As a natural biopolymer material,silk fibroin with unique mechanical properties can be used in the preparation of biocomposite hydrogels for strain sensors.But,the electromechanical properties of bio-composite hydroge...As a natural biopolymer material,silk fibroin with unique mechanical properties can be used in the preparation of biocomposite hydrogels for strain sensors.But,the electromechanical properties of bio-composite hydrogel strain sensors are still insufficient,such as the deterioration of electrical signals and low sensitivity,which need to develop a hydrogel with a stable transmission network for electric con-duction.Herein,a silk fibroin biocomposite hydrogel is prepared by incorporating tannic acid and MXene nanosheets into a polyacrylamide and silk fibroin double network.The electromechanical properties of hydrogels are improved by optimizing the proportion of material components.As a result,the double network structure and supramolecular interaction enhance the stretchability of hydrogels(692% fracture strain).The hydrogel also exhibits good biocompatibility and conductivity(0.85 S/m),which shows the application prospect in wearable sensors.The wireless strain sensor assembled by this biocomposite hy-drogel presents good portability and sensing performance,such as high sensitivity(gauge factor=6.04),wide working range(500% strain),and outstanding stability(1000 cycles at 100%strain).The results in-dicate that the hydrogel strain sensor can be used to monitor human body movement.The biocomposite hydrogel is expected to be applied in the field of wearable strain sensors,and this study can provide a new way for the design of flexible electronic materials.展开更多
Stretchable electronics that monitor joint activity and treat diseases based on liquid metal could be used in the development of healthcare applications.Such devices can be seamlessly integrated with human skin.Howeve...Stretchable electronics that monitor joint activity and treat diseases based on liquid metal could be used in the development of healthcare applications.Such devices can be seamlessly integrated with human skin.However,most high-precision microstructures and complex patterns are difficult to fabricate due to the limitations of conventional fabrication solutions,resulting in suboptimal performance under practical conditions.Here,a liquid-metal stretchable system utilizing natural leaf veins was reported as microstructures,which was based on a biomimetic concept and utilized an all-solution process for the preparation of complex microstructures.The systems are ultra-high tensile(800%tensile strain),environmentally stable(20 days)and mechanically durable(300-cycle).The system can accurately recognize the wearer's finger bending level as well as simple gesture signals.At the same time,the system acts as a wearable heater,which can realize the fast heating behavior of heating up to 50℃in 3 min under the human body-safe voltage(1.5 V).The tensile stability is demonstrated by the heterogeneous integration of lasers(405 nm)with the system interconnects for a stretchable and wearable light source.展开更多
Flexible electronic devices are often subjected to large and repeated deformation,so that their functional components such as metal interconnects need to sustain strains up to tens of percent,which is far beyond the i...Flexible electronic devices are often subjected to large and repeated deformation,so that their functional components such as metal interconnects need to sustain strains up to tens of percent,which is far beyond the intrinsic deformability of metal materials(~1%).To meet the stringent requirements of flexible electronics,metal/elastomer bilayers,a stretchable structure that consists of a metal film adhered to a stretchable elastomer substrate,have been developed to improve the stretch capability of metal interconnects.Previous studies have predicted that the metal/elastomer bilayers are much more stretchable than freestanding metal films.However,these investigations usually assume perfect bonding between the metal and elastomer layers.In this work,the effect of the metal/elastomer interface with a finite interfacial stiffness on the stretchability of bilayer structures is analyzed.The results show that the assumption of perfect interface(with infinite interfacial stiffness)may lead to an overestimation of the stretchability of bilayer structures.It is also demonstrated that increased adhesion between the metal and elastomer layers can enhance the stretchability of the metal layer.展开更多
The dimensional properties and uniarial stretchability of cotton interlock and interlock with missing needle are discussed on the basis of definition system for double knits. K values used widely to describe the dimen...The dimensional properties and uniarial stretchability of cotton interlock and interlock with missing needle are discussed on the basis of definition system for double knits. K values used widely to describe the dimensional properties of plain knitted structures are developed into the study of double knitted structures in this paper. K values are not constants, the numerical values of which will depend on the actual configuration of various knitted structures. It is suggested that the effect of knitted structures on dimensional properties and stretchability can be described by K values.展开更多
In the rapidly evolving field of wearable electronics,stretchy organic solar cells(OSCs)have emerged as promising candidates for portable power sources,necessitating materials with superior mechanical flexibility.Howe...In the rapidly evolving field of wearable electronics,stretchy organic solar cells(OSCs)have emerged as promising candidates for portable power sources,necessitating materials with superior mechanical flexibility.However,the inherent rigidity of conjugated backbones in top-performance photovoltaic polymers,such as PM6,poses a significant challenge,as it makes photovoltaic films prone to fracture under mechanical strain.Consequently,improving the mechanical properties of these films is a crucial research frontier for advancing stretchable photovoltaic technologies.This tutorial review provides a thorough examination of current strategies aimed at bolstering the mechanical resilience of polymer photovoltaic thin films,elucidated through a selection of pertinent examples leveraging the PM6-based systems.We first explore the prevalent strategy of incorporating third components,including vip polymer donors/acceptors and insulating polymers,to improve stretchability.We then discuss the structural design of PM6 aimed at reducing the backbone rigidity.Additionally,we summarize various predictive models for assessing the mechanical properties of these photovoltaic films.Finally,the future challenges and perspectives for stretchy OSCs are explored.展开更多
