Flexible high-temperature electronics is a compliant form of high-temperature electronics to expand the application areas of conventional flexible one.In aerospace applications,electronic devices are not only required...Flexible high-temperature electronics is a compliant form of high-temperature electronics to expand the application areas of conventional flexible one.In aerospace applications,electronic devices are not only required to be deformable but also to be able to withstand extreme temperatures.The disadvantages of current flexible electronics,such as high cost,large differences between components,and even requiring independent debugging,are acceptable.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
Large,3D curved electronics are a trend of the microelectronic industry due to their unique ability to conformally coexist with complex surfaces while retaining the electronic functions of 2D planar integrated circuit...Large,3D curved electronics are a trend of the microelectronic industry due to their unique ability to conformally coexist with complex surfaces while retaining the electronic functions of 2D planar integrated circuit technologies.However,these curved electronics present great challenges to the fabrication processes.Here,we propose a reconfigurable,mask-free,conformal fabrication strategy with a robot-like system,called robotized‘transfer-and-jet’printing,to assemble diverse electronic devices on complex surfaces.This novel method is a ground-breaking advance with the unique capability to integrate rigid chips,flexible electronics,and conformal circuits on complex surfaces.Critically,each process,including transfer printing,inkjet printing,and plasma treating,are mask-free,digitalized,and programmable.The robotization techniques,including measurement,surface reconstruction and localization,and path programming,break through the fundamental constraints of 2D planar microfabrication in the context of geometric shape and size.The transfer printing begins with the laser lift-off of rigid chips or flexible electronics from donor substrates,which are then transferred onto a curved surface via a dexterous robotic palm.Then the robotic electrohydrodynamic printing directly writes submicrometer structures on the curved surface.Their permutation and combination allow versatile conformal microfabrication.Finally,robotized hybrid printing is utilized to successfully fabricate a conformal heater and antenna on a spherical surface and a flexible smart sensing skin on a winged model,where the curved circuit,flexible capacitive and piezoelectric sensor arrays,and rigid digital–analog conversion chips are assembled.Robotized hybrid printing is an innovative printing technology,enabling additive,noncontact and digital microfabrication for 3D curved electronics.展开更多
The recently developed hard-magnetic soft(HMS)materials manufactured by embedding high-coercivity micro-particles into soft matrices have received considerable attention from researchers in diverse fields,e.g.,soft ro...The recently developed hard-magnetic soft(HMS)materials manufactured by embedding high-coercivity micro-particles into soft matrices have received considerable attention from researchers in diverse fields,e.g.,soft robotics,flexible electronics,and biomedicine.Theoretical investigations on large deformations of HMS structures are significant foundations of their applications.This work is devoted to developing a powerful theoretical tool for modeling and computing the complicated nonplanar deformations of flexible beams.A so-called quaternion beam model is proposed to break the singularity limitation of the existing geometrically exact(GE)beam model.The singularity-free governing equations for the three-dimensional(3D)large deformations of an HMS beam are first derived,and then solved with the Galerkin discretization method and the trustregion-dogleg iterative algorithm.The correctness of this new model and the utilized algorithms is verified by comparing the present results with the previous ones.The superiority of a quaternion beam model in calculating the complicated large deformations of a flexible beam is shown through several benchmark examples.It is found that the purpose of the HMS beam deformation is to eliminate the direction deviation between the residual magnetization and the applied magnetic field.The proposed new model and the revealed mechanism are supposed to be useful for guiding the engineering applications of flexible structures.展开更多
Epsilon-near-zero(ENZ) materials exhibit great potentials in the practical applications of sensors,electronic skin,and wearable devices,when they own the properties of flexibility and compression.In this work,the silv...Epsilon-near-zero(ENZ) materials exhibit great potentials in the practical applications of sensors,electronic skin,and wearable devices,when they own the properties of flexibility and compression.In this work,the silver nanorods(AgNRs)/carbon fiber felt(CFF) composites with ENZ property from 1 kHz to 1 MHz were achieved by adjusting the content of AgNRs and the compressed elastic deformation.展开更多
The realization of natural and authentic facial expressions in humanoid robots poses a challenging and prominent research domain,encompassing interdisciplinary facets including mechanical design,sensing and actuation ...The realization of natural and authentic facial expressions in humanoid robots poses a challenging and prominent research domain,encompassing interdisciplinary facets including mechanical design,sensing and actuation control,psychology,cognitive science,flexible electronics,artificial intelligence(AI),etc.We have traced the recent developments of humanoid robot heads for facial expressions,discussed major challenges in embodied AI and flexible electronics for facial expression recognition and generation,and highlighted future trends in this field.Developing humanoid robot heads with natural and authentic facial expressions demands collaboration in interdisciplinary fields such as multi-modal sensing,emotional computing,and human-robot interactions(HRIs)to advance the emotional anthropomorphism of humanoid robots,bridging the gap between humanoid robots and human beings and enabling seamless HRIs.展开更多
