The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an over...The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an overwhelming tendency,providing powerful tools for remote health monitoring and personal health management.Among many candidates,two-dimensional(2D)materials stand out due to several exotic mechanical,electrical,optical,and chemical properties that can be efficiently integrated into atomic-thin films.While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene,the rapid development of new 2D materials with exotic properties has opened up novel applications,particularly in smart interaction and integrated functionalities.This review aims to consolidate recent progress,highlight the unique advantages of 2D materials,and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices.We begin with an in-depth analysis of the advantages,sensing mechanisms,and potential applications of 2D materials in wearable biodevice fabrication.Following this,we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body.Special attention is given to showcasing the integration of multi-functionality in 2D smart devices,mainly including self-power supply,integrated diagnosis/treatment,and human–machine interaction.Finally,the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of2D materials for advanced biodevices.展开更多
Flexible electronic technology has laid the foundation for complex human-computer interaction system,and has attracted great attention in the field of human motion detection and soft robotics.Graphene has received an ...Flexible electronic technology has laid the foundation for complex human-computer interaction system,and has attracted great attention in the field of human motion detection and soft robotics.Graphene has received an extensive attention due to its excellent electrical conductivity;however,how to use it to fabricate wearable flexible sensors with complex structures remains challenging.In this study,we studied the rheological behavior of graphene/polydimethylsiloxane ink and proposed an optimal graphene ratio,which makes the ink have an good printability and conductivity at the same time.Then,based on the theory of Peano fractal layout,we proposed a two-dimensional structure that can withstand multi-directional tension by replacing the traditional arris structure with the arc structure.After that,we manufactured circular arc fractal structure sensor by adjusting ink composition and printing structure through direct ink writing method.Finally,we evaluated the detection performance and repeatability of the sensor.This method provides a simple and effective solution for fabricating wearable flexible sensors and exhibits the potential to fabricate 3D complex flexible electronic devices.展开更多
Sensors play an important role in information perception during the age of intelligence,particularly in areas such as environmental monitoring and human perception.To meet the huge demands for information acquisition ...Sensors play an important role in information perception during the age of intelligence,particularly in areas such as environmental monitoring and human perception.To meet the huge demands for information acquisition in the whole society,the development of elaborated sensor structures using patterned manufacturing technology is important to improve the performance of sensors.Creating patterned structures can enhance the interaction between the sensitive material and target matter,increase the contact area between the sensor and the target matter,amplify the effect of target matter on the sensor structure,and enhance the density of information sensing by building arrays.This review presents a comprehensive overview of patterned micro-nanostructure manufacturing techniques for performance enhancement of flexible sensors,including printing,exposure lithography,mould method,soft lithography,nanoimprinting lithography,and laser direct writing technology.Meanwhile,it introduces the evaluation methods of flexible sensor performance and discusses how patterned structures influence this performance.Finally,some practical application examples of patterned manufacturing techniques are introduced according to different types of flexible sensors.This review also summarises and provides an outlook on the role of these techniques in enhancing sensor performance offering valuable insights for future developments in the patterned manufacturing of flexible sensors.展开更多
With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition...With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition.Two-dimensional(2D)materials have been widely welcomed by researchers as sensitive layers,which broadens the range and application of flexible sensors due to the advantages of their large specific surface area,tunable energy bands,controllable thickness at the atomic level,stable mechanical properties,and excellent optoelectronic properties.This review focuses on five different types of 2D materials for monitoring pressure,humidity,sound,gas,and so on,to realize the recognition and conversion of human body and environmental signals.Meanwhile,the main problems and possible solutions of flexible sensors based on 2D materials as sensitive layers are summarized.展开更多
Flexible sensors have great potential for monitoring human body motion signals. This paper presents a flexible sensor that uses zinc oxide (ZnO) to improve the mechanical properties and electrical conductivity of PVA ...Flexible sensors have great potential for monitoring human body motion signals. This paper presents a flexible sensor that uses zinc oxide (ZnO) to improve the mechanical properties and electrical conductivity of PVA hydrogel. The composite hydrogel has excellent conductive properties and high strain sensitivity, making it suitable for motion monitoring. The PVA/ZnO conductive hydrogel is tested on various body parts, showing effective feedback on movement changes and good electrical signal output effects for different motion degrees, confirming its feasibility in flexible sensors. The sensor exhibits good mechanical properties, electrical conductivity, and tensile strain sensing performance, making it a promising sensor material. It can accurately monitor wrist bending, finger deformation, bending, and large-scale joint movements due to its wide monitoring range and recoverable strain. The results show that the PVA/ZnO conductive hydrogel can provide effective feedback in flexible sensors, which is suitable for use in motion monitoring.展开更多
Nanomaterial-based flexible sensors(NMFSs)can be tightly attached to the human skin or integrated with clothing to monitor human physiological information,provide medical data,or explore metaverse spaces.Nanomaterials...Nanomaterial-based flexible sensors(NMFSs)can be tightly attached to the human skin or integrated with clothing to monitor human physiological information,provide medical data,or explore metaverse spaces.Nanomaterials have been widely incorporated into flexible sensors due to their facile processing,material compatibility,and unique properties.This review highlights the recent advancements in NMFSs involving various nanomaterial frameworks such as nanoparticles,nanowires,and nanofilms.Different triggering interaction interfaces between NMFSs and metaverse/virtual reality(VR)applications,e.g.skin-mechanics-triggered,temperature-triggered,magnetically triggered,and neural-triggered interfaces,are discussed.In the context of interfacing physical and virtual worlds,machine learning(ML)has emerged as a promising tool for processing sensor data for controlling avatars in metaverse/VR worlds,and many ML algorithms have been proposed for virtual interaction technologies.This paper discusses the advantages,disadvantages,and prospects of NMFSs in metaverse/VR applications.展开更多
