Self-healable, recyclable, ultrastretchable, and high-performanceNO_(2) sensors based on an organohydrogel for room and sub-zero temperature and wireless operation

To date,development of high-performance,stretchable gas sensors operating at and below room temperature(RT)remains a challenge in terms of traditional sensing materials.Herein,we report on a high-performance NO_(2) gas sensor based on a self-healable,recyclable,ultrastretchable,and stable polyvinyl alcohol–cellulose nanofibril double-network organohydrogel,which features ultrahigh sensitivity(372%/ppm),low limit of detection(2.23 ppb),relatively fast response and recovery time(41/144 s for 250 ppb NO_(2)),good selectivity against interfering gases(NH3,CO_(2),ethanol,and acetone),excellent reversibility,repeatability,and long-term stability at RT or even at−20°C.In particular,this sensor shows outstanding stability against large deformations and mechanical damages so that it works normally after rapid self-healing or remolding after undergoing mechanical damage without significant performance degradation,which has major advantages compared to state-of-the-art gas sensors.The high NO_(2) sensitivity and selectivity are attributed to the selective redox reactions at the threephase interface of gas,gel,and electrode,which is even boosted by applying tensile strain.With a specific electrical circuit design,a wireless NO_(2) alarm system based on this sensor is created to enable continuous,real-time,and wireless NO_(2) detection to avoid the risk of exposure to NO_(2) higher than threshold concentrations.

Patternable and transferable silver nanowire conductors via plasma-enhanced cryo-transferring process towards highly stretchable and transparent capacitive touch sensor array

Stretchable transparent electrode(STE)plays a key role in numerous emerging applications as an indispensable component for future stretchable devices.The embedded STE,as a promising candidate,possesses balanced performances and facile preparation procedures.However,it still suffers from the defects of conductive materials caused by the transferring,which results in the irreversible failure of devices.In this work,a patternable silver nanowire(AgNW)STE was fabricated by a plasma-enhanced cryo-transferring(PEC-transferring)process.Owing to the plasma-induced sintering,the AgNW network obtained remarkable improvement in robustness,which ensured the intact network after transferring and thus led to superior tensile electrical properties of the STE.Furthermore,serpentine patterns were utilized to optimize the tensile electrical properties of the STE,which achieved a figure of merit of 292.8 and 150%resistance changing under 50%strain.As a practical application,a 4×3 array of the mutual-capacitive type stretchable touch sensors was demonstrated for future touch sensors in stretchable devices.The PEC-transferring process opened a new avenue for patternable embedded STEs and exhibited its high potential in wearable electronics and the Internet of Thing devices.

基于马兰戈尼效应制备具有周期性褶皱结构的石墨烯薄膜及其在高灵敏应变探测中的应用

石墨烯薄膜中可控的微纳结构,有利于调控其物理性质并拓宽其在柔性电子器件中的应用.近年来,研究人员致力于控制石墨烯薄膜中褶皱、起伏波纹等微纳结构的形成.但是,在石墨烯薄膜中可控地形成有序的褶皱状结构仍然面临巨大挑战.本文报道了一种简单地制备具有周期性平行褶皱结构的石墨烯薄膜的方法,即通过将溶液表面自组装形成的石墨烯薄膜转移至预拉伸的聚二甲基硅氧烷(PDMS)基底上而得到.制备的石墨烯薄膜中,褶皱的宽度可以简单地通过改变基底的预拉伸形变来控制.当PDMS基底预拉伸应变分别为10%、20%和50%时,薄膜中褶皱的平均宽度分别为3.68、2.99和2.01µm.本文还进一步研究和分析了双层堆叠、褶皱状石墨烯薄膜,在拉伸形变时的形貌结构变化.此外,本文基于该褶皱状石墨烯薄膜,构建了应变传感器.该传感器展现出高灵敏度、宽探测范围和优良的循环稳定性,其在实时运动探测、健康监测和电子皮肤等领域有着广阔应用前景.

Self-powered electronic paper with energy supplies and information inputs solely from mechanical motions

The electronic paper(E-paper)displays features such as flexibility,sunlight visibility,and low power consumption,which makes it ideal for Internet of Things(IoT)applications where the goal is to eliminate bulky power modules.Here,we report a unique self-powered E-paper(SPEP),where information inputs and energy supplies are all converted from mechanical motion by a triboelectric nanogenerator(TENG).The operation of an electrophoretic E-paper is first investigated,identifying the current density as a determinative parameter for driving pigment particle motion and color change.Electrical and optical responses of the E-paper driven by a slidingmode TENG are then found to be consistent with that under a current source mode.All-in-one monochromic and chromatic SPEPs integrated with a flexible transparent TENG are finally demonstrated,and a pixelated SPEP is discussed for future research.The sliding-driven mechanism of SPEP allows for a potential handwriting function,is free of an extra power supply,and promises undoubtedly a wide range of future applications.

