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It remains a challenge to produce soft robots that can mimic the responsive adaptability of living organisms. Rather than fabricating soft robots from bulk hydrogels,hydrogels are integrated into the interfacial assembly of aqueous two-phase systems to generate ultra-soft and elastic all-aqueous aquabots that exhibit responsive adaptability, that can shrink on demand and have electrically conductive functions. The adaptive functions of the aquabots provide a new platform to develop minimally invasive surgical devices, targeted drug delivery systems, and flexible electronic sensors and actuators.

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]

[Display omitted] • Conductive hydrogels prepared by electrohydrodynamic printing exhibit enhanced conductivity. • Ion-electron conductive hydrogel with MXene co-ILs composite conductive network. • Hydrogel exhibited good mechanical properties, excellent sensing performance, and high frost resistance. • Hydrogel-based flexible strain sensor for human motion detection and information transmission. Conductive hydrogels with high performance and frost resistance are essential for flexible electronics, electronic skin, and soft robots. Nonetheless, the preparation of hydrogel-based flexible strain sensors with rapid response, wide strain detection range, and high sensitivity remains a considerable challenge. Furthermore, the inevitable freezing and evaporation of water in sub-zero temperatures and dry environments lead to the loss of flexibility and conductivity in hydrogels, which seriously limits their practical application. In this work, ionic liquids (ILs) and MXene are introduced into gelatin/polyacrylamide (PAM) precursor solution, and a PAM/gelatin/ILs/MXene/glycerol (PGIMG) hydrogel-based flexible strain sensor with MXene co-ILs ion–electron composite conductive network is prepared by combining the electrohydrodynamic (EHD) printing method and in-situ photopolymerization. The introduction of ILs provides an ionic conductive channel for the hydrogel. The introduction of MXene nanosheets forms an interpenetrating network with gelatin and PAM, which not only provides a conductive channel, but also improves the mechanical and sensing properties of the hydrogel-based flexible strain sensor. The prepared PGIMG hydrogel with the MXene co-ILs ion–electron composite conductive network demonstrates a tensile strength of 0.21 MPa at 602.82 % strain, the conductivity of 1.636 × 10−3 S/cm, high sensitivity (Gauge Factor, GF = 4.17), a wide strain detection range (1–600 %), and the response/recovery times (73 ms and 74 ms). In addition, glycerol endows the hydrogel with excellent freezing (−60 °C) and water retention properties. The application of the hydrogel-based flexible strain sensor in the field of human motion detection and information transmission shows the great potential of wearable devices, electronic skin, and information encryption transmission. [ABSTRACT FROM AUTHOR]

Flexible electronics have become imperative in an emerging era of the Internet of Things (IoT), as they offer promising alternatives to rigid and complex circuitry for the development of wearable devices. As a result, the research field of flexible gas sensors is increasingly being investigated, including different potential materials, with the aim of high selectivity and sensitivity. In this study, a flexible ammonia (NH3) sensor unit was fabricated using cellulose nanofibers (C-NFs) as a flexible supporting framework and sensing material coating of Ti3C2Tx MXene. The fabricated sensor displayed higher selectivity to NH3 relative to other interferents in the ppm concentration range. The results revealed that the MXene/C-NFs-based sensor exhibited a response of 2.4% towards 5 ppm NH3 with faster response and recovery times of 42 s and 69 s, respectively, which were improved relative to a pristine MXene-based sensor with sensing response of 1.42% and response/recovery time of 67 s/104 s. This enhanced sensing performance was ascribed to the large specific surface area and efficient charge transport pathways provided by the one-dimensional structure of C-NFs, which facilitated the surface adsorption/desorption of NH3 molecules. In addition, the fabricated sensor demonstrated excellent flexibility features and reproducible sensing properties at different bending angles and bending cycles, with low sensing response attenuation of 5.2% under a maximum bending angle of 120°. Overall, this work illustrates the feasibility of employing a nanofiber matrix as a flexible sensing framework along with a porous absorption/desorption surface for next-generation wearable gas sensors. [ABSTRACT FROM AUTHOR]

