Natural organisms have different techniques to avoid enemies,such as chameleon skin with innate camouflage ability to change with the surrounding environment.Inspired by this,a microfluidic biomimetic chameleon skin b...Natural organisms have different techniques to avoid enemies,such as chameleon skin with innate camouflage ability to change with the surrounding environment.Inspired by this,a microfluidic biomimetic chameleon skin based on infrared(IR)information processing is proposed for active thermal camouflage in a dynamic infrared background.Microfluidic circulation in microcavities distributed under the skin is controlled by a thermal camouflage system.The structure and working principle of the biomimetic skin are introduced,and the thermal camouflage system is established and tested to explore the heat transfer characteristics between the skin and the fluid.The mechanism of collecting the background infrared information and regulating the skin temperature through the control signal generated by the infrared information processing system is illustrated.Furthermore,the dynamic thermal response of the skin is tested when transitioning between different temperature backgrounds,modeling the ambient temperature of the sand,woodland and lakes where chameleons live.The performance of the skin is evaluated by measuring the camouflage responding time of the skin to an external heat source.The results show that the chameleon biomimetic skin is naturally transitioned and matched by infrared information processing and microfluidics.The limitation that the conventional thermal camouflage technology cannot adapt to the dynamic combat environment is overcome and the weaknesses of a small camouflage band range and a single form of camouflage are resolved in this study,thus effectively improving the target’s survivability in combat.展开更多
The surface of lotus leaves has a hierarchical micro–nano-rough structure.We determined that the papillary structure also possesses hierarchical features on the microscale.We used alumina particles as rough structure...The surface of lotus leaves has a hierarchical micro–nano-rough structure.We determined that the papillary structure also possesses hierarchical features on the microscale.We used alumina particles as rough structure building units to construct a Hierarchical Papillary microrough Structure(HPS)on a ceramic surface.The effects of the spatial distribution of HPS on the abrasion resistance and mechanical stability of hydrophobic coatings were investigated.Furthermore,for each HPS,the falling sand abrasion process was analyzed using finite element fluid mechanics analysis.A denser or more two-dimensional HPS implied that more area was impacted by the falling sand and that the abrasion amount and rate were higher.This is contrary to the common belief that when there are more wear-resistant substances on the surface,the abrasion resistance is better;thus,abrasion resistance does not necessarily depend entirely on the concentration of wear-resistant substances on the surface,but it is also influenced by the abrasion mode and the spatial distribution structure of the wear-resistant substances.The 3D stacked HPS(3D-HPS)with excellent abrasion resistance and rich pore structure considerably enhanced the mechanical stability of the hydrophobic coatings.These findings provide novel insights and a theoretical basis for designing spatial structures on high abrasion-resistant superhydrophobic ceramic surfaces.展开更多
Bioinspired Soft Bending Actuators (SBA) are increasingly being used in rehabilitation, assistant robots, and grippers. Despite many investigations on free motion modeling, understanding how these actuators interact w...Bioinspired Soft Bending Actuators (SBA) are increasingly being used in rehabilitation, assistant robots, and grippers. Despite many investigations on free motion modeling, understanding how these actuators interact with the environment requires more detailed research. It is caused by high compliance and nonlinearity of bioinspired soft material, which leads to serious challenges in contact conditions. In this paper, a continuous deformation analysis is presented to describe the free motion nonlinear behavior of the actuator. Based on the achieved result, this study proposes static modeling of SBA affected by a concentrated external force. For this purpose, the finite rigid element method is utilized, which is based on discretizing the actuator into smaller parts and assuming these parts as rigid serial links connected by nonlinear torsional springs. To verify the proposed model, two kinds of forces are considered to be acting on the actuator, i.e. following force and constant direction force. In addition, the effect of gravity on the actuator configuration is also investigated. The validity of the model has been demonstrated through experiments in free motion, contact conditions and the presence of gravity. It generally shows that the prediction error of robot configuration is lower than 7.5%.展开更多
The influence of minor environmental factors,such as the geomagnetic field,on the biomineralization of nacres,is often ignored but a great deal of research has confirmed its important role in the normal mineralization...The influence of minor environmental factors,such as the geomagnetic field,on the biomineralization of nacres,is often ignored but a great deal of research has confirmed its important role in the normal mineralization of calcium carbonate.Although the geomagnetic field is weak,its cumulative effects need to be considered given that the biomineralization process can take years.Accordingly,the authors of this paper have investigated the effects of weak magnetic fields(25 Gs or 50 Gs)on calcium carbonate mineralization and analyzed the mechanism involved.The results show that even a weak magnetic field conduces to the formation of vaterite or aragonite,in the induction order of precursor→vaterite→aragonite.The stronger the magnetic field and the longer the time,the more obvious the induction effect.The effect of a magnetic field is strongest in the aging stage and weakest in the solution stage.Inductions by egg-white protein and by a magnetic field inhibit each other,but they both restrict particle growth.These findings highlight the importance of minor environmental factors for biomineralization and can serve as a reference for biomimetic preparation of a CaCO_(3)nacre-like structure and for anti-scale technology for circulating cooling water.展开更多