In this study,we proposed a self-healing conductive hydrogel based on polysaccharides and Li+to serve as flexible sensors.At first,the oxidized sodium alginate(OSA)was obtained through the oxidation reaction of sodium...In this study,we proposed a self-healing conductive hydrogel based on polysaccharides and Li+to serve as flexible sensors.At first,the oxidized sodium alginate(OSA)was obtained through the oxidation reaction of sodium alginate(SA).Then OSA,carboxymethyl chitosan(CMC),and agarose(AGO)were dissolved in LiCl solution,respectively.Finally,the hydrogel was obtained through heating,mixing,and cooling processes.Because of the Schiff base structure and hydrogen bonding,the hydrogel demonstrates good mechanical and self-healing properties.The presence of Li+provides good conductivity for the hydrogel.In addition,we demonstrated the application of the hydrogel as the flexible sensors.It can perceive the process of pressing Morse code with the index finger as a pressure sensor and monitor sliding movement of the thumb as the strain sensor to browse the web with the mobile phone.Thus,the selfhealing conductive hydrogel may have potential applications in flexible wearable sensors.展开更多
Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,...Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,ease of chemical functionalization,moisture sensitivity,and mechanical stability,enabling them to be promising candidates as flexible supporting substrates and flexible sensitive materials.Significant progress consequently has been achieved to improve mechanical,electrical,and chemical performance.The latest advance in materials synthesis,structure design,fabrication control,and working mechanism of novel cellulose-based flexible sensors are reviewed and discussed,including strain sensors,humidity sensors,and harmful gas sensors.Various strategies were summarized to enhance sensor performance by surface group modifications,inorganic and organic conducting fillers optimization,multilayer structure design.Newly emerged processing techniques of self-assembly,vacuum filtration,and 3D printing were introduced as well to construct multiscale microstructures.The integration of multiple sensors toward smart and healthy exercise monitoring system is briefly reviewed.The facing challenges and future opportunities of cellulose-based flexible sensors were discussed and proposed at the end.This review provides inspiration and guidelines on how to design and fabricate cellulose-based flexible sensors.展开更多
Over the past decade,global industrial and research interest in flexible sensors has boosted their applications in diverse fields across intelligent medicines,human-machine interactions,soft robotics and Metaverse.Amo...Over the past decade,global industrial and research interest in flexible sensors has boosted their applications in diverse fields across intelligent medicines,human-machine interactions,soft robotics and Metaverse.Among them,multimodal flexible sensor systems play a critical role due to their capability to simultaneously detect multiple stimuli.This review presents an overview of recent advances in decoupled multimodal flexible sensor systems exploring spatial decoupling,temporal decoupling,signal processing,and other methods.Several categories of the systems are highlighted based on anti-interference structure,combinations of multiple mechanisms,surface functional modification,interlayer additional electrical properties and layer-specific differentiated outputs.Furthermore,the significant roles of machine learning and circuit strategies in decoupling mixed stimuli are illustrated.The burgeoning innovations in this research field should benefit the intelligent transformation of society,particularly amid rapid rise of artificial intelligence and automation.展开更多
Flexible electronic devices with compliant mechanical deformability and electrical reliability have been a focal point of research over the past decade,particularly in the fields of wearable devices,brain-computer int...Flexible electronic devices with compliant mechanical deformability and electrical reliability have been a focal point of research over the past decade,particularly in the fields of wearable devices,brain-computer interfaces(BCIs),and electronic skins.These emerging applications impose stringent requirements on flexible sensors,necessitating not only their ability to withstand dynamic strains and conform to irregular surfaces but also to ensure long-term stable monitoring.To meet these demands,onedimensional nanowires,with high aspect ratios,large surface-to-volume ratios,and programmable geometric engineering,are widely regarded as ideal candidates for constructing high-performance flexible sensors.Various innovative assembly techniques have enabled the effective integration of these nanowires with flexible substrates.More excitingly,semiconductor nanowires,prepared through low-cost and efficient catalytic growth methods,have been successfully employed in the fabrication of highly flexible and stretchable nanoprobes for intracellular sensing.Additionally,nanowire arrays can be deployed on the cerebral cortex to record and analyze neural activity,opening new avenues for the treatment of neurological disorders.This review systematically examines recent advancements in nanowire-based flexible sensing technologies applied to wearable electronics,BCIs,and electronic skins,highlighting key design principles,operational mechanisms,and technological milestones achieved through growth,assembly,and transfer processes.These developments collectively advance high-performance health monitoring,deepen our understanding of neural activities,and facilitate the creation of novel,flexible,and stretchable electronic skins.Finally,we also present a summary and perspectives on the current challenges and future opportunities for nanowirebased flexible sensors.展开更多
Flexible electronic devices have garnered increasing attention for their applications in wearable devices,biomedical systems,soft robots,and flexible displays.However,the current sensors face limitations regarding low...Flexible electronic devices have garnered increasing attention for their applications in wearable devices,biomedical systems,soft robots,and flexible displays.However,the current sensors face limitations regarding low sensitivity,poor stability,and inadequate adhesion bonding between stimuli‐responsive functional materials and flexible substrates.To over-come these challenges and enable the further development of sensor devices,surface modification of stimuli‐responsive materials with amy-loid aggregates has emerged as a promising approach to enhance func-tionality and create superior multifunctional sensors.This review presents recent research advancements in the flexible sensors based on protein amyloid aggregation.The article begins by explaining the basic principles of protein amyloid aggregation,followed by outlining the process of preparing 1D to 3D amyloid‐based composite materials.Finally,it discusses the utilization of protein amyloid aggregation as a surface modification technique for developing flexible sensors.Based on this foundation,we identify the shortcomings associated with protein amyloid aggregate composites and propose possible solutions to address them.We believe that comprehensive investigations in this area will expedite the development of high‐performance flexible sensors with high sensitivity,high structural stability,and strong interface adhesion,especially the implantable flexible sensors for health monitoring.展开更多