It is increasingly crucial for flexible electronics to efficiently and reliably peel large-area, ultra-thin flexible films off from rigid substrate serving as substrates of flexible electronics device, especially in i...It is increasingly crucial for flexible electronics to efficiently and reliably peel large-area, ultra-thin flexible films off from rigid substrate serving as substrates of flexible electronics device, especially in industrial production. This paper experimentally investigated the mechanism and technologic characteristics of laser lift-off(LLO) process of ultra-thin(～ 2 μm) polyimide(PI)film. It was found increasingly difficult to obtain desirable ultra-thin PI film by LLO with the decrease of the film thickness. The optimal process parameters were achieved considering laser fluence and accumulated irradiation times(AIT), which were found to be strongly correlative to the thickness of PI film. The process mechanism of LLO of PI film was disclosed that laser ablation of interfacial PI will result in the formation of gas products between the PI and glass substrate, enabling the change of interface microstructures to reduce the interface bond strength. The amount of gas products mainly determines the result of LLO process for ultra-thin PI film, from residual adhesion to wrinkles or cracking. The strategy of multi-scanning based on multiple irradiations of low-energy laser pulses was presented to effectively achieve a reliable LLO process of ultra-thin PI film. This study provides an attractive route to optimize the LLO process for large-scale production of ultra-thin flexible electronics.展开更多
Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)...Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)and low fabrication cost. Although the world's best PSC successfully achieves a considerable PCE of over 20% within a very limited timeframe after intensive efforts, the stability, high cost, and up-scaling of PSCs still remain issues. Recently, inorganic perovskite material, CsPbBr_3, is emerging as a promising photo-sensitizer with excellent durability and thermal stability, but the efficiency is still embarrassing. In this work, we intend to address these issues by exploiting CsPbBr_3 as light absorber, accompanied by using Cu-phthalocyanine(CuPc) as hole transport material(HTM) and carbon as counter electrode. The optimal device acquires a decent PCE of 6.21%, over 60% higher than those of the HTM-free devices. The systematic characterization and analysis reveal a more effective charge transfer process and a suppressed charge recombination in PSCs after introducing CuPc as hole transfer layer. More importantly, our devices exhibit an outstanding durability and a promising thermal stability, making it rather meaningful in future fabrication and application of PSCs.展开更多
Flexible electronics such as mechanically compliant displays,sensors and solar cells,have important applications in the fields of energy,national defence and biomedicine,etc.Various types of flexible electronics have ...Flexible electronics such as mechanically compliant displays,sensors and solar cells,have important applications in the fields of energy,national defence and biomedicine,etc.Various types of flexible electronics have been proposed or developed by the improvements in structural designs,material properties and device integrations.However,the manufacturing of flexible electronics receives little attention,which limits its mass production and industrialization.The increasing demands on the size,functionality,resolution ratio and reliability of flexible electronics bring several significant challenges in their manufacturing processes.This work aims to report the state-of-art technologies and applications of flexible electronics manufacturing.Three key technologies including electrohydrodynamic direct-writing,flip chip and automatic optical inspection are highlighted.The mechanism and developments of these technologies are discussed in detail.Based on these technologies,the present work develops three kinds of manufacturing equipment,i.e.,inkjet printing manufacturing equipment,robotized additive manufacturing equipment,and roll-to-roll manufacturing equipment.The advanced manufacturing processes,equipment and systems for flexible electronics pave the way for applications of new displays,smart sensing skins and epidermal electronics,etc.By reviewing the developments of flexible electronics manufacturing technology and equipment,it can be found that the existing advances greatly promote the applications and commercialization of flexible electronics.Since flexible electronics manufacturing contains many multi-disciplinary problems,the current investigations are confronted with great challenges.Therefore,further developments of the reviewed manufacturing technology and equipment are necessary to break the current limitations of manufacturing resolution,efficiency and reliability.展开更多
Inorganic-based micro light-emitting diodes (microLEDs) offer more fascinating properties and unique demands in next-generation displays. However, the small size of the microLED chip (1–100 µm) makes it extremel...Inorganic-based micro light-emitting diodes (microLEDs) offer more fascinating properties and unique demands in next-generation displays. However, the small size of the microLED chip (1–100 µm) makes it extremely challenging for high efficiency and low cost to accurately, selectively, integrate millions of microLED chips. Recent impressive technological advances have overcome the drawbacks of traditional pick-and-place techniques when they were utilized in the assembly of microLED display, including the most broadly recognized laser lift-off technique, contact micro-transfer printing (µTP) technique, laser non-contact µTP technique, and self-assembly technique. Herein, we firstly review the key developments in mass transfer technique and highlight their potential value, covering both the state-of-the-art devices and requirements for mass transfer in the assembly of the ultra-large-area display and virtual reality glasses. We begin with the significant challenges and the brief history of mass transfer technique, and expand that mass transfer technique is composed of two major techniques, namely, the epitaxial Lift-off technique and the pick-and-place technique. The basic concept and transfer effects for each representative epitaxial Lift-off and pick-and-place technique in mass transfer are then overviewed separately. Finally, the potential challenges and future research directions of mass transfer are discussed.展开更多
Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although i...Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although it is well known that ink rheology and processing parameters have a direct impact on the resolution and shape of the printed objects,the underlying mechanisms of these key factors on the printability and quality of DIW technique remain poorly understood.To tackle this issue,we systematically analyzed the printability and quality through extrusion mechanism modeling and experimental validating.Hybrid non-Newtonian fluid inks were first prepared,and their rheological properties were measured.Then,finite element analysis of the whole DIW process was conducted to reveal the flow dynamics of these inks.The obtained optimal process parameters(ink rheology,applied pressure,printing speed,etc)were also validated by experiments where high-resolution(<100μm)patterns were fabricated rapidly(>70 mm s^(-1)).Finally,as a process research demonstration,we printed a series of microstructures and circuit systems with hybrid inks and silver inks,showing the suitability of the printable process parameters.This study provides a strong quantitative illustration of the use of DIW for the high-speed preparation of high-resolution,high-precision samples.展开更多
