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Electronics today has evolved significantly, including its application in transparent and flexible devices. Flexible electronics offers new product concepts, including low production cost, low energy consumption, and sustainable and environmentally friendly materials. This concept leads to the development of novel materials that realize today's requirements. Incorporating optically transparent and flexible thin-film-based devices into the electronic circuitry helps in maintaining high conductivity along with achieving the similar electronic behavior of the conventional electronic gadgets. Thin-film diodes (TFDs) and thin-film transistors (TFTs) are the core materials to be incorporated as building blocks for flexible devices. Among them, oxide-based thin films have been marked to be significant because of their efficient electrical performance, low temperature processing, and device flexibility. The present article reviews the concepts and application of zinc oxide (ZnO) as the semiconducting material for flexible thin-film devices. We also review flexible and transparent TFDs and TFTs that are based prominently on ZnO as the semiconducting material. Furthermore, the present issues have also been addressed. [ABSTRACT FROM AUTHOR]

Polyvinylidene difluoride trifluoroethylene (PVDF-TrFE) has received widespread application in flexible electronics and biomedical devices but is limited in its sensing modalities to piezoelectricity and pyroelectricity. The addition of optically or magnetically active nanoparticles could provide additional sensing modalities in the same element, which could drive miniaturization of such sensors. Europium barium titanate (EBTO) is one such optically active nanoparticle that could add functionality to such a nanocomposite. In this work, multifunctional nanocomposites of PVDF-TrFE and EBTO are successfully synthesized and characterized for their material and electronic properties. The nanocomposite in this work is the first known multifunctional nanocomposite with PVDF-TrFE and a fluorescent nanoparticle. [ABSTRACT FROM AUTHOR]

Conjugated polymer-based organic/inorganic hybrid materials become the current research frontier and show great potential to integrate flexible polymers and rigid solid materials, which have been widely used in the field of various flexible electronics and optical devices. In this study, based on the multiple vapor phase infiltration (VPI) process, various precursor molecules (diethylzinc DEZ, trimethylaluminum TMA, H2O) are applied for the in situ modification of PBTTT-C14 films. The conductivity of the PBTTT-C14/Al2O3:ZnO (AZO) film is significantly enhanced, and the maximum value of conductivity is 1.16 S cm−1, which is eight orders of magnitude higher than the undoped PBTTT-C14 thin film. Here, the change of morphologies and crystalline states are analyzed via SEM, AFM, and XRD. And the chemical changes during the VPI process of PBTTT-C14 are characterized through Raman, XPS, and UV–vis. During the AZO VPI process, the formation of new ZnS matrix in the polymer subsurface can generate new additional electron conduction pathways through the crosslinking of polymer chains with inorganic materials, and the addition of Al2O3 can bring about the increase of average grain size of ZnO crystals, which is also benefit to the conductivity increase of PBTTT-C14 thin film. Generally, the synergistic effect between the inorganic and polymer constituents results in the significantly enhancement of the conductivity of PBTTT-C14/AZO thin films. [ABSTRACT FROM AUTHOR]

Transdermal drug delivery (TDD) has gained clinical approval over several decades, with extensive research dedicated to novel drug and device development. Despite notable research progress, the market adoption of TDD devices has not met anticipated levels, with oral administration and injection remaining predominant delivery methods. To maximize the potential of TDD, we identify bottlenecks hindering its widespread clinical application and propose promising research avenues. We begin by analyzing stringent demands necessary to truly benefit patients, addressing significant challenges in biomechanics, nanomedicine, and flexible electronics. Subsequently, we delve into skin anatomy, enhancement strategies, nano-carriers, and their underlining mechanisms, highlighting the importance and framework of quantitative modeling. Based on these discussions, we highlight the core strength of TDD, such as automatic precise administration based on feedback and high delivery efficiencies, especially applicable to localized conditions (e.g., central nervous system diseases, tumors). Finally, we envision the future of intelligent TDD device and its operation scenario, aiming to steer research efforts toward faster translation of laboratory innovations into widely used products for sufferers. [ABSTRACT FROM AUTHOR]

Spreading of liquids on soft solids often occurs intermittently, i.e., the liquid's wetting front switches between sticking and slipping. Studies of this so-called stick-slip wetting on soft solids mostly are confined within quasi-static or forced spreading conditions. In these situations, because the sticking duration is set much larger than the viscoelastic relaxation time of the solid, a ridge is persistently and fully developed at the wetting front as the soft solid yields to the liquid's surface tension. The sticking duration and spreading velocity, therefore, were shown to have little impact to the contact angle change required for stick-to-slip transitions. For unsteady wetting of soft solids, a commonly encountered but largely unexplored situation, we hypothesize that the stick-to-slip transition is controlled not only by a combination of sticking duration and the spreading velocity, but also by an increasing depinning threshold caused by the growing ridge at the wetting front. We performed unsteady wetting experiment on soft solids by letting water droplets spread freely on soft solid surfaces of various stiffness. We capture both the stick-slip spreading behavior and growing wetting ridges using synchronous high-speed imaging and high-speed interferometry. Recorded data of liquid spreading and solid deforming at the wetting front were analyzed to shed light on the relation between stick-slip characteristics and the growing wetting ridge. We find that intermittent wetting on a soft solid surface results from a competition between three key factors: liquid inertia, capillary force change during sticking, and growing pinning force caused by the solid's viscoelastic response. We theoretically formulate their quantitative contributions to predict how stick-to-slip transitions occur, i.e., how the contact angle change and sticking duration depend on the liquid's spreading velocity and the solid's viscoelastic characteristics. This provides a mechanistic understanding and methods to control unsteady wetting phenomena in diverse applications, from tissue engineering and fabrication of flexible electronics to biomedicine. [ABSTRACT FROM AUTHOR]

As the number of wirelessly connected devices continues to grow, dealing with the huge volume of data traffic has become a major challenge. This has led to a greater emphasis on sub-6 GHz applications in 5G, as faster speeds and more extensive services are increasingly necessary to support a wide range of emerging applications. These applications require wireless devices with compact dimensions and highly flexible mechanical properties that can adapt to their environmental needs. To achieve this, flexible polymers offer numerous advantages, including lightweight, low cost, easy processability, and the ability to conform to complex and irregular surfaces, making them ideal for use in wearable devices and other flexible electronics applications. This work provides a thorough analysis of a dual-band microstrip patch antenna, measuring 18 × 27 × 0.3 mm3 for polyimide polymer (PI) and 19.5 × 29.5 × 0.3 mm3 for liquid crystal polymer (LCP). The obtained results obviously depict that the antenna performs better in terms of reflection coefficient (S11) and the realized gain (dBi) at the (2.34–2.56 GHz) and (4.45–5.78 GHz) frequency bands when the substrate is approximately 0.3 mm thick. The antenna also maintains its performance during bending tests. Furthermore, the LCP polymer provides a higher gain of about 3.51 dBi as compared to the polyimide polymer (PI). The results suggest that the proposed antenna is suitable for a wide range of wireless 5G communication devices operating in the sub-6 GHz band. [ABSTRACT FROM AUTHOR]

