Switchable adhesives have attracted widespread attention due to their strong reusability and adaptability to operate stably in complex environments.However,the simple fabrication of adhesive structures and reliable co...Switchable adhesives have attracted widespread attention due to their strong reusability and adaptability to operate stably in complex environments.However,the simple fabrication of adhesive structures and reliable control of adhesion remain challenging.Here,we developed a neodymium iron boron/polydimethylsiloxane(NdFeB/PDMS)magnetic composite with optimal mechanical and magnetic performance.Then we fabricated lamellar structures and setal arrays using a molding and magnetic field-induced process,imitating the multi-level adhesion system of gecko feet.The lamellar can be deformed under the action of a magnetic field to control the adhesion,the setal array is used to enhance adhesion and provide self-cleanability to the adhering surface.Switchable adhesion was realized by applying an external magnetic field,where the maximum adhesion strength was 5.1 kPa,the switchable range was within 40%.Through finite element analysis simulations and experimental verification,it was proved that the adhesion force variation was ascribed to the magnetic field-induced surface deformation.Finally,we installed the adhesive on the end of the robotic arm,realizing the transfer of the target object.This work provides a simple method to fabricate a gecko-like surface and a practical strategy to realize switchable adhesion,which sheds light on broad application potential in production lines,medical products,more.展开更多
Controlled and switchable adhesion is commonly observed in biological systems.In recent years,many scholars have focused on making switchable bio-inspired adhesives.However,making a bio-inspired adhesive with high adh...Controlled and switchable adhesion is commonly observed in biological systems.In recent years,many scholars have focused on making switchable bio-inspired adhesives.However,making a bio-inspired adhesive with high adhesion performance and excellent dynamic switching properties is still a challenge.A Shape Memory Polymer Bio-inspired Adhesive(SMPBA)was successfully developed,well realizing high adhesion(about 337 kPa),relatively low preload(about90 kPa),high adhesion-to-preload ratio(about 3.74),high switching ratio(about 6.74),and easy detachment,which are attributed to the controlled modulus and contact area by regulating temperature and the Shape Memory Effect(SME).Furthermore,SMPBA exhibits adhesion strength of80–337 kPa on various surfaces(silicon,iron,and aluminum)with different roughness(Ra=0.021–10.280)because of the conformal contact,reflecting outstanding surface adaptability.The finite element analysis verifies the bending ability under different temperatures,while the adhesion model analyzes the influence of preload on contact area and adhesion.Furthermore,an Unmanned Aerial Vehicle(UAV)landing device with SMPBA was designed and manufactured to achieve UAV landing on and detaching from various surfaces.This study provides a novel switchable bio-inspired adhesive and UAV landing method.展开更多
Transfer printing based on switchable adhesive is essential for developing unconventional systems,including flexible electronics,stretchable electronics,and micro light-emitting diode(LED)displays.Here we report a des...Transfer printing based on switchable adhesive is essential for developing unconventional systems,including flexible electronics,stretchable electronics,and micro light-emitting diode(LED)displays.Here we report a design of switchable dry adhesive based on shape memory polymer(SMP)with hemispherical indenters,which offers a continuously tunable and reversible adhesion through the combination of the preloading effect and the thermal actuation of SMP.Experimental and numerical studies reveal the fundamental aspects of design,fabrication,and operation of the switchable dry adhesive.Demonstrations of this adhesive concept in transfer printing of flat objects(e.g.,silicon wafers),three-dimensional(3D)objects(e.g.,stainless steel balls),and rough objects(e.g.,frosted glasses)in two-dimensional(2D)or 3D layouts illustrate its unusual manipulation capabilities in heterogeneous material integration applications.展开更多
Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust des...Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust design of a thermal actuated switchable dry adhesive,which features a stiff sphere embedded in a thermally responsive shape memory polymer(SMP)substrate and encapsulated by an elastomeric membrane.This construct bypasses the unfavorable micro-and nano-fabrication processes and yields an adhesion switchability of over1000 by combining the peel-rate dependent effect of the elastomeric membrane and the thermal actuation of the sub-surface embedded stiff sphere.Experimental and numerical studies reveal the underlying thermal actuated mechanism and provide insights into the design and operation of the switchable adhesive.Demonstrations of this concept in stamps for transfer printing of fragile objects,such as silicon wafers,silicon chips,and inorganic micro-LED chips,onto challenging non-adhesive surfaces illustrate its potential in heterogeneous material integration applications,such as flexible electronics manufacturing and deterministic assembly.展开更多