Flexible electronics offer a versatile, rapid, cost-effective and portable solution to monitor water contamination, which poses serious threat to the environment and human health. This review paper presents a comprehensive exploration of the versatile platforms of flexible electronics in the context of heavy metal ion detection in water systems. The review overviews of the fundamental principles of heavy metal ion detection, surveys the state-of-the-art materials and fabrication techniques for flexible sensors, analyses key performance metrics and limitations, and discusses future opportunities and challenges. By highlighting recent advances in nanomaterials, polymers, wireless integration, and sustainability, this review aims to serve as an essential resource for researchers, engineers, and policy makers seeking to address the critical challenge of heavy metal contamination in water resources. The versatile promise of flexible electronics is thoroughly elucidated to inspire continued innovation in this emerging technology arena. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) like the zeolitic imidazolate framework (ZIF‐8) have a high surface area, tunable porosity, and robust thermal and chemical stability, making them attractive candidates for various applications. Here, a strategy is shown that spans that functionality and provides strong photoluminescence (PL) emission, unlocking ZIF‐8‐based materials for chemical and temperature sensors based on PL. The approach is based on laser processing that dramatically boosts the PL response of laser‐irradiated ZIF‐8 (LI ZIF‐8), achieving a 70‐fold increase in intensity relative to the pristine material. The PL characteristics of the irradiated material can be easily tuned by varying the laser power and irradiation time with in situ and real‐time spectroscopic analysis providing insights into the process dynamics. It is found that the observed PL enhancement is primarily due to the laser‐induced transformation of ZIF‐8 into nitrogen‐doped nanocarbons and ZnO nanostructures. The versatility of this laser processing approach is leveraged to create flexible electronics by integrating the LI ZIF‐8/nanocarbon architectures into thermoplastic polyurethane (TPU). The multifunctional composite material shows excellent performance as flexible electrodes for human‐body monitoring applications, as well as both temperature and flexure sensors with remarkable mechanical resilience. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) possess low operating voltage and excellent amplification capability and show promising applications in biosensors and flexible electronics. However, the active layers of OECTs are usually dense films, which show limited ion penetration/transport, resulting in limited performances of OECTs. Here, unprecedented high‐performance flexible multifunctional OECTs based on nanoporous (mainly 2–60 nm), high‐specific‐surface‐area (255–281 m2 g−1), and flexible conjugated polymer aerogel films are developed. The nanoporous structures effectively facilitate ion penetration/transport, leading to significantly enhanced transconductance (48.5–53.5 mS) and on/off ratio (6.4 × 104) of the OECTs compared with those of dense devices. The resulting OECT‐based glucose sensors exhibit an ultralow detection limit of 1 pm, approximately two to three orders of magnitude lower than those of the previously reported OECT glucose sensors, and an ultrabroad detection range of 1 pm–5 m. They can detect trace amounts of glucose in sweat, serum, saliva, and urine in real time. Moreover, the OECTs can be used for high‐performance flexible artificial synapses and electrocardiogram monitoring. This work provides a powerful strategy toward highly sensitive biosensors, artificial synapses, and electrophysiological signal monitoring. [ABSTRACT FROM AUTHOR]

Tremendous popularity is observed for multifunctional flexible electronics with appealing applications in intelligent electronic skins, human–machine interfaces, and healthcare sensing. However, the reported sensing electronics, mostly can hardly provide ultrasensitive sensing sensitivity, wider sensing range, and robust cycling stability simultaneously, and are limited of efficient heat conduction out from the contacted skin interface after wearing flexible electronics on human skin to satisfy thermal comfort of human skin. Inspired from the ultrasensitive tactile perception microstructure (epidermis/spinosum/signal transmission) of human skin, a flexible comfortably wearable ultrasensitive electronics is hereby prepared from thermal conductive boron nitride nanosheets‐incorporated polyurethane elastomer matrix with MXene nanosheets‐coated surface microdomes as epidermis/spinosum layers assembled with interdigitated electrode as sensing signal transmission layer. It demonstrates appealing sensing performance with ultrasensitive sensitivity (≈288.95 kPa−1), up to 300 kPa sensing range, and up to 20 000 sensing cycles from obvious contact area variation between microdome microstructures and the contact electrode under external compression. Furthermore, the bioinspired electronics present advanced thermal management by timely efficient thermal dissipation out from the contacted skin surface to meet human skin thermal comfort with the incorporated thermal conductive boron nitride nanosheets. Thus, it is vitally promising in wearable artificial electronic skins, intelligent human‐interactive sensing, and personal health management. [ABSTRACT FROM AUTHOR]