Recently, cubic perovskite SrTMO 3 (TM = V, Nb, and Mo) compounds have attracted great interest as correlated transparent conducting oxides (CTCOs). However, in theory, none of these three oxides is capable of completely covering the entire visible (Vis) light wavelength range with transparency. Herein, epitaxial orthorhombic CaMoO 3 thin films were grown on flexible mica substrates using a pulsed laser deposition (PLD) method. By exploiting the tilting of MoO 6 octahedra, an optimal balance between plasma energy (ћω p) and electrical conductivity (σ) was realized in CaMoO 3. Electronic transport characterizations indicated that the σ value of CaMoO 3 is comparable to that of SrTMO 3. The optical transmittance spectra demonstrated that the CaMoO 3 film possesses superior Vis transparency compared to SrTMO 3. From the ellipsometry analysis, it was found that the O 2p – V 3d interband transition occurs at around 4.16 eV while the screened plasma energy (ћω p) is approximately 1.37 eV. The favorable absorption edges for both the long and short wavelength regions ensure the high transparency of CaMoO 3 across the entire Vis spectrum. Additionally, bending cyclic tests illustrated the excellent mechanical durability and endurance of the CaMoO 3 /mica films. The present work is instructive for exploring alternative CTCOs beyond SrTMO 3 , demonstrating that the optimal balance between ћω p and σ can be realized by manipulating the TMO 6 octahedral tilting to improve the transparent conducting performance of correlated perovskite-type oxides. [ABSTRACT FROM AUTHOR]

Multi‐functional actuation systems involve the mechanical integration of multiple actuation and sensor devices with external energy sources. The intricate combination makes it difficult to meet the requirements of lightweight. Hence, polypyrrole@graphene‐bacterial cellulose (PPy@G‐BC) films are proposed to construct multi‐responsive and bilayer actuators integrated with multi‐mode self‐powered sensing function. The PPy@G‐BC film not only exhibits good photo‐thermoelectric (PTE) properties but also possesses good hydrophilicity and high Young's modulus. Thus, the PPy@G‐BC films are used as active layers in multi‐responsive bilayer actuators integrated with self‐powered sensing functions. Here, two types of multi‐functional actuators integrated with self‐powered sensing functions is designed. One is a light‐driven actuator that realizes the self‐powered temperature sensing function through the PTE effect. Assisted by a machine learning algorithm, the self‐powered bionic hand can realize intelligent gesture recognition with an accuracy rate of 96.8%. The other is humidity‐driven actuators integrated a zinc‐air battery, which can realize self‐powered humidity sensing. Based on the above advantages, these two multi‐functional actuators are ingeniously integrated into a single device, which can simultaneously perform self‐powered temperature/humidity sensing while grasping objects. The highly integrated design enables the efficient utilization of environmental energy sources and complementary synergistic monitoring of multiple physical properties without increasing system complexity. [ABSTRACT FROM AUTHOR]

Hydrogel‐based flexible solid‐state supercapacitors (SSCs) hold great promise for wearable electronics, yet significant challenges persist in simultaneously achieving excellent mechanical properties, high ionic conductivity, outstanding electrochemical properties, and wide operating temperature ranges. Here, this study presents a straightforward method for synthesizing dual crosslinked polyvinyl alcohol‐polyimide (PVA‐PI) organohydrogels via a simple one‐pot synthesis followed by a freezing‐thawing process. The controlled dual crosslinked networks with significanonetly different crosslinking densities and robust intermolecular hydrogen bonding interactions facilitated by the macromolecular crosslinker of PI, endow the organohydrogels with both high mechanical properties and ionic conductivity. Furthermore, SSCs based on PVA‐PI organohydrogels are fabricated, which can exhibit outstanding electrochemical performance at temperatures ranging from −40 to 80 °C. Specifically, the energy density reaches 16.7 µWh cm−2 even at −40 °C under a power density of 410.0 µW cm−2. These SSCs also show excellent performance stability under various deformations, such as bending and compression, alongside exceptional long‐term cycling stability (over 10 000 cycles) with high capacitance retention from −40 to 50 °C. The synthesis strategy, along with a robust mechanism for enhancing mechanical properties of hydrogels, demonstrated in this study offers insights for the development of strong hydrogels/organohydrogels with broad temperature adaptability for soft electronic applications. [ABSTRACT FROM AUTHOR]

Flexible graphene‐based paper electrodes (FGPEs) are a new class of study and the research on this electrode material has been carried out for approximately ten years. FGPEs have many advantages compared to classical solid electrodes such as being flexible, foldable, adaptable to flexible electronics, being cut, easily shaped, and effective and adjustable modification. In this work, the applicability of FGPEs modified with polyindole (PIN) thin films and zinc oxide nanoparticles (ZnO‐NPs) to energy‐storage systems as a supercapattery design is presented, and especially the limitations of ZnO‐NPs for energy‐storage applications are revealed to inform researchers working for a similar purpose. Capacitance calculations have been performed using both cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD) experiments. It was observed that the rGO/PIN paper demonstrated almost 30 times more energy‐storage capacity than that of the rGO/PIN/ZnO paper due to the electrochemical instability of ZnO‐NPs on the flexible electrode platform at the applied potential region in 1.0 M HClO4 solution. The rGO/PIN paper with a highly flexible property exhibited an energy density of 74.5 W h cm−2 and a power density of 2258 W cm−2 at a current density of 2.2 mA cm−2, revealing hopeful results for future modular and flexible approaches. [ABSTRACT FROM AUTHOR]

This paper describes the design, fabrication, integration, characterization, and demonstration of a novel flexible double-sided curvature sensor array for use in soft robotics. The paper explores the performance and potential applications of a piezoresistive sensor array consisting of four gold strain gauges on a flexible polyimide (PI) substrate arranged in a Wheatstone bridge configuration. Multiple sensor strips were arranged like the fingers of a hand. Integrating Shape Memory Alloy (SMA) foils alongside the fingers was explored to mimic a human hand-gripping motion controlled with temperature, while curvature sensor array strips measure the resulting finger shapes. Moreover, object sensing in a flexible granular material gripper was demonstrated. The sensors were embedded within Polydimethylsiloxane (PDMS) to enhance their tactile feel and adhesive properties. The findings of this study are promising for future applications, particularly in robotics and prosthetics, as the ability to accurately mimic human hand movements and reconstruct sensor surfaces paves the way for robotic hand functionality. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D printing inks into liquid bath anti-solvent forms fibers in designated locations. • Structural and electronic properties are tunable by the anti-solvent. • Coiled carbon nanotube yarns stretch up to 50 % with under 1 % change in resistance. • Printed nanotube yarns have specific conductivity on par with metals. Inspired by methods of wet fiber spinning, we introduce a process using a 3D printer to create dense carbon nanotube (CNT) fibers and extensible coils with metal-like DC specific conductivity. An extrusion-based printer with an immersed nozzle extrudes a homogeneous shear-thinning ink (with initially < 1 % CNT concentration in water) into a liquid bath of antisolvent, inducing immediate precipitation-driven solidification slightly beyond the nozzle tip. This process forms continuous fibers of CNTs with conductivity up to 3 × 105 S/m, exceeding that of dense graphite and approaching that of CNTs spun from similar inks in a continuous fiber spinning process (6 × 105 S/m). The specific conductivity is up to 1 × 103 S m2/kg, comparable with gold (2.3 × 103 S m2/kg). The printing regimes are analyzed, with consideration of the draw ratio imposed during printing. Particular focus is placed on adjusting the speed of counter-diffusion of the ink solvent and the bath liquid, which allows for tuning of fiber diameter, conductivity, and specific conductivity respectively over ranges of one, four, and five orders of magnitude. The conductivity of resulting fibers is maximized when the speed of solvent counter-diffusion is high and the radius reduction is largest. When extrusion speed is also high relative to speed of the nozzle motion, a fluid mechanical coiling instability emerges which creates filaments with periodic coils, allowing for intricate designs to be formed along a linear extrusion path. Once dried, these densely coiled structures initially maintain their shape and can subsequently undergo up to 50 % strain with under 1 % change in resistance and 170 % linear extension with 20 % increase in resistance as the coils unwind. The resulting complex coil structures have applications in lightweight circuitry and as flexible interconnects. [ABSTRACT FROM AUTHOR]