Achieving rubber-like stretchability in cellulose ionogels presents a substantial challenge due to the intrinsically extended chain configuration of cellulose.Inspired by the molecular configuration of natural rubber,...Achieving rubber-like stretchability in cellulose ionogels presents a substantial challenge due to the intrinsically extended chain configuration of cellulose.Inspired by the molecular configuration of natural rubber,we address this challenge by using cyanoethyl as a substitute for 1.5 hydroxyl on the D-glucose unit of cellulose.This strategy innovatively triggers the transformation of cellulose molecules into a coiled chain configuration,facilitating the creation of an ultra-stretchable ionogel free from any petrochemical polymers.The resultant ionogel demonstrates mechanical ductility comparable to that of a rubber band,achieving an elongation strain of nearly 1,000%while maintaining a tensile strength of up to 1.8 MPa and exhibiting a biomodulus akin to that of human skin,recorded at 63 kPa.Additionally,this stretchable ionogel presents skin-like self-healing behavior,favorable biocompatibility,and noteworthy thermoelectric properties,highlighted by a Seebeck coefficient of approximately 68 mV K−1.This study delineates a feasible molecular approach for developing stretchable ionogels from biomass resources,potentially revolutionizing self-powered stretchable electronics for integration with human tissues and skin.展开更多
Incorporating flexible conjugation breakers into conjugated polymers to develop intrinsically stretchable polymer semiconductors has garnered much attention.However,it still remains challenging to improve mechanical s...Incorporating flexible conjugation breakers into conjugated polymers to develop intrinsically stretchable polymer semiconductors has garnered much attention.However,it still remains challenging to improve mechanical stretchability without compromising the charge transport property of polymer semiconductors.Herein,we report an approach to enhance the mechanical stretchability of the polymer semiconductor while largely maintaining its semiconducting performance by incorporating di-2-thienylsulfide as the p-πconjugation units into the backbone of poly(3,6-di(thiophen-2-yl)diketopyrrolo-[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophen)(PDPP-TT).Compared to the parent polymer PDPP-TT,the incorporation of the p-πconjugation units induces the twisting of the backbone and weakens the interchain packing order,resulting in higher crack onset strain and better mechanical durability.The polymer semiconductor in which the molar ratio of the repeat unit with di-2-thienylsulfides is 10%exhibits a crack onset strain greater than 100%and can retain its initial charge mobility after 1000 stretching-releasing cycles under 50%strain.Our studies show that incorporation of p-πconjugation units such as di-2-thienylsulfide into backbones of polymer semiconductors provides a feasible approach to balance the stretchability and charge mobility,thus making it a promising way for future development of stretchable polymer semiconductors.展开更多
The development of strain sensors with high stretchability and stability is an inevitable requirement for achieving full-range and long-term use of wearable electronic devices.Herein,a resistive micromesh reinforced s...The development of strain sensors with high stretchability and stability is an inevitable requirement for achieving full-range and long-term use of wearable electronic devices.Herein,a resistive micromesh reinforced strain sensor(MRSS)with high stretchability and stability is prepared,consisting of a laser-scribed graphene(LSG)layer and two styrene-block-poly(ethylene-ran-butylene)-block-poly-styrene micromesh layers embedded in Ecoflex.The micromesh reinforced structure endows the MRSS with combined characteris-tics of a high stretchability(120%),excellent stability(with a repetition error of 0.8%after 11000 cycles),and outstanding sensitivity(gauge factor up to 2692 beyond 100%).Impressively,the MRSS can still be used continauously within the working range without damage,even if stretched to 300%.Furthermore,compared with different structure sensors,the mechanism of the MRSS with high stretchability and stability is elucidated.What's more,a multilayer finite element model,based on the layered structure of the LSG and the morphology of the cracks,is proposed to investigate the strain sensing behavior and failure mechanism of the MRSS.Finally,due to the outstanding performance,the MRSS not only performes well in monitoring full-range human motions,but also achieves intelligent recognitions of various respiratory activities and ges-tures assisted by neural network algorithms(the accuracy up to 94.29%and 100%,respectively).This work provides a new approach for designing high-performance resistive strain sensors and shows great potential in full-range and long-term intelligent health management and human-machine interac-tions applications.展开更多
Intrinsic stretchability is a promising attribute of polymer organic solar cells(OSCs).However,rigid molecular blocks typically exhibit poor tensile properties,rendering polymers vulnerable to mechanical stress.In thi...Intrinsic stretchability is a promising attribute of polymer organic solar cells(OSCs).However,rigid molecular blocks typically exhibit poor tensile properties,rendering polymers vulnerable to mechanical stress.In this study,we introduce a different approach utilizing all-small-molecule donors and acceptors to fabricate stretchable OSCs.An elastomer,styrene-b-ethylene-butylene-styrene(SEBS),was embedded to modulate film crystallization and stretchability.SEBS effectively confines the growth process of donors and acceptors,leading to enhancement of the crystallization quality,thus contributing to enhanced device efficiencies.Meanwhile,SEBS can absorb and release mechanical stress during stretching,thereby preventing mechanical degradation of donors and acceptors.The mechanical properties of the OSCs were significantly improved by the incorporation of SEBS.Notably,the crack-onset strain increased from 1.03% to 5.99% with SEBS embedding.These findings present a straightforward strategy for achieving stretchable OSCs using all small molecules,offering a different perspective for realizing stretchable devices.展开更多
With the rapid development of flexible wearable electronics,the demand for stretchable energy storage devices has surged.In this work,a novel gradient-layered architecture was design based on single-pore hollow lignin...With the rapid development of flexible wearable electronics,the demand for stretchable energy storage devices has surged.In this work,a novel gradient-layered architecture was design based on single-pore hollow lignin nanospheres(HLNPs)-intercalated two-dimensional transition metal carbide(Ti_(3)C_(2)T_(x) MXene)for fabricating highly stretchable and durable supercapacitors.By depositing and inserting HLNPs in the MXene layers with a bottom-up decreasing gradient,a multilayered porous MXene structure with smooth ion channels was constructed by reducing the overstacking of MXene lamella.Moreover,the micro-chamber architecture of thin-walled lignin nanospheres effectively extended the contact area between lignin and MXene to improve ion and electron accessibility,thus better utilizing the pseudocapacitive property of lignin.All these strategies effectively enhanced the capacitive performance of the electrodes.In addition,HLNPs,which acted as a protective phase for MXene layer,enhanced mechanical properties of the wrinkled stretchable electrodes by releasing stress through slip and deformation during the stretch-release cycling and greatly improved the structural integrity and capacitive stability of the electrodes.Flexible electrodes and symmetric flexible all-solid-state supercapacitors capable of enduring 600%uniaxial tensile strain were developed with high specific capacitances of 1273 mF cm^(−2)(241 F g^(−1))and 514 mF cm^(−2)(95 F g^(−1)),respectively.Moreover,their capacitances were well preserved after 1000 times of 600%stretch-release cycling.This study showcased new possibilities of incorporating biobased lignin nanospheres in energy storage devices to fabricate stretchable devices leveraging synergies among various two-dimensional nanomaterials.展开更多