Bilateral rehabilitation systems with bilateral or unilateral assistive robots have been developed for hemiplegia patients to recover their one-side paralysis.However,the compliant robotic assistance to promote bilate...Bilateral rehabilitation systems with bilateral or unilateral assistive robots have been developed for hemiplegia patients to recover their one-side paralysis.However,the compliant robotic assistance to promote bilateral inter-limb coordination remains a challenge that should be addressed.In this paper,a biomimetic variable stiffness modulation strategy for the Variable Stiffness Actuator(VSA)integrated robotic is proposed to improve bilateral limb coordination and promote bilateral motor skills relearning.An Electromyography(EMG)-driven synergy reference stiffness estimation model of the upper limb elbow joint is developed to reproduce the muscle synergy effect on the affected side limb by independent real-time stiffness control.Additionally,the bilateral impedance control is incorporated for realizing compliant patient-robot interaction.Preliminary experiments were carried out to evaluate the tracking performance and investigate the multiple task intensities’influence on bilateral motor skills relearning.Experimental results evidence the proposed method could enable bilateral motor task skills relearning with wide-range task intensities and further promote bilateral inter-limb coordination.展开更多
The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction ofmotion on opener surface against soil were studied by finite element method (FEM) simulation and t...The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction ofmotion on opener surface against soil were studied by finite element method (FEM) simulation and the effects of these designson tool force and power requirements were examined experimentally.Geometrical structures of the cuticle surfaces of dungbeetle (Copris ochus Motschulsky) were examined by stereoscopy.The structures of the cuticle surfaces and Ultra High Mo-lecular Weight Polyethylene (UHMWPE) material were modeled on surface of tine furrow opener as biomimetic designs.Sevenfurrow openers were analyzed in ANSYS program (a FEM simulation software).The biomimetic furrow opener surfaces withUHMWPE structures were found to have lower equivalent pressure and pressure in the direction of motion as compared to theconventional surface and to the biomimetic surfaces with textured steel-35 structures.It was found that the tool force and powerwere increased with the cutting depth and operating speed and the biomimetic furrow opener with UHMWPE tubular sectionridges showed the lowest resistance and power requirement against soil..展开更多
Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness ...Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are investigated.Atheoretical model is proposed to study wetting transitions.The results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting transition.Furthermore, a numerical simulationbased on the meso scale Lattice Boltzmann Method （LBM） is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with r<sub>s</sub>= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·s<sup>-1</sup> and aninitial vertical distance of 20 μm from droplet centre to the top of pots.In spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter’s equation which gives θ<sub>CB</sub>=154.40°.展开更多
Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features o...Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.展开更多
Cartilage tissue engineering based on biomimetic scaffolds has become a rapidly developing strategy for repairing cartilage defects. In this study, a biphasic CAN-PAC hydrogel for osteochondral defect(OCD)regeneration...Cartilage tissue engineering based on biomimetic scaffolds has become a rapidly developing strategy for repairing cartilage defects. In this study, a biphasic CAN-PAC hydrogel for osteochondral defect(OCD)regeneration was fabricated based on the density difference between the two layers via a thermally reactive,rapid cross-linking method. The upper hydrogel was cross-linked by CSMA and NIPAm, and the lower hydrogel was composed of PECDA, AAm and PEGDA. The interface between the two layers was first grafted by the physical cross-linking of calcium gluconate and alginate, followed by the chemical cross-linking of the carbon-carbon double bonds in the other components. The pore sizes of the upper and lower hydrogels were ~ 187.4 and ~ 112.6 μm, respectively. The moduli of the upper and lower hydrogels were ~ 0.065 and~ 0.261 MPa. This prepared bilayer hydrogel exhibited the characteristics of mimetic composition, mimetic structure and mimetic stiffness, which provided a microenvironment for sustaining cell attachment and viability. Meanwhile, the biodegradability and biocompatibility of the CAN-PAC hydrogel were examined in vivo. Furthermore, an osteochondral defect model was developed in rabbits, and the bilayer hydrogels were implanted into the defect. The regenerated tissues in the bilayer hydrogel group exhibited new translucent cartilage and repaired subchondral bone, indicating that the hydrogel can enhance the repair of osteochondral defects.展开更多
Current studies of a seawater axial piston pump mainly solve the problems of corrosion and wear in a slipper pair by selecting materials with corrosion resistance, self-lubrication, and wear resistance. In addition, a...Current studies of a seawater axial piston pump mainly solve the problems of corrosion and wear in a slipper pair by selecting materials with corrosion resistance, self-lubrication, and wear resistance. In addition, an appropriate biomimetic non-smooth surface design for the slipper pair can further improve the tribological behavior. In this paper, 316 L stainless steel and CF/PEEK were selected to process the upper and bottom specimens, and the biomimetic non-smooth surface was introduced into the interface between the friction pair. The friction and wear tests were performed on a MMD-5 A tester at a rotation speed of 1000 r/min and load of 200 N under seawater lubricated condition. The results indicate that the main friction form of the smooth surface friction pair corresponds to abrasive wear and adhesive wear and that it exhibits a friction coe cient of 0.05–0.07, a specimen temperature of 56 ℃, a high wear rate, and surface roughness. Pits on the non-smooth surface friction pairs produced hydrodynamic lubrication and reduced abrasive wear, and thus the plowing e ect is their main friction form. The non-smooth surface friction pairs exhibit a friction coe cient of 0.03–0.04, a specimen temperature of 48 ℃, a low wear rate, and surface roughness. The study has important theoretical significance for enriching the lubrication, friction, and wear theory of a seawater axial piston pump, and economic significance and military significance for promoting the marine development and the national defense military.展开更多