This study develops a flexible strain sensor with electromagnetic interference(EMI)shielding,hydrophobicity,and acid/alkali resistance by integrating a bi-ordered porous structure with a micro-raised surface.The struc...This study develops a flexible strain sensor with electromagnetic interference(EMI)shielding,hydrophobicity,and acid/alkali resistance by integrating a bi-ordered porous structure with a micro-raised surface.The structure,mimicking lotus leaves,is fabricated using magnetic field-assisted freezing orientation and laser ablation on graphene(Gr)/Fe nanowire(NW)-infused aerogel and polydimethylsiloxane.The sensor,with a Gr to Fe NW ratio of 9:1,shows a high gauge factor of 85.19 in the 0–30%tensile strain.These values are 304%,430%,702%,and 1226%of the samples with Gr to Fe NWs ratios of 7:1,5:1,3:1,and 1:1,respectively.It achieves an EMI shielding efficiency(SE)of 20.02 dB and a specific SE of 807.48 dB cm^(2)/g in the 8.2–12.4 GHz range,150%higher than isotropic samples.The sensor exhibits a contact angle of 155.76°,maintaining hydrophobic stability under stretching and showing excellent resistance to acid and alkali.Additionally,the sensor can be integrated into wearable devices like gloves for gesture recognition,machine hand manipulation,and controlling neon bulbs,demonstrating potential for applications in field robotics and human-robot interaction.展开更多
Liquid leakage of pipeline networks not only results in considerableresource wastage but also leads to environmental pollution and ecological imbalance.In response to this global issue, a bioinspired superhydrophobic ...Liquid leakage of pipeline networks not only results in considerableresource wastage but also leads to environmental pollution and ecological imbalance.In response to this global issue, a bioinspired superhydrophobic thermoplastic polyurethane/carbon nanotubes/graphene nanosheets flexible strain sensor (TCGS) hasbeen developed using a combination of micro-extrusion compression molding andsurface modification for real-time wireless detection of liquid leakage. The TCGSutilizes the synergistic effects of Archimedean spiral crack arrays and micropores,which are inspired by the remarkable sensory capabilities of scorpions. This designachieves a sensitivity of 218.13 at a strain of 2%, which is an increase of 4300%. Additionally, it demonstrates exceptional durability bywithstanding over 5000 usage cycles. The robust superhydrophobicity of the TCGS significantly enhances sensitivity and stability indetecting small-scale liquid leakage, enabling precise monitoring of liquid leakage across a wide range of sizes, velocities, and compositionswhile issuing prompt alerts. This provides critical early warnings for both industrial pipelines and potential liquid leakage scenariosin everyday life. The development and utilization of bioinspired ultrasensitive flexible strain sensors offer an innovative and effectivesolution for the early wireless detection of liquid leakage.展开更多
This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurem...This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurement range.Inspired by the structure of bamboo slips,we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric electrode.The resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%.The integration of patterned liquid metal enables customisable tuning of the sensor’s response,while the porous fabric structure ensures superior comfort and air permeability for the wearer.Our design not only optimises the sensor’s performance but also enhances the electrical stability that is essential for practical applications.Through systematic investigation,we reveal the intrinsic mechanisms governing the sensor’s response,offering valuable insights for the design of wearable strain sensors.The sensor’s exceptional performance across a spectrum of applications,from micro-strain to large-strain detection,highlights its potential for a wide range of real-world uses,demonstrating a significant advancement in the field of flexible electronics.展开更多
The emergence of two-dimensional nanomaterials,especially MXene,significantly overcomes the limitations of flexible pressure sensors regarding their sensing abilities,mechanical properties,and electromagnetic shieldin...The emergence of two-dimensional nanomaterials,especially MXene,significantly overcomes the limitations of flexible pressure sensors regarding their sensing abilities,mechanical properties,and electromagnetic shielding effectiveness.This advancement underscores their great potential for use in wearable and medical monitoring devices.However,single-layer MXene is highly prone to oxidation when exposed to air and tends to stack between layers.Combining MXene with other functional materials to create heterojunction structures effectively addresses the stacking problem while also providing the resulting composites with excellent electrical conductivity,mechanical flexibility,and electromagnetic shielding capabilities,which are essential for enhancing sensor performance.This review systematically outlines various microstructural designs and improvement strategies aimed at boosting the sensing efficiency of different flexible pressure sensors based on MXene.It offers a comprehensive analysis of their significance in medical monitoring,anticipates future challenges and opportunities,and serves as an important reference for advancing precision and personalized approaches in medical monitoring.展开更多
Flexible piezoresistive sensors based on biomimetic microstructures are prospective for broad application in motion monitoring.However,the design and preparation processes of most biomimetic microstructures in the exi...Flexible piezoresistive sensors based on biomimetic microstructures are prospective for broad application in motion monitoring.However,the design and preparation processes of most biomimetic microstructures in the existing studies are complicated,and there are few studies on pore size control.Herein,the porous structure of human bones was used as a biomimetic prototype,and optimally designed by creating a theoretical equivalent sensor model and a finite element model.Soluble raw materials such as sugar and salt in different particle sizes were pressed into porous templates.Based on the template method,porous structures in different pore sizes were prepared using polydimethylsiloxane(PDMS)polymer as the substrate.On this basis,graphene oxide conductive coating was prepared with the modified Hummers method and then deposited via dip coating onto the substrate.Finally,a PDMS-based porous structure biomimetic flexible piezoresistive sensor was developed.Mechanically,the deformation of the sensor under the same load increased with the pore size rising from 0.3 to 1.5 mm.Electrically,the resistance rang of the sensor was enlarged as the pore size rose.The resistance variation rates of samples with pore sizes of 0.3,1.0,and 1.5 mm at approximately the 200th cycle were 63%,79%,and 81%,respectively;at the 500th cycle,these values were 63%,77%,and 79%;and at the 1000th cycle,they stabilized at 63%,74%,and 76%.These results indicate that the fabricated sensor exhibits high stability and fatigue resistance.At the pressure of 0–25 kPa,the sensitivity rose from 0.0688 to 0.1260 kPa−1,and the performance was enhanced by 83%.After 1,000 cycles of compression testing,the signal output was stable,and no damage was caused to the substrate.Further application tests showed the biomimetic sensor accurately and effectively identified human joint motions and gestures,and has potential application value in human motion monitoring.展开更多