Spintronics, micro/nanofabrication, and the semiconductor industry are undergoing significant transformations, highlighting the need for flexible technologie. This study examines the possibility of integrating topological insulators (TIs), specifically Bi2Te3 thin films (13–191 nm), into flexible spintronic applications through scalable magneto‐sputtering techniques, and investigates how structural organization influences electrical and topological properties through post‐thermal annealing. Films annealed above 250 °C display improved polycrystalline structure, larger crystallites, fewer local defects, and higher a room‐temperature Seebeck coefficient (S) and resistivity (ρ), suggesting decreased bulk electronic contributions. A metastable transport regime is identified in the temperature‐dependent resistivity of films annealed at 300 °C between 20–100 K; in this range, the thinnest film exhibits markedly metallic behavior, signaling the presence of topological surface states (TSS). Magnetoresistance measurements of as‐grown and annealed films, between 3–20 K, demonstrate weak antilocalization. Applying the Hikami‐Larkin‐Nagaoka model, α‐coefficients are found to scale with thickness from 0.5–1, indicating thickness‐controlled coupling of the TSS. Post‐annealing at 300 °C, the phase coherence length, Lϕ, of the thinner films increases, while the temperature dephasing rate shifts from ∼0.7 (as‐grown) to ∼0.5 (post‐annealing), aligning with expected values for 2D TSS. These are encouraging findings for large‐scale manufacturing flexible TI technologies, without sacrificing tunabilit. [ABSTRACT FROM AUTHOR]

PVA/AgNO3 composite films were prepared on fused silica substrates using a casting technique and irradiated with blue light to synthesize silver nanoparticles (AgNPs) within the polymer matrix. The physical and chemical properties of the films were analyzed, revealing increased crystallinity and the formation of Ag nanoparticles and nanorods after irradiation. FTIR spectra showed a vibrational band of Ag–O at 760 cm⁻1 after 30 min of irradiation. The absorption coefficient exhibited a transition band between 400 and 500 nm, with peak amplitude increasing with irradiation time, indicating more Ag nanostructure formation. Differential scanning calorimetry (DSC) analysis showed a rise in melting temperature from 62 to 84 °C and a decrease in crystallization temperature from 188 to 185 °C. Thermogravimetric analysis (TGA) indicated thermal stability with minor mass loss up to 270 °C. Electrical conductivity increased from 2.29 to 3.35 µS.cm⁻1 with increased blue light irradiation time. Our study documents the efficient synthesis of well-distributed AgNPs within the PVA matrix using blue light irradiation, which significantly enhances the optical, thermal, and electrical properties of the composite films. These improved properties make the films suitable for applications in sensors, flexible electronics, and antimicrobial coatings. [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]

With the increasing demands for artificial intelligence, robotics, electronic skin, healthcare, and energy storage/conversion, the research focus on flexible electronics has started to shift from being merely bendable and rollable to being stretchable. In recent years, stretchable aerogels and foams have drawn significant attention in the field of flexible electronics due to their unique porous structures, low density, high porosity, and high flexibility. This work provides a comprehensive review of the state‐of‐the‐art developments in stretchable aerogels and foams, encompassing their preparation, structures, properties, and applications. The preparation methods, typical structures of stretchable aerogels and foams, stretching principle, and the relationship between their structures, stretchability, and other properties are investigated. Their latest applications in stretchable strain/pressure sensors, electrodes and conductors, chemical sensors and biosensors, supercapacitors, batteries, triboelectric nanogenerators, electromagnetic shielding, microwave absorption, thermal management, adsorption, separation/filtration, and shape memory are introduced. Furthermore, the challenges and opportunities of stretchable aerogels and foams are summarized. This work provides a guideline for the development of stretchable aerogels and foams and next‐generation high‐performance flexible electronics based on stretchable porous materials. [ABSTRACT FROM AUTHOR]

Eutectogels, composed of deep eutectic solvents (DESs) and polymeric networks, are promising as pivotal components in flexible energy storage, soft robotics, wearable electronic devices, etc. However, an inherent trade‐off between ionic conductivity and mechanical properties, which stems from the antagonism between the DES and polymeric networks, restricts the advancement of eutectogels. Herein, a sequentially enhanced strategy via freeze‐casting, solvent exchanges, and wet annealing to construct supramolecular poly(vinyl alcohol) (PVA) eutectogels with ultratough mechanical properties and high ionic conductivity is proposed. The trade‐off is reconciled by building aligned through‐pores to facilitate efficient ion transport and by further rationally regulating the aggregation structures of PVA chains to reinforce the supporting networks. Consequently, the resulting supramolecular PVA eutectogels demonstrate state‐of‐the‐art mechanical‐conductive comprehensive performances among existing eutectogels with an elongation of 3281%, a toughness of 196 MJ m−3, a fatigue threshold of 1100 J m−2, and ionic conductivity of 5.2 mS cm−1. These appealing characteristics are highly desirable for advanced soft conductors. This study will provide insights into designing next‐generation high‐performance supramolecular materials for flexible electronics is believed. [ABSTRACT FROM AUTHOR]