Energy‐harvesting technologies offer a sustainable, maintenance‐free alternative to conventional energy‐storage solutions in distributed low‐power applications. Flexible thermoelectric generators (TEGs) can generate electric power from a temperature gradient, even on complex surfaces. Organic materials are ideal candidates for flexible TEGs due to their good solution‐processability, natural abundance, low weight, and flexibility. Electronic and thermoelectric properties of organic materials have steadily progressed, while device architectures leveraging their advantages are largely missing. Here, a design and fabrication method are proposed for producing fully screen‐printed, flexible monolithic organic TEGs scalable up to m2, compatible with any screen‐printable ink. This approach is validated, along with its scalability, by printing TEGs composed of two different active inks, in three configurations, with up to 800 thermoelements, with performances well matching simulations based on materials parameters. It is demonstrated that by using an additive‐free graphene ink, a remarkable power density of 15 nW cm−2 at ΔT = 29.5 K can be achieved, with an estimated weight‐normalized power output of 1 µW g−1, highlighting a strong potential in portability. Owing to such power density, only limited areas are required to generate microwatts, sufficient for operating low‐power electronic devices such as sensors, and wearables. [ABSTRACT FROM AUTHOR]

Developing stretchable strain sensors with high sensitivity and stability is crucial for various applications such as prosthetic hands, human health monitoring, and human‐machine interactions. However, achieving these qualities simultaneously remains challenging. Here, an inherently stretchable strain sensor is presented that integrates ultrahigh sensitivity and robust stability, enabling stretch, press, or bend sensing capabilities. This sensor employs a softer elastomeric channel filled with liquid metal (LM) as the conductive path. A stiffer elastomer convex integrated into the channel serves as a strain‐manipulated gate, controlling opening gap of electrical current flow path. During deformation, the softer elastomer undergoes cross sectional reduction due to the Poisson effect, while the stiffer convex gate retains its geometry. This heterogeneous deformation behavior leads to significant contraction or closure of the LM channel, resulting in increased resistance and a remarkable enhancement in sensitivity by more than two orders of magnitude. The all‐soft design maintains exceptional stability even under extended or repetitive substantial deformations. With the ability to monitor subtle and large human body movements, detect grip actions of soft grippers reliably, and monitor the gradual and extended growth process of plants, this sensor holds significant potential for advancements in flexible electronics. [ABSTRACT FROM AUTHOR]

Smart responsive organic emitters, which exhibit tunable emission properties in response to external stimuli, can serve as a new generation of intelligent optoelectronic materials because of their versatile applications, such as multicolor displays, information encryption, visual sensing, and matter detection. In recent years, significant advancements have been made in the development of smart responsive organic emitters. However, there is still a lack of a systematic review that provides a comprehensive insight into smart responsive organic emitters from the perspectives of intrinsic mechanisms and versatile applications. Hence, this review concentrates on analyzing the intrinsic mechanisms, which can clarify the relationships between material systems and tunable emission behaviors. This process can provide helpful design principles for smart responsive organic emitters. Furthermore, versatile smart applications have been highlighted to deepen the understanding of the practical values of such smart responsive emitters. This work summarizes the state‐of‐the‐art progress of smart responsive emitters and highlights the existing challenges and future development directions. It aims to provide inspiration and guidelines for the construction of novel smart responsive organic emitters, thereby broadening and stimulating their prominent applications in various fields such as electronic information and flexible electronics. [ABSTRACT FROM AUTHOR]

Design of mechanical metamaterials with a negative Poisson's ratio (NPR), known as auxetics, is of great importance in the development of flexible electronics and tissue engineering. However, the mechanical performance of conventional auxetic metamaterials is largely hindered by the high porosity and lack of tunability, which restricts their practical engineering applications. Here, this study presents a programmable approach for designing integrated two‐phase auxetic composite metamaterials with pore‐free structure, robust interfaces, and customized mechanical properties by substituting the vacancy of the auxetic lattices (frame phase) with hydrogel‐based soft fillers (matrix phase). Manipulated by two‐phase stiffness contrast, integrated composite metamaterials exhibit a functional transition between auxetic and non‐auxetic behaviors. Rationally designing Young's modulus ratios in spatial domains endows the programming of composite metamaterials with the desired spatial heterogeneity. Furthermore, the incorporation of temperature‐responsive hydrogels to auxetic frames also enbles the development of dynamic programmable composites with the thermo‐driven adaptability. As a practical application demonstration, designed programmable composites are used to dynamically tune the phononic bandgaps. The design strategy of integrated two‐phase composite metamaterials paves the way for the development of advanced auxetic engineering materials with programmable mechanical properties, providing opportunity for conformal electronic patches, bio‐scaffolds, and smart functionality applications. [ABSTRACT FROM AUTHOR]

Electronic skin (E‐skin) that can mimic the flexibility and stretchability of human skin with sensing capabilities, holds transformative potential in robotics, wearable technology, and healthcare. However, developing E‐skin poses significant challenges such as creating durable materials with skin‐like flexibility, integrating biosensing abilities, and using advanced fabrication techniques for wearable or implantable applications. To overcome these hurdles, a 3D‐printed electronic skin utilizing a novel class of nanoengineered hydrogels with tunable electronic and thermal biosensing capabilities is fabricated. This methodology takes advantage of the shear–thinning behavior in hydrogel precursors, allowing to construct intricate 2D and 3D electronic structures. The elasticity of skin using triple crosslinking in a robust fungal exopolysaccharide, and pullulan is simulated, while defect‐rich 2D molybdenum disulfide (MoS2) nanoassemblies ensure high electrical conductivity. The addition of polydopamine nanoparticles enhances adhesion to wet tissue. The hydrogel exhibits outstanding flexibility, stretchability, adhesion, moldability, and electrical conductivity. A distinctive feature of this technology is the precise detection of dynamic changes in strain, pressure, and temperature. As a human motion tracker, phonatory‐recognition platform, flexible touchpad, and thermometer, this technology represents a breakthrough in flexible wearable skins and holds transformative potential for the future of robotics and human‐machine interfaces. [ABSTRACT FROM AUTHOR]

Developing the elastomer materials with high mechanical robustness through simple and environmentally friendly methods poses significant challenges. In this research, a simple solvent‐free polymerization method is reported to synthesize a transparent polyurea‐urethane elastomer using polycaprolactone (PCL) as soft segment and adjusting various hard segments. The target elastomer successfully combine acceptable mechanical performance and exceptional crack tolerance, whereby the notched samples can readily lift 25000 times (a rarely reported value) its weight. Moreover, the superhigh elastic restorability allow target elastomer recover to its original dimension from elongation over 5 times or to fracture. These results are attained due to the presence of densely and uniformly distributed hard microdomains within the elastomer, leading to effective energy dissipation. Furthermore, owing to the linear structure of the molecular chains and the reversible hydrogen‐bonding interactions between the chains, target elastomer can be conveniently healed and recycled under heating conditions. This research can provide a general and feasible strategy for the construction of elastomer materials with exceptional comprehensive properties, and the elastomers are expected to be applied in emerging fields such as protective elements and flexible electronics. [ABSTRACT FROM AUTHOR]