Despite extensive efforts in designing and preparing switchable underwater adhesives,it is not easy to regulate the underwater adhesion strength locally and remotely.Here,we design and synthesize photoreversible copol...Despite extensive efforts in designing and preparing switchable underwater adhesives,it is not easy to regulate the underwater adhesion strength locally and remotely.Here,we design and synthesize photoreversible copolymer of poly[dopamine methacrylamide-co-methoxyethyl-acrylate-co-7-(2-methacryloyloxyethoxy)-4-methylcoumarin].Due to the dynamic formation and breaking of chemical crosslinking networks within the smart adhesives,the material shows widely tunable adhesion strength from∼150 to∼450 kPa and long-range reversible maneuverability under orthogonal 254 and 365 nm ultraviolet light stimulation via the coumarin dimerization and cycloreversion.Moreover,the adhesive exhibits good circulation performance and stability in an acid–base environment.It also demonstrated that the bolt can be coated with the smart adhesive material for on-demand bonding.This design principle opens the door to the development of remotely controllable high-performance smart underwater adhesives.展开更多
As an emerging processing technology,transfer printing enables the assembly of functional material arrays(called inks)on various substrates with micro/nanoscale resolution and has been widely used in the fabrication o...As an emerging processing technology,transfer printing enables the assembly of functional material arrays(called inks)on various substrates with micro/nanoscale resolution and has been widely used in the fabrication of flexible electronics and display systems.The critical steps in transfer printing are the ink pick-up and printing processes governed by the switching of adhesion states at the stamp/ink interface.In this review,we first introduce the history of transfer printing in terms of the transfer methods,transferred materials,and applications.Then,the fundamental characteristics of the transfer printing system and typical strategies for regulating the stamp/ink interfacial adhesion strength are summarized and exemplified.Finally,future challenges and opportunities for developing the novel stamps,inks,and substrates with intelligent adhesion capability are discussed,aiming to inspire the innovation in the design of transfer printing systems.展开更多
Smart dry adhesives,a rapidly growing class of intelligent materials and structures,are engineered to provide strong,robust adhesion when needed while also allowing for controlled,easy detachment in response to specif...Smart dry adhesives,a rapidly growing class of intelligent materials and structures,are engineered to provide strong,robust adhesion when needed while also allowing for controlled,easy detachment in response to specific stimuli.Traditional smart adhesives,often exemplified by fibrillar structures made of elastomers,face a number of challenges.These include limitations on maximum adhesion strength imposed by microstructural dimensions,restricted adaptability to surfaces with varying degrees of roughness,and an inherent trade-off between adhesion strength and switchability.This review explores how shape memory polymers(SMPs)can address these challenges and,through their rubber-to-glass(R2G)transition capability,provide a powerful foundation for the next generation of smart dry adhesives.Specifically,we summarize and elucidate the mechanisms by which SMPs enhance adhesion strength and switchability through material characteristics such as tunable stiffness,shape-locking,and shape-memory effects.Additionally,we discuss a wide range of innovative designs and applications of SMP adhesives,offering insights into the ongoing challenges and emerging opportunities in this rapidly evolving field.展开更多
The remarkable functionality of biological systems in detecting and adapting to various environmental conditions has inspired the design of the latest electronics and robots with advanced features.This review focuses ...The remarkable functionality of biological systems in detecting and adapting to various environmental conditions has inspired the design of the latest electronics and robots with advanced features.This review focuses on intelligent bio-inspired strategies for developing soft bioelectronics and robotics that can accommodate nanocomposite adhesives and integrate them into biological surfaces.The underlying principles of the material and structural design of nanocomposite adhesives were investigated for practical applications with excellent functionalities,such as soft skin-attachable health care sensors,highly stretchable adhesive electrodes,switchable adhesion,and untethered soft robotics.In addition,we have discussed recent progress in the development of effective fabrication methods for micro/nanostructures for integration into devices,presenting the current challenges and prospects.展开更多
基金the National Nature Science Foundation of China(No.52275210)the Natural Science Foundation of Shaanxi Province(No.2022JM-175)+1 种基金the Fundamental Research Funds for the Central UniversitiesSEM facility of Instrument Analysis Center of Xi'an Jiaotong University,China.