Using three-dimensional computer simulations,we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency.The plate is driven by an oscillating internal mom...Using three-dimensional computer simulations,we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency.The plate is driven by an oscillating internal moment approximating the actuation mechanism of a piezoelectric macro fiber composite(MFC) bimorph. We show in our simulations that the addition of a passive attachment increases both swimming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actuated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.展开更多
We have studied a biomimetic swimmer based on the motion of bacteria such as Escherichia coli (E. coli) theoretically andexperimentally. The swimmer has an ellipsoidal cell body propelled by a helical filament. The pe...We have studied a biomimetic swimmer based on the motion of bacteria such as Escherichia coli (E. coli) theoretically andexperimentally. The swimmer has an ellipsoidal cell body propelled by a helical filament. The performance of this swimmer wasestimated by modeling the dynamics of a swimmer in viscous fluid. We applied the Resistive Force Theory (RFT) on this modelto calculate the linear swimming speed and the efficiency of the model. A parametric study on linear velocity and efficiency tooptimize the design of this swimmer was demonstrated. In order to validate the theoretical results, a biomimetic swimmer wasfabricated and an experiment setup was prepared to measure the swimming speed and thrust force in silicone oil. The experimentalresults agree well with the theoretical values predicted by RFT. In addition, we studied the flow patterns surrounding thefilament with a finite element simulation with different Reynolds number (Re) to understand the mechanism of propulsion. Thesimulation results provide information on the nature of flow patterns generated by swimming filament. Furthermore, the thrustforces from the simulation were compared with the thrust forces from theory. The simulation results are in good agreement withthe theoretical results.展开更多
The use of oscillating flexible fins in propulsion has been the subject of several studies in recent years, but attention israrely paid to the specific role of stiffness profile in thrust production.Stiffness profile ...The use of oscillating flexible fins in propulsion has been the subject of several studies in recent years, but attention israrely paid to the specific role of stiffness profile in thrust production.Stiffness profile is defined as the variation in localchordwise bending stiffness (EI) of a fin, from leading to trailing edge.In this study, flexible fins with a standard NACA0012shape were tested alongside fins with a stiffness profile mimicking that of a Pumpkinseed Sunfish (Lepomis gibbosus).The finswere oscillated with a pitching sinusoidal motion over a range of frequencies and amplitudes, while torque, lateral force andstatic thrust were measured.Over the range of oscillation parameters tested, it was shown that the fin with a biomimetic stiffness profile offered a significantimprovement in static thrust, compared to a fin of similar dimensions with a standard NACA0012 aerofoil profile.Thebiomimetic fin also produced thrust more consistently over each oscillation cycle.A comparison of fin materials of different stiffness showed that the improvement was due to the stiffness profile itself, andwas not simply an effect of altering the overall stiffness of the fin.Fins of the same stiffness profile were observed to follow thesame thrust-power curve, independent of the stiffness of the moulding material.Biomimetic fins were shown to produce up to26% greater thrust per watt of input power, within the experimental range.展开更多
Bioinspired superhydrophobic surfaces have attracted many industrial and academic interests in recent years.Inspired by unique superhydrophobicity and anisotropic friction properties of snake scale surfaces,this study...Bioinspired superhydrophobic surfaces have attracted many industrial and academic interests in recent years.Inspired by unique superhydrophobicity and anisotropic friction properties of snake scale surfaces,this study explores the feasibility to produce a bionic superhydrophobic stainless steel surface via laser precision engineering,which allows the realization of directional superhydrophobicity and dynamic control of its water transportation.Dynamic mechanism of water sliding on hierarchical snake scale structures is studied,which is the key to reproduce artificially bioinspired multifunctional materials with great potentials to be used for water harvesting,droplet manipulation,pipeline transportation,and vehicle acceleration.展开更多
Biomimetic surface is an effective ways to promote the performance grade and applied range of materials without alteringtheir substrate.Many improved properties such as resisting fatigue,enduring wear,etc,have been ac...Biomimetic surface is an effective ways to promote the performance grade and applied range of materials without alteringtheir substrate.Many improved properties such as resisting fatigue,enduring wear,etc,have been achieved by applyingbiomimetic morphology or structure to some engineering material surfaces.In this paper,aiming to reveal the relationshipbetween thermal cracking behavior and mechanical properties of engineering materials with biomimetic surface,biomimeticspecimens were fabricated using laser technique by imitating the heterogeneous structure on the surface of plant leaves.Theeffect of thermal fatigue cycling on the tensile properties of H13 die steel specimens with different surfaces (several types ofbiomimetic surfaces and a smooth surface) was compared and investigated.As a result,due to the coupling effects of themorphological features on the surface and the microstructure characteristics within unit zone,these specimens with biomimeticsurface exhibit remarkably enhanced Ultimate Tensile Strength (UTS) and 0.2% Yield Strength (YS) compared with referencespecimens while corresponding ductility remains largely unaffected even heightened,whether the thermal fatigue loads or not.The relative mechanisms leading to these improvements have been discussed.展开更多