Neuromorphic computing, inspired by the functionality of biological neural networks, has emerged as a promising paradigm for artificial intelligence applications, especially in the field of flexible electronics. Among the various artificial synaptic devices, floating‐gate synaptic transistors exhibit long‐term synaptic plasticity, but they face the challenge of achieving flexible compatibility. In this work, the first demonstration of a flexible MXene floating‐gate synaptic transistor is reported, which uses multiple layers of MXene as floating gates and MXene nanosheets as charge state modulators. The device shows excellent mechanical flexibility and can operate at low voltages, which improves its suitability for wearable electronic devices. It can also emulate Pavlovian conditioned reflexes under external stress, suggesting its potential for cognitive learning. Moreover, the device is utilized for handwritten digit recognition by simulating a fully connected neural network, achieving a high recognition accuracy of 92.0%. This demonstrates its practical applicability in neuromorphic computing. Besides, this research achieves the patterning of MXene and its application in flexible floating‐gate transistors. It provides a new solution for the integrated fabrication of flexible artificial synaptic devices. [ABSTRACT FROM AUTHOR]

By virtue of reversible energy dissipation and good ionic conductivity, metal ions have been extensively introduced to construct hydrogels. However, the traditional soaking method to prepare metal ions coordination hydrogels (MI‐HG) faces the challenge of diffusion and combination of metal ions, leading to weak mechanical properties. Inspired by the leather mineral tanning mechanism, a strategy that controls the accessibility of hydrogels by pickling and basifying processes thus significantly improving the strength and toughness of MI‐HG is proposed. To achieve this, polyvinyl alcohol/poly(acrylamide‐co‐acrylic acid) (PVA/PAM‐co‐PAA) hydrogels‐bearing ligands similar to those of leather collagen are fabricated. Zr4+, Cr3+, Al3+, and Fe3+ commonly used for mineral tanning are chosen as the metal source. The results demonstrate that the mechanical properties of the products (MI‐HGTanning) are significantly promoted, especially for Cr3+ and Zr4+. For example, the tensile strength of Zr‐HGTanning and toughness of Cr‐HGTanning reach 7.79 ± 0.41 Mpa and 28.01 ± 3.1 MJ m−3, approximately three and seven times that of their soaking samples. From macro to micro characterization and by theoretical simulation, the mineral tanning mechanism of metal ions first permeating and then effectively combining with carboxylates, thus improving the mechanical performance of MI‐HGTanning is deciphered, the products of which are promised applications in flexible force sensors. [ABSTRACT FROM AUTHOR]

Developing flexible thermal management materials is quite urgent for emerging flexible electronics and wearable devices. Here, a novel strategy is used to prepare hydroxyl-functionalized boron nitride@polyurethane (BNOH@PU) composites with desired BN orientation in the in-plane direction through the foaming process of PU and hot-pressing. BNOH flakes can react with isocyanates to form amido linkages, which is beneficial for reducing interfacial thermal resistance (ITR) between BNOH and PU. In addition, BNOH flakes will be rearranged along the direction of PU backbones through the volume compression of the foaming process and trend to be oriented in the in-plane direction after hot-pressing. The out-of-plane or in-plane thermal conductivities of the composites are 1.69 and 3.19 W m−1 K−1 at 30 wt% BNOH content, and the corresponding thermal conductivity enhancement (TCE) is 1986% and 3838%, respectively. Meanwhile, BNOH@PU exhibited low ITR between BNOH flakes (1.252 × 10−7 K m2/W), good flexibility and stretchability, which was a promising thermal management material for wearable devices. The interfacial thermal resistance (ITR) and the phonon scattering between fillers and polymer matrix could be reduced significantly via the hydroxyl functionalization of BN. In-plane thermal conductivity enhanced BNOH@PU composites with desired BN orientation in the in-plane direction through the foaming process of PU and hot-pressing. [ABSTRACT FROM AUTHOR]

We report for the first time MoS2/CNT hybrid nanostructures for memristor applications on flexible and bio-degradable cellulose paper. In our approach, we varied two different weight percentages (10% and 20%) of CNT's in MoS2 to improve the MoS2 conductivity and investigate the memristor device characteristics. The device with 10% CNT shows a low V SET voltage of 2.5 V, which is comparatively small for planar devices geometries. The device exhibits a long data retention time and cyclic current–voltage stability of ∼104 s and 102 cycles, making it a potential candidate in flexible painted electronics. Along with good electrical performance, it also demonstrates a high mechanical stability for 1000 bending cycles. The conduction mechanism in the MoS2-CNT hybrid structure is corroborated by percolation and defect-induced filament formation. Additionally, the device displays synaptic plasticity performance, simulating potentiation and depression processes. Furthermore, such flexible and biodegradable cellulose-based paper electronics may pave the way to address the environmental pollution caused by electronic waste in the near future. [ABSTRACT FROM AUTHOR]

Polymer gels, consisting of cross‐linked polymer network systems swollen by a solvent, show great potential in biomedicine, flexible electronics, and artificial muscles, due to their tissue‐like mechanical properties. Due to the presence of a large amount of solvent, the improvement of the mechanical properties of the polymer gel is a challenge. Moreover, combining high toughness with useful properties, such as 3D printability or shape‐memory, in one polymer gel system is even more challenging. In this study, a simple and efficient method is developed for the fabrication of tough polymer gels by polymerizing 2‐hydroxyethyl methacrylate (HEMA) in a mixture of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). The polymerized elastic networkpresents distinct compatibility with PEG (compatible) and PPG (poorly compatible), resulting in in‐situ phase separation at the microscale. The resulting phase‐separated gel demonstrates high strength (8.0 MPa), favorable fracture strain (430%), and large toughness (17.0 MJ m−3). The separated hard phasewith a high glass transition temperature (75 °C) endows the whole soft polymer gel with the property of shape memory at room temperature. Finally, the fabrication of tunable tough PEGgels is combined with 3D printing as well as with shape memory properties, demonstrating the use of PEGgels for 4D printing. [ABSTRACT FROM AUTHOR]

The rapid development of ultrawideband (UWB) communication systems has resulted in increasing performance requirements for the antenna system. In addition to a wide bandwidth, fast propagation rates and compact dimensions, flexibility, wearability or portability are also desirable for UWB antennas, as are excellent notch characteristics. Although progress has been made in the development of flexible/wearable antennas desired notch properties are still rather limited. Moreover, most presently available flexible UWB antennas are fabricated using environmentally not attractive subtractive etching-based processes. The usage of facile additive sustainably inkjet printing processes also utilizing low temperature plasma-activated conductive inks is rarely reported. In addition, the currently used tri-notched flexible UWB antenna designs have a relatively large footprint, which poses difficulties when integrated into miniaturized and compact communication devices. In this work, a silver nano ink is used to fabricate the antenna via inkjet printing and an efficient plasma sintering procedure. For the targeted UWB applications miniaturized tri-notched flexible antenna is realized on a flexible polyethylene terephthalate (PET) substrate with a compact size of 17.6 mm × 16 mm × 0.12 mm. The antenna operates in the UWB frequency band (2.9–10.61 GHz), and can shield interferences from WiMAX (3.3–3.6 GHz), WLAN (5.150–5.825 GHz) and X-uplink (7.9–8.4 GHz) bands, as well as exhibits a certain of bendability. Three nested "C" slots of different sizes were adopted to achieve notch features. The simulation and test results demonstrate that the proposed antenna can generate signal radiation in the desired UWB frequency band while retaining the desired notch properties and having acceptable SAR values on-body, making it a viable candidate for usage in flexible or wearable communication transmission devices. The research provides a facile and highly efficient method for fabricating flexible/wearable UWB antennas, that is, the effective combination of inkjet printing processing, flexible substrates, low temperature-activated conductive ink and antenna structure design. [ABSTRACT FROM AUTHOR]