文摘Switchable adhesives have attracted widespread attention due to their strong reusability and adaptability to operate stably in complex environments.However,the simple fabrication of adhesive structures and reliable control of adhesion remain challenging.Here,we developed a neodymium iron boron/polydimethylsiloxane(NdFeB/PDMS)magnetic composite with optimal mechanical and magnetic performance.Then we fabricated lamellar structures and setal arrays using a molding and magnetic field-induced process,imitating the multi-level adhesion system of gecko feet.The lamellar can be deformed under the action of a magnetic field to control the adhesion,the setal array is used to enhance adhesion and provide self-cleanability to the adhering surface.Switchable adhesion was realized by applying an external magnetic field,where the maximum adhesion strength was 5.1 kPa,the switchable range was within 40%.Through finite element analysis simulations and experimental verification,it was proved that the adhesion force variation was ascribed to the magnetic field-induced surface deformation.Finally,we installed the adhesive on the end of the robotic arm,realizing the transfer of the target object.This work provides a simple method to fabricate a gecko-like surface and a practical strategy to realize switchable adhesion,which sheds light on broad application potential in production lines,medical products,more.
基金financial support from the National Natural Science Foundation of China(No.51605220)the Jiangsu Province Natural Science Foundation,China(No.BK20160793)+1 种基金the Postgraduate Research and Practice Innovation Program of Nanjing University of Aeronautics and Astronautics,China(No.xcxjh20210514)the Fundamental Research Funds for the Central Universities,China(No.XCA2205406)。
文摘Controlled and switchable adhesion is commonly observed in biological systems.In recent years,many scholars have focused on making switchable bio-inspired adhesives.However,making a bio-inspired adhesive with high adhesion performance and excellent dynamic switching properties is still a challenge.A Shape Memory Polymer Bio-inspired Adhesive(SMPBA)was successfully developed,well realizing high adhesion(about 337 kPa),relatively low preload(about90 kPa),high adhesion-to-preload ratio(about 3.74),high switching ratio(about 6.74),and easy detachment,which are attributed to the controlled modulus and contact area by regulating temperature and the Shape Memory Effect(SME).Furthermore,SMPBA exhibits adhesion strength of80–337 kPa on various surfaces(silicon,iron,and aluminum)with different roughness(Ra=0.021–10.280)because of the conformal contact,reflecting outstanding surface adaptability.The finite element analysis verifies the bending ability under different temperatures,while the adhesion model analyzes the influence of preload on contact area and adhesion.Furthermore,an Unmanned Aerial Vehicle(UAV)landing device with SMPBA was designed and manufactured to achieve UAV landing on and detaching from various surfaces.This study provides a novel switchable bio-inspired adhesive and UAV landing method.
基金The authors acknowledge the supports of the National Natural Science Foundation of China(Grant Nos.11872331 and U20A6001)Zhejiang University K.P.Chao’s High Technology Development Foundation.
文摘Transfer printing based on switchable adhesive is essential for developing unconventional systems,including flexible electronics,stretchable electronics,and micro light-emitting diode(LED)displays.Here we report a design of switchable dry adhesive based on shape memory polymer(SMP)with hemispherical indenters,which offers a continuously tunable and reversible adhesion through the combination of the preloading effect and the thermal actuation of SMP.Experimental and numerical studies reveal the fundamental aspects of design,fabrication,and operation of the switchable dry adhesive.Demonstrations of this adhesive concept in transfer printing of flat objects(e.g.,silicon wafers),three-dimensional(3D)objects(e.g.,stainless steel balls),and rough objects(e.g.,frosted glasses)in two-dimensional(2D)or 3D layouts illustrate its unusual manipulation capabilities in heterogeneous material integration applications.
基金financial support from the National Natural Science Foundation of China(Grant Nos.11872331 and U20A6001)the Zhejiang University K P Chao’s High Technology Development Foundation。
文摘Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust design of a thermal actuated switchable dry adhesive,which features a stiff sphere embedded in a thermally responsive shape memory polymer(SMP)substrate and encapsulated by an elastomeric membrane.This construct bypasses the unfavorable micro-and nano-fabrication processes and yields an adhesion switchability of over1000 by combining the peel-rate dependent effect of the elastomeric membrane and the thermal actuation of the sub-surface embedded stiff sphere.Experimental and numerical studies reveal the underlying thermal actuated mechanism and provide insights into the design and operation of the switchable adhesive.Demonstrations of this concept in stamps for transfer printing of fragile objects,such as silicon wafers,silicon chips,and inorganic micro-LED chips,onto challenging non-adhesive surfaces illustrate its potential in heterogeneous material integration applications,such as flexible electronics manufacturing and deterministic assembly.
基金support from the National Natural Science Foundation of China (Nos.22102201,22032006,52205232,and 22072169)the National Key Research and Development Program of China (No.2021YFA0716304)+3 种基金NSAF (No.U2030201)Gansu Province Basic Research Innovation Group Project (No.22JR5RA093)Shandong Laboratory of Yantai Advanced Materials and Green Manufacturing (No.AMGM0717)the Special Research Assistant Project of the Chinese Academy of Sciences.