The conventional electronic systems enabled by rigid electronic are prone to malfunction under deformation,greatly limiting their application prospects.As an emerging platform for applications in healthcare monitoring...The conventional electronic systems enabled by rigid electronic are prone to malfunction under deformation,greatly limiting their application prospects.As an emerging platform for applications in healthcare monitoring and human-machine interface(HMI),flexible electronics have attracted growing attention due to its remarkable advantages,such as stretchability,flexibility,conformability,and wearing comfort.However,to realize the overall electronic systems,rigid components are also required for functions such as signal acquisition and transmission.Therefore,flexible hybrid electronics(FHE),which simultaneously possesses the desirable flexibility and enables the integration of rigid components for functionality,has been emerging as a promising strategy.This paper reviews the enabling integration techniques for FHE,including technologies for two-dimensional/three-dimensional(2 D/3 D) interconnects,bonding of rigid integrated circuit(IC) chips to soft substrate,stress-isolation structures,and representative applications of FHE.In addition,future challenges and opportunities involved in FHE-based systems are also discussed.展开更多
Multi-material 3D fabrication at the nanoscale has been a long-sought goal in additive manufacturing,with great potential for the direct construction of functional micro/nanosystems rather than just arbitrary 3D struc...Multi-material 3D fabrication at the nanoscale has been a long-sought goal in additive manufacturing,with great potential for the direct construction of functional micro/nanosystems rather than just arbitrary 3D structures.To achieve this goal,researchers have introduced several nanoscale 3D printing principles,explored various multi-material switching and combination strategies,and demonstrated their potential applications in 3D integrated circuits,optoelectronics,biological devices,micro/nanorobots,etc.Although some progress has been made,it is still at the primary stage,and a serious breakthrough is needed to directly construct functional micro/nano systems.In this perspective,the development,current status and prospects of multi-material 3D nanoprinting are presented.We envision that this 3D printing will unlock innovative solutions and make significant contributions to various technologies and industries in the near future.展开更多
This paper reports on an efficient fabrication process for a polymeric cantilever covered with conductive nano silver. The entire structure can be constructed additively using a printing process, without the use of an...This paper reports on an efficient fabrication process for a polymeric cantilever covered with conductive nano silver. The entire structure can be constructed additively using a printing process, without the use of an etching process or a sacrificial layer. The fabricated cantilever exhibits good linearity and forms a submillimeter-ordered air gap between itself and the substrate surface. Fine operation of a capacitive force gauge was obtained using the capacitance between the conductive cantilever and an electrode on the substrate. This process is expected to make possible the efficient manufacturing of various types of sensors that measure mechanical strain in a cantilever structure.展开更多
Solution-processed organic field-effect transistors(OFETs)are of great interest in both academia and industry because of the potential to reduce the production cost.However,the performance of these devices can be adve...Solution-processed organic field-effect transistors(OFETs)are of great interest in both academia and industry because of the potential to reduce the production cost.However,the performance of these devices can be adversely affected by the interfacial incompatibility between solution-deposited electrodes and organic semiconductors in comparison with conventional methods.To address this critical challenge,we developed all-solution processed OFETs with low contact resistance by utilizing a multifunctional buffer layer inserted on different commercial p-type semiconductors.The buffer layer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is designed to effectively reduce the large Schottky barriers at the Ag/semiconductor interfaces.PEDOT:PSS also offers the function of proper affinity with Ag,resulting in the formation of hybrid PEDOT:PSS/Ag electrode patterns.High-performance poly[2,5-bis(alkyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-5,5′-di(thiophen-2-yl)-2,2′-(E)-2-(2-(thiophen-2-yl)vinyl)thiophene](PDVT-10)OFET including low contact resistance of 789Ωcm,high average mobility of 10.5 cm^(2)V^(−1)s^(−1),exceptional operational and bending stability,and a substantial enhancement in performance were realized compared to conventional methods.A pseudo-complementary inverter based on the fully solution-based and buffer layer approach was further developed,showing a voltage gain>260.Our approach can potentially overcome the device performance limitation and advance the development of low-cost,large-scale,flexible all-solution-processed OFETs.展开更多
Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological signal.The paper presents an analytical approac...Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological signal.The paper presents an analytical approach to study interfacial mechanics of the 2D planar EEDs on the checkerboard buckling patterns of human skin.Energy variation method is proposed to determine a criterion whether EEDs laminate conformally onto the skin surface under undeformed and stretched cases.EEDs with low bending stiffness(thin,soft devices/backing layer),smooth and soft skin,and strong adhesion promote conformal contact.Furthermore,the adhesion energy at the EED/skin interface is measured by the homemade peeling experiment platform with different substrate thicknesses and areal coverages.The upper limit of the areal coverage for EED conformal contact with the skin is proposed with given EED/skin properties.Conformability of EEDs are validated by experiments with different substrate thickness,areal coverage and external loadings.It provides a design guideline for EED to conformally contact with the skin surface for more accurate biological signal monitoring.展开更多