The ability to shape and pattern conductors has been indispensable for manufacturing functional devices. Herein, a series of patterned liquid metals–based flexible electronics are fabricated via magnetic printing. The combination of highly conductive liquid metals and flexible photosensitive resins endows the as‐prepared devices with excellent electrical and mechanical properties, such as high electric conductivity (8 × 104 S m−1), low detection hysteresis, good durability, and environmental stability. What's more, strain‐insensitive flexible electronics can be achieved by designing the structure of liquid metal‐based conductors, and the resistance is only increased 0.13 Ω at 100% strain. Therefore, the as‐prepared liquid metals‐based flexible electronics have promising applications in stretchable conductors. [ABSTRACT FROM AUTHOR]

In recent years, hydrogel-based wearable flexible electronic devices have attracted much attention. However, hydrogel-based sensors are affected by structural fatigue, material aging, and water absorption and swelling, making stability and accuracy a major challenge. In this study, we present a DN-SPEZ dual-network hydrogel prepared using polyvinyl alcohol (PVA), sodium alginate (SA), ethylene glycol (EG), and ZnSO4 and propose a self-calibration compensation strategy. The strategy utilizes a metal salt solution to adjust the carrier concentration of the hydrogel to mitigate the resistance drift phenomenon to improve the stability and accuracy of hydrogel sensors in amphibious scenarios, such as land and water. The ExpGrow model was used to characterize the trend of the ∆R/R0 dynamic response curves of the hydrogels in the stress tests, and the average deviation of the fitted curves ϵ ¯ was calculated to quantify the stability differences of different groups. The results showed that the stability of the uncompensated group was much lower than that of the compensated group utilizing LiCl, NaCl, KCl, MgCl2, and AlCl3 solutions ( ϵ ¯ in the uncompensated group in air was 276.158, 1.888, 2.971, 30.586, and 13.561 times higher than that of the compensated group in LiCl, NaCl, KCl, MgCl2, and AlCl3, respectively; ϵ ¯ in the uncompensated group in seawater was 10.287 times, 1.008 times, 1.161 times, 4.986 times, 1.281 times, respectively, higher than that of the compensated group in LiCl, NaCl, KCl, MgCl2 and AlCl3). In addition, for the ranking of the compensation effect of different compensation solutions, the concentration of the compensation solution and the ionic radius and charge of the cation were found to be important factors in determining the compensation effect. Detection of events in amphibious environments such as swallowing, robotic arm grasping, Morse code, and finger–wrist bending was also performed in this study. This work provides a viable method for stability and accuracy enhancement of dual-network hydrogel sensors with strain and pressure sensing capabilities and offers solutions for sensor applications in both airborne and underwater amphibious environments. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDCs) are a promising class of two‐dimensional (2D) materials for flexible electronic applications due to their low integration temperature, good electronic properties, and excellent mechanical flexibility. Moreover, TMDCs offer the possibility of co‐integrating both n‐ and p‐type transistors on the same substrate, enabling the realization of complementary metal‐oxide‐semiconductor (CMOS) circuits. In this study, n‐type MoS2 field‐effect transistors (FETs), and p‐type WSe2‐FETs integrated on a flexible foil substrate fabricated by standard thin‐film technology are presented. These devices exhibit high stability in their electronic operation under strain and repeated bending cycles. A CMOS inverter based on these transistors is also successfully demonstrated, which shows excellent switching behaviour with high gain (up to 100), high noise margin (0.87 · VDD), and low average static power consumption (40 pW). [ABSTRACT FROM AUTHOR]

The spinal cord is crucial for transmitting motor and sensory information between the brain and peripheral systems. Spinal cord injuries can lead to severe consequences, including paralysis and autonomic dysfunction. We introduce thin-film, flexible electronics for circumferential interfacing with the spinal cord. This method enables simultaneous recording and stimulation of dorsal, lateral, and ventral tracts with a single device. Our findings include successful motor and sensory signal capture and elicitation in anesthetized rats, a proof-of-concept closed-loop system for bridging complete spinal cord injuries, and device safety verification in freely moving rodents. Moreover, we demonstrate potential for human application through a cadaver model. This method sees a clear route to the clinic by using materials and surgical practices that mitigate risk during implantation and preserve cord integrity. [ABSTRACT FROM AUTHOR]

In recent years, the demand for electronic materials has significantly increased, driven by industrial needs and the pursuit of cost‐efficient alternatives. This comprehensive study investigates the effects of Mn substitution on LaFeO3 through the implementation of the GGA approach in density functional theory. The research findings demonstrate remarkable consistency with the experimental outcomes reported in the existing literature pertaining to the studied compounds. However, this study unveils novel insights into the mechanical and optical characteristics of the doped structures, which have not been previously reported. The structural stability is rigorously examined through multiple stability criteria, encompassing structural optimization, tests of elastic stability, and enthalpy of formation calculations. Furthermore, the electronic and optical properties of the compounds exhibit exceptional improvements in conductivity and reflectivity as a result of the doping process. The band structure analysis reveals the presence of a Moss‐Burstein shift. Investigation of the magnetic properties indicates an increase in the magnetic moment value due to the Fe‐Mn degeneracy resulting from increased Mn content. Mechanical analysis of the elastic moduli B, G, and Y demonstrates an enhanced strength and metal‐like conductivity, attributed to the induced anharmonicity. Moreover, the internal strain factor suggests a higher degree of bond flexibility, implying potential applications of these compounds in flexible electronics. [ABSTRACT FROM AUTHOR]

Addressing the challenges in teaching the Nernst equation in inorganic chemistry, this experiment introduces the cutting-edge zinc-air battery as a teaching model. By altering the concentration of oxidizing and reducing materials, students explore the key factors of the Nernst equation, enhancing their understanding of electrochemical processes. Simultaneously, the experiment incorporates flexible electronics technology, using carrageenan as a safe and environmentally friendly solid electrolyte to guide students in learning and constructing solid zinc-air batteries. The batteries are tested for voltage performance at various bending angles to assess their flexibility. Moreover, to foster creativity, students design and build various forms of solid zinc-air batteries to power electronic devices. This experiment is closely aligned with fundamental electrochemical knowledge and state-of-the-art technology, allowing students to deepen their understanding of the Nernst equation while gaining practical experience in creating flexible electronic devices. This approach sparks students' interest in electrochemistry and proves cost-effective with promising results. [ABSTRACT FROM AUTHOR]

In this study, a Y2O3 insulator was fabricated via the sol–gel process and the effect of precursors and annealing processes on its electrical performance was studied. Yttrium(III) acetate hydrate, yttrium(III) nitrate tetrahydrate, yttrium isopropoxide oxide, and yttrium(III) tris (isopropoxide) were used as precursors, and UV/ozone treatment and high-temperature annealing were performed to obtain Y2O3 films from the precursors. The structure and surface morphologies of the films were characterized via grazing-incidence X-ray diffraction and scanning probe microscopy. Chemical component analysis was performed via X-ray spectroscopy. Electrical insulator characteristics were analyzed based on current density versus electrical field data and frequency-dependent dielectric constants. The Y2O3 films fabricated using the acetate precursor and subjected to the UV/ozone treatment showed a uniform and flat surface morphology with the lowest number of oxygen vacancy defects and unwanted byproducts. The corresponding fabricated capacitors showed the lowest current density (Jg) value of 10−8 A/cm2 at 1 MV/cm and a stable dielectric constant in a frequency range of 20 Hz–100 KHz. At 20 Hz, the dielectric constant was 12.28, which decreased to 10.5 at 105 Hz. The results indicate that high-quality, high-k insulators can be fabricated for flexible electronics using suitable precursors and the suggested low-temperature fabrication methods. [ABSTRACT FROM AUTHOR]