With the emergence of Y-series small molecule acceptors,polymerizing the small molecule acceptors with aromatic linker units has attracted significant research attention,which has greatly advanced the photovoltaic per...With the emergence of Y-series small molecule acceptors,polymerizing the small molecule acceptors with aromatic linker units has attracted significant research attention,which has greatly advanced the photovoltaic performance of all-polymer solar cells.Despite the rapid increase in efficiency,the unique characteristics(e.g.,mechanical stretchability and flexibility)of all-polymer systems were still not thoroughly explored.In this work,we demonstrate an effective approach to simultaneously improve device performance,stability,and mechanical robustness of all-polymer solar cells by properly suppressing the aggregation and crystallization behaviors of polymerized Y-series acceptors.Strikingly,when introducing 50 wt%PYF-IT(a fluorinated version of PY-IT)into the well-known PM6:PY-IT system,the all-polymer devices delivered an impressive photovoltaic efficiency of 16.6%,significantly higher than that of the control binary cell(15.0%).Compared with the two binary systems,the optimal ternary blend exhibits more efficient charge separation and balanced charge transport accompanying with less recombination.Moreover,a high-performance 1.0 cm^(2)large-area device of 15%efficiency was demonstrated for the optimized ternary all-polymer blend,which offered a desirable PCE of 14.5%on flexible substrates and improved mechanical flexibility after bending 1000 cycles.Notably,these are among the best results for 1.0 cm^(2)all-polymer OPVs thus far.This work also heralds a bright future of all-polymer systems for flexible wearable energy-harvesting applications.展开更多
Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality c...Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality characteristics of SPOF limit their integration with traditional fiber optic sensors.This article introduces for the first time a flexible fiber optic vibration sensor based on laser interference technology,which can be applied to vibration measurement under high stretch conditions.This sensor utilizes elastic optical fibers made of polydimethylsiloxane(PDMS)as sensing elements,combined with phase generating carrier technology,to achieve vibration measurement at 50−260 Hz within the stretch range of 0−42%.展开更多
Bionic hydrogels offer significant advantages over conventional counterparts,boasting superior properties like enhanced adhesion,stretchability,conductivity,biocompatibility and versatile functionalities.Their physico...Bionic hydrogels offer significant advantages over conventional counterparts,boasting superior properties like enhanced adhesion,stretchability,conductivity,biocompatibility and versatile functionalities.Their physicochemical resemblance to biological tissues makes bionic hydrogels ideal interfaces for bioelectronic devices.In contrast,conventional hydrogels often exhibit inadequate performance,such as easy detachment,lack of good skin compliance,and inadequate conductivity,failing to meet the rigorous demands of bioelectronic applications.Bionic hydrogels,inspired by biological designs,exhibit exceptional physicochemical characteristics that fulfill diverse criteria for bioelectronic applications,driving the advancement of bioelectronic devices.This review first introduces a variety of materials used in the fabrication of bionic hydrogels,including natural polymers,synthetic polymers,and other materials.Then different mechanisms of hydrogel bionics,are categorized into material bionics,structural bionics,and functional bionics based on their bionic approaches.Subsequently,various applications of bionic hydrogels in the field of bioelectronics were introduced,including physiological signal monitoring,tissue engineering,and human-machine interactions.Lastly,the current development and future prospects of bionic hydrogels in bioelectronic devices are summarized.Hopefully,this comprehensive review could inspire advancements in bionic hydrogels for applications in bioelectronic devices.展开更多
The Design and manufacturing of a noble piezoresistive pressure sensor(PS) for subtle pressures(<1 kPa) were presented. Meanwhile, in the studies conducted in the field of pressure sensors, the measurement of subtl...The Design and manufacturing of a noble piezoresistive pressure sensor(PS) for subtle pressures(<1 kPa) were presented. Meanwhile, in the studies conducted in the field of pressure sensors, the measurement of subtle pressures has received less attention. The limitations in the inherent gauge factor in silicon, have led to the development of polymer and composite resistive sensitive elements. However,in the development of resistance sensing elements, the structure of composite elements with reinforcement core has not been used. The proposed PS had a composite sandwich structure consisting of a nanocomposite graphene layer covered by layers of PDMS at the bottom and on the top coupled with a polyimide(PI) core. Various tests were performed to analyze the PS. The primary design target was improved sensitivity, with a finite-element method(FEM) utilized to simulate the stress profile over piezoresistive elements and membrane deflection at various pressures. The PS manufacturing process is based on Laser-engraved graphene(LEG) technology and PDMS casting. Experimental data indicated that the manufactured PS exhibits a sensitivity of 67.28 mV/kPa for a pressure range of 30-300 Pa in ambient temperature.展开更多
Flexible and stretchable energy storage devices are highly desirable for wearable electronics,particularly in the emerging fields of smart clothes,medical instruments,and stretchable skin.Lithium metal batteries(LMBs)...Flexible and stretchable energy storage devices are highly desirable for wearable electronics,particularly in the emerging fields of smart clothes,medical instruments,and stretchable skin.Lithium metal batteries(LMBs) with high power density and long cycle life are one of the ideal power sources for flexible and stretchable energy storage devices.However,the current LMBs are usually too rigid and bulky to meet the requirements of these devices.The electrolyte is the critical component that determines the energy density and security of flexible and stretchable LMBs.Among various electrolytes,gel polymer electrolytes(GPEs) perform excellent flexibility,safety,and high ionic conductivity compared with traditional liquid electrolytes and solid electrolytes,fulfilling the next generation deformable LMBs.This essay mainly reviews and highlights the recent progress in GPEs for flexible/stretchable LMBs and provides some useful insights for people interested in this field.Additionally,the multifunctional GPEs with self-healing,flame retardant,and temperature tolerance abilities are summarized.Finally,the perspectives and opportunities for flexible and stretchable GPEs are discussed.展开更多