The optically transparent antenna is becoming a very attractive proposition for various applications, such as wearable devices and vehicle radars. The fabrication of transparent flexible/conformal antennas is a long-l...The optically transparent antenna is becoming a very attractive proposition for various applications, such as wearable devices and vehicle radars. The fabrication of transparent flexible/conformal antennas is a long-lasting interest in academia and industry.However, the preparation of radio-frequency radiators with excellent conductivity and optical transmittance is still quite challenging. Herein, we introduce a facile approach to directly fabricate optically transparent flexible and conformal coplanar waveguide-fed antennas using programmable electrohydrodynamic lithography. Metallic meshes with transmittance above 90%have been successfully created based on the conformal electrohydrodynamic printing of high-viscosity photoresist masks, and the corresponding sheet resistance can be tuned down to ~2 Ω/□. Then, the geometrical structure of the proposed transparent antenna has been systematically optimized because of the basic radio frequency components, including the radiator, feeder line,ground plane, and size of metallic meshes. Optically transparent flexible and conformal antennas are finally obtained, presenting an optical transmittance of 92% and 55%, respectively. The simulated and measured results demonstrate that the transparent antennas with a good optoelectronic performance indeed exhibit a nice electromagnetic behavior. We believe that this newly developed conformal electrohydrodynamic lithography method can be utilized to fabricate a variety of other transparent electronic devices, such as transparent electromagnetic shielding meshes on aircraft canopies, in the future.展开更多
Flexible smart sensing skin is a key enabling technology for the future"Fly-by-Feel"control of morphing aircraft.It represents the next-generation skin of aircraft that can exhibit a more powerful sensing fu...Flexible smart sensing skin is a key enabling technology for the future"Fly-by-Feel"control of morphing aircraft.It represents the next-generation skin of aircraft that can exhibit a more powerful sensing function than a conventional one and could be mounted on arbitrary curvilinear surfaces,especially for advanced autonomic,morphing aircraft.Recent significant technical advances in flexible electronics have overcome many historic drawbacks of conventional smart skin,e.g.,only a limited number of discrete block sensors can be integrated due to the inevitable structural damage and heavy guidelines.Herein,we review the key developments in flexible sensors technology and highlight both the state-of-the-art devices and the potential applications for the measurement of aircraft.We begin with the importance of flexible smart skin for morphing aircraft and then expand to the latest progress in various types of flexible sensors.Then we highlight flexible sensors as smart skin to measure aerodynamic parameters and monitor the structural health,and further to achieve the Fly-by-Feel control.Finally,the challenges and opportunities on flexible smart sensing skin are discussed,from the functional design to practical applications.展开更多
The internal availability of silent speech serves as a translator for people with aphasia and keeps human–machine/human interactions working under various disturbances.This paper develops a silent speech strategy to ...The internal availability of silent speech serves as a translator for people with aphasia and keeps human–machine/human interactions working under various disturbances.This paper develops a silent speech strategy to achieve all-weather,natural interactions.The strategy requires few usage specialized skills like sign language but accurately transfers high-capacity information in complicated and changeable daily environments.In the strategy,the tattoo-like electronics imperceptibly attached on facial skin record high-quality bio-data of various silent speech,and the machine-learning algorithm deployed on the cloud recognizes accurately the silent speech and reduces the weight of the wireless acquisition module.A series of experiments show that the silent speech recognition system(SSRS)can enduringly comply with large deformation(~45%)of faces by virtue of the electricitypreferred tattoo-like electrodes and recognize up to 110 words covering daily vocabularies with a high average accuracy of 92.64%simply by use of small-sample machine learning.We successfully apply the SSRS to 1-day routine life,including daily greeting,running,dining,manipulating industrial robots in deafening noise,and expressing in darkness,which shows great promotion in real-world applications.展开更多
The facial expressions are a mirror of the elusive emotion hidden in the mind,and thus,capturing expressions is a crucial way of merging the inward world and virtual world.However,typical facial expression recognition...The facial expressions are a mirror of the elusive emotion hidden in the mind,and thus,capturing expressions is a crucial way of merging the inward world and virtual world.However,typical facial expression recognition(FER)systems are restricted by environments where faces must be clearly seen for computer vision,or rigid devices that are not suitable for the time-dynamic,curvilinear faces.Here,we present a robust,highly wearable FER system that is based on deep-learning-assisted,soft epidermal electronics.The epidermal electronics that can fully conform on faces enable high-fidelity biosignal acquisition without hindering spontaneous facial expressions,releasing the constraint of movement,space,and light.The deep learning method can significantly enhance the recognition accuracy of facial expression types and intensities based on a small sample.The proposed wearable FER system is superior for wide applicability and high accuracy.The FER system is suitable for the individual and shows essential robustness to different light,occlusion,and various face poses.It is totally different from but complementary to the computer vision technology that is merely suitable for simultaneous FER of multiple individuals in a specific place.This wearable FER system is successfully applied to human-avatar emotion interaction and verbal communication disambiguation in a real-life environment,enabling promising human-computer interaction applications.展开更多
基金financially supported by the National Key R&D Program of China (No.2021YFB3200700)the National Natural Science Foundation of China (Nos.52205593 and 51925503)Xplorer Prize (2020-1036)。
文摘Flexible high-temperature electronics is a compliant form of high-temperature electronics to expand the application areas of conventional flexible one.In aerospace applications,electronic devices are not only required to be deformable but also to be able to withstand extreme temperatures.The disadvantages of current flexible electronics,such as high cost,large differences between components,and even requiring independent debugging,are acceptable.