文摘Despite extensive efforts in designing and preparing switchable underwater adhesives,it is not easy to regulate the underwater adhesion strength locally and remotely.Here,we design and synthesize photoreversible copolymer of poly[dopamine methacrylamide-co-methoxyethyl-acrylate-co-7-(2-methacryloyloxyethoxy)-4-methylcoumarin].Due to the dynamic formation and breaking of chemical crosslinking networks within the smart adhesives,the material shows widely tunable adhesion strength from∼150 to∼450 kPa and long-range reversible maneuverability under orthogonal 254 and 365 nm ultraviolet light stimulation via the coumarin dimerization and cycloreversion.Moreover,the adhesive exhibits good circulation performance and stability in an acid–base environment.It also demonstrated that the bolt can be coated with the smart adhesive material for on-demand bonding.This design principle opens the door to the development of remotely controllable high-performance smart underwater adhesives.
基金National Natural Science Foundation of China,Grant/Award Number:22035008International Partnership Program of Chinese Academy of Sciences,Grant/Award Number:1A1111KYSB20200010。
文摘As an emerging processing technology,transfer printing enables the assembly of functional material arrays(called inks)on various substrates with micro/nanoscale resolution and has been widely used in the fabrication of flexible electronics and display systems.The critical steps in transfer printing are the ink pick-up and printing processes governed by the switching of adhesion states at the stamp/ink interface.In this review,we first introduce the history of transfer printing in terms of the transfer methods,transferred materials,and applications.Then,the fundamental characteristics of the transfer printing system and typical strategies for regulating the stamp/ink interfacial adhesion strength are summarized and exemplified.Finally,future challenges and opportunities for developing the novel stamps,inks,and substrates with intelligent adhesion capability are discussed,aiming to inspire the innovation in the design of transfer printing systems.
基金support from the Ministry of Education(MOE)of Singapore under the Academic Research Fund Tier 2[MOE-T2EP50122-0001]support from the National Key R&D Program of China[2022YFB3805700]+1 种基金support from the National Natural Science Foundation of China[U23A20412]support from the China Scholarship Council program[202406120073].
文摘Smart dry adhesives,a rapidly growing class of intelligent materials and structures,are engineered to provide strong,robust adhesion when needed while also allowing for controlled,easy detachment in response to specific stimuli.Traditional smart adhesives,often exemplified by fibrillar structures made of elastomers,face a number of challenges.These include limitations on maximum adhesion strength imposed by microstructural dimensions,restricted adaptability to surfaces with varying degrees of roughness,and an inherent trade-off between adhesion strength and switchability.This review explores how shape memory polymers(SMPs)can address these challenges and,through their rubber-to-glass(R2G)transition capability,provide a powerful foundation for the next generation of smart dry adhesives.Specifically,we summarize and elucidate the mechanisms by which SMPs enhance adhesion strength and switchability through material characteristics such as tunable stiffness,shape-locking,and shape-memory effects.Additionally,we discuss a wide range of innovative designs and applications of SMP adhesives,offering insights into the ongoing challenges and emerging opportunities in this rapidly evolving field.
基金supported by the R&D program of the Ministry of Trade,Industry&Energy(No.20016252,Development of a hybrid-type high-performance multimodal electronic skin sensor and a scalable module for robot manipulation)supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(Ministry of Science and ICT,MSIT)(No.RS-2023-00214236)+1 种基金the National Research Council of Science&Technology(NST)grant by the Korea government(MSIT)(No.CRC230231-000)the Korea Evaluation Institute of Industrial Technology(KEIT)grant funded by the Korean government(MOTIE,No.RS-2022-00154781,Development of large-area wafer-level flexible/stretchable hybrid sensor platform technology for form factor-free highly integrated convergence sensors).
文摘The remarkable functionality of biological systems in detecting and adapting to various environmental conditions has inspired the design of the latest electronics and robots with advanced features.This review focuses on intelligent bio-inspired strategies for developing soft bioelectronics and robotics that can accommodate nanocomposite adhesives and integrate them into biological surfaces.The underlying principles of the material and structural design of nanocomposite adhesives were investigated for practical applications with excellent functionalities,such as soft skin-attachable health care sensors,highly stretchable adhesive electrodes,switchable adhesion,and untethered soft robotics.In addition,we have discussed recent progress in the development of effective fabrication methods for micro/nanostructures for integration into devices,presenting the current challenges and prospects.