One-step plasmonic welding and photolithographic patterning of silver nanowire network by UV-programable surface atom diffusion

Silver nanowire(AgNW)based transparent electrode(TE)plays a pivotal role in optoelectronics where TE is generally required to have fine pattern and high performance.Despite the rapid technological advances in either welding or patterning of AgNWs,there are few studies that combine the two processes in a simple and practical manner.Here,aiming to fabricate high-performance patterned AgNW TE,we develop a simplified photolithography that enables both plasmonic nanowelding with low-level UV exposure(20 mW/cm^(2))and high-resolution micropatterning without photoresist and etching process by conjugating AgNW with diphenyliodonium nitrate(DPIN)and UV-curable cellulose.The cellulose as a binder can effectively enhance plasmonic heating,adhesion,and stability,while the photosensitive DPIN,capable of modulating surface atom diffusion,can boost the plasmonic welding at AgNW junction and induce patterning in AgNW network with Plateau-Rayleigh instability.The fabricated AgNW TE has high figure of merit of up to 1,000(3.7Ω/sq at 90%transmittance)and minimal pattern size down to 3µm,along with superior robustness.Finally,a flexible smart window with high performance is demonstrated using the patterned and welded AgNW TEs,verifying the applicability of the simplified photolithography technique to optoelectronic devices.

Direct stamping multifunctional tactile sensor for pressure and temperature sensing

Flexible and wearable sensors have broad application prospects in health monitoring and artificial intelligence.Many different single-functional sensing devices have been developed in recent years,such as pressure sensors and temperature sensors.However,it is still a great challenge to design and fabricate tactile sensors with multiple sensing functions.Herein,we propose a simple direct stamping method for the fabrication of multifunctional tactile sensors.It can detect pressure and temperature stimuli signals simultaneously.This pressure/temperature sensor possesses high sensitivity(0.67 kPa^(-1)),large linear range(0.75-5 kPa),and fast response speed(15.6 ms)in pressure sensing.It also has a high temperature sensitivity(1.41%/℃)and great linearity(0.99)for temperature sensing in the range of-30 to 30℃.All these excellent performances indicate that this pressure/temperature sensor has great potential in applications for artificial intelligence and health monitoring.

Self-assembled monolayer modulated Plateau-Rayleigh instability and enhanced chemical stability of silver nanowire for invisibly patterned,stable transparent electrodes

Patterned silver nanowire(AgNW)networks have been widely used as transparent electrodes in many optoelectrical devices.However,obvious patterning visibility and poor thermostability of AgNW are still limiting its practical application.Herein,we report self-assembled monolayer(SAM)modulated Plateau-Rayleigh instability(PRI)of AgNW,which allows invisible patterning and superior stability of the AgNW network.Two opposite effects of different SAMs on the PRI are identified:the alkanethiol SAMs activate surface atom diffusion while the mercaptobenzoheterocyclic(MBH)SAMs suppress the diffusion.The degradation temperature of the AgNWs can be therefore,for the first time,tuned in the range of 193-381℃,so that the AgNW network can be patterned via PRI with a tiny optical difference between the insulative and conductive regions,i.e.,patterning invisible.Besides,the MBH SAMs provide AgNW with excellent durability under thermal annealing and oxidation,which enhances the maximum heating temperature of the AgNW transparent heater by over 120℃.Beyond the micro-patterning,we consider that the developed SAM strategy can be extended to other metal nanowires for stability improvement and has huge potential in nanoengineering of one-dimensional metal materials.

Actively logical modulation of MEMS-based terahertz metamaterial

The integration of micro-electro-mechanical system (MEMS) with metamaterial has provided a novel route to achieve programmability via its reconfigurable capabilities. Here,we propose and demonstrate a MEMS-based metadevice by using switchable winding-shaped cantilever metamaterial (WCM) for active logical modulation.WCM can be actuated by external driving voltage,and the logical modulation bit is performed by releasing MEMS cantilevers to represent "on" and "off" states. While the underneath substrate surface of a MEMS-based metadevice is rough after releasing the cantilevers,the metadevice is allowed to operate on the reconfigurable switching state and avoid the snapping down of the device when the system is overloaded. Such a reconfigurable and programmable MEMS-based metadevice exhibits multifunctional characteristics to simultaneously perform the logic operations of "OR" and "AND" gates. By exploiting the tuning mechanism of the MEMS-based metadevice,the arbitrary metamaterial configuration can be implanted into WCM. This opens a wide avenue to further enlarge the operating frequency range and applications in optoelectronic fields. These unique results provide various possibilities in multifunctional switching,active logical modulating,and optical computing applications.