The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro fl...The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro flow control elements which have been explored in parallel with the rapid developments in micro fabrication technologies, the present focus is on its application to biomimetics. As soil animals (in fact all living creatures) such as earthworms and dung beetles carry bioelectricity, the relative movement between the creatures and the surrounding soil which is a multi-component medium with moist content will generate electrophoresis or electroosmosis forces. Such forces drive the ionized moist content, normally water, to migrate from positive to negative poles under the action of electric double layer (EDL) effect, and effectively reduce the adhesion or drag.Predicting the electroosmotically driven flow in the vicinity of biological and animal surfaces is a key problem of drag/adhesion reduction and biomimetics design. The aim of this article is to demonstrate how the theory of electroosmotically driven flow has developed and to describe its broader significance for anti adhesion of soil animals and biomimetics design of soil machinery tools.展开更多
Over millions of years of evolution,nature has created organisms with overwhelming performances due to their unique materials and structures,providing us with valuable inspirations for the development of next-generati...Over millions of years of evolution,nature has created organisms with overwhelming performances due to their unique materials and structures,providing us with valuable inspirations for the development of next-generation biomedical devices.As a promising new technology,3D printing enables the fabrication of multiscale,multi-material,and multi-functional threedimensional(3D)biomimetic materials and structures with high precision and great flexibility.The manufacturing challenges of biomedical devices with advanced biomimetic materials and structures for various applications were overcome with the flourishing development of 3D printing technologies.In this paper,the state-of-the-art additive manufacturing of biomimetic materials and structures in the field of biomedical engineering were overviewed.Various kinds of biomedical applications,including implants,lab-on-chip,medicine,microvascular network,and artificial organs and tissues,were respectively discussed.The technical challenges and limitations of biomimetic additive manufacturing in biomedical applications were further investigated,and the potential solutions and intriguing future technological developments of biomimetic 3D printing of biomedical devices were highlighted.展开更多
The development of a massively producible vaccine against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),a novel coronavirus,is essential for stopping the current coronavirus disease(COVID-19)pandemic.A v...The development of a massively producible vaccine against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),a novel coronavirus,is essential for stopping the current coronavirus disease(COVID-19)pandemic.A vaccine must stimulate effective antibody and T cell responses in vivo to induce long-term protection.Scientific researchers have been developing vaccine candidates for the severe acute respiratory syndrome(SARS)and Middle East respiratory syndrome(MERS)since the outbreaks of these diseases.The prevalence of new biotechnologies such as genetic engineering has shed light on the generation of vaccines against novel viruses.In this review,we present the status of the development of coronavirus vaccines,focusing particularly on the biomimetic nanoparticle technology platform,which is likely to have a major role in future developments of personalized medicine.展开更多
Currently,the cancer immunotherapy has made great progress while antitumor vaccine attracts substantial attention.Still,the selection of adjuvants as well as antigens are always the most crucial issues for better vacc...Currently,the cancer immunotherapy has made great progress while antitumor vaccine attracts substantial attention.Still,the selection of adjuvants as well as antigens are always the most crucial issues for better vaccination.In this study,we proposed a biomimetic antitumor nanovaccine based on biocompatible nanocarriers and tumor cell membrane antigens.Briefly,endogenous calcium pyrophosphate nanogranules with possible immune potentiating effect are designed and engineered,both as delivery vehicles and adjuvants.Then,these nanocarriers are coated with lipids and B16-OVA tumor cell membranes,so the biomembrane proteins can serve as tumor-specific antigens.It was found that calcium pyrophosphate nanogranules themselves were compatible and possessed adjuvant effect,while membrane proteins including tumor associated antigen were transferred onto the nanocarriers.It was demonstrated that such a biomimetic nanovaccine could be well endocytosed by dendritic cells,promote their maturation and antigen-presentation,facilitate lymph retention,and trigger obvious immune response.It was confirmed that the biomimetic vaccine could induce strong T-cell response,exhibit excellent tumor therapy and prophylactic effects,and simultaneously possess nice biocompatibility.In general,the present investigation might provide insights for the further design and application of antitumor vaccines.展开更多
The paper presents a detailed analysis of experimental data in order to characterize the elastic properties of arteries.Suchanalysis would provide a good basis for evaluation of biomimetic vascular grafts.Since the la...The paper presents a detailed analysis of experimental data in order to characterize the elastic properties of arteries.Suchanalysis would provide a good basis for evaluation of biomimetic vascular grafts.Since the latter needs to exhibit similarproperties of native tissue,it is important to accurately characterize the biomimetic sample in a large range of applied stresses.The stress-strain properties vary according to the specific pathology(e.g.arteriosclerosis,aneurism)and the tissue graft must bechosen correctly.Two models are proposed in this paper on the stress-strain characteristics.An extension for frequency-domainanalysis is provided for one of the models.The comparison between vascular grafts and native tissue for carotid and thoracicarteries in pigs are in good agreement with results from literature.The proposed experimental method offers suitable parametersfor identifying models which characterize both elasticity and stiffness properties of the analyzed tissues(stress-strain).Theproposed models show good performance in characterizing the intrinsic material properties.展开更多
基金The authors would like to give their acknowledgment to the National Natural Science Foundation of China for the support(No.51175101)on this paper.
