposed to enhance the seismic performance of existing tunnels.This paper aims to investigate the effectiveness of an innovative approach for reducing the seismic risk of existing tunnels by using soft material walls(SMW)symmetrically installed in the surrounding soils.The investigation is performed with a two-dimensional numerical model and the effectiveness of SMW in mitigating the seismic-induced lining forces is quantitatively evaluated by reduction ratio.The influences of nonlinear properties of soil,SMW and tunnel lining on the isolation effectiveness are also discussed.The parametric studies show that the computed reduction ratio is strongly affected by the modulus ratio between the SMW and the soil,the wall geometric parameter,and the flexibility ratio.It is more effective for the thick and soft isolation walls that are inserted near a stiff tunnel in the soft soil.The tunnel seismic response can be reduced by up to 50%for the scenarios investigated.Notably,the parametric study identifies an optimum normalized depth of SMW and recommends a relation between the maximum isolation effect and the flexibility ratio.Finally,simple charts are suggested in this work for estimating the isolation effect in specific conditions of the soil and the tunnel.Along these lines,the results of this work may be used in the seismic retrofitting of an existing tunnel,aiding the preliminary design of the isolation walls.
基金supported by the National Natural Science Foundation of China(52225307 and 22105193)the CAS Project for Young Scientists in Basic Research(YSBR-004)+1 种基金the Fundamental Research Funds for the Central Universities(20720220007 and 20720220011)partially carried out at the University of Science and Technology of China(USTC)Center of Micro and Nanoscale Research and Fabrication。
文摘Responsive soft materials capable of complex,reversible,and rapid geometric deformations under external stimuli hold significant potential for applications in minimally invasive medicine,wearable devices,and soft robotics.In this study,we present a novel approach for designing reconfigurable three dimensional(3D)deformable magnetic soft materials through photothermal programming.By embedding hard magnetic particles within a polymer matrix composed of fibrous polypyrrole(PPy)and semi-crystalline polymer,we develop magnetic composites that can be remotely controlled to achieve precise,programmable deformations under an external magnetic field.The key innovation lies in utilizing the photothermal effect of PPy,which temporarily alters the viscosity of the composite when irradiated with infrared light,allowing dynamic orientation of the magnetic particles.Upon cooling,the magnetic anisotropy is solidified,enabling rapid and reversible geometric changes.This method allows for intricate control over the magnetization distribution,leading to the development of multifunctional devices with various potential applications such as complex 3D deformations for soft robotics,multimodal electrical switches,rewritable quick response codes,and shape-adaptable grippers.Our study not only enhances the understanding of magnetic moment programming in soft materials but also opens new avenues for the design of adaptive and responsive materials for advanced technological applications.
基金supported by the National Key Research&Development Program of China(Grant No.2020YFB1313504)the State Key Laboratory of Mechanics and Control for Aerospace Structures of Nanjing University of Aeronautics and Astronautics.
文摘Gecko-inspired robots have significant potential applications;however,deviations in the yaw direction during locomotion are inevitable for legged robots that lack external sensing.These deviations cause the robot to stray from its intended path.Therefore,a cost-effective and straightforward solution is essential for reducing this deviation.In nature,the tail is often used to maintain balance and stability.Similarly,it has been used in robots to improve manoeuvrability and stability.Our aim is to reduce this deviation using a morphological computation approach,specifically by adding a tail.To test this hypothesis,we investigated four different tails(rigid plate,rigid gecko-shaped,soft plate,and soft gecko-shaped)and assessed the deviation of the robot with these tails on different slopes.Additionally,to evaluate the influence of different tail parameters,such as material,shape,and linkage,we investigated the locomotion performance in terms of the robot's climbing speed on slopes,its ability to turn at narrow corners,and the resistance of the tails to external disturbances.A new auto-reset joint was designed to ensure that a disturbed tail could be quickly reset.Our results demonstrate that the yaw deviation of the robot can be reduced by applying a tail.Among the four tails,the soft gecko-shaped tail was the most effective for most tasks.In summary,our findings demonstrate the functional role of the tail in reducing yaw deviation,improving climbing ability and stability and provide a reference for selecting the most suitable tail for geckoinspired robots.