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The authors acknowledge support from the National Nat-ural Science Foundation of China(51635007,51925503,51705179)Natural Science Foundation of Hubei Province of China(2020CFA028).
文摘Large,3D curved electronics are a trend of the microelectronic industry due to their unique ability to conformally coexist with complex surfaces while retaining the electronic functions of 2D planar integrated circuit technologies.However,these curved electronics present great challenges to the fabrication processes.Here,we propose a reconfigurable,mask-free,conformal fabrication strategy with a robot-like system,called robotized‘transfer-and-jet’printing,to assemble diverse electronic devices on complex surfaces.This novel method is a ground-breaking advance with the unique capability to integrate rigid chips,flexible electronics,and conformal circuits on complex surfaces.Critically,each process,including transfer printing,inkjet printing,and plasma treating,are mask-free,digitalized,and programmable.The robotization techniques,including measurement,surface reconstruction and localization,and path programming,break through the fundamental constraints of 2D planar microfabrication in the context of geometric shape and size.The transfer printing begins with the laser lift-off of rigid chips or flexible electronics from donor substrates,which are then transferred onto a curved surface via a dexterous robotic palm.Then the robotic electrohydrodynamic printing directly writes submicrometer structures on the curved surface.Their permutation and combination allow versatile conformal microfabrication.Finally,robotized hybrid printing is utilized to successfully fabricate a conformal heater and antenna on a spherical surface and a flexible smart sensing skin on a winged model,where the curved circuit,flexible capacitive and piezoelectric sensor arrays,and rigid digital–analog conversion chips are assembled.Robotized hybrid printing is an innovative printing technology,enabling additive,noncontact and digital microfabrication for 3D curved electronics.
基金Project supported by the National Key Research and Development Program of China(No.2018YFA0703200)the National Natural Science Foundation of China(Nos.52205594 and51820105008)+1 种基金the China National Postdoctoral Program for Innovative Talents(No.BX20220118)the China Postdoctoral Science Foundation(No.2021M701306)。
文摘The recently developed hard-magnetic soft(HMS)materials manufactured by embedding high-coercivity micro-particles into soft matrices have received considerable attention from researchers in diverse fields,e.g.,soft robotics,flexible electronics,and biomedicine.Theoretical investigations on large deformations of HMS structures are significant foundations of their applications.This work is devoted to developing a powerful theoretical tool for modeling and computing the complicated nonplanar deformations of flexible beams.A so-called quaternion beam model is proposed to break the singularity limitation of the existing geometrically exact(GE)beam model.The singularity-free governing equations for the three-dimensional(3D)large deformations of an HMS beam are first derived,and then solved with the Galerkin discretization method and the trustregion-dogleg iterative algorithm.The correctness of this new model and the utilized algorithms is verified by comparing the present results with the previous ones.The superiority of a quaternion beam model in calculating the complicated large deformations of a flexible beam is shown through several benchmark examples.It is found that the purpose of the HMS beam deformation is to eliminate the direction deviation between the residual magnetization and the applied magnetic field.The proposed new model and the revealed mechanism are supposed to be useful for guiding the engineering applications of flexible structures.
基金financially supported by the National Natural Science Foundation of China (Nos. 51871146, 52271182 and 52105575)the Natural Science Foundation of Shanghai (No. 22ZR1426800)+1 种基金the Young Elite Scientist Sponsorship Program by China Association for Science and Technology (No. YESS20200257)the Innovation Program of Shanghai Municipal Education Commission (No. 2019-01-07-00-10-E00053)。
文摘Epsilon-near-zero(ENZ) materials exhibit great potentials in the practical applications of sensors,electronic skin,and wearable devices,when they own the properties of flexibility and compression.In this work,the silver nanorods(AgNRs)/carbon fiber felt(CFF) composites with ENZ property from 1 kHz to 1 MHz were achieved by adjusting the content of AgNRs and the compressed elastic deformation.
基金supported by the National Natural Science Foundation of China(nos.52188102 and 51925503)the Science and Technology Development Fund of Macao SAR(file na.0117/2024/AMJ)+1 种基金Zhuhai UM Science&Technology Research Institute(CP-009-2024)the State Key Laboratory of Intelligent Manufacturing Equipment and Tech-nology(IMETKF2024003),HUST,Wuhan,China.
文摘The realization of natural and authentic facial expressions in humanoid robots poses a challenging and prominent research domain,encompassing interdisciplinary facets including mechanical design,sensing and actuation control,psychology,cognitive science,flexible electronics,artificial intelligence(AI),etc.We have traced the recent developments of humanoid robot heads for facial expressions,discussed major challenges in embodied AI and flexible electronics for facial expression recognition and generation,and highlighted future trends in this field.Developing humanoid robot heads with natural and authentic facial expressions demands collaboration in interdisciplinary fields such as multi-modal sensing,emotional computing,and human-robot interactions(HRIs)to advance the emotional anthropomorphism of humanoid robots,bridging the gap between humanoid robots and human beings and enabling seamless HRIs.