Nanoporous gold (np-Au) has found its use in applications ranging from catalysis to biosensing, where pore morphology plays a critical role in performance. While the morphology evolution of bulk np-Au has been widely studied, knowledge about its thin-film form is limited. This work hypothesizes that the mechanical compliance of the thin film substrate can play a critical role in the morphology evolution. Via experimental and finite-element-analysis approaches, we investigate the morphological variation in np-Au thin films deposited on compliant silicone (PDMS) substrates of a range of thicknesses anchored on rigid glass supports and compare those to the morphology of np-Au deposited on glass. More macroscopic (10 s to 100 s of microns) cracks and discrete islands form in the np-Au films on PDMS compared to on glass. Conversely, uniformly distributed microscopic (100 s of nanometers) cracks form in greater numbers in the np-Au films on glass than those on PDMS, with the cracks located within the discrete islands. The np-Au films on glass also show larger ligament and pore sizes, possibly due to higher residual stresses compared to the np-Au/PDMS films. The effective elastic modulus of the substrate layers decreases with increasing PDMS thickness, resulting in secondary np-Au morphology effects, including a reduction in macroscopic crack-to-crack distance, an increase in microscopic crack coverage, and a widening of the microscopic cracks. However, changes in the ligament/pore widths with PDMS thickness are negligible, allowing for independent optimization for cracking. We expect these results to inform the integration of functional np-Au films on compliant substrates into emerging applications, including flexible electronics. [ABSTRACT FROM AUTHOR]

Most basic flexible electronic structures include the development of micro-electrodes, micro-resistors, micro-heaters and interconnecting lines between them to the signal conditioning circuitry over a flexible substrate. Biocompatibility of these metallic elements is thus a prerequisite for successful realization of any wearable or implantable devices as it determines the degradation effects of the material and the living cells or tissues at the target site. Present paper attempts to test the biocompatibility of a micro-electrode array (MEA) patch made of copper for use in Electrical Stimulation (ES) applications using various simulated body solutions like simulated body fluid (SBF), simulated sweat (SS), and physiological saline (PS) solution. Fabricated MEA structures also demonstrated excellent mechanical stability and good electrical continuity for up to 750 bending cycles highlighting its high flexibility. The paper also aims to observe the degradation study of the fabricated electrodes with coatings like polyvinyl alcohol (PVA) hydrogel and commercially available electrode hydrogel with and without the application of ES. Optimization of PVA coating thickness over the electrodes for promoting effective electrical conduction has also been reported through simulation studies. The results obtained demonstrated the effectiveness of PVA hydrogels over commercial ones. However, the absence of an adhesive layer over the PVA sheets decreased its compatibility period. Tests with applied ES retained electrically stable structures for up to only 24 h compared to a large stability time of ~ 5 days for those without any ES under the test solutions indicating its possible usage for disposable type wearable applications over skin surface. [ABSTRACT FROM AUTHOR]

Flexible electronics, also referred to as printable electronics, represent an interesting technology for implementing electronic circuits via depositing electronic devices onto flexible substrates, boosting their possible applications. Among all flexible electronics, interdigitated electrodes (IDEs) are currently being used for different sensor applications since they offer significant benefits beyond their functionality as capacitors, like the generation of high output voltage, fewer fabrication steps, convenience of application of sensitive coatings, material imaging capability and a potential of spectroscopy measurements via electrical excitation frequency variation. This review examines the role of IDEs in printed and flexible electronics since they are progressively being incorporated into a myriad of applications, envisaging that the growth pattern will continue in the next generations of flexible circuits to come. [ABSTRACT FROM AUTHOR]

Direct printing of conjugated polymer thin‐film transistors enables the fabrication of deformable devices with low cost, high throughput, and large area. However, a relatively poor device performance of printed devices remains a major obstacle to their application in high‐end display backplanes and integrated circuits. In this study, high‐performance and highly stackable printed organic transistors is developed, arrays, and circuits using a near‐amorphous polymer, indacenodithiophene‐co‐benzothiadiazole (IDT‐BT). The printed devices exhibited high saturation mobility (>1 cm2 V−1 s−1), high on/off ratio (>107), and low subthreshold slope (245 mV dec−1). In addition, 16 × 16 printed IDT‐BT arrays achieved 100% fabrication yield, with excellent device‐to‐device uniformity and low variations of mobility (9.55%) and threshold voltage (4.51%), and good operational and environmental stability (>365 days). Furthermore, five stacked 3D transistors are demonstrated with an excellent 3D uniformity without compromising device performance due to a low required thermal budget for processing amorphous IDT‐BT. Finally, a new concept of 3D universal logic gate with high voltage gain (33.91 V/V) and record density (100 printed transistors per cm2) is proposed and fabricated, which is relevant for the commercialization of low‐cost printed display backplanes and high‐density integrated circuits based on highly processable polymeric semiconductors. [ABSTRACT FROM AUTHOR]

Conductive hydrogel is considered a promising wearable sensor material. Developing flexible conductive hydrogel sensors with stretchability, adhesion, and stability remains challenging. In this study, a transparent, self‐adhesive, antifreeze, anti‐UV, stretchable, conductive, and reusable hydrogel with polyacrylamide/glycerol/gelatin/tannic acid/Fe3+ (PGGT‐Fe3+) structure is successfully constructed through a simple one‐pot polymerization method. The PGGT‐Fe3+ hydrogel is composed of dual networks of polyacrylamide and gelatin for organic cross‐linking, using water/glycerol as the dispersion medium, and incorporates a viscous substance: tannic acid, and a conductive substance: metal ions (Fe3+). Due to the introduction of the abundant amino, carboxylic acid, and hydroxyl functional groups on gelatin and tannic acid, the PGGT‐Fe3+ hydrogel exhibits excellent and repeatable adhesion capabilities on various surfaces (including glass, metal, plastic, and pigskin) with maximum adhesion strength of 98 kPa when attached to pigskin. Furthermore, based on the stable conductive network and high conductivity, the hydrogel not only exhibits strain sensitivity, fast response, and stability but also can stably collect epidermal bio signals. In conclusion, this work provides a new approach to the design and development of next‐generation multifunctional conductive hydrogels and opens up vast possibilities for their applications in the flexible electronics field. [ABSTRACT FROM AUTHOR]

It remains a huge challenge to efficiently recycle the printed circuit boards (PCBs) because of the diversity and complexity of the PCBs in terms of material composition. The recycling of PCBs highly depends on the design of the polymers that make up the polymer substrates and conductive pastes. Herein, closed‐loop recyclable plastics for use as the polymer substrates and for the preparation of the conductive pastes are fabricated by dynamically cross‐linking phenylboronic acid‐functionalized poly(methylmethacrylate) (PMMA‐B) and poly(urea‐urethane) (PUU‐B) with boroxines. The closed‐loop recyclable plastic, which is denoted as PMMA‐PUU exhibits a breaking strength of 71.0 MPa and Young's modulus of 1.8 GPa. Because of the dynamic nature of boroxines, the PMMA‐PUU0.6 plastic can be depolymerized in the N, N‐dimethylacetamide/ethanol mixture solvent. The depolymerized PMMA and PUU can be efficiently recovered in high yields and purity through their solubility differences in selective solvents. Conductive pastes suitable for printing of electrical circuits are fabricated through complexation of Ag particles with PMMA‐PUU. PCBs composed of PMMA‐PUU substrates and PMMA‐PUU‐based conductive pastes are flexible, healable, and recyclable. The closed‐loop recycling of the PCBs enables the collection of highly purified Ag particles, PMMA‐B, and PUU‐B monomers even when the PCBs are mixed with polymer wastes. [ABSTRACT FROM AUTHOR]