文摘Natural organisms have different techniques to avoid enemies,such as chameleon skin with innate camouflage ability to change with the surrounding environment.Inspired by this,a microfluidic biomimetic chameleon skin based on infrared(IR)information processing is proposed for active thermal camouflage in a dynamic infrared background.Microfluidic circulation in microcavities distributed under the skin is controlled by a thermal camouflage system.The structure and working principle of the biomimetic skin are introduced,and the thermal camouflage system is established and tested to explore the heat transfer characteristics between the skin and the fluid.The mechanism of collecting the background infrared information and regulating the skin temperature through the control signal generated by the infrared information processing system is illustrated.Furthermore,the dynamic thermal response of the skin is tested when transitioning between different temperature backgrounds,modeling the ambient temperature of the sand,woodland and lakes where chameleons live.The performance of the skin is evaluated by measuring the camouflage responding time of the skin to an external heat source.The results show that the chameleon biomimetic skin is naturally transitioned and matched by infrared information processing and microfluidics.The limitation that the conventional thermal camouflage technology cannot adapt to the dynamic combat environment is overcome and the weaknesses of a small camouflage band range and a single form of camouflage are resolved in this study,thus effectively improving the target’s survivability in combat.
基金supported by the National College Students Innovation and Entrepreneurship Training Program(No:202110895003,China)Pingxiang City Science and Technology Plan Project(No:2021C0102,China)National Natural Science Foundation of China(Nos.5217020839,52001175,China).
文摘The surface of lotus leaves has a hierarchical micro–nano-rough structure.We determined that the papillary structure also possesses hierarchical features on the microscale.We used alumina particles as rough structure building units to construct a Hierarchical Papillary microrough Structure(HPS)on a ceramic surface.The effects of the spatial distribution of HPS on the abrasion resistance and mechanical stability of hydrophobic coatings were investigated.Furthermore,for each HPS,the falling sand abrasion process was analyzed using finite element fluid mechanics analysis.A denser or more two-dimensional HPS implied that more area was impacted by the falling sand and that the abrasion amount and rate were higher.This is contrary to the common belief that when there are more wear-resistant substances on the surface,the abrasion resistance is better;thus,abrasion resistance does not necessarily depend entirely on the concentration of wear-resistant substances on the surface,but it is also influenced by the abrasion mode and the spatial distribution structure of the wear-resistant substances.The 3D stacked HPS(3D-HPS)with excellent abrasion resistance and rich pore structure considerably enhanced the mechanical stability of the hydrophobic coatings.These findings provide novel insights and a theoretical basis for designing spatial structures on high abrasion-resistant superhydrophobic ceramic surfaces.
文摘Bioinspired Soft Bending Actuators (SBA) are increasingly being used in rehabilitation, assistant robots, and grippers. Despite many investigations on free motion modeling, understanding how these actuators interact with the environment requires more detailed research. It is caused by high compliance and nonlinearity of bioinspired soft material, which leads to serious challenges in contact conditions. In this paper, a continuous deformation analysis is presented to describe the free motion nonlinear behavior of the actuator. Based on the achieved result, this study proposes static modeling of SBA affected by a concentrated external force. For this purpose, the finite rigid element method is utilized, which is based on discretizing the actuator into smaller parts and assuming these parts as rigid serial links connected by nonlinear torsional springs. To verify the proposed model, two kinds of forces are considered to be acting on the actuator, i.e. following force and constant direction force. In addition, the effect of gravity on the actuator configuration is also investigated. The validity of the model has been demonstrated through experiments in free motion, contact conditions and the presence of gravity. It generally shows that the prediction error of robot configuration is lower than 7.5%.
基金supported by the National Natural Science Foundation of China(12272329)the Sichuan University Student Innovation and Entrepreneurship Training Program(S202110619066)+2 种基金the Project of State Key Laboratory of Environment-friendly Energy Materials,Southwest University of Science and Technology(No.20fksy18)the Undergraduate Innovation Fund Project by Southwest University of Science and Technology(CX21-098)the NHC Key Laboratory of Nuclear Technology Medical Transformation(Mianyang Central Hospital)(21HYX019)。
文摘The influence of minor environmental factors,such as the geomagnetic field,on the biomineralization of nacres,is often ignored but a great deal of research has confirmed its important role in the normal mineralization of calcium carbonate.Although the geomagnetic field is weak,its cumulative effects need to be considered given that the biomineralization process can take years.Accordingly,the authors of this paper have investigated the effects of weak magnetic fields(25 Gs or 50 Gs)on calcium carbonate mineralization and analyzed the mechanism involved.The results show that even a weak magnetic field conduces to the formation of vaterite or aragonite,in the induction order of precursor→vaterite→aragonite.The stronger the magnetic field and the longer the time,the more obvious the induction effect.The effect of a magnetic field is strongest in the aging stage and weakest in the solution stage.Inductions by egg-white protein and by a magnetic field inhibit each other,but they both restrict particle growth.These findings highlight the importance of minor environmental factors for biomineralization and can serve as a reference for biomimetic preparation of a CaCO_(3)nacre-like structure and for anti-scale technology for circulating cooling water.