基金the National Natural Science Foundation of China(Grant Nos.51635007&51705180)Hubei Province Technology Innovation Special Projects(2017AAA002)
文摘It is increasingly crucial for flexible electronics to efficiently and reliably peel large-area, ultra-thin flexible films off from rigid substrate serving as substrates of flexible electronics device, especially in industrial production. This paper experimentally investigated the mechanism and technologic characteristics of laser lift-off(LLO) process of ultra-thin(～ 2 μm) polyimide(PI)film. It was found increasingly difficult to obtain desirable ultra-thin PI film by LLO with the decrease of the film thickness. The optimal process parameters were achieved considering laser fluence and accumulated irradiation times(AIT), which were found to be strongly correlative to the thickness of PI film. The process mechanism of LLO of PI film was disclosed that laser ablation of interfacial PI will result in the formation of gas products between the PI and glass substrate, enabling the change of interface microstructures to reduce the interface bond strength. The amount of gas products mainly determines the result of LLO process for ultra-thin PI film, from residual adhesion to wrinkles or cracking. The strategy of multi-scanning based on multiple irradiations of low-energy laser pulses was presented to effectively achieve a reliable LLO process of ultra-thin PI film. This study provides an attractive route to optimize the LLO process for large-scale production of ultra-thin flexible electronics.
基金the financial support from the National Natural Science Foundation of China (Grant Nos. 51675210 and 51675209)the China Postdoctoral Science Foundation (Grant No. 2016M602283)
文摘Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)and low fabrication cost. Although the world's best PSC successfully achieves a considerable PCE of over 20% within a very limited timeframe after intensive efforts, the stability, high cost, and up-scaling of PSCs still remain issues. Recently, inorganic perovskite material, CsPbBr_3, is emerging as a promising photo-sensitizer with excellent durability and thermal stability, but the efficiency is still embarrassing. In this work, we intend to address these issues by exploiting CsPbBr_3 as light absorber, accompanied by using Cu-phthalocyanine(CuPc) as hole transport material(HTM) and carbon as counter electrode. The optimal device acquires a decent PCE of 6.21%, over 60% higher than those of the HTM-free devices. The systematic characterization and analysis reveal a more effective charge transfer process and a suppressed charge recombination in PSCs after introducing CuPc as hole transfer layer. More importantly, our devices exhibit an outstanding durability and a promising thermal stability, making it rather meaningful in future fabrication and application of PSCs.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0703200)the National Natural Science Foundation of China(Grant Nos.51820105008 and 52188102)。
文摘Flexible electronics such as mechanically compliant displays,sensors and solar cells,have important applications in the fields of energy,national defence and biomedicine,etc.Various types of flexible electronics have been proposed or developed by the improvements in structural designs,material properties and device integrations.However,the manufacturing of flexible electronics receives little attention,which limits its mass production and industrialization.The increasing demands on the size,functionality,resolution ratio and reliability of flexible electronics bring several significant challenges in their manufacturing processes.This work aims to report the state-of-art technologies and applications of flexible electronics manufacturing.Three key technologies including electrohydrodynamic direct-writing,flip chip and automatic optical inspection are highlighted.The mechanism and developments of these technologies are discussed in detail.Based on these technologies,the present work develops three kinds of manufacturing equipment,i.e.,inkjet printing manufacturing equipment,robotized additive manufacturing equipment,and roll-to-roll manufacturing equipment.The advanced manufacturing processes,equipment and systems for flexible electronics pave the way for applications of new displays,smart sensing skins and epidermal electronics,etc.By reviewing the developments of flexible electronics manufacturing technology and equipment,it can be found that the existing advances greatly promote the applications and commercialization of flexible electronics.Since flexible electronics manufacturing contains many multi-disciplinary problems,the current investigations are confronted with great challenges.Therefore,further developments of the reviewed manufacturing technology and equipment are necessary to break the current limitations of manufacturing resolution,efficiency and reliability.
文摘Inorganic-based micro light-emitting diodes (microLEDs) offer more fascinating properties and unique demands in next-generation displays. However, the small size of the microLED chip (1–100 µm) makes it extremely challenging for high efficiency and low cost to accurately, selectively, integrate millions of microLED chips. Recent impressive technological advances have overcome the drawbacks of traditional pick-and-place techniques when they were utilized in the assembly of microLED display, including the most broadly recognized laser lift-off technique, contact micro-transfer printing (µTP) technique, laser non-contact µTP technique, and self-assembly technique. Herein, we firstly review the key developments in mass transfer technique and highlight their potential value, covering both the state-of-the-art devices and requirements for mass transfer in the assembly of the ultra-large-area display and virtual reality glasses. We begin with the significant challenges and the brief history of mass transfer technique, and expand that mass transfer technique is composed of two major techniques, namely, the epitaxial Lift-off technique and the pick-and-place technique. The basic concept and transfer effects for each representative epitaxial Lift-off and pick-and-place technique in mass transfer are then overviewed separately. Finally, the potential challenges and future research directions of mass transfer are discussed.