A variety of organic electrochemical transistors have been recently developed; however, their self-healing performance has been largely ignored. In this study, we propose the use of a lithium-ion composite electrolyte membrane as a dielectric layer and the use of poly(3-hexylthiophene) (P3HT) as a channel layer to fabricate flexible self-supporting organic synaptic transistors. A variety of synaptic behaviors were emulated within the proposed organic synaptic transistors. By leveraging the self-healing features of polymer electrolytes, along with cross-linking reactions and low-resistance lithium-ion transmission, the device maintained its electrical performance. Testing involving different curvatures also revealed the device's potential for use in flexible electronics. Significantly, due to the device's self-healing ability, consistent dataset recognition rates were sustained. This work highlights its vast prospects in the field of flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

Flexible and stretchable microdevices incorporate highly deformable structures, facilitating precise functionality at the micro- and millimetre scale. Flexible microdevices have showcased extensive utility in the fields of biomedicine, microfluidics, and soft robotics. Actuation plays a critical role in transforming energy between different forms, ensuring the effective operation of devices. However, when it comes to actuating flexible microdevices at the small millimetre or even microscale, translating actuation mechanisms from conventional rigid large-scale devices is not straightforward. The recent development of actuation mechanisms leverages the benefits of device flexibility, particularly in transforming conventional actuation concepts into more efficient approaches for flexible devices. Despite many reviews on soft robotics, flexible electronics, and flexible microfluidics, a specific and systematic review of the actuation mechanisms for flexible and stretchable microdevices is still lacking. Therefore, the present review aims to address this gap by providing a comprehensive overview of state-of-the-art actuation mechanisms for flexible and stretchable microdevices. We elaborate on the different actuation mechanisms based on fluid pressure, electric, magnetic, mechanical, and chemical sources, thoroughly examining and comparing the structure designs, characteristics, performance, advantages, and drawbacks of these diverse actuation mechanisms. Furthermore, the review explores the pivotal role of materials and fabrication techniques in the development of flexible and stretchable microdevices. Finally, we summarise the applications of these devices in biomedicine and soft robotics and provide perspectives on current and future research. [ABSTRACT FROM AUTHOR]

Stretchable conductors (SCs) have garnered significant attention in both academia and industry, owing to their promising applications in flexible electronics. However, achieving a highly resilient and rapidly rebounding SC that enables prompt electrical response to applied strain, while also being fully recyclable and self‐healable, remains a challenge. Here, the design and preparation of a high‐performance SC based on a small bio‐molecule (α‐Lipoic acid) are reported, using a straightforward, cost‐effective, and scalable method. The engineered SC exhibits a ≈100% rebound ratio and fast rebound speed (≈0.4 s) under repeated high strains, along with outstanding electrical sensitivity to both deformation and temperature variation. This ensures that the SC possesses high precision and real‐time sensing attributes. Moreover, the SC features high optical transparency (>97%), robust reversible adhesion to diverse surfaces (up to 5.0 MPa), efficient room‐temperature self‐healing properties, and full recyclability. The superior properties of the SC are fundamentally attributed to the installed hierarchical dynamic bonding at the molecular level, which enables continuous energy dissipation and is analyzed through DFT calculations. The developed SC holds great potential for applications in soft electronics and human–machine interfaces. [ABSTRACT FROM AUTHOR]

Requirements for the material with high tensile strength and elongation at break are proposed with the development of soft and stretchable electronics. The nitrile butadiene rubber (NBR) crosslinked by coordination bonds has excellent tensile properties and is expected to be used in the flexible electronics field, but the effect of strain rate on tensile properties of crosslinked NBR needs to be further analyzed. In this work, the NBR with dual crosslinked networks was prepared by methods of double ligands crosslinking, covalence-coordination crosslinking, and bimetallic coordination crosslinking. Furthermore, the strain rate sensitivity of tensile properties of NBR with dual crosslinked networks was studied by considering the strain rate as a variable. The results indicated that the strength of the coordination bonds formed by the second ligand had significant effects on the tensile properties of NBR: The coordination bonds with low strength could protect the integrity of the crosslinked network, but the tensile properties of NBR with two different kinds of strong coordination bonds would be more dependent on the strain rate. In covalence-coordination crosslinked or bimetallic crosslinked NBR, the synergy between the two crosslinked networks could not only increase the strength and elongation at break of NBR but also reduce the influence of strain rate on the tensile properties of NBR. [ABSTRACT FROM AUTHOR]

Camouflage skin holds immense potential for a variety of advanced applications, such as artificial intelligence, soft robotics, and flexible/wearable electronics. Currently, most existing materials for constructing camouflage skin are mainly based on inorganic materials with an inverse opal scaffold, which significantly limits their further development because of the poor mechanical properties and environmental instability. Inspired by rana slvaticas, a new type of camouflage skin based on one‐dimentional (1D) photonic crystal (PC) gel is designed and synthesized, which combines the advantages of 1D PC structures with 3D flexible gels in a single skin device. Taking advantage of the unique structures, the resulting camouflage skins demonstrated attractive properties, including excellent mechanical performance, self‐adaptive camouflage capabilities, and long‐term stability in ambient conditions. Specifically, the camouflage skin can quickly recognize and match the background by modulating the optical signals of external stimuli. The synergistic effect of the glycerol, the dodecyl glycerol itaconate (DGI), and the nano‐space structures altogether contribute to the outstanding long‐term environmental stability of the camouflage skin. Overall, by combining the bio‐inspired concept and molecular engineering strategy, camouflage skin based on PC gels is synthesized, which greatly enriched the application and development in the smart skins field. [ABSTRACT FROM AUTHOR]

Stretchable alternating current electroluminescent (ACEL) devices have a bright future in wearable electronics and soft robotics. Still, their market application is hindered by high operating voltages. The voltage can be reduced by increasing the relative permittivity of the dielectric elastomer in the emissive layer. Here, a fluorine‐free high‐permittivity silicone elastomer functionalized with cyanopropyl side groups, specially designed for application in stretchable ACEL devices, is introduced. The polar silicone elastomer exhibits excellent mechanical properties and a dielectric permittivity four times higher than commercial PDMS. Light‐emitting devices based on the polar elastomer reach 7.5 times higher maximum luminance at the same electric field than PDMS‐based devices and turn on at a 50% lower electric field. Besides, the polar elastomer‐based devices perform better than all materials tested in literature in achieving high luminance at low electric fields. Stretchable ACEL devices are built from the polar elastomer which shows bright and uniform light emission and can be operated up to 50% strain. The high‐permittivity silicones are promising materials for stretchable ACEL devices and can help their breakthrough to market application by overcoming the drawback of high operating voltages. [ABSTRACT FROM AUTHOR]