文摘Bilateral rehabilitation systems with bilateral or unilateral assistive robots have been developed for hemiplegia patients to recover their one-side paralysis.However,the compliant robotic assistance to promote bilateral inter-limb coordination remains a challenge that should be addressed.In this paper,a biomimetic variable stiffness modulation strategy for the Variable Stiffness Actuator(VSA)integrated robotic is proposed to improve bilateral limb coordination and promote bilateral motor skills relearning.An Electromyography(EMG)-driven synergy reference stiffness estimation model of the upper limb elbow joint is developed to reproduce the muscle synergy effect on the affected side limb by independent real-time stiffness control.Additionally,the bilateral impedance control is incorporated for realizing compliant patient-robot interaction.Preliminary experiments were carried out to evaluate the tracking performance and investigate the multiple task intensities’influence on bilateral motor skills relearning.Experimental results evidence the proposed method could enable bilateral motor task skills relearning with wide-range task intensities and further promote bilateral inter-limb coordination.
基金supported by the National Natural Science Foundation of China (Grant no. 50675087 and Grant no. 50635030)the National Hi-tech Project (863 Project) (Grant no. SQ2008AA04ZX1478650)+3 种基金the Key Project of Science and Technology Research of Ministry of Education of China (Grant no. 106061)the National Key Technologies R&D Program (Grant no. 2006BAD11A08)the National Science Fund for Distinguished Young Scholars of China (Grant no. 50025516)the "985 Project" of Jilin University.
文摘The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction ofmotion on opener surface against soil were studied by finite element method (FEM) simulation and the effects of these designson tool force and power requirements were examined experimentally.Geometrical structures of the cuticle surfaces of dungbeetle (Copris ochus Motschulsky) were examined by stereoscopy.The structures of the cuticle surfaces and Ultra High Mo-lecular Weight Polyethylene (UHMWPE) material were modeled on surface of tine furrow opener as biomimetic designs.Sevenfurrow openers were analyzed in ANSYS program (a FEM simulation software).The biomimetic furrow opener surfaces withUHMWPE structures were found to have lower equivalent pressure and pressure in the direction of motion as compared to theconventional surface and to the biomimetic surfaces with textured steel-35 structures.It was found that the tool force and powerwere increased with the cutting depth and operating speed and the biomimetic furrow opener with UHMWPE tubular sectionridges showed the lowest resistance and power requirement against soil..
基金supported by the Royal Society(UK)-NSFC(China)joint project,2009-2011by China Natural Science Foundation major International collaborative project 2010-2013 under grant No.50920105504
文摘Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are investigated.Atheoretical model is proposed to study wetting transitions.The results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting transition.Furthermore, a numerical simulationbased on the meso scale Lattice Boltzmann Method （LBM） is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with r<sub>s</sub>= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·s<sup>-1</sup> and aninitial vertical distance of 20 μm from droplet centre to the top of pots.In spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter’s equation which gives θ<sub>CB</sub>=154.40°.
文摘Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.
基金financially supported by grants from the National Natural Science Foundation of China (81671031, 81470721 and 31600778)Sichuan Science and Technology Innovation Team (2014TD0001)
文摘Cartilage tissue engineering based on biomimetic scaffolds has become a rapidly developing strategy for repairing cartilage defects. In this study, a biphasic CAN-PAC hydrogel for osteochondral defect(OCD)regeneration was fabricated based on the density difference between the two layers via a thermally reactive,rapid cross-linking method. The upper hydrogel was cross-linked by CSMA and NIPAm, and the lower hydrogel was composed of PECDA, AAm and PEGDA. The interface between the two layers was first grafted by the physical cross-linking of calcium gluconate and alginate, followed by the chemical cross-linking of the carbon-carbon double bonds in the other components. The pore sizes of the upper and lower hydrogels were ~ 187.4 and ~ 112.6 μm, respectively. The moduli of the upper and lower hydrogels were ~ 0.065 and~ 0.261 MPa. This prepared bilayer hydrogel exhibited the characteristics of mimetic composition, mimetic structure and mimetic stiffness, which provided a microenvironment for sustaining cell attachment and viability. Meanwhile, the biodegradability and biocompatibility of the CAN-PAC hydrogel were examined in vivo. Furthermore, an osteochondral defect model was developed in rabbits, and the bilayer hydrogels were implanted into the defect. The regenerated tissues in the bilayer hydrogel group exhibited new translucent cartilage and repaired subchondral bone, indicating that the hydrogel can enhance the repair of osteochondral defects.
基金Supported by National Natural Science Foundation of China(Grant No.51375421)Key Project of Science and Technology Plan of Higher Education of Hebei Province of China(Grant No.ZD20131027)Youth Project of Basic Research Project of Yanshan University(Grant No.14LGB032)
文摘Current studies of a seawater axial piston pump mainly solve the problems of corrosion and wear in a slipper pair by selecting materials with corrosion resistance, self-lubrication, and wear resistance. In addition, an appropriate biomimetic non-smooth surface design for the slipper pair can further improve the tribological behavior. In this paper, 316 L stainless steel and CF/PEEK were selected to process the upper and bottom specimens, and the biomimetic non-smooth surface was introduced into the interface between the friction pair. The friction and wear tests were performed on a MMD-5 A tester at a rotation speed of 1000 r/min and load of 200 N under seawater lubricated condition. The results indicate that the main friction form of the smooth surface friction pair corresponds to abrasive wear and adhesive wear and that it exhibits a friction coe cient of 0.05–0.07, a specimen temperature of 56 ℃, a high wear rate, and surface roughness. Pits on the non-smooth surface friction pairs produced hydrodynamic lubrication and reduced abrasive wear, and thus the plowing e ect is their main friction form. The non-smooth surface friction pairs exhibit a friction coe cient of 0.03–0.04, a specimen temperature of 48 ℃, a low wear rate, and surface roughness. The study has important theoretical significance for enriching the lubrication, friction, and wear theory of a seawater axial piston pump, and economic significance and military significance for promoting the marine development and the national defense military.