Triboelectric nanogenerators(TENGs)are emerging as new technologies to harvest electrical power from mechanical energy.With the distinctive working mechanism of triboelectric nanogenerators,they attract particular int...Triboelectric nanogenerators(TENGs)are emerging as new technologies to harvest electrical power from mechanical energy.With the distinctive working mechanism of triboelectric nanogenerators,they attract particular interest in healthcare monitoring,wearable electronics,and deformable energy harvesting,which raises the requirement for highly conformable devices with substantial energy outputs.Here,a simple,low-cost strategy for fabricating stretchable triboelectric nanogenerators with ultra-high electrical output is developed.The TENG is prepared using PTFE micron particles(PPTENG),contributing a different electrostatic induction process compared to TENG based on dielectric films,which was associated with the dynamics of particle motions in PP-TENG.The generator achieved an impressive voltage output of 1000 V with a current of 25 lA over a contact area of 40320 mm^(2).Additionally,the TENG exhibits excellent durability with a stretching strain of 500%,and the electrical output performance does not show any significant degradation even after 3000 cycles at a strain of 400%.The unique design of the device provides high conformability and can be used as a self-powered sensor for human motion detection.展开更多
This paper examines the transport analysis,including both heat transfer and mass transfer,in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface.The influence of magnetic fi...This paper examines the transport analysis,including both heat transfer and mass transfer,in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface.The influence of magnetic fields is also inspected in terms of their physical characteristics.To depict the phenomena of transport,modified versions of both Fick's and Fourier's laws are used.Additionally,the characteristics of both heterogeneous and homogeneous chemical reactions are also incorporated.Utilizing a curvilinear coordinate system,the flow problem is formulated as partial differential equations(PDEs)for momentum,concentration,microorganism field,and energy.An analytical solution to the obtained flow equations is achieved utilizing the homotopy analysis method(HAM).The effects of significant flow parameters on the pressure and microorganism fields,velocity,oscillation velocity,concentration,and temperature distributions are shown via graphs.Furthermore,the variations in skin friction,mass transfer rate,heat transfer rate,and local motile number due to different involved parameters are presented in tables and are analyzed in detail.Graphical results indicate that the curves of velocity and temperature fields are enhanced as the values of the solid volume fraction variables increase.It is also verified that the concentration rate field decreases as the values of the homogeneous reaction strength parameter and the radius of curvature parameter increase,and it increases with the Schmidt number and the heterogeneous reaction strength parameter.Tabular outcomes show a favorable response of the motile number to advanced values of the Peclet number,the Schmidt number,the microorganism difference parameter,and the bio-convective Lewis number.展开更多
The soft nature has endowed conjugated polymers with promising applications in a wide range of field-effect transistor(FET)based flexible electronics.With unremitting efforts on revealing the molecular structure-prope...The soft nature has endowed conjugated polymers with promising applications in a wide range of field-effect transistor(FET)based flexible electronics.With unremitting efforts on revealing the molecular structure-property relationships,numerous novel conjugated polymers with high mobility and excellent mechanical property have been developed in the past decades.Incorporating hydrogen-bonding(H-bonding)units into semiconducting polymers is one of the most successful strategies for designing high-performance semiconducting materials.In this review,we aim to highlight the roles of H-bonding units in the performances of polymeric FETs from three aspects.These include(i)charge mobility enhancement for semiconducting polymers after incorporation of H-bonding units into the side chains,(ii)the effects of H-bonding units on the stretchability of conjugated polymers,and(iii)the improvement of self-healing properties of conjugated polymers containing dynamic hydrogen bonds due to the H-bonding units in the side chains or conjugated backbones.展开更多
Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body.As the primary compliant conductors used in these devices,metallic nanostructure/elastomer composite...Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body.As the primary compliant conductors used in these devices,metallic nanostructure/elastomer composites often struggle to form conformal contact with the textured skin.Hybrid electrodes have been consequently developed based on conductive nanocomposite and soft hydrogels to establish seamless skin-device interfaces.However,chemical modifications are typically needed for reliable bonding,which can alter their original properties.To overcome this limitation,this study presents a facile fabrication approach for mechanically interlocked nanocomposite/hydrogel hybrid electrodes.In this physical process,soft microfoams are thermally laminated on silver nanowire nanocomposites as a porous interface,which forms an interpenetrating network with the hydrogel.The microfoam-enabled bonding strategy is generally compatible with various polymers.The resulting interlocked hybrids have a 28-fold improved interfacial toughness compared to directly stacked hybrids.These electrodes achieve firm attachment to the skin and low contact impedance using tissue-adhesive hydrogels.They have been successfully integrated into an epidermal sleeve to distinguish hand gestures by sensing mus-cle contractions.Interlocked nanocomposite/hydrogel hybrids reported here offer a promising platform to combine the benefits of both materials for epidermal devices and systems.展开更多
Despite the growing demand for transparent conductive films in smart and wearable electronics for electromagnetic interference(EMI)shielding,achieving a flexible EMI shielding film,while maintaining a high transmittan...Despite the growing demand for transparent conductive films in smart and wearable electronics for electromagnetic interference(EMI)shielding,achieving a flexible EMI shielding film,while maintaining a high transmittance remains a significant challenge.Herein,a flexible,transparent,and conductive copper(Cu)metal mesh film for EMI shielding is fabricated by self-forming crackle template method and electroplating technique.The Cu mesh film shows an ultra-low sheet resistance(0.18Ω□^(-1)),high transmittance(85.8%@550 nm),and ultra-high figure of merit(>13,000).It also has satisfactory stretchability and mechanical stability,with a resistance increases of only 1.3%after 1,000 bending cycles.As a stretchable heater(ε>30%),the saturation temperature of the film can reach over 110°C within 60 s at 1.00 V applied voltage.Moreover,the metal mesh film exhibits outstanding average EMI shielding effectiveness of 40.4 dB in the X-band at the thickness of 2.5μm.As a demonstration,it is used as a transparent window for shielding the wireless communication electromagnetic waves.Therefore,the flexible and transparent conductive Cu mesh film proposed in this work provides a promising candidate for the next-generation EMI shielding applications.展开更多
基金supported by the National Key Re-search and Development Program of China(No.2021YFA0715700)the National Natural Science Foundation of China(No.52003212).