Conductive gels have shown vast potential as flexible sensors for applications in health monitoring,soft robots,and human-machine interfaces.Nevertheless,there remains a significant challenge to integrate low hysteres...Conductive gels have shown vast potential as flexible sensors for applications in health monitoring,soft robots,and human-machine interfaces.Nevertheless,there remains a significant challenge to integrate low hysteresis,environmental tolerance,and high sensitivity in one component for accurate and stable signal outputs.In this work,a conductive organohydrogel is prepared by the radical polymerization of 3-acrylamidophenylboronic acid(APBA)and acrylamide(AM)in the presence of MXene followed by a solvent-replacement strategy.The organohydrogel exhibits high stretchability(>900%),robust elasticity(residual strain<12%),superior environmental tolerance(−60 to 60°C),and long-term stability in an open environment(>60 days)owing to the presence of B-N coordination and multiple hydrogen-bonding interactions within the gel network.As a flexible sensor,it can precisely distinguish successive tiny(1%)and large tensile strains(700%)even stored at−20°C for 7 days,and output reliable electrical signals of electrocardiograms and electromyograms with neglectable attenuation when exposed at the ambient environment for one week.Moreover,the organohydrogel shows remarkable temperature sensitivity with temperature coefficient of resistance of−2.71%/°C,and can accurately differentiate the temperatures of different human body parts with tiny differences for health monitoring.Our work may give a solution to design reliable gel-based flexible sensors for various applications.展开更多
For advanced conductive hydrogels,adaptable mechanical properties and high conductivity are essential requirements for practical application,e.g.,soft electronic devices.Here,a straightforward strategy to develop a me...For advanced conductive hydrogels,adaptable mechanical properties and high conductivity are essential requirements for practical application,e.g.,soft electronic devices.Here,a straightforward strategy to develop a mechanically robust hydrogel with high conductivity by constructing complicated 3D structures composed of covalently cross-linked polymer network and two nanofillers with distinguishing dimensions is reported.The combination of one-dimensional quaternized cellulose nanofibrils(QACNF)and two-dimensional MXene nanosheets not only provides prominent and tunable mechanical properties modulated by materials composition,but results in electronically conductive path with high conductivity(1281 mS m^(-1)).Owing to the uniform interconnectivity of network structure attributed to the strong macro-molecular interaction and nano-reinforced effect,the resultant hydrogel exhibits a balanced mechanical feature,i.e.,high tensile strength(449 kPa),remarkable stretchability(>1700%),and ultra-high toughness(5.46 MJ m^(-3)),outperforming those of virgin one.Additionally,the enhanced conductive characteristic with the aid of QACNF enables hydrogels with impressive electromechanical behavior,containing high sensitivity(maximum gauge factor:2.24),wide working range(0-1465%),and fast response performance(response time:141 ms,recover time:140 ms).Benefiting from the excellent mechanical performance,a flexible strain sensor based on such conductive hydrogel can deliver an appealing sensing performance of monitoring multi-scale deformations,from large and monotonous mechanical deformation to tiny and complex physiological motions(e.g.,joint movement and signature/vocal recognition).Together,the hydrogel material in this work opens up opportunities in the design and fabrication of advanced gel-based materials for emerging wearable electronics.展开更多
Flexible sensors are used widely in wearable devices, specifically flexible piezoresistive sensors, which are common and easy to manipulate.However, fabricating such sensors is expensive and complex, so proposed here ...Flexible sensors are used widely in wearable devices, specifically flexible piezoresistive sensors, which are common and easy to manipulate.However, fabricating such sensors is expensive and complex, so proposed here is a simple fabrication approach involving a sensor containing microstructures replicated from a sandpaper template onto which polydimethylsiloxane containing a mixture of graphene and carbon nanotubes is spin coated. The surface morphologies of three versions of the sensor made using different grades of sandpaper are observed, and the corresponding pressure sensitivities and linearity and hysteresis characteristics are assessed and analyzed. The results show that the sensor made using 80-mesh sandpaper has the best sensing performance. Its sensitivity is 0.341 kPa-1in the loading range of 0–1.6 kPa, it responds to small external loading of 100 Pa with a resistance change of 10%, its loading and unloading response times are 0.126 and 0.2 s, respectively,and its hysteresis characteristic is ~7%, indicating that the sensor has high sensitivity, fast response, and good stability. Thus, the presented piezoresistive sensor is promising for practical applications in flexible wearable electronics.展开更多
Human-machine interactions(HMIs)have advanced rapidly in recent decades in the fields of healthcare,work,and life.However,people with disabilities and other mobility problems do not have corresponding high-tech aids f...Human-machine interactions(HMIs)have advanced rapidly in recent decades in the fields of healthcare,work,and life.However,people with disabilities and other mobility problems do not have corresponding high-tech aids for them to enjoy the convenience of HMIs.In this paper,we propose a sensor with a wave-shaped(corrugated)electrode embedded in a friction layer,which exhibits high sensitivity to skin fold excitation and enormous potential in HMIs.Attributing to the wave-shaped electrode design,it has no built-in cavities,and its small size allows it to flexibly cope with folds at different angles.By specifying the carbon nanotube hybrid silicone film as the electrode layer material and silicone film as the friction layer,good electrical output performance,tensile properties,and biocompatibility can be achieved.Then,the sensor is tested on various joints and skin folds of the human body,the output signals of which can be distinguished between normal physiological behavior and test behavior.Based on this sensor,we designed a medical alarm system,a robotic arm assistive system,and a cell phone application control system for the disabled to help them in the fields of healthcare,work,and life.In conclusion,our research presents a feasible technology to enhance HMIs and makes a valuable contribution to the development of high-tech aids for the disabled.展开更多
基金the support from the National Natural Science Foundation of China(22272004,62272041)the Fundamental Research Funds for the Central Universities(YWF-22-L-1256)+1 种基金the National Key R&D Program of China(2023YFC3402600)the Beijing Institute of Technology Research Fund Program for Young Scholars(No.1870011182126)。
文摘The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an overwhelming tendency,providing powerful tools for remote health monitoring and personal health management.Among many candidates,two-dimensional(2D)materials stand out due to several exotic mechanical,electrical,optical,and chemical properties that can be efficiently integrated into atomic-thin films.While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene,the rapid development of new 2D materials with exotic properties has opened up novel applications,particularly in smart interaction and integrated functionalities.This review aims to consolidate recent progress,highlight the unique advantages of 2D materials,and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices.We begin with an in-depth analysis of the advantages,sensing mechanisms,and potential applications of 2D materials in wearable biodevice fabrication.Following this,we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body.Special attention is given to showcasing the integration of multi-functionality in 2D smart devices,mainly including self-power supply,integrated diagnosis/treatment,and human–machine interaction.Finally,the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of2D materials for advanced biodevices.