基金supported by National Natural Science Foundation of China(Nos.52188102,U2013213,51820105008)the Technology Innovation Project of Hubei Province of China under Grant No.2019AEA171+1 种基金The project of introducing innovative leading talents in Songshan Lake High-tech Zone,Dongguan City,Guangdong Province(No.2019342101RSFJ-G)the support from Flexible Electronics Research Center of HUST for providing experiment facility。
文摘Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although it is well known that ink rheology and processing parameters have a direct impact on the resolution and shape of the printed objects,the underlying mechanisms of these key factors on the printability and quality of DIW technique remain poorly understood.To tackle this issue,we systematically analyzed the printability and quality through extrusion mechanism modeling and experimental validating.Hybrid non-Newtonian fluid inks were first prepared,and their rheological properties were measured.Then,finite element analysis of the whole DIW process was conducted to reveal the flow dynamics of these inks.The obtained optimal process parameters(ink rheology,applied pressure,printing speed,etc)were also validated by experiments where high-resolution(<100μm)patterns were fabricated rapidly(>70 mm s^(-1)).Finally,as a process research demonstration,we printed a series of microstructures and circuit systems with hybrid inks and silver inks,showing the suitability of the printable process parameters.This study provides a strong quantitative illustration of the use of DIW for the high-speed preparation of high-resolution,high-precision samples.
基金the National Natural Science Foundation of China(Grant Nos.51820105008,U2013213,and 92048302)the Technology Innovation Project of Hubei Province of China(Grant No.2019AEA171)。
文摘The conventional electronic systems enabled by rigid electronic are prone to malfunction under deformation,greatly limiting their application prospects.As an emerging platform for applications in healthcare monitoring and human-machine interface(HMI),flexible electronics have attracted growing attention due to its remarkable advantages,such as stretchability,flexibility,conformability,and wearing comfort.However,to realize the overall electronic systems,rigid components are also required for functions such as signal acquisition and transmission.Therefore,flexible hybrid electronics(FHE),which simultaneously possesses the desirable flexibility and enables the integration of rigid components for functionality,has been emerging as a promising strategy.This paper reviews the enabling integration techniques for FHE,including technologies for two-dimensional/three-dimensional(2 D/3 D) interconnects,bonding of rigid integrated circuit(IC) chips to soft substrate,stress-isolation structures,and representative applications of FHE.In addition,future challenges and opportunities involved in FHE-based systems are also discussed.
基金financially National Natural Science Foundation of China(Nos.52075209 and 51925503)Natural Science Foundation for Distinguished Young Scholars of Hubei province of China(No.2022CFA066)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2021QNRC001)。
文摘Multi-material 3D fabrication at the nanoscale has been a long-sought goal in additive manufacturing,with great potential for the direct construction of functional micro/nanosystems rather than just arbitrary 3D structures.To achieve this goal,researchers have introduced several nanoscale 3D printing principles,explored various multi-material switching and combination strategies,and demonstrated their potential applications in 3D integrated circuits,optoelectronics,biological devices,micro/nanorobots,etc.Although some progress has been made,it is still at the primary stage,and a serious breakthrough is needed to directly construct functional micro/nano systems.In this perspective,the development,current status and prospects of multi-material 3D nanoprinting are presented.We envision that this 3D printing will unlock innovative solutions and make significant contributions to various technologies and industries in the near future.
文摘This paper reports on an efficient fabrication process for a polymeric cantilever covered with conductive nano silver. The entire structure can be constructed additively using a printing process, without the use of an etching process or a sacrificial layer. The fabricated cantilever exhibits good linearity and forms a submillimeter-ordered air gap between itself and the substrate surface. Fine operation of a capacitive force gauge was obtained using the capacitance between the conductive cantilever and an electrode on the substrate. This process is expected to make possible the efficient manufacturing of various types of sensors that measure mechanical strain in a cantilever structure.
基金supported by the Ministry of Science and Technology of China through the National Key R&D Plan(2022YFA1205900)the Chinese Academy of Sciences(Hundred Talents Plan,Youth Innovation Promotion Association)+2 种基金the Strategic Priority Research Program of Sciences(XDB0520201)the Young Scientists in Basic Research(YSBR-053)the National Natural Science Foundation of China(T2225028,22475219,U22A6002,and U21A20497).
文摘Solution-processed organic field-effect transistors(OFETs)are of great interest in both academia and industry because of the potential to reduce the production cost.However,the performance of these devices can be adversely affected by the interfacial incompatibility between solution-deposited electrodes and organic semiconductors in comparison with conventional methods.To address this critical challenge,we developed all-solution processed OFETs with low contact resistance by utilizing a multifunctional buffer layer inserted on different commercial p-type semiconductors.The buffer layer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is designed to effectively reduce the large Schottky barriers at the Ag/semiconductor interfaces.PEDOT:PSS also offers the function of proper affinity with Ag,resulting in the formation of hybrid PEDOT:PSS/Ag electrode patterns.High-performance poly[2,5-bis(alkyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-5,5′-di(thiophen-2-yl)-2,2′-(E)-2-(2-(thiophen-2-yl)vinyl)thiophene](PDVT-10)OFET including low contact resistance of 789Ωcm,high average mobility of 10.5 cm^(2)V^(−1)s^(−1),exceptional operational and bending stability,and a substantial enhancement in performance were realized compared to conventional methods.A pseudo-complementary inverter based on the fully solution-based and buffer layer approach was further developed,showing a voltage gain>260.Our approach can potentially overcome the device performance limitation and advance the development of low-cost,large-scale,flexible all-solution-processed OFETs.