文摘Using three-dimensional computer simulations,we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency.The plate is driven by an oscillating internal moment approximating the actuation mechanism of a piezoelectric macro fiber composite(MFC) bimorph. We show in our simulations that the addition of a passive attachment increases both swimming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actuated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education Science and Technology(Grant number:2010-0018884)
文摘We have studied a biomimetic swimmer based on the motion of bacteria such as Escherichia coli (E. coli) theoretically andexperimentally. The swimmer has an ellipsoidal cell body propelled by a helical filament. The performance of this swimmer wasestimated by modeling the dynamics of a swimmer in viscous fluid. We applied the Resistive Force Theory (RFT) on this modelto calculate the linear swimming speed and the efficiency of the model. A parametric study on linear velocity and efficiency tooptimize the design of this swimmer was demonstrated. In order to validate the theoretical results, a biomimetic swimmer wasfabricated and an experiment setup was prepared to measure the swimming speed and thrust force in silicone oil. The experimentalresults agree well with the theoretical values predicted by RFT. In addition, we studied the flow patterns surrounding thefilament with a finite element simulation with different Reynolds number (Re) to understand the mechanism of propulsion. Thesimulation results provide information on the nature of flow patterns generated by swimming filament. Furthermore, the thrustforces from the simulation were compared with the thrust forces from theory. The simulation results are in good agreement withthe theoretical results.
基金a grant from the Engineering and Physical Sciences Research Council of the United Kingdom
文摘The use of oscillating flexible fins in propulsion has been the subject of several studies in recent years, but attention israrely paid to the specific role of stiffness profile in thrust production.Stiffness profile is defined as the variation in localchordwise bending stiffness (EI) of a fin, from leading to trailing edge.In this study, flexible fins with a standard NACA0012shape were tested alongside fins with a stiffness profile mimicking that of a Pumpkinseed Sunfish (Lepomis gibbosus).The finswere oscillated with a pitching sinusoidal motion over a range of frequencies and amplitudes, while torque, lateral force andstatic thrust were measured.Over the range of oscillation parameters tested, it was shown that the fin with a biomimetic stiffness profile offered a significantimprovement in static thrust, compared to a fin of similar dimensions with a standard NACA0012 aerofoil profile.Thebiomimetic fin also produced thrust more consistently over each oscillation cycle.A comparison of fin materials of different stiffness showed that the improvement was due to the stiffness profile itself, andwas not simply an effect of altering the overall stiffness of the fin.Fins of the same stiffness profile were observed to follow thesame thrust-power curve, independent of the stiffness of the moulding material.Biomimetic fins were shown to produce up to26% greater thrust per watt of input power, within the experimental range.
基金This work was supported by the Advanced Remanufacturing and Technology Centre(ARTC)under its RIE2020 Advanced Manufacturing and Engineering(AME)IAF PP Grant(No.A19C2a0019).
文摘Bioinspired superhydrophobic surfaces have attracted many industrial and academic interests in recent years.Inspired by unique superhydrophobicity and anisotropic friction properties of snake scale surfaces,this study explores the feasibility to produce a bionic superhydrophobic stainless steel surface via laser precision engineering,which allows the realization of directional superhydrophobicity and dynamic control of its water transportation.Dynamic mechanism of water sliding on hierarchical snake scale structures is studied,which is the key to reproduce artificially bioinspired multifunctional materials with great potentials to be used for water harvesting,droplet manipulation,pipeline transportation,and vehicle acceleration.
基金supported by the Key Program of National Natural Science Foundation of China (Grant No.50635030)the National Natural Science Foundation for Youths (No.51005097)+1 种基金the Major Program of the Science and Technology Development of Jilin Province (Grant No.09ZDGG001)the Fundamental Science Research Funds for the Central Universities (No.200903275)
文摘Biomimetic surface is an effective ways to promote the performance grade and applied range of materials without alteringtheir substrate.Many improved properties such as resisting fatigue,enduring wear,etc,have been achieved by applyingbiomimetic morphology or structure to some engineering material surfaces.In this paper,aiming to reveal the relationshipbetween thermal cracking behavior and mechanical properties of engineering materials with biomimetic surface,biomimeticspecimens were fabricated using laser technique by imitating the heterogeneous structure on the surface of plant leaves.Theeffect of thermal fatigue cycling on the tensile properties of H13 die steel specimens with different surfaces (several types ofbiomimetic surfaces and a smooth surface) was compared and investigated.As a result,due to the coupling effects of themorphological features on the surface and the microstructure characteristics within unit zone,these specimens with biomimeticsurface exhibit remarkably enhanced Ultimate Tensile Strength (UTS) and 0.2% Yield Strength (YS) compared with referencespecimens while corresponding ductility remains largely unaffected even heightened,whether the thermal fatigue loads or not.The relative mechanisms leading to these improvements have been discussed.