基金the National Key Research and Development Program of China(No.2020YFB1313100)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA16020803)+2 种基金the National Natural Science Foundation of China(Nos.51875557 and 52205319)the Research Equipment Development Program of the Chinese Academy of Sciences(No.YJKYYQ20190045)the Foundation of State Key Laboratory of Robotics(Nos.2021-Z01,2022-Z04 and 2023-Z01)。
文摘Flexible electronic technology has laid the foundation for complex human-computer interaction system,and has attracted great attention in the field of human motion detection and soft robotics.Graphene has received an extensive attention due to its excellent electrical conductivity;however,how to use it to fabricate wearable flexible sensors with complex structures remains challenging.In this study,we studied the rheological behavior of graphene/polydimethylsiloxane ink and proposed an optimal graphene ratio,which makes the ink have an good printability and conductivity at the same time.Then,based on the theory of Peano fractal layout,we proposed a two-dimensional structure that can withstand multi-directional tension by replacing the traditional arris structure with the arc structure.After that,we manufactured circular arc fractal structure sensor by adjusting ink composition and printing structure through direct ink writing method.Finally,we evaluated the detection performance and repeatability of the sensor.This method provides a simple and effective solution for fabricating wearable flexible sensors and exhibits the potential to fabricate 3D complex flexible electronic devices.
基金financial support from the National Key Research and Development Program of China(Grant 2024YFB3212100)National Natural Science Foundation of China(NSFC Grant Nos.62422409,62174152 and 62374159)from the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020115)。
文摘Sensors play an important role in information perception during the age of intelligence,particularly in areas such as environmental monitoring and human perception.To meet the huge demands for information acquisition in the whole society,the development of elaborated sensor structures using patterned manufacturing technology is important to improve the performance of sensors.Creating patterned structures can enhance the interaction between the sensitive material and target matter,increase the contact area between the sensor and the target matter,amplify the effect of target matter on the sensor structure,and enhance the density of information sensing by building arrays.This review presents a comprehensive overview of patterned micro-nanostructure manufacturing techniques for performance enhancement of flexible sensors,including printing,exposure lithography,mould method,soft lithography,nanoimprinting lithography,and laser direct writing technology.Meanwhile,it introduces the evaluation methods of flexible sensor performance and discusses how patterned structures influence this performance.Finally,some practical application examples of patterned manufacturing techniques are introduced according to different types of flexible sensors.This review also summarises and provides an outlook on the role of these techniques in enhancing sensor performance offering valuable insights for future developments in the patterned manufacturing of flexible sensors.
基金support of National Natural Science Foundation of China(Nos.52192610,62422120,52371202,52203307,52125205,52202181,and 52102184)Natural Science Foundation of Beijing(Nos.L223006 and 2222088).
文摘With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition.Two-dimensional(2D)materials have been widely welcomed by researchers as sensitive layers,which broadens the range and application of flexible sensors due to the advantages of their large specific surface area,tunable energy bands,controllable thickness at the atomic level,stable mechanical properties,and excellent optoelectronic properties.This review focuses on five different types of 2D materials for monitoring pressure,humidity,sound,gas,and so on,to realize the recognition and conversion of human body and environmental signals.Meanwhile,the main problems and possible solutions of flexible sensors based on 2D materials as sensitive layers are summarized.
文摘Flexible sensors have great potential for monitoring human body motion signals. This paper presents a flexible sensor that uses zinc oxide (ZnO) to improve the mechanical properties and electrical conductivity of PVA hydrogel. The composite hydrogel has excellent conductive properties and high strain sensitivity, making it suitable for motion monitoring. The PVA/ZnO conductive hydrogel is tested on various body parts, showing effective feedback on movement changes and good electrical signal output effects for different motion degrees, confirming its feasibility in flexible sensors. The sensor exhibits good mechanical properties, electrical conductivity, and tensile strain sensing performance, making it a promising sensor material. It can accurately monitor wrist bending, finger deformation, bending, and large-scale joint movements due to its wide monitoring range and recoverable strain. The results show that the PVA/ZnO conductive hydrogel can provide effective feedback in flexible sensors, which is suitable for use in motion monitoring.
基金financially supported by China Scholarship Council(CSC)under the Grant CSC(No.202107585001)Jilin Provincial Science and Technology Program(Nos.20210101069JC and 20190702002GH)+2 种基金Science and Technology Program of Changchun(No.21ZGM18)‘111’Project of China(No.D17017)the Hong Kong Research Grants Council(Project Nos.11207222 and 11210819)for partially supporting this work。
文摘Nanomaterial-based flexible sensors(NMFSs)can be tightly attached to the human skin or integrated with clothing to monitor human physiological information,provide medical data,or explore metaverse spaces.Nanomaterials have been widely incorporated into flexible sensors due to their facile processing,material compatibility,and unique properties.This review highlights the recent advancements in NMFSs involving various nanomaterial frameworks such as nanoparticles,nanowires,and nanofilms.Different triggering interaction interfaces between NMFSs and metaverse/virtual reality(VR)applications,e.g.skin-mechanics-triggered,temperature-triggered,magnetically triggered,and neural-triggered interfaces,are discussed.In the context of interfacing physical and virtual worlds,machine learning(ML)has emerged as a promising tool for processing sensor data for controlling avatars in metaverse/VR worlds,and many ML algorithms have been proposed for virtual interaction technologies.This paper discusses the advantages,disadvantages,and prospects of NMFSs in metaverse/VR applications.
基金support from National Natural Science Foundation of China(51873009)Beijing Natural Science Foundation(2192042).
文摘In this study,we proposed a self-healing conductive hydrogel based on polysaccharides and Li+to serve as flexible sensors.At first,the oxidized sodium alginate(OSA)was obtained through the oxidation reaction of sodium alginate(SA).Then OSA,carboxymethyl chitosan(CMC),and agarose(AGO)were dissolved in LiCl solution,respectively.Finally,the hydrogel was obtained through heating,mixing,and cooling processes.Because of the Schiff base structure and hydrogen bonding,the hydrogel demonstrates good mechanical and self-healing properties.The presence of Li+provides good conductivity for the hydrogel.In addition,we demonstrated the application of the hydrogel as the flexible sensors.It can perceive the process of pressing Morse code with the index finger as a pressure sensor and monitor sliding movement of the thumb as the strain sensor to browse the web with the mobile phone.Thus,the selfhealing conductive hydrogel may have potential applications in flexible wearable sensors.
基金the NSFC Funds under Grant 52075440National Key Research and Development Program of China(No.2021YFD1600402)+2 种基金Central Guidance on Local Science and Technology Development Fund of Shaanxi Province(No.2020-ZYYD-NCC-9)Shaanxi Provincial Department of Education Collaborative Innovation Center Project(20JY052)National Natural Science Foundation of China(No.52072075)。
文摘Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,ease of chemical functionalization,moisture sensitivity,and mechanical stability,enabling them to be promising candidates as flexible supporting substrates and flexible sensitive materials.Significant progress consequently has been achieved to improve mechanical,electrical,and chemical performance.The latest advance in materials synthesis,structure design,fabrication control,and working mechanism of novel cellulose-based flexible sensors are reviewed and discussed,including strain sensors,humidity sensors,and harmful gas sensors.Various strategies were summarized to enhance sensor performance by surface group modifications,inorganic and organic conducting fillers optimization,multilayer structure design.Newly emerged processing techniques of self-assembly,vacuum filtration,and 3D printing were introduced as well to construct multiscale microstructures.The integration of multiple sensors toward smart and healthy exercise monitoring system is briefly reviewed.The facing challenges and future opportunities of cellulose-based flexible sensors were discussed and proposed at the end.This review provides inspiration and guidelines on how to design and fabricate cellulose-based flexible sensors.
基金support from the National Natural Science Foundation of China(Nos.52475610 and 52105593)the Zhejiang Provincial Natural Science Foundation of China(No.LDQ24E050001)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(Nos.2023C03007 and 2024C01173).
文摘Over the past decade,global industrial and research interest in flexible sensors has boosted their applications in diverse fields across intelligent medicines,human-machine interactions,soft robotics and Metaverse.Among them,multimodal flexible sensor systems play a critical role due to their capability to simultaneously detect multiple stimuli.This review presents an overview of recent advances in decoupled multimodal flexible sensor systems exploring spatial decoupling,temporal decoupling,signal processing,and other methods.Several categories of the systems are highlighted based on anti-interference structure,combinations of multiple mechanisms,surface functional modification,interlayer additional electrical properties and layer-specific differentiated outputs.Furthermore,the significant roles of machine learning and circuit strategies in decoupling mixed stimuli are illustrated.The burgeoning innovations in this research field should benefit the intelligent transformation of society,particularly amid rapid rise of artificial intelligence and automation.
基金support received from the National Key Research Program of China(No.92164201)National Natural Science Foundation of China for Distinguished Young Scholars(No.62325403)+2 种基金Natural Science Foundation of Jiangsu Province(BK20230498)Jiangsu Funding Program for Excellent Postdoctoral Talent(2024ZB427)the National Natural Science Foundation of China(61934004).
文摘Flexible electronic devices with compliant mechanical deformability and electrical reliability have been a focal point of research over the past decade,particularly in the fields of wearable devices,brain-computer interfaces(BCIs),and electronic skins.These emerging applications impose stringent requirements on flexible sensors,necessitating not only their ability to withstand dynamic strains and conform to irregular surfaces but also to ensure long-term stable monitoring.To meet these demands,onedimensional nanowires,with high aspect ratios,large surface-to-volume ratios,and programmable geometric engineering,are widely regarded as ideal candidates for constructing high-performance flexible sensors.Various innovative assembly techniques have enabled the effective integration of these nanowires with flexible substrates.More excitingly,semiconductor nanowires,prepared through low-cost and efficient catalytic growth methods,have been successfully employed in the fabrication of highly flexible and stretchable nanoprobes for intracellular sensing.Additionally,nanowire arrays can be deployed on the cerebral cortex to record and analyze neural activity,opening new avenues for the treatment of neurological disorders.This review systematically examines recent advancements in nanowire-based flexible sensing technologies applied to wearable electronics,BCIs,and electronic skins,highlighting key design principles,operational mechanisms,and technological milestones achieved through growth,assembly,and transfer processes.These developments collectively advance high-performance health monitoring,deepen our understanding of neural activities,and facilitate the creation of novel,flexible,and stretchable electronic skins.Finally,we also present a summary and perspectives on the current challenges and future opportunities for nanowirebased flexible sensors.
基金National Key R&D Program of China,Grant/Award Numbers:2020YFA0710400,2020YFA0710402,2020YFA0710403Natural Science Foundation of Shaanxi Province,Grant/Award Number:2024JC‐YBMS‐304+4 种基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:GK202305001,GK202205017111 Project,Grant/Award Number:B14041International Science and Technology Cooperation Program of Shaanxi Province,Grant/Award Number:2022KWZ‐24National Science Fund for Distinguished Young Scholars,Grant/Award Number:52225301Key Science&Technology Innovation Team of Shaanxi Province,Grant/Award Number:2022TD‐35。
文摘Flexible electronic devices have garnered increasing attention for their applications in wearable devices,biomedical systems,soft robots,and flexible displays.However,the current sensors face limitations regarding low sensitivity,poor stability,and inadequate adhesion bonding between stimuli‐responsive functional materials and flexible substrates.To over-come these challenges and enable the further development of sensor devices,surface modification of stimuli‐responsive materials with amy-loid aggregates has emerged as a promising approach to enhance func-tionality and create superior multifunctional sensors.This review presents recent research advancements in the flexible sensors based on protein amyloid aggregation.The article begins by explaining the basic principles of protein amyloid aggregation,followed by outlining the process of preparing 1D to 3D amyloid‐based composite materials.Finally,it discusses the utilization of protein amyloid aggregation as a surface modification technique for developing flexible sensors.Based on this foundation,we identify the shortcomings associated with protein amyloid aggregate composites and propose possible solutions to address them.We believe that comprehensive investigations in this area will expedite the development of high‐performance flexible sensors with high sensitivity,high structural stability,and strong interface adhesion,especially the implantable flexible sensors for health monitoring.
基金supported by the Chongqing New Youth Innovation Talent Program(Grant No.CSTB2024NSCQ-QCXMX0086)National Natural Science Foundation of China(Grant No.52205589)+4 种基金Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202300606)Natural Science Foundation of Anhui Province(Grant No.2208085QE141)China Postdoctoral Science Foundation(Grant Nos.2023T160765,2022MD713695)Young Elite Scientists Sponsorship Program by CAST(China Association for Science and Technology)(Grant No.2022QNRC001)Hong Kong Scholars Program。
文摘This study develops a flexible strain sensor with electromagnetic interference(EMI)shielding,hydrophobicity,and acid/alkali resistance by integrating a bi-ordered porous structure with a micro-raised surface.The structure,mimicking lotus leaves,is fabricated using magnetic field-assisted freezing orientation and laser ablation on graphene(Gr)/Fe nanowire(NW)-infused aerogel and polydimethylsiloxane.The sensor,with a Gr to Fe NW ratio of 9:1,shows a high gauge factor of 85.19 in the 0–30%tensile strain.These values are 304%,430%,702%,and 1226%of the samples with Gr to Fe NWs ratios of 7:1,5:1,3:1,and 1:1,respectively.It achieves an EMI shielding efficiency(SE)of 20.02 dB and a specific SE of 807.48 dB cm^(2)/g in the 8.2–12.4 GHz range,150%higher than isotropic samples.The sensor exhibits a contact angle of 155.76°,maintaining hydrophobic stability under stretching and showing excellent resistance to acid and alkali.Additionally,the sensor can be integrated into wearable devices like gloves for gesture recognition,machine hand manipulation,and controlling neon bulbs,demonstrating potential for applications in field robotics and human-robot interaction.
基金the National Natural Science Foundation of China(Grant No.52203037,52103031,and 52073107)the Natural Science Foundation of Hubei Province of China(Grant No.2022CFB649)the National Key Research and Development Program of China(Grant No.2022YFC3901902).
文摘Liquid leakage of pipeline networks not only results in considerableresource wastage but also leads to environmental pollution and ecological imbalance.In response to this global issue, a bioinspired superhydrophobic thermoplastic polyurethane/carbon nanotubes/graphene nanosheets flexible strain sensor (TCGS) hasbeen developed using a combination of micro-extrusion compression molding andsurface modification for real-time wireless detection of liquid leakage. The TCGSutilizes the synergistic effects of Archimedean spiral crack arrays and micropores,which are inspired by the remarkable sensory capabilities of scorpions. This designachieves a sensitivity of 218.13 at a strain of 2%, which is an increase of 4300%. Additionally, it demonstrates exceptional durability bywithstanding over 5000 usage cycles. The robust superhydrophobicity of the TCGS significantly enhances sensitivity and stability indetecting small-scale liquid leakage, enabling precise monitoring of liquid leakage across a wide range of sizes, velocities, and compositionswhile issuing prompt alerts. This provides critical early warnings for both industrial pipelines and potential liquid leakage scenariosin everyday life. The development and utilization of bioinspired ultrasensitive flexible strain sensors offer an innovative and effectivesolution for the early wireless detection of liquid leakage.
基金support from the National Key R&D Program of China(2021YFB3200700)the National Natural Science Foundation of China(Grant No.0214100221,51925503).
文摘This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurement range.Inspired by the structure of bamboo slips,we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric electrode.The resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%.The integration of patterned liquid metal enables customisable tuning of the sensor’s response,while the porous fabric structure ensures superior comfort and air permeability for the wearer.Our design not only optimises the sensor’s performance but also enhances the electrical stability that is essential for practical applications.Through systematic investigation,we reveal the intrinsic mechanisms governing the sensor’s response,offering valuable insights for the design of wearable strain sensors.The sensor’s exceptional performance across a spectrum of applications,from micro-strain to large-strain detection,highlights its potential for a wide range of real-world uses,demonstrating a significant advancement in the field of flexible electronics.
基金financially supported by the National Natural Science Foundation of China(No.62205091)the Fundamental Research Foundation for Universities of Heilongjiang Province(No.2022-KYYWF-0121)+1 种基金the Natural Science Foundation of Heilongjiang Province Project(No.LH2022F028)the National Key Research and Development Program of China(No.2023YFF1206100)。
文摘The emergence of two-dimensional nanomaterials,especially MXene,significantly overcomes the limitations of flexible pressure sensors regarding their sensing abilities,mechanical properties,and electromagnetic shielding effectiveness.This advancement underscores their great potential for use in wearable and medical monitoring devices.However,single-layer MXene is highly prone to oxidation when exposed to air and tends to stack between layers.Combining MXene with other functional materials to create heterojunction structures effectively addresses the stacking problem while also providing the resulting composites with excellent electrical conductivity,mechanical flexibility,and electromagnetic shielding capabilities,which are essential for enhancing sensor performance.This review systematically outlines various microstructural designs and improvement strategies aimed at boosting the sensing efficiency of different flexible pressure sensors based on MXene.It offers a comprehensive analysis of their significance in medical monitoring,anticipates future challenges and opportunities,and serves as an important reference for advancing precision and personalized approaches in medical monitoring.
基金supported by the National Natural Science Foundation of China(52175270)the Project of Scientifc and Technological Development Plan of Jilin Province(20220508130RC)+3 种基金the Science and Technology Development Program of Jilin Province(YDZJ202501ZYTS370)the Scientific Research Project of Education Department of Jilin Province(JJKH20251196KJ)the Scientific Research Project of Education Department of Jilin Province(JJKH20251195KJ)the Key Project of State Key Laboratory of Changchun City(23GZZ14).
文摘Flexible piezoresistive sensors based on biomimetic microstructures are prospective for broad application in motion monitoring.However,the design and preparation processes of most biomimetic microstructures in the existing studies are complicated,and there are few studies on pore size control.Herein,the porous structure of human bones was used as a biomimetic prototype,and optimally designed by creating a theoretical equivalent sensor model and a finite element model.Soluble raw materials such as sugar and salt in different particle sizes were pressed into porous templates.Based on the template method,porous structures in different pore sizes were prepared using polydimethylsiloxane(PDMS)polymer as the substrate.On this basis,graphene oxide conductive coating was prepared with the modified Hummers method and then deposited via dip coating onto the substrate.Finally,a PDMS-based porous structure biomimetic flexible piezoresistive sensor was developed.Mechanically,the deformation of the sensor under the same load increased with the pore size rising from 0.3 to 1.5 mm.Electrically,the resistance rang of the sensor was enlarged as the pore size rose.The resistance variation rates of samples with pore sizes of 0.3,1.0,and 1.5 mm at approximately the 200th cycle were 63%,79%,and 81%,respectively;at the 500th cycle,these values were 63%,77%,and 79%;and at the 1000th cycle,they stabilized at 63%,74%,and 76%.These results indicate that the fabricated sensor exhibits high stability and fatigue resistance.At the pressure of 0–25 kPa,the sensitivity rose from 0.0688 to 0.1260 kPa−1,and the performance was enhanced by 83%.After 1,000 cycles of compression testing,the signal output was stable,and no damage was caused to the substrate.Further application tests showed the biomimetic sensor accurately and effectively identified human joint motions and gestures,and has potential application value in human motion monitoring.
基金supported by the National Natural Science Foundation of China(Nos.52173139 and 52322309)the“Young Talent Support Plan”of Xi'an Jiaotong University,Innovation Capability Support Program of Shaanxi(No.2023-CXTD-43)+1 种基金Fundamental Research Funds for the Central Universities,CHD(No.300102314401)the Natural Science Foundation of Shaanxi Province(No.2024JC-YBQN-0586).
文摘Conductive gels have shown vast potential as flexible sensors for applications in health monitoring,soft robots,and human-machine interfaces.Nevertheless,there remains a significant challenge to integrate low hysteresis,environmental tolerance,and high sensitivity in one component for accurate and stable signal outputs.In this work,a conductive organohydrogel is prepared by the radical polymerization of 3-acrylamidophenylboronic acid(APBA)and acrylamide(AM)in the presence of MXene followed by a solvent-replacement strategy.The organohydrogel exhibits high stretchability(>900%),robust elasticity(residual strain<12%),superior environmental tolerance(−60 to 60°C),and long-term stability in an open environment(>60 days)owing to the presence of B-N coordination and multiple hydrogen-bonding interactions within the gel network.As a flexible sensor,it can precisely distinguish successive tiny(1%)and large tensile strains(700%)even stored at−20°C for 7 days,and output reliable electrical signals of electrocardiograms and electromyograms with neglectable attenuation when exposed at the ambient environment for one week.Moreover,the organohydrogel shows remarkable temperature sensitivity with temperature coefficient of resistance of−2.71%/°C,and can accurately differentiate the temperatures of different human body parts with tiny differences for health monitoring.Our work may give a solution to design reliable gel-based flexible sensors for various applications.
基金supported by the National Natural Science Foundation of China(Nos.52203148,51973047,and 12002113)the Research Foundation of Talented Scholars of Zhejiang A&F University(Nos.2020FR070 and 2021FR024)+1 种基金the Zhejiang A&F University Scientific Research Training Program for Undergraduates(No.S202210341186)the Key Research and Development Program of Shaanxi(No.2022-JBGS3-09).
文摘For advanced conductive hydrogels,adaptable mechanical properties and high conductivity are essential requirements for practical application,e.g.,soft electronic devices.Here,a straightforward strategy to develop a mechanically robust hydrogel with high conductivity by constructing complicated 3D structures composed of covalently cross-linked polymer network and two nanofillers with distinguishing dimensions is reported.The combination of one-dimensional quaternized cellulose nanofibrils(QACNF)and two-dimensional MXene nanosheets not only provides prominent and tunable mechanical properties modulated by materials composition,but results in electronically conductive path with high conductivity(1281 mS m^(-1)).Owing to the uniform interconnectivity of network structure attributed to the strong macro-molecular interaction and nano-reinforced effect,the resultant hydrogel exhibits a balanced mechanical feature,i.e.,high tensile strength(449 kPa),remarkable stretchability(>1700%),and ultra-high toughness(5.46 MJ m^(-3)),outperforming those of virgin one.Additionally,the enhanced conductive characteristic with the aid of QACNF enables hydrogels with impressive electromechanical behavior,containing high sensitivity(maximum gauge factor:2.24),wide working range(0-1465%),and fast response performance(response time:141 ms,recover time:140 ms).Benefiting from the excellent mechanical performance,a flexible strain sensor based on such conductive hydrogel can deliver an appealing sensing performance of monitoring multi-scale deformations,from large and monotonous mechanical deformation to tiny and complex physiological motions(e.g.,joint movement and signature/vocal recognition).Together,the hydrogel material in this work opens up opportunities in the design and fabrication of advanced gel-based materials for emerging wearable electronics.
基金supported financially by the Science and Technology Cooperation and Exchange Special Project of Shanxi Province(Grant No.202204041101006)the Fundamental Research Program of Shanxi Province(Grant Nos.20210302123013,202203021222077,and 202203021222069)the Shanxi Scholarship Council of China(Grant No.2023-130).
文摘Flexible sensors are used widely in wearable devices, specifically flexible piezoresistive sensors, which are common and easy to manipulate.However, fabricating such sensors is expensive and complex, so proposed here is a simple fabrication approach involving a sensor containing microstructures replicated from a sandpaper template onto which polydimethylsiloxane containing a mixture of graphene and carbon nanotubes is spin coated. The surface morphologies of three versions of the sensor made using different grades of sandpaper are observed, and the corresponding pressure sensitivities and linearity and hysteresis characteristics are assessed and analyzed. The results show that the sensor made using 80-mesh sandpaper has the best sensing performance. Its sensitivity is 0.341 kPa-1in the loading range of 0–1.6 kPa, it responds to small external loading of 100 Pa with a resistance change of 10%, its loading and unloading response times are 0.126 and 0.2 s, respectively,and its hysteresis characteristic is ~7%, indicating that the sensor has high sensitivity, fast response, and good stability. Thus, the presented piezoresistive sensor is promising for practical applications in flexible wearable electronics.
基金supported by the Guizhou Provincial Science and Technology Foundation(No.ZK[2022]General 112)the National Natural Science Foundation of China(No.42267009).
文摘Human-machine interactions(HMIs)have advanced rapidly in recent decades in the fields of healthcare,work,and life.However,people with disabilities and other mobility problems do not have corresponding high-tech aids for them to enjoy the convenience of HMIs.In this paper,we propose a sensor with a wave-shaped(corrugated)electrode embedded in a friction layer,which exhibits high sensitivity to skin fold excitation and enormous potential in HMIs.Attributing to the wave-shaped electrode design,it has no built-in cavities,and its small size allows it to flexibly cope with folds at different angles.By specifying the carbon nanotube hybrid silicone film as the electrode layer material and silicone film as the friction layer,good electrical output performance,tensile properties,and biocompatibility can be achieved.Then,the sensor is tested on various joints and skin folds of the human body,the output signals of which can be distinguished between normal physiological behavior and test behavior.Based on this sensor,we designed a medical alarm system,a robotic arm assistive system,and a cell phone application control system for the disabled to help them in the fields of healthcare,work,and life.In conclusion,our research presents a feasible technology to enhance HMIs and makes a valuable contribution to the development of high-tech aids for the disabled.