With the trend of integration and miniaturization of stretchable electronics, thermal management has been a crucial issue. Developing novel materials with high thermal conductivity (TC) and flexibility is urgent. Herein, we report a stretchable polydimethylsiloxane (PDMS)/boron nitride nanosheet (BNNS)@spherical aluminum oxide (Al2O3) composite with high TC and electrical insulation prepared by a two‐step strategy of sucrose‐template and hot‐pressing. An effective foam‐pressing route benefits the composites to form a three‐dimensional thermally conductive networks, improving the in‐plane TC value of the resultant composite to 4.03 W/(mK) at the filler mass fraction of 35.7 wt% and enhancing to 4.66 W/(mK) under 40% stretching ratio. Meanwhile, the composites can be restored to their former state and retain thermally conductive stability with repeated bending and twisting tests. Moreover, the composites were applied in LED with stretching, exhibiting good heat dissipation performance. These results demonstrate this PDMS composite can be potentially utilized as a high‐performance material to solve thermal management problems in flexible electronics. Highlights: The heat conduction network is prepared by sucrose‐template and hot‐pressing.BNNS@P‐Al2O3 fillers are self‐assembled via the electrostatic interaction.The composites exhibit good thermal conduction and superior flexibility.The thermal conductivity of the composite increases after stretching.The composites can retain thermal conductive stability after deformation. [ABSTRACT FROM AUTHOR]

Flexible electronics is a new generation of electronic devices in which electronic components are integrated into flexible substrates. It is used in the fabrication of displays, solar cells, integrated circuits, and increasingly in the fabrication of electronic skin (E-skin), which can mimic the properties of human skin by being able to follow skin movements and flexures without loss of mechanical and electrical properties. E-skin is suitable for integrating various sensors to monitor personal health. Conductive polymers are used in flexible electronics due to their electrical conductivity, low mass, and stability. However, their main disadvantage is their brittleness, which is why they don't possess flexibility property without modification. Therefore, in this work, the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was used as the main chain and the side branches of poly(acrylate-urethane) (PAU) were grafted onto it by atom transfer radical polymerization (ATRP) onto it, obtaining the grafted copolymer PEDOT-g-PAU. In this way, the main chain of PEDOT retains the property of electrical conductivity without losing conjugation, while the side branches of PAU have the ability to crosslink non-covalently through hydrogen bonds with PAU side branches of adjacent polymer molecules due to the presence of oxygen in their structure. The presence of hydrogen bonds allows increasing the stretchability and flexibility of the material, and they also have the ability to spontaneously renew themselves when they break due to excessive stress. Three different synthesis conditions were used to obtain polymers of different structure, which were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and measurement of electrical conductivity with a four-point probe (4PP) method. The obtained graft copolymer was prepared in the form of ink and printed on a polyurethane (PU) substrate using inkjet technique. The conductivity of the printed layer, its elongation and adhesion were investigated, while possible delamination of the printed polymer layer was also monitored. The results showed that the PEDOT-g-PAU copolymer was successfully synthesized and inkjet printing on PU film was successful. The obtained material has satisfactory electrical and mechanical properties and could be used for the integration of fully functional biosensors with further optimization of the composition. [ABSTRACT FROM AUTHOR]

Organohydrogels composed of immiscible hydrophilic and hydrophobic components have outstanding advantages in environmental adaptability, thus exhibiting potential applications in the fields of soft actuators, artificial sensors, energy storage devices, and so on. This paper provides a comprehensive overview of the latest developments in organohydrogels, from construction to performance and application. After a brief introduction, typical cases of organohydrogels and their construction methods are analyzed and summarized, including organohydrogels with heterogeneous networks, organohydrogels with binary solvent, emulsion‐based organohydrogels, and macroscopic hybrid gels. Then, their promising applications of soft actuators, flexible electronics, and anti‐counterfeiting platforms are outlined. Finally, the current challenges and future prospects of this emerging area are discussed. This review can be a significant reference for the development of environmentally adaptable materials and the expansion of new applications. [ABSTRACT FROM AUTHOR]

Understanding viscoelastic behavior of dielectric elastomers for artificial muscle application is important to regulate actuation performance, response time, energy density, sensitivity, duty cycle, etc. The performance of elastomers is widely recognized as being influenced by various fillers, including functional particles and poly-reagents. However, the impact of fillers on the viscoelastic properties of VHB 4910 remains to be fully understood. In this work, a new range of particulate-polymer filled VHB elastomers are studied for the effects of barium titanate and Ketjenblack particles dispersed trimethylolpropane trimethylacrylate on viscoelastic properties. This followed characterization of stress-relaxation and creep behavior to realize the time-dependent mechanical performance. Also, the stress-softening and energy dissipation behavior are examined to find the number of cycles required to reach the equilibrium energy state. Viscoelastic properties of elastomer including elastic modulus, toughness, are found to significantly reduced as a result of modified poroelastic effects due to incorporated fillers. The mechanical properties of composites are evidenced to depend on the size of the particulates and the amount of polymer reagent within elastomer. Theoretical analysis comparing deformation, relaxation, and creep mechanisms in biomedical materials validates the potential of modified elastomers for use in soft actuation devices, particularly in the field of artificial muscles. This work may help in recognizing the strategies to tune viscoelastic behavior of microporous elastomers for potential applications in flexible electronics. [ABSTRACT FROM AUTHOR]

Conductive hydrogels amalgamate characteristics of both biomedical materials and conductive materials, finding applications in medical rehabilitation, motion monitoring, and human-machine interaction among others. To enhance the innovative awareness and experimental skills of undergraduate students majoring in flexible electronics, this experiment designs a conductive hydrogel crosslinked by nanogel materials. By exploring the initiator concentration and cross-linking mechanisms during the polymerization of co-polymeric hydrogels, the impact of material structural components on the durability and sensing performance of hydrogel-based flexible electronic devices were elucidated. Through taking part in this novel experimental design, undergraduates majored in flexible electronics can acquire key points on polymer emulsion polymerization, hydrogel synthesis, stress-strain sensing property characterization, gaining a deeper understanding of the influence of cross-linking agent structural design on material functionality. Additionally, this experiment developed a hydrogel based flexible and wearable sensing system based on hydrogel flexible electronic sensors. By integrating a smart glove capable of controlling a small car's movement and a hydrogel controller for computer game control, we tightly merge cutting-edge research with undergraduate experimental teaching tasks. This integration is beneficial in stimulating the research interest and innovative exploration spirit among undergraduates majoring in flexible electronics, materials, and electronic information. [ABSTRACT FROM AUTHOR]

[Display omitted] • Composite electrode and microstructure enable high sensitivity in broad linear range. • IPSs provide precision in object measurements, even under heavy loads. • IPSs monitor and recognize vibrations across a broad frequency range. Monitoring non-contact high-frequency vibrations requires improving the sensitivity and linear response of iontronic pressure sensors (IPSs). In this study, we incorporate composite electrodes comprising silver nanowires (Ag NWs) and MXene into IPSs to enhance electronic conduction and pseudocapacitance. Moreover, we utilize a novel surface-pillar microstructure, along with an internally randomized multi-bubble structure within the dielectric layer, to significantly expand the linear response range of the sensor. The resulting IPS device demonstrates exceptional linear sensitivity, measuring approximately 153.83 kPa−1, across a broad pressure range of up to 260 kPa. Additionally, it exhibits long-term stability, rapid response and recovery characteristics, and remains functional underwater. Notably, these devices exhibit remarkable capabilities in monitoring ultrasonic vibrations and accurately identifying sound wave vibrations. The integration of composite electrodes, microstructure designs, and their compatibility with underwater applications positions these IPSs as highly promising tools for precise measurements and advancements in flexible electronics technology. [ABSTRACT FROM AUTHOR]