文摘The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro flow control elements which have been explored in parallel with the rapid developments in micro fabrication technologies, the present focus is on its application to biomimetics. As soil animals (in fact all living creatures) such as earthworms and dung beetles carry bioelectricity, the relative movement between the creatures and the surrounding soil which is a multi-component medium with moist content will generate electrophoresis or electroosmosis forces. Such forces drive the ionized moist content, normally water, to migrate from positive to negative poles under the action of electric double layer (EDL) effect, and effectively reduce the adhesion or drag.Predicting the electroosmotically driven flow in the vicinity of biological and animal surfaces is a key problem of drag/adhesion reduction and biomimetics design. The aim of this article is to demonstrate how the theory of electroosmotically driven flow has developed and to describe its broader significance for anti adhesion of soil animals and biomimetics design of soil machinery tools.
基金The authors acknowledge Arizona State University for the start-up funding support.
文摘Over millions of years of evolution,nature has created organisms with overwhelming performances due to their unique materials and structures,providing us with valuable inspirations for the development of next-generation biomedical devices.As a promising new technology,3D printing enables the fabrication of multiscale,multi-material,and multi-functional threedimensional(3D)biomimetic materials and structures with high precision and great flexibility.The manufacturing challenges of biomedical devices with advanced biomimetic materials and structures for various applications were overcome with the flourishing development of 3D printing technologies.In this paper,the state-of-the-art additive manufacturing of biomimetic materials and structures in the field of biomedical engineering were overviewed.Various kinds of biomedical applications,including implants,lab-on-chip,medicine,microvascular network,and artificial organs and tissues,were respectively discussed.The technical challenges and limitations of biomimetic additive manufacturing in biomedical applications were further investigated,and the potential solutions and intriguing future technological developments of biomimetic 3D printing of biomedical devices were highlighted.
基金This work was supported by the Fundamental Research Funds for the Central Universities(No.2042020kf1015)National Natural Science Foundation of China(No.81672114,81702627)the Medical talented youth development project in the Health Commission of Hubei Province(No.WJ2019Q049).
文摘The development of a massively producible vaccine against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),a novel coronavirus,is essential for stopping the current coronavirus disease(COVID-19)pandemic.A vaccine must stimulate effective antibody and T cell responses in vivo to induce long-term protection.Scientific researchers have been developing vaccine candidates for the severe acute respiratory syndrome(SARS)and Middle East respiratory syndrome(MERS)since the outbreaks of these diseases.The prevalence of new biotechnologies such as genetic engineering has shed light on the generation of vaccines against novel viruses.In this review,we present the status of the development of coronavirus vaccines,focusing particularly on the biomimetic nanoparticle technology platform,which is likely to have a major role in future developments of personalized medicine.
基金supported by the National Key R&D Program of China(2017YFA0205600)the National Natural Science Foundation of China(81690264,81821004).
文摘Currently,the cancer immunotherapy has made great progress while antitumor vaccine attracts substantial attention.Still,the selection of adjuvants as well as antigens are always the most crucial issues for better vaccination.In this study,we proposed a biomimetic antitumor nanovaccine based on biocompatible nanocarriers and tumor cell membrane antigens.Briefly,endogenous calcium pyrophosphate nanogranules with possible immune potentiating effect are designed and engineered,both as delivery vehicles and adjuvants.Then,these nanocarriers are coated with lipids and B16-OVA tumor cell membranes,so the biomembrane proteins can serve as tumor-specific antigens.It was found that calcium pyrophosphate nanogranules themselves were compatible and possessed adjuvant effect,while membrane proteins including tumor associated antigen were transferred onto the nanocarriers.It was demonstrated that such a biomimetic nanovaccine could be well endocytosed by dendritic cells,promote their maturation and antigen-presentation,facilitate lymph retention,and trigger obvious immune response.It was confirmed that the biomimetic vaccine could induce strong T-cell response,exhibit excellent tumor therapy and prophylactic effects,and simultaneously possess nice biocompatibility.In general,the present investigation might provide insights for the further design and application of antitumor vaccines.
文摘The paper presents a detailed analysis of experimental data in order to characterize the elastic properties of arteries.Suchanalysis would provide a good basis for evaluation of biomimetic vascular grafts.Since the latter needs to exhibit similarproperties of native tissue,it is important to accurately characterize the biomimetic sample in a large range of applied stresses.The stress-strain properties vary according to the specific pathology(e.g.arteriosclerosis,aneurism)and the tissue graft must bechosen correctly.Two models are proposed in this paper on the stress-strain characteristics.An extension for frequency-domainanalysis is provided for one of the models.The comparison between vascular grafts and native tissue for carotid and thoracicarteries in pigs are in good agreement with results from literature.The proposed experimental method offers suitable parametersfor identifying models which characterize both elasticity and stiffness properties of the analyzed tissues(stress-strain).Theproposed models show good performance in characterizing the intrinsic material properties.