文摘As a natural biopolymer material,silk fibroin with unique mechanical properties can be used in the preparation of biocomposite hydrogels for strain sensors.But,the electromechanical properties of bio-composite hydrogel strain sensors are still insufficient,such as the deterioration of electrical signals and low sensitivity,which need to develop a hydrogel with a stable transmission network for electric con-duction.Herein,a silk fibroin biocomposite hydrogel is prepared by incorporating tannic acid and MXene nanosheets into a polyacrylamide and silk fibroin double network.The electromechanical properties of hydrogels are improved by optimizing the proportion of material components.As a result,the double network structure and supramolecular interaction enhance the stretchability of hydrogels(692% fracture strain).The hydrogel also exhibits good biocompatibility and conductivity(0.85 S/m),which shows the application prospect in wearable sensors.The wireless strain sensor assembled by this biocomposite hy-drogel presents good portability and sensing performance,such as high sensitivity(gauge factor=6.04),wide working range(500% strain),and outstanding stability(1000 cycles at 100%strain).The results in-dicate that the hydrogel strain sensor can be used to monitor human body movement.The biocomposite hydrogel is expected to be applied in the field of wearable strain sensors,and this study can provide a new way for the design of flexible electronic materials.
基金financially supported by the National Key Research and Development Program of China(No.2021YFA1401100)the National Natural Science Foundation of China(Nos.61825403 and 61921005)。
文摘Stretchable electronics that monitor joint activity and treat diseases based on liquid metal could be used in the development of healthcare applications.Such devices can be seamlessly integrated with human skin.However,most high-precision microstructures and complex patterns are difficult to fabricate due to the limitations of conventional fabrication solutions,resulting in suboptimal performance under practical conditions.Here,a liquid-metal stretchable system utilizing natural leaf veins was reported as microstructures,which was based on a biomimetic concept and utilized an all-solution process for the preparation of complex microstructures.The systems are ultra-high tensile(800%tensile strain),environmentally stable(20 days)and mechanically durable(300-cycle).The system can accurately recognize the wearer's finger bending level as well as simple gesture signals.At the same time,the system acts as a wearable heater,which can realize the fast heating behavior of heating up to 50℃in 3 min under the human body-safe voltage(1.5 V).The tensile stability is demonstrated by the heterogeneous integration of lasers(405 nm)with the system interconnects for a stretchable and wearable light source.
文摘Flexible electronic devices are often subjected to large and repeated deformation,so that their functional components such as metal interconnects need to sustain strains up to tens of percent,which is far beyond the intrinsic deformability of metal materials(~1%).To meet the stringent requirements of flexible electronics,metal/elastomer bilayers,a stretchable structure that consists of a metal film adhered to a stretchable elastomer substrate,have been developed to improve the stretch capability of metal interconnects.Previous studies have predicted that the metal/elastomer bilayers are much more stretchable than freestanding metal films.However,these investigations usually assume perfect bonding between the metal and elastomer layers.In this work,the effect of the metal/elastomer interface with a finite interfacial stiffness on the stretchability of bilayer structures is analyzed.The results show that the assumption of perfect interface(with infinite interfacial stiffness)may lead to an overestimation of the stretchability of bilayer structures.It is also demonstrated that increased adhesion between the metal and elastomer layers can enhance the stretchability of the metal layer.
文摘The dimensional properties and uniarial stretchability of cotton interlock and interlock with missing needle are discussed on the basis of definition system for double knits. K values used widely to describe the dimensional properties of plain knitted structures are developed into the study of double knitted structures in this paper. K values are not constants, the numerical values of which will depend on the actual configuration of various knitted structures. It is suggested that the effect of knitted structures on dimensional properties and stretchability can be described by K values.
基金supported by the Science Fund for Distinguished Young Scholars of Tianjin Municipality(23JCJQJC00240)the National Natural Science Foundation of China(52121002)+1 种基金the Start-up Grant of Peiyang Scholar Program from Tianjin Universitythe Fundamental Research Funds for the Central Universities.
文摘In the rapidly evolving field of wearable electronics,stretchy organic solar cells(OSCs)have emerged as promising candidates for portable power sources,necessitating materials with superior mechanical flexibility.However,the inherent rigidity of conjugated backbones in top-performance photovoltaic polymers,such as PM6,poses a significant challenge,as it makes photovoltaic films prone to fracture under mechanical strain.Consequently,improving the mechanical properties of these films is a crucial research frontier for advancing stretchable photovoltaic technologies.This tutorial review provides a thorough examination of current strategies aimed at bolstering the mechanical resilience of polymer photovoltaic thin films,elucidated through a selection of pertinent examples leveraging the PM6-based systems.We first explore the prevalent strategy of incorporating third components,including vip polymer donors/acceptors and insulating polymers,to improve stretchability.We then discuss the structural design of PM6 aimed at reducing the backbone rigidity.Additionally,we summarize various predictive models for assessing the mechanical properties of these photovoltaic films.Finally,the future challenges and perspectives for stretchy OSCs are explored.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFD2200504)the Central Guidance Fund for Local Science and Technology Development Projects(Grant No.2024JH6/100700013)+1 种基金the National Natural Science Foundation of China(Grant Nos.32171720 and 32371823)the National Science Fund for Distinguished Young Scholars(Grant No.31925028).
文摘Achieving rubber-like stretchability in cellulose ionogels presents a substantial challenge due to the intrinsically extended chain configuration of cellulose.Inspired by the molecular configuration of natural rubber,we address this challenge by using cyanoethyl as a substitute for 1.5 hydroxyl on the D-glucose unit of cellulose.This strategy innovatively triggers the transformation of cellulose molecules into a coiled chain configuration,facilitating the creation of an ultra-stretchable ionogel free from any petrochemical polymers.The resultant ionogel demonstrates mechanical ductility comparable to that of a rubber band,achieving an elongation strain of nearly 1,000%while maintaining a tensile strength of up to 1.8 MPa and exhibiting a biomodulus akin to that of human skin,recorded at 63 kPa.Additionally,this stretchable ionogel presents skin-like self-healing behavior,favorable biocompatibility,and noteworthy thermoelectric properties,highlighted by a Seebeck coefficient of approximately 68 mV K−1.This study delineates a feasible molecular approach for developing stretchable ionogels from biomass resources,potentially revolutionizing self-powered stretchable electronics for integration with human tissues and skin.