In recent years, flexible and wearable biosensor technologies have gained significant attention due to their potential to revolutionize healthcare monitoring. Among the various components involved in these biosensors, the electrode material plays a crucial role in ensuring accurate and reliable detection. In this regard, polymer electrodes, such as Poly(3,4 ethylenedioxythiophene): poly(styrenesulfonate), combined with graphene (PEDOT:PSS/graphene), have emerged as promising candidates due to their unique mechanical properties and excellent electrical conductivity. Understanding the mechanical behavior of these polymer electrodes on flexible substrates is essential to ensure the stability and durability of wearable biosensors. In this paper, PEDOT:PSS/graphene composite was spray-coated on flexible substrates at different growth conditions to explore the effect of the deposition parameters and mode of mechanical loading (longitudinal or transversal) on the electrical and mechanical behavior of the fabricated samples. It was found that the coating grown at lower temperatures and higher spraying pressure exhibited stable behavior no matter the applied stress type. [ABSTRACT FROM AUTHOR]

Polyurethanes (PU) have drawn great attention due to their excellent mechanical properties and self-healing and recyclable abilities. Lignin is a natural and renewable raw material in nature, composed of a large number of hydroxyl groups, and has a great potential to replace petroleum polyols in PU synthesis. This review summarizes the recent advances in modification methods such as the liquefaction, alkylation, and demethylation of lignin, and a systematic analysis of how to improve the reactivity and monomer substitution of lignin during polyurethane synthesis for the green manufacturing of high-performance polyurethanes was conducted. Polyurethane can be used in the form of films, foams, and elastomers instead of conventional materials as a dielectric or substrate material to improve the reliability and durability of flexible sensors; this review summarizes the green synthesis of polyurethanes and their applications in flexible electronics, which are expected to provide inspiration for the wearable electronics sector. [ABSTRACT FROM AUTHOR]

The fabrication of flexible electronics has gained extensive attention due to the growing demand of flexible devices. Among various methods, laser direct writing technology has emerged as a promising approach due to its advantages of high processing accuracy and simplicity. This research focuses on the preparation of copper microelectrodes using laser‐induced reduction of CuO nanoparticles (Cu NPs) on polyethylene terephthalate films. First, the influence of various parameters on the conductivity of the copper microelectrodes is investigated. Second, flexible copper microelectrodes with a minimum resistivity of 62.29 μΩ cm and an adhesion grade of 4B level are successfully fabricated. Building upon these results, a capacitive pressure sensor is developed with optimal sensitivity of 3.99 Pa−1, good hysteresis of 3.99%, and response and recovery times of 1.2 and 1.3 s, respectively. Repeatability tests confirm the sensor's stability and fatigue resistance. This research provides valuable insights for the production of flexible sensors. [ABSTRACT FROM AUTHOR]

Highly stretchable aerogel films are attractive for advanced next‐generation stretchable electronics. However, it is a great challenge to achieve high stretchability for aerogel films. Here, several types of unprecedented ultra‐stretchable semiconducting polymer‐based aerogel films with crimpled porous structures are developed via crosslinking and template methods combined with uniaxial and biaxial pre‐stretching strategies. The semiconducting aerogel films obtained by uniaxial pre‐stretching exhibit ultrahigh stretchability up to 100–200%, while those obtained by biaxial pre‐stretching show high biaxial stretchability up to 50%. The resulting aerogel films show strain‐insensitive electrical and joule heating properties. A prototype of the aerogel film‐based stretchable organic electrochemical transistor (OECT) is developed for the first time. Benefiting from their unique porous structures, the aerogel film‐based OECTs exhibit enhanced on/off ratio and transconductance compared with corresponding dense film‐based OECTs, high stretchability up to 100%, and high stretching stability with 10 000 stretching cycles under 30% strain. It is demonstrated that the aerogel film‐based OECTs can be applied as high‐performance stretchable artificial synapses and biosensors. This work gives a versatile strategy toward highly stretchable aerogel films promising for flexible electronics. [ABSTRACT FROM AUTHOR]

Reliable interfacial bonding is an essential guarantee that flexible electronics can output realistic signals, especially for underwater scenes. However, conventional self‐adhesive materials usually suffer from underwater adhesion failure, conflict between adhesion and cohesion, as well as adverse effects of isotropous adhesion and residue, greatly limiting their applications in flexible electronics. Herein, a Janus hydrophobic structural gel (HSG) with asymmetric adhesion is fabricated by a "grafting one twig on another" approach (in situ constructing a hydrophobic anti‐adhesive gel on the top of a hydrophobic self‐adhesive gel). The hydrophobic adhesion layer with long C18 aliphatic chains achieves a reliable underwater bonding (interfacial toughness exceeds 80 J m−2) with the assistance of high mobility of polymer chains, multiple interfacial interactions, and effective removal of interfacial liquid. The hydrophobic anti‐adhesion layer containing poly(ionic liquid) is more robust due to electrostatic and ion‐dipole interactions, ensuring the mechanical strength of the integral HSG. Such asymmetