Continuous monitoring of biosignals is essential for advancing early disease detection,personalized treatment,and health management.Flexible electronics,capable of accurately monitoring biosignals in daily life,have g...Continuous monitoring of biosignals is essential for advancing early disease detection,personalized treatment,and health management.Flexible electronics,capable of accurately monitoring biosignals in daily life,have garnered considerable attention due to their softness,conformability,and biocompatibility.However,several challenges remain,including imperfect skin-device interfaces,limited breathability,and insufficient mechanoelectrical stability.On-skin epidermal electronics,distinguished by their excellent conformability,breathability,and mechanoelectrical robustness,offer a promising solution for high-fidelity,long-term health monitoring.These devices can seamlessly integrate with the human body,leading to transformative advancements in future personalized healthcare.This review provides a systematic examination of recent advancements in on-skin epidermal electronics,with particular emphasis on critical aspects including material science,structural design,desired properties,and practical applications.We explore various materials,considering their properties and the corresponding structural designs developed to construct high-performance epidermal electronics.We then discuss different approaches for achieving the desired device properties necessary for long-term health monitoring,including adhesiveness,breathability,and mechanoelectrical stability.Additionally,we summarize the diverse applications of these devices in monitoring biophysical and physiological signals.Finally,we address the challenges facing these devices and outline future prospects,offering insights into the ongoing development of on-skin epidermal electronics for long-term health monitoring.展开更多
Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is p...Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.展开更多
Gecko-inspired van der Waals force-based adhesion technology demonstrates significant potential for robotic operations.While superior adhesion is achieved under parallel contact during testing,engineering operations o...Gecko-inspired van der Waals force-based adhesion technology demonstrates significant potential for robotic operations.While superior adhesion is achieved under parallel contact during testing,engineering operations often involve non-parallel contact,weakening adhesion,and compromising task stability and efficiency.Stable attachment under such non-parallel contacts remains challenging.Inspired by the soft muscle and rigid bone in the gecko’s sole,this study proposes a self-adaptive core-shell dry adhesive by embedding a thin,rigid piece into a soft,thick elastomer comprising a top adhesion tip with a mushroom-like geometry for interfacial adhesion based on the van der Waals force and a bottom core-shell configuration for interface stress regulation.Unlike traditional core-shell structures with a fixed“dead core,”the proposed“live core”rotates within the soft shell,mimicking skeletal joints.This enables stress equalization at the interface and facilitates adaptive contact to macroscopic interfacial angle errors.This innovative core-shell configuration demonstrates an adhesion strength 100 times higher than conventional homogeneous structures under non-parallel contact and offers anti-overturning ability by mitigating torsional effects.The proposed strategy can advance the development of gecko-inspired adhesion-based devices and systems.展开更多
Surface nanopatterning of semiconductor optoelectronic devices is a powerful way to improve their quality and performance.However,photoelectric devices’inherent stress sensitivity and inevitable warpage pose a huge c...Surface nanopatterning of semiconductor optoelectronic devices is a powerful way to improve their quality and performance.However,photoelectric devices’inherent stress sensitivity and inevitable warpage pose a huge challenge on fabricating nanostructures large-scale.Electric-driven flexible-roller nanoimprint lithography for nanopatterning the optoelectronic wafer is proposed in this study.The flexible nanoimprint template twining around a roller is continuously released and recovered,controlled by the roller’s simple motion.The electric field applied to the template and substrate provides the driving force.The contact line of the template and the substrate gradually moves with the roller to enable scanning and adapting to the entire warped substrate,under the electric field.In addition,the driving force generated from electric field is applied to the surface of substrate,so that the substrate is free from external pressure.Furthermore,liquid resist completely fills in microcavities on the template by powerful electric field force,to ensure the fidelity of the nanostructures.The proposed nanoimprint technology is validated on the prototype.Finally,nano-grating structures are fabricated on a gallium nitride light-emitting diode chip adopting the solution,achieving polarization of the light source.展开更多
Compared with conventional manipulating methods,such as vacuum suction,electromagnetic adsorption,and mechanical clamping,gecko-inspired adhesives possess the ability of attaching on various surfaces with extensive ap...Compared with conventional manipulating methods,such as vacuum suction,electromagnetic adsorption,and mechanical clamping,gecko-inspired adhesives possess the ability of attaching on various surfaces with extensive applications in space operation,industrial manufacturing,etc.However,adhesive structures with high adhesion on one certain surface may lose their adhesive performance when gripping another surface.Achieving a good adhesion on objects with unknown surface morphology in a simple way is still a great challenge for gecko-inspired adhesives.Inspired by the interaction of the gecko’s actuating muscle and adhesive structures,we propose a smart adhesive film to adaptively manipulate objects with unknown surface morphology,consisting of magnetic artificial muscle and mushroom-shaped structures at the microscale.Controlled by the magnetic field,the adhesive film can conformally contact the target surfaces with flat/curved morphology or smooth/rough topography,and easily separated from the contacting interfaces,which process is performed without complex image recognition or detection sensors on predetermining the detailed morphology of the opposing surfaces.This specific characteristic enables the smart adhesive film to successfully grip,transfer and release the unknown objects,extending the operating specification of geckoinspired adhesives.Especially,in the manipulating process,the objects would not be dropped down from the smart adhesive film even if the magnetic field is suddenly removed,which is seldom achieved by other soft grippers.The proposed adhesion strategy extends gecko-inspired adhesives from specific types of surfaces to unknown surface morphology,opening an avenue for the development of gecko-inspired adhesive-based devices and systems.展开更多
Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study pr...Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study proposes a discretely-supported nanoimprint.lithography(NIL)technique to fabricate nanostructures on the extremely non-planar surface,namely high-spatial-frequency stepped surface.The designed discretely imprinting template implanted a discretely-supported intermediate buffer layer made of sparse pillars arrays.This allowed the simultaneous generation of air-cushion-like buffer and reliable support to the thin structured layer in the template.The resulting low bending stiffness and distributed concentrated load of the template jointly overcome the contact difficulty with a stepped surface,and enable the template to encase the stepped protrusion as tight as possible.Based on the proposed discretely-supported NIL,nanostructures were fabricated on the luminous interface of light emitting diodes chips that covered with micrometer step electrodes pad.About 96%of the utilized indium tin oxide transparent current spreading layer surface on top of the light emitting diode(LED)chips was coated with nanoholes array,with an increase by more than 40%in the optical output power.The excellent ability of nanopatterning a non-planar substrate could potentially lead innovate design and development of high performance device based on discretely-supported NIL.展开更多
The integrated perception capable of detecting and monitoring varieties of activities is one of the ultimate purposes of wearable electronics and intelligent robots.Limited by the space occupation,it lacks practical f...The integrated perception capable of detecting and monitoring varieties of activities is one of the ultimate purposes of wearable electronics and intelligent robots.Limited by the space occupation,it lacks practical feasibility to stack multiple types of single sensors on each other.Herein,a high-sensitivity dual-function capacitive sensor with proximity sensing and pressure sensing is proposed.The fringing electric field can be confined in the proximity-sensitive area by fibrous loop-patterned electrode,leading to more stolen charges when object approaching and thus a high proximity sensitivity.The high-permittivity doped structured dielectric layer reduces the compressive stiffness and enhances the rate of compression-caused increase in the equivalent relative permittivity of the dielectric layer,resulting in a larger increase in capacitance and thus a high pressure sensitivity.The electrodes and dielectric layer together compose the capacitor and act as the sensor without taking up additional space.The decoupling of proximity-sensing and pressure-sensing modes can be achieved by decrease or increase in capacitance.Combined with array distribution and sequential scanning,the sensors can be used for detection of motion trajectory,contour recognition,pressure distribution.展开更多
Highly sensitive flexible pressure sensors play an important role to ensure the safety and friendliness during the human-robot interaction process.Microengineering the active layer has been shown to improve performanc...Highly sensitive flexible pressure sensors play an important role to ensure the safety and friendliness during the human-robot interaction process.Microengineering the active layer has been shown to improve performance of pressure sensors.However,the current structural strategy almost relying on axial compression deformation suffers structural stifening,and together with the limited area growth efficiency of conformal interface,essentially limiting the maximum sensitivity.Here,inspired by the interface contact behavior of gecko's feet,we design a slant hierarchical microstructure to act as an electrode contacting with an ionic gel layer,fundamentally eliminating the pressure resistance and maximizing functional interface expansion to achieving ultrasensitive sensitivity.Such a structuring strategy dramatically improves the relative capacitance change both in the low-and high-pressure region,thereby boosting the sensitivity up to 36000kPa^(-1) and effective measurement range up to 30okPa.To verify the advantages of high sensitivity,the sensor is integrated with a soft magnetic robot to demonstrate a biomimetic Venus flytrap.The ability to perceive weak stimuli allows the sensor to be used as a sensory and feedback window,realizing the capture of small live insects and the transportation of fragile objects.展开更多
Improving droplet velocity as much as possible is considered as the key to improving both printing speed and printing distance of the piezoelectric drop-on-demand inkjet printing technology.There are 3 tough and contr...Improving droplet velocity as much as possible is considered as the key to improving both printing speed and printing distance of the piezoelectric drop-on-demand inkjet printing technology.There are 3 tough and contradictory issues that need to be addressed simultaneously,namely,the actuation pressure of the piezoelectric printhead,satellite droplets,and the air resistance,which seems almost impossible to achieve with classical methods.Herein,a novel solution is introduced.By modulating the positive crosstalk effect inside and outside the printhead,self-tuning can be achieved,including self-reinforcing of the actuation pressure,self-restraining of satellite droplets,and self-weakening of the air resistance,thereby greatly improving droplet velocity.Based on these mechanisms,waveform design methods for different inks and printheads are investigated.The results demonstrate that monodisperse droplet jetting with a maximum velocity of 27.53 m/s can be achieved,reaching 3 to 5 times that of the classical method(5 to 8 m/s).Correspondingly,the printing speed and distance can be simultaneously increased by almost 10 times,demonstrating an ability of direct printing on irregular surface.Meanwhile,the compatibility of ink materials is expanded,as the Ohnesorge number and the viscosity of printable inks for the printhead used are increased from 0.36–0.72 to 0.03–1.18 and from 10–12 cp to 1–40.3 cp,respectively,even breaking the traditional limitations of the piezoelectric printing technology(Ohnesorge number of 0.1 to 1;viscosity of 1 to 25 cp).All the above provide a new perspective for improving droplet velocity and may even offer a game-changing choice for expanding the boundaries of the piezoelectric drop-on-demand inkjet printing technology.展开更多
Conformal electronic devices on freeform surface play a critical role in the emerging smart robotics,smart skins,and integrated sensing systems.However,their functional structures such as circuits tend to tear-off,bre...Conformal electronic devices on freeform surface play a critical role in the emerging smart robotics,smart skins,and integrated sensing systems.However,their functional structures such as circuits tend to tear-off,break,or crack under mechanical or thermal influence when in service,thus limiting the application reliability of conformal electronics.Herein,inspired by the tree root system,template-confined additive(TCA)printing technology was presented for reliable fabrication of robust circuits.TCA printing technology involves the penetration of adhesive into the functional material,thereby enhancing the mechanical robustness of the circuits,allowing them to maintain their electrical performance despite the presence of external damaging factors such as scratching,abrasion,folding,and high temperatures.For example,herein,the circuits could withstand mechanical abrasion at temperatures as high as 350°C without compromising electrical properties.Benefiting from the confines of template,the printed circuits achieved resolutions of up to 300 nm,suitable for various materials such as P(VDF-TrFE),MWCNTs,and AgNPs,which enabled the multi-material self-aligned fabrication.Furthermore,the versatility of TCA printing was presented by fabricating circuits on arbitrary substrates,and realizing various devices,such as conformal temperature/humidity sensing system and epidermal ultra-thin energy storage system.These applications present the significant potential of TCA printing in fabricating intelligent devices.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.52025055,52375576,52350349)Key Research and Development Program of Shaanxi(Program No.2022GXLH-01-12)+2 种基金Joint Fund of Ministry of Education for Equipment Pre-research(No.8091B03012304)Aeronautical Science Foundation of China(No.2022004607001)the Fundamental Research Funds for the Central Universities(No.xtr072024031).
文摘Continuous monitoring of biosignals is essential for advancing early disease detection,personalized treatment,and health management.Flexible electronics,capable of accurately monitoring biosignals in daily life,have garnered considerable attention due to their softness,conformability,and biocompatibility.However,several challenges remain,including imperfect skin-device interfaces,limited breathability,and insufficient mechanoelectrical stability.On-skin epidermal electronics,distinguished by their excellent conformability,breathability,and mechanoelectrical robustness,offer a promising solution for high-fidelity,long-term health monitoring.These devices can seamlessly integrate with the human body,leading to transformative advancements in future personalized healthcare.This review provides a systematic examination of recent advancements in on-skin epidermal electronics,with particular emphasis on critical aspects including material science,structural design,desired properties,and practical applications.We explore various materials,considering their properties and the corresponding structural designs developed to construct high-performance epidermal electronics.We then discuss different approaches for achieving the desired device properties necessary for long-term health monitoring,including adhesiveness,breathability,and mechanoelectrical stability.Additionally,we summarize the diverse applications of these devices in monitoring biophysical and physiological signals.Finally,we address the challenges facing these devices and outline future prospects,offering insights into the ongoing development of on-skin epidermal electronics for long-term health monitoring.
基金supported by National Natural Science Foundation of China(No.52025055 and 52275571)Basic Research Operation Fund of China(No.xzy012024024).
文摘Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.
基金supported by the National Natural Science Foundation(52025055,52175546,and 52405624)the Shaanxi University Youth Innovation Team.
文摘Gecko-inspired van der Waals force-based adhesion technology demonstrates significant potential for robotic operations.While superior adhesion is achieved under parallel contact during testing,engineering operations often involve non-parallel contact,weakening adhesion,and compromising task stability and efficiency.Stable attachment under such non-parallel contacts remains challenging.Inspired by the soft muscle and rigid bone in the gecko’s sole,this study proposes a self-adaptive core-shell dry adhesive by embedding a thin,rigid piece into a soft,thick elastomer comprising a top adhesion tip with a mushroom-like geometry for interfacial adhesion based on the van der Waals force and a bottom core-shell configuration for interface stress regulation.Unlike traditional core-shell structures with a fixed“dead core,”the proposed“live core”rotates within the soft shell,mimicking skeletal joints.This enables stress equalization at the interface and facilitates adaptive contact to macroscopic interfacial angle errors.This innovative core-shell configuration demonstrates an adhesion strength 100 times higher than conventional homogeneous structures under non-parallel contact and offers anti-overturning ability by mitigating torsional effects.The proposed strategy can advance the development of gecko-inspired adhesion-based devices and systems.
基金financed by the National Natural Science Foundation of China(Nos.52025055 and 5227050783)。
文摘Surface nanopatterning of semiconductor optoelectronic devices is a powerful way to improve their quality and performance.However,photoelectric devices’inherent stress sensitivity and inevitable warpage pose a huge challenge on fabricating nanostructures large-scale.Electric-driven flexible-roller nanoimprint lithography for nanopatterning the optoelectronic wafer is proposed in this study.The flexible nanoimprint template twining around a roller is continuously released and recovered,controlled by the roller’s simple motion.The electric field applied to the template and substrate provides the driving force.The contact line of the template and the substrate gradually moves with the roller to enable scanning and adapting to the entire warped substrate,under the electric field.In addition,the driving force generated from electric field is applied to the surface of substrate,so that the substrate is free from external pressure.Furthermore,liquid resist completely fills in microcavities on the template by powerful electric field force,to ensure the fidelity of the nanostructures.The proposed nanoimprint technology is validated on the prototype.Finally,nano-grating structures are fabricated on a gallium nitride light-emitting diode chip adopting the solution,achieving polarization of the light source.
基金supported by National Natural Science Foundation(52175546,12102248)the Fundamental Research Funds for the Central Universities of China(grant No.xzd012023046)Funded Project of Shanghai Aerospace Science and Technology(No.SAST2022-078).
文摘Compared with conventional manipulating methods,such as vacuum suction,electromagnetic adsorption,and mechanical clamping,gecko-inspired adhesives possess the ability of attaching on various surfaces with extensive applications in space operation,industrial manufacturing,etc.However,adhesive structures with high adhesion on one certain surface may lose their adhesive performance when gripping another surface.Achieving a good adhesion on objects with unknown surface morphology in a simple way is still a great challenge for gecko-inspired adhesives.Inspired by the interaction of the gecko’s actuating muscle and adhesive structures,we propose a smart adhesive film to adaptively manipulate objects with unknown surface morphology,consisting of magnetic artificial muscle and mushroom-shaped structures at the microscale.Controlled by the magnetic field,the adhesive film can conformally contact the target surfaces with flat/curved morphology or smooth/rough topography,and easily separated from the contacting interfaces,which process is performed without complex image recognition or detection sensors on predetermining the detailed morphology of the opposing surfaces.This specific characteristic enables the smart adhesive film to successfully grip,transfer and release the unknown objects,extending the operating specification of geckoinspired adhesives.Especially,in the manipulating process,the objects would not be dropped down from the smart adhesive film even if the magnetic field is suddenly removed,which is seldom achieved by other soft grippers.The proposed adhesion strategy extends gecko-inspired adhesives from specific types of surfaces to unknown surface morphology,opening an avenue for the development of gecko-inspired adhesive-based devices and systems.
基金financed by the National Key R&D Program of China(No.2017YFB1102900)the Natural Science Foundation of China(No.51805422)+1 种基金the China Postdoctoral Science Foundation(No.2019M653592)the Basic Research Program of Natural Science of Shaanxi Province of China(No.2019JLM-5).
文摘Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study proposes a discretely-supported nanoimprint.lithography(NIL)technique to fabricate nanostructures on the extremely non-planar surface,namely high-spatial-frequency stepped surface.The designed discretely imprinting template implanted a discretely-supported intermediate buffer layer made of sparse pillars arrays.This allowed the simultaneous generation of air-cushion-like buffer and reliable support to the thin structured layer in the template.The resulting low bending stiffness and distributed concentrated load of the template jointly overcome the contact difficulty with a stepped surface,and enable the template to encase the stepped protrusion as tight as possible.Based on the proposed discretely-supported NIL,nanostructures were fabricated on the luminous interface of light emitting diodes chips that covered with micrometer step electrodes pad.About 96%of the utilized indium tin oxide transparent current spreading layer surface on top of the light emitting diode(LED)chips was coated with nanoholes array,with an increase by more than 40%in the optical output power.The excellent ability of nanopatterning a non-planar substrate could potentially lead innovate design and development of high performance device based on discretely-supported NIL.
基金the National Key Research and Development Program of China(No.2021YFB2011500)the National Natural Science Foundation of China(Nos.52025055 and 51905415)+4 种基金Institutional Foundation of The First Affiliated Hospital of Xi’an Jiaotong University,the China Gas Turbine Establishment of Aero Engine Corporation of China(No.GJCZ-2019-0039)the National Postdoctoral Program for Innovative Talents(No.BX20180251)Young Talent Fund of University Association for Science and Technology in Shaanxi,China(No.20200404)Basic Research Program of Natural Science of Shaanxi Province of China(Nos.2019JLM-5 and 2021JLM-42)Shaanxi University Youth Innovation Team.
文摘The integrated perception capable of detecting and monitoring varieties of activities is one of the ultimate purposes of wearable electronics and intelligent robots.Limited by the space occupation,it lacks practical feasibility to stack multiple types of single sensors on each other.Herein,a high-sensitivity dual-function capacitive sensor with proximity sensing and pressure sensing is proposed.The fringing electric field can be confined in the proximity-sensitive area by fibrous loop-patterned electrode,leading to more stolen charges when object approaching and thus a high proximity sensitivity.The high-permittivity doped structured dielectric layer reduces the compressive stiffness and enhances the rate of compression-caused increase in the equivalent relative permittivity of the dielectric layer,resulting in a larger increase in capacitance and thus a high pressure sensitivity.The electrodes and dielectric layer together compose the capacitor and act as the sensor without taking up additional space.The decoupling of proximity-sensing and pressure-sensing modes can be achieved by decrease or increase in capacitance.Combined with array distribution and sequential scanning,the sensors can be used for detection of motion trajectory,contour recognition,pressure distribution.
基金This work was supported by the National Key Research and Development Programof China(Grant No.2021YFB2011500)National Natural Science Foundation of China(Grant Nos.52025055 and 51905415)+4 种基金Natural ScienceFoundationofShaanxiProvince,China(2019JLM-5)Institutional Foundation of the First Affiliated Hospital of Xi'an Jiaotong University,China Gas Turbine Establishment of Aero Engine Corporation of China(GJCZ-2019-0039)National Postdoctoral Program for InnovativeTalents(No.BX20180251)hina Postdoctoral ScienceFoundation(No.2019M653588)YoungTalent Fund of UniversityAssociationfor ScienceandTechnology in Shaanxi,China(20200404).
文摘Highly sensitive flexible pressure sensors play an important role to ensure the safety and friendliness during the human-robot interaction process.Microengineering the active layer has been shown to improve performance of pressure sensors.However,the current structural strategy almost relying on axial compression deformation suffers structural stifening,and together with the limited area growth efficiency of conformal interface,essentially limiting the maximum sensitivity.Here,inspired by the interface contact behavior of gecko's feet,we design a slant hierarchical microstructure to act as an electrode contacting with an ionic gel layer,fundamentally eliminating the pressure resistance and maximizing functional interface expansion to achieving ultrasensitive sensitivity.Such a structuring strategy dramatically improves the relative capacitance change both in the low-and high-pressure region,thereby boosting the sensitivity up to 36000kPa^(-1) and effective measurement range up to 30okPa.To verify the advantages of high sensitivity,the sensor is integrated with a soft magnetic robot to demonstrate a biomimetic Venus flytrap.The ability to perceive weak stimuli allows the sensor to be used as a sensory and feedback window,realizing the capture of small live insects and the transportation of fragile objects.
基金the National Key Research and Development Program of China(Grant No.2017YFB1102900)the National Natural Science Foundation of China(Grant Nos.52025055 and 12232013).
文摘Improving droplet velocity as much as possible is considered as the key to improving both printing speed and printing distance of the piezoelectric drop-on-demand inkjet printing technology.There are 3 tough and contradictory issues that need to be addressed simultaneously,namely,the actuation pressure of the piezoelectric printhead,satellite droplets,and the air resistance,which seems almost impossible to achieve with classical methods.Herein,a novel solution is introduced.By modulating the positive crosstalk effect inside and outside the printhead,self-tuning can be achieved,including self-reinforcing of the actuation pressure,self-restraining of satellite droplets,and self-weakening of the air resistance,thereby greatly improving droplet velocity.Based on these mechanisms,waveform design methods for different inks and printheads are investigated.The results demonstrate that monodisperse droplet jetting with a maximum velocity of 27.53 m/s can be achieved,reaching 3 to 5 times that of the classical method(5 to 8 m/s).Correspondingly,the printing speed and distance can be simultaneously increased by almost 10 times,demonstrating an ability of direct printing on irregular surface.Meanwhile,the compatibility of ink materials is expanded,as the Ohnesorge number and the viscosity of printable inks for the printhead used are increased from 0.36–0.72 to 0.03–1.18 and from 10–12 cp to 1–40.3 cp,respectively,even breaking the traditional limitations of the piezoelectric printing technology(Ohnesorge number of 0.1 to 1;viscosity of 1 to 25 cp).All the above provide a new perspective for improving droplet velocity and may even offer a game-changing choice for expanding the boundaries of the piezoelectric drop-on-demand inkjet printing technology.
基金supported by the National Key Research and Development Project(No.2021YFB2011500(XL))National Nature Science Foundation of China(No.52025055(JS))+2 种基金National Nature Science Foundation of China(No.51975467(XL))Joint Fund Project-Enterprise-Shaanxi Coal Joint Fund Project(NO.2021JLM-42(XL))Key Research and Development Program of Shaanxi(No.2022GXLH-01-12).
文摘Conformal electronic devices on freeform surface play a critical role in the emerging smart robotics,smart skins,and integrated sensing systems.However,their functional structures such as circuits tend to tear-off,break,or crack under mechanical or thermal influence when in service,thus limiting the application reliability of conformal electronics.Herein,inspired by the tree root system,template-confined additive(TCA)printing technology was presented for reliable fabrication of robust circuits.TCA printing technology involves the penetration of adhesive into the functional material,thereby enhancing the mechanical robustness of the circuits,allowing them to maintain their electrical performance despite the presence of external damaging factors such as scratching,abrasion,folding,and high temperatures.For example,herein,the circuits could withstand mechanical abrasion at temperatures as high as 350°C without compromising electrical properties.Benefiting from the confines of template,the printed circuits achieved resolutions of up to 300 nm,suitable for various materials such as P(VDF-TrFE),MWCNTs,and AgNPs,which enabled the multi-material self-aligned fabrication.Furthermore,the versatility of TCA printing was presented by fabricating circuits on arbitrary substrates,and realizing various devices,such as conformal temperature/humidity sensing system and epidermal ultra-thin energy storage system.These applications present the significant potential of TCA printing in fabricating intelligent devices.