基金Project supported by the National Natural Science Foundation of China(Nos.12202009 and12002004)。
文摘Magneto-active soft materials,composed of hard-magnetic particles embedded in polymeric matrices,have found widespread applications in soft robotics,active metamaterials,and shape-morphing structures across various length scales due to their ability to undergo reversible,untethered,and rapid deformation in response to magnetic actuation.At small scales,surface effects play a crucial role in the mechanical behavior of these soft materials.In this paper,we theoretically investigate the influence of surface effects on the buckling instability and large deformation of magneto-active soft beams under a uniform magnetic field.The theoretical model is derived according to the principle of minimum potential energy and numerically solved with the finite difference method.By employing the developed theoretical model,parametric studies are performed to explore how surface effects influence the buckling instability and large deformation of magneto-active soft cantilever beams with varying geometric parameters under different uniform magnetic fields.Our results reveal that the influence of surface effects on the mechanical behavior of magneto-active soft beams depends not only on the geometric parameters but also on the magnetic field strength.Specifically,when the magnetic field strength is relatively small,surface effects reduce the deformation of magneto-active soft beams,particularly for beams with smaller thicknesses and larger length-to-thickness ratios.However,when the magnetic field strength is sufficiently large,and the beam's deformation becomes saturated,surface effects have little influence on the deformation.This work uncovers the role of surface effects in the mechanical behavior of magnetoactive soft materials,which could provide guidelines for the design and optimization of small-scale magnetic-active soft material-based applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.11432008,11572179,and 11172155)
文摘Characterizing the mechanical properties of soft materials and biological tissues is of great significance for understanding their deformation behaviors. In this paper, a regional stretching method is proposed to measure the elastic and hyperelastic properties of a soft material with an adhesive surface or with the aid of glue. Theoretical and dimensional analyses are performed to investigate the regional stretch problem for soft materials that obey the neo-Hookean model, the Mooney-Rivlin model, or the Arruda-Boyce model. Finite element simulations are made to determine the expressions of the dimensionless functions that correlate the stretch response with the constitutive parameters. Thereby, an inverse approach is established to determine the elastic and hyperelastic properties of the tested materials. The regional stretch method is also compared to the indentation technique. Finally, experiments are performed to demonstrate the effectiveness of the proposed method.
基金This work was supported by the National Natural Science Foundation of China(No.52175172)Natural Science Foundation of Anhui Province of China(Nos.2108085ME174 and 2108085QE228)+1 种基金Natural Science Research Fund of Higher Education of Anhui Province(No.KJ2020A0230)the Open Project of the Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials(No.GFST2021KF05).
文摘Surface texturing is a smart strategy that is commonly used in nature or industry to improve the tribological properties of sliding surfaces.Herein,we focus on the recent research progress pertaining to the wet friction modification of soft elastomers via texturing.To consider the pertinent physical mechanisms,we present and discuss the fundamentals of wet sliding on soft surfaces(including dewetting and wetting transitions in compliant contacts).Subsequently,we consider the methods in which the characteristic textures regulate and control wet sliding behaviors on soft surfaces;these textures range from conventional patterns of dimples to bioinspired architectures and can either positively or adversely impact the interfacial friction force.Furthermore,we briefly address the perspectives,potential applications,and challenges of texture design for modifying the friction characteristics of soft materials.
基金The authors acknowledge the support from the National Natural Science Foundation of China(No.11872195)the 111 Project(No.B14044)。
文摘The hard-magnetic soft materials which can sustain high residual magnetic flux density gradually attract the attention of researchers because of potential applications in soft robotics and biomedical fields.In this work,we focus on the dynamic response of hardmagnetic soft materials.The dynamic motion equations are derived by the Euler-Lagrange equation.The effects of the aspect radio on the nonlinear vibration of the hard-magnetic soft cuboid under the force and applied magnetic fields in different directions are investigated.The amplitude-frequency curves demonstrate that the aspect ratio also has an influence on the frequency and amplitude of the primary resonance.Moreover,to eliminate undesired vibration responses,the PID controller is applied to the vibration of the hardmagnetic soft materials,and the desired results can be obtained.
基金funded by the International Cooperation Program of the Natural Science Foundation of China(No.52261135542)Zhejiang Provincial Natural Science Foundation of China(No.LD22E050002)the Russian Science Foundation(No.23-43-00057)for financial support。
文摘Integrated printing of magnetic soft robots with complex structures using recyclable materials to achieve sustainability of the soft robots remains a persistent challenge.Here,we propose a kind of ferromagnetic fibers that can be used to print soft robots with complex structures.These ferromagnetic fibers are recyclable and can make soft robots sustainable.The ferromagnetic fibers based on thermoplastic polyurethane(TPU)/NdFeB hybrid particles are extruded by an extruder.We use a desktop three-dimensional(3D)printer to demonstrate the feasibility of printing two-dimensional(2D)and complex 3D soft robots.These printed soft robots can be recycled and reprinted into new robots once their tasks are completed.Moreover,these robots show almost no difference in actuation capability compared to prior versions and have new functions.Successful applications include lifting,grasping,and moving objects,and these functions can be operated untethered wirelessly.In addition,the locomotion of the magnetic soft robot in a human stomach model shows the prospect of medical applications.Overall,these fully recyclable ferromagnetic fibers pave the way for printing and reprinting sustainable soft robots while also effectively reducing e-waste and robotics waste materials,which is important for resource conservation and environmental protection.
基金supported by the National Research Foundation of Korea(NRF)(No.2021R1C1C2009703)the Gachon University Research Fund of 2022(GCU-202300890001).
文摘A touch sensor is an essential component in meeting the growing demand for human-machine interfaces.These sensors have been developed in wearable,attachable,and even implantable forms to acquire a wide range of information from humans.To be applied to the human body,sensors are required to be biocompatible and not restrict the natural movement of the body.Ionic materials are a promising candidate for soft touch sensors due to their outstanding properties,which include high stretchability,transparency,ionic conductivity,and biocompatibility.Here,this review discusses the unique features of soft ionic touch point sensors,focusing on the ionic material and its key role in the sensor.The touch sensing mechanisms include piezocapacitive,piezoresistive,surface capacitive,piezoelectric,and triboelectric and triboresistive sensing.This review analyzes the implementation hurdles and future research directions of the soft ionic touch sensors for their transformative potential.