基金supported by NSFC(22322507,22075293)the Beijing Municipal Natural Science Foundation(Z220025)+2 种基金the Chinese Academy of Sciences(XDB0520000,XDB0960101,GJTD-2020-02,YSBR-110)supported by NSFC(22021002,22090021,T2441002,22422509)the Youth Innovation Promotion Association CAS(No.2022031).
文摘Incorporating flexible conjugation breakers into conjugated polymers to develop intrinsically stretchable polymer semiconductors has garnered much attention.However,it still remains challenging to improve mechanical stretchability without compromising the charge transport property of polymer semiconductors.Herein,we report an approach to enhance the mechanical stretchability of the polymer semiconductor while largely maintaining its semiconducting performance by incorporating di-2-thienylsulfide as the p-πconjugation units into the backbone of poly(3,6-di(thiophen-2-yl)diketopyrrolo-[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophen)(PDPP-TT).Compared to the parent polymer PDPP-TT,the incorporation of the p-πconjugation units induces the twisting of the backbone and weakens the interchain packing order,resulting in higher crack onset strain and better mechanical durability.The polymer semiconductor in which the molar ratio of the repeat unit with di-2-thienylsulfides is 10%exhibits a crack onset strain greater than 100%and can retain its initial charge mobility after 1000 stretching-releasing cycles under 50%strain.Our studies show that incorporation of p-πconjugation units such as di-2-thienylsulfide into backbones of polymer semiconductors provides a feasible approach to balance the stretchability and charge mobility,thus making it a promising way for future development of stretchable polymer semiconductors.
基金supported by National Natural Science Foundation of China(Nos.62201624,32000939,21775168,22174167,51861145202,U20A20168)Shenzhen Science and Technology Program(No.RCBS20221008093310024)+2 种基金Shenzhen Research Funding Program(No.JCYJ20190807160401657,JCYJ201908073000608)the Open Research Fund Program of Beijing National Research Center for Information Science and Technology(No.BR2023KF02010)support from Key Laboratory of Sensing Technology and Biomedical Instruments of Guangdong Province(No.2020B1212060077).
文摘The development of strain sensors with high stretchability and stability is an inevitable requirement for achieving full-range and long-term use of wearable electronic devices.Herein,a resistive micromesh reinforced strain sensor(MRSS)with high stretchability and stability is prepared,consisting of a laser-scribed graphene(LSG)layer and two styrene-block-poly(ethylene-ran-butylene)-block-poly-styrene micromesh layers embedded in Ecoflex.The micromesh reinforced structure endows the MRSS with combined characteris-tics of a high stretchability(120%),excellent stability(with a repetition error of 0.8%after 11000 cycles),and outstanding sensitivity(gauge factor up to 2692 beyond 100%).Impressively,the MRSS can still be used continauously within the working range without damage,even if stretched to 300%.Furthermore,compared with different structure sensors,the mechanism of the MRSS with high stretchability and stability is elucidated.What's more,a multilayer finite element model,based on the layered structure of the LSG and the morphology of the cracks,is proposed to investigate the strain sensing behavior and failure mechanism of the MRSS.Finally,due to the outstanding performance,the MRSS not only performes well in monitoring full-range human motions,but also achieves intelligent recognitions of various respiratory activities and ges-tures assisted by neural network algorithms(the accuracy up to 94.29%and 100%,respectively).This work provides a new approach for designing high-performance resistive strain sensors and shows great potential in full-range and long-term intelligent health management and human-machine interac-tions applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52303239 and 51933001)Natural Science Foundation of Shandong Province(Nos.ZR2022QB141 and 2023HWYQ-087).
文摘Intrinsic stretchability is a promising attribute of polymer organic solar cells(OSCs).However,rigid molecular blocks typically exhibit poor tensile properties,rendering polymers vulnerable to mechanical stress.In this study,we introduce a different approach utilizing all-small-molecule donors and acceptors to fabricate stretchable OSCs.An elastomer,styrene-b-ethylene-butylene-styrene(SEBS),was embedded to modulate film crystallization and stretchability.SEBS effectively confines the growth process of donors and acceptors,leading to enhancement of the crystallization quality,thus contributing to enhanced device efficiencies.Meanwhile,SEBS can absorb and release mechanical stress during stretching,thereby preventing mechanical degradation of donors and acceptors.The mechanical properties of the OSCs were significantly improved by the incorporation of SEBS.Notably,the crack-onset strain increased from 1.03% to 5.99% with SEBS embedding.These findings present a straightforward strategy for achieving stretchable OSCs using all small molecules,offering a different perspective for realizing stretchable devices.
基金supported by Natural Science and Engineering Research Council of Canada(RGPIN-2017-06737)Canada Research Chairs program,the National Key Research and Development Program of China(2017YFD0601005,2022YFD0904201)+1 种基金the National Natural Science Foundation of China(51203075)the China Scholarship Council(Grant No.CSC202208320361).
文摘With the rapid development of flexible wearable electronics,the demand for stretchable energy storage devices has surged.In this work,a novel gradient-layered architecture was design based on single-pore hollow lignin nanospheres(HLNPs)-intercalated two-dimensional transition metal carbide(Ti_(3)C_(2)T_(x) MXene)for fabricating highly stretchable and durable supercapacitors.By depositing and inserting HLNPs in the MXene layers with a bottom-up decreasing gradient,a multilayered porous MXene structure with smooth ion channels was constructed by reducing the overstacking of MXene lamella.Moreover,the micro-chamber architecture of thin-walled lignin nanospheres effectively extended the contact area between lignin and MXene to improve ion and electron accessibility,thus better utilizing the pseudocapacitive property of lignin.All these strategies effectively enhanced the capacitive performance of the electrodes.In addition,HLNPs,which acted as a protective phase for MXene layer,enhanced mechanical properties of the wrinkled stretchable electrodes by releasing stress through slip and deformation during the stretch-release cycling and greatly improved the structural integrity and capacitive stability of the electrodes.Flexible electrodes and symmetric flexible all-solid-state supercapacitors capable of enduring 600%uniaxial tensile strain were developed with high specific capacitances of 1273 mF cm^(−2)(241 F g^(−1))and 514 mF cm^(−2)(95 F g^(−1)),respectively.Moreover,their capacitances were well preserved after 1000 times of 600%stretch-release cycling.This study showcased new possibilities of incorporating biobased lignin nanospheres in energy storage devices to fabricate stretchable devices leveraging synergies among various two-dimensional nanomaterials.