文摘Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological signal.The paper presents an analytical approach to study interfacial mechanics of the 2D planar EEDs on the checkerboard buckling patterns of human skin.Energy variation method is proposed to determine a criterion whether EEDs laminate conformally onto the skin surface under undeformed and stretched cases.EEDs with low bending stiffness(thin,soft devices/backing layer),smooth and soft skin,and strong adhesion promote conformal contact.Furthermore,the adhesion energy at the EED/skin interface is measured by the homemade peeling experiment platform with different substrate thicknesses and areal coverages.The upper limit of the areal coverage for EED conformal contact with the skin is proposed with given EED/skin properties.Conformability of EEDs are validated by experiments with different substrate thickness,areal coverage and external loadings.It provides a design guideline for EED to conformally contact with the skin surface for more accurate biological signal monitoring.
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFB3200703)the National Natural Science Foundation of China (Grant Nos. 52175537, 51975235, and52188102)。
文摘The optically transparent antenna is becoming a very attractive proposition for various applications, such as wearable devices and vehicle radars. The fabrication of transparent flexible/conformal antennas is a long-lasting interest in academia and industry.However, the preparation of radio-frequency radiators with excellent conductivity and optical transmittance is still quite challenging. Herein, we introduce a facile approach to directly fabricate optically transparent flexible and conformal coplanar waveguide-fed antennas using programmable electrohydrodynamic lithography. Metallic meshes with transmittance above 90%have been successfully created based on the conformal electrohydrodynamic printing of high-viscosity photoresist masks, and the corresponding sheet resistance can be tuned down to ~2 Ω/□. Then, the geometrical structure of the proposed transparent antenna has been systematically optimized because of the basic radio frequency components, including the radiator, feeder line,ground plane, and size of metallic meshes. Optically transparent flexible and conformal antennas are finally obtained, presenting an optical transmittance of 92% and 55%, respectively. The simulated and measured results demonstrate that the transparent antennas with a good optoelectronic performance indeed exhibit a nice electromagnetic behavior. We believe that this newly developed conformal electrohydrodynamic lithography method can be utilized to fabricate a variety of other transparent electronic devices, such as transparent electromagnetic shielding meshes on aircraft canopies, in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.51925503 and 51635007)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Program for HUST Academic Frontier Youth Team。
文摘Flexible smart sensing skin is a key enabling technology for the future"Fly-by-Feel"control of morphing aircraft.It represents the next-generation skin of aircraft that can exhibit a more powerful sensing function than a conventional one and could be mounted on arbitrary curvilinear surfaces,especially for advanced autonomic,morphing aircraft.Recent significant technical advances in flexible electronics have overcome many historic drawbacks of conventional smart skin,e.g.,only a limited number of discrete block sensors can be integrated due to the inevitable structural damage and heavy guidelines.Herein,we review the key developments in flexible sensors technology and highlight both the state-of-the-art devices and the potential applications for the measurement of aircraft.We begin with the importance of flexible smart skin for morphing aircraft and then expand to the latest progress in various types of flexible sensors.Then we highlight flexible sensors as smart skin to measure aerodynamic parameters and monitor the structural health,and further to achieve the Fly-by-Feel control.Finally,the challenges and opportunities on flexible smart sensing skin are discussed,from the functional design to practical applications.
基金supported by the National Natural Science Foundation of China(grant nos.51925503,U1713218)the Program for HUST Academic Frontier Youth Team.
文摘The internal availability of silent speech serves as a translator for people with aphasia and keeps human–machine/human interactions working under various disturbances.This paper develops a silent speech strategy to achieve all-weather,natural interactions.The strategy requires few usage specialized skills like sign language but accurately transfers high-capacity information in complicated and changeable daily environments.In the strategy,the tattoo-like electronics imperceptibly attached on facial skin record high-quality bio-data of various silent speech,and the machine-learning algorithm deployed on the cloud recognizes accurately the silent speech and reduces the weight of the wireless acquisition module.A series of experiments show that the silent speech recognition system(SSRS)can enduringly comply with large deformation(~45%)of faces by virtue of the electricitypreferred tattoo-like electrodes and recognize up to 110 words covering daily vocabularies with a high average accuracy of 92.64%simply by use of small-sample machine learning.We successfully apply the SSRS to 1-day routine life,including daily greeting,running,dining,manipulating industrial robots in deafening noise,and expressing in darkness,which shows great promotion in real-world applications.
基金supported by the National Natural Science Foundation of China(grant number 51925503)the Program for HUST Academic Frontier Youth Teamthe HUST“Qihang Fund.”。
文摘The facial expressions are a mirror of the elusive emotion hidden in the mind,and thus,capturing expressions is a crucial way of merging the inward world and virtual world.However,typical facial expression recognition(FER)systems are restricted by environments where faces must be clearly seen for computer vision,or rigid devices that are not suitable for the time-dynamic,curvilinear faces.Here,we present a robust,highly wearable FER system that is based on deep-learning-assisted,soft epidermal electronics.The epidermal electronics that can fully conform on faces enable high-fidelity biosignal acquisition without hindering spontaneous facial expressions,releasing the constraint of movement,space,and light.The deep learning method can significantly enhance the recognition accuracy of facial expression types and intensities based on a small sample.The proposed wearable FER system is superior for wide applicability and high accuracy.The FER system is suitable for the individual and shows essential robustness to different light,occlusion,and various face poses.It is totally different from but complementary to the computer vision technology that is merely suitable for simultaneous FER of multiple individuals in a specific place.This wearable FER system is successfully applied to human-avatar emotion interaction and verbal communication disambiguation in a real-life environment,enabling promising human-computer interaction applications.