基金This research was made possible thanks to the financial support of the National Natural Science Foundation of China(Nos.52073207 and 52121002)the Fundamental Research Funds for the Central Universities.L.Ye also appreciates the Peiyang Scholar Program of Tianjin University for support。
文摘With the emergence of Y-series small molecule acceptors,polymerizing the small molecule acceptors with aromatic linker units has attracted significant research attention,which has greatly advanced the photovoltaic performance of all-polymer solar cells.Despite the rapid increase in efficiency,the unique characteristics(e.g.,mechanical stretchability and flexibility)of all-polymer systems were still not thoroughly explored.In this work,we demonstrate an effective approach to simultaneously improve device performance,stability,and mechanical robustness of all-polymer solar cells by properly suppressing the aggregation and crystallization behaviors of polymerized Y-series acceptors.Strikingly,when introducing 50 wt%PYF-IT(a fluorinated version of PY-IT)into the well-known PM6:PY-IT system,the all-polymer devices delivered an impressive photovoltaic efficiency of 16.6%,significantly higher than that of the control binary cell(15.0%).Compared with the two binary systems,the optimal ternary blend exhibits more efficient charge separation and balanced charge transport accompanying with less recombination.Moreover,a high-performance 1.0 cm^(2)large-area device of 15%efficiency was demonstrated for the optimized ternary all-polymer blend,which offered a desirable PCE of 14.5%on flexible substrates and improved mechanical flexibility after bending 1000 cycles.Notably,these are among the best results for 1.0 cm^(2)all-polymer OPVs thus far.This work also heralds a bright future of all-polymer systems for flexible wearable energy-harvesting applications.
文摘Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality characteristics of SPOF limit their integration with traditional fiber optic sensors.This article introduces for the first time a flexible fiber optic vibration sensor based on laser interference technology,which can be applied to vibration measurement under high stretch conditions.This sensor utilizes elastic optical fibers made of polydimethylsiloxane(PDMS)as sensing elements,combined with phase generating carrier technology,to achieve vibration measurement at 50−260 Hz within the stretch range of 0−42%.
基金supported by the Scientific and Technological Project in Henan Province(242102231002)Henan Province Science and Technology Research and Development Program Joint Fund Advantageous Discipline Cultivation Project(No.232301420033)the Foundation for Outstanding Young Teachers in Universities of Henan Province(2021GGJS014).
文摘Bionic hydrogels offer significant advantages over conventional counterparts,boasting superior properties like enhanced adhesion,stretchability,conductivity,biocompatibility and versatile functionalities.Their physicochemical resemblance to biological tissues makes bionic hydrogels ideal interfaces for bioelectronic devices.In contrast,conventional hydrogels often exhibit inadequate performance,such as easy detachment,lack of good skin compliance,and inadequate conductivity,failing to meet the rigorous demands of bioelectronic applications.Bionic hydrogels,inspired by biological designs,exhibit exceptional physicochemical characteristics that fulfill diverse criteria for bioelectronic applications,driving the advancement of bioelectronic devices.This review first introduces a variety of materials used in the fabrication of bionic hydrogels,including natural polymers,synthetic polymers,and other materials.Then different mechanisms of hydrogel bionics,are categorized into material bionics,structural bionics,and functional bionics based on their bionic approaches.Subsequently,various applications of bionic hydrogels in the field of bioelectronics were introduced,including physiological signal monitoring,tissue engineering,and human-machine interactions.Lastly,the current development and future prospects of bionic hydrogels in bioelectronic devices are summarized.Hopefully,this comprehensive review could inspire advancements in bionic hydrogels for applications in bioelectronic devices.
文摘The Design and manufacturing of a noble piezoresistive pressure sensor(PS) for subtle pressures(<1 kPa) were presented. Meanwhile, in the studies conducted in the field of pressure sensors, the measurement of subtle pressures has received less attention. The limitations in the inherent gauge factor in silicon, have led to the development of polymer and composite resistive sensitive elements. However,in the development of resistance sensing elements, the structure of composite elements with reinforcement core has not been used. The proposed PS had a composite sandwich structure consisting of a nanocomposite graphene layer covered by layers of PDMS at the bottom and on the top coupled with a polyimide(PI) core. Various tests were performed to analyze the PS. The primary design target was improved sensitivity, with a finite-element method(FEM) utilized to simulate the stress profile over piezoresistive elements and membrane deflection at various pressures. The PS manufacturing process is based on Laser-engraved graphene(LEG) technology and PDMS casting. Experimental data indicated that the manufactured PS exhibits a sensitivity of 67.28 mV/kPa for a pressure range of 30-300 Pa in ambient temperature.
基金financial support from National Natural Science Foundation of China(Nos.22005186 and 51877132) was acknowledged。
文摘Flexible and stretchable energy storage devices are highly desirable for wearable electronics,particularly in the emerging fields of smart clothes,medical instruments,and stretchable skin.Lithium metal batteries(LMBs) with high power density and long cycle life are one of the ideal power sources for flexible and stretchable energy storage devices.However,the current LMBs are usually too rigid and bulky to meet the requirements of these devices.The electrolyte is the critical component that determines the energy density and security of flexible and stretchable LMBs.Among various electrolytes,gel polymer electrolytes(GPEs) perform excellent flexibility,safety,and high ionic conductivity compared with traditional liquid electrolytes and solid electrolytes,fulfilling the next generation deformable LMBs.This essay mainly reviews and highlights the recent progress in GPEs for flexible/stretchable LMBs and provides some useful insights for people interested in this field.Additionally,the multifunctional GPEs with self-healing,flame retardant,and temperature tolerance abilities are summarized.Finally,the perspectives and opportunities for flexible and stretchable GPEs are discussed.
基金financially supported by the Sichuan Provincial Science and Technology Fund for Distinguished Young Scholars,China(Grant No.2022JDJQ0028)Research Startup Fund by Sichuan University,China(Grant No.YJ202218).
文摘Triboelectric nanogenerators(TENGs)are emerging as new technologies to harvest electrical power from mechanical energy.With the distinctive working mechanism of triboelectric nanogenerators,they attract particular interest in healthcare monitoring,wearable electronics,and deformable energy harvesting,which raises the requirement for highly conformable devices with substantial energy outputs.Here,a simple,low-cost strategy for fabricating stretchable triboelectric nanogenerators with ultra-high electrical output is developed.The TENG is prepared using PTFE micron particles(PPTENG),contributing a different electrostatic induction process compared to TENG based on dielectric films,which was associated with the dynamics of particle motions in PP-TENG.The generator achieved an impressive voltage output of 1000 V with a current of 25 lA over a contact area of 40320 mm^(2).Additionally,the TENG exhibits excellent durability with a stretching strain of 500%,and the electrical output performance does not show any significant degradation even after 3000 cycles at a strain of 400%.The unique design of the device provides high conformability and can be used as a self-powered sensor for human motion detection.
文摘This paper examines the transport analysis,including both heat transfer and mass transfer,in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface.The influence of magnetic fields is also inspected in terms of their physical characteristics.To depict the phenomena of transport,modified versions of both Fick's and Fourier's laws are used.Additionally,the characteristics of both heterogeneous and homogeneous chemical reactions are also incorporated.Utilizing a curvilinear coordinate system,the flow problem is formulated as partial differential equations(PDEs)for momentum,concentration,microorganism field,and energy.An analytical solution to the obtained flow equations is achieved utilizing the homotopy analysis method(HAM).The effects of significant flow parameters on the pressure and microorganism fields,velocity,oscillation velocity,concentration,and temperature distributions are shown via graphs.Furthermore,the variations in skin friction,mass transfer rate,heat transfer rate,and local motile number due to different involved parameters are presented in tables and are analyzed in detail.Graphical results indicate that the curves of velocity and temperature fields are enhanced as the values of the solid volume fraction variables increase.It is also verified that the concentration rate field decreases as the values of the homogeneous reaction strength parameter and the radius of curvature parameter increase,and it increases with the Schmidt number and the heterogeneous reaction strength parameter.Tabular outcomes show a favorable response of the motile number to advanced values of the Peclet number,the Schmidt number,the microorganism difference parameter,and the bio-convective Lewis number.
基金supported by the National Key R&D Program of China(2018YFE0200700)NSFC(21790363,21871271,22090021,22075293,22021002,22071254).
文摘The soft nature has endowed conjugated polymers with promising applications in a wide range of field-effect transistor(FET)based flexible electronics.With unremitting efforts on revealing the molecular structure-property relationships,numerous novel conjugated polymers with high mobility and excellent mechanical property have been developed in the past decades.Incorporating hydrogen-bonding(H-bonding)units into semiconducting polymers is one of the most successful strategies for designing high-performance semiconducting materials.In this review,we aim to highlight the roles of H-bonding units in the performances of polymeric FETs from three aspects.These include(i)charge mobility enhancement for semiconducting polymers after incorporation of H-bonding units into the side chains,(ii)the effects of H-bonding units on the stretchability of conjugated polymers,and(iii)the improvement of self-healing properties of conjugated polymers containing dynamic hydrogen bonds due to the H-bonding units in the side chains or conjugated backbones.
基金We acknowledge the support from the National Key Research and Development Program of China(Grant No.2022YFA1405000)the Natural Science Foundation of Jiangsu Province,Major Project(Grant No.BK20212004)+1 种基金the National Natural Science Foundation of China(Grant No.62374083)the State Key Laboratory of Analytical Chemistry for Life Science(Grant No.5431ZZXM2205).
文摘Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body.As the primary compliant conductors used in these devices,metallic nanostructure/elastomer composites often struggle to form conformal contact with the textured skin.Hybrid electrodes have been consequently developed based on conductive nanocomposite and soft hydrogels to establish seamless skin-device interfaces.However,chemical modifications are typically needed for reliable bonding,which can alter their original properties.To overcome this limitation,this study presents a facile fabrication approach for mechanically interlocked nanocomposite/hydrogel hybrid electrodes.In this physical process,soft microfoams are thermally laminated on silver nanowire nanocomposites as a porous interface,which forms an interpenetrating network with the hydrogel.The microfoam-enabled bonding strategy is generally compatible with various polymers.The resulting interlocked hybrids have a 28-fold improved interfacial toughness compared to directly stacked hybrids.These electrodes achieve firm attachment to the skin and low contact impedance using tissue-adhesive hydrogels.They have been successfully integrated into an epidermal sleeve to distinguish hand gestures by sensing mus-cle contractions.Interlocked nanocomposite/hydrogel hybrids reported here offer a promising platform to combine the benefits of both materials for epidermal devices and systems.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.523712475,2072415 and 62101352)Shenzhen Science and Technology Program(RCBS20210706092343016).
文摘Despite the growing demand for transparent conductive films in smart and wearable electronics for electromagnetic interference(EMI)shielding,achieving a flexible EMI shielding film,while maintaining a high transmittance remains a significant challenge.Herein,a flexible,transparent,and conductive copper(Cu)metal mesh film for EMI shielding is fabricated by self-forming crackle template method and electroplating technique.The Cu mesh film shows an ultra-low sheet resistance(0.18Ω□^(-1)),high transmittance(85.8%@550 nm),and ultra-high figure of merit(>13,000).It also has satisfactory stretchability and mechanical stability,with a resistance increases of only 1.3%after 1,000 bending cycles.As a stretchable heater(ε>30%),the saturation temperature of the film can reach over 110°C within 60 s at 1.00 V applied voltage.Moreover,the metal mesh film exhibits outstanding average EMI shielding effectiveness of 40.4 dB in the X-band at the thickness of 2.5μm.As a demonstration,it is used as a transparent window for shielding the wireless communication electromagnetic waves.Therefore,the flexible and transparent conductive Cu mesh film proposed in this work provides a promising candidate for the next-generation EMI shielding applications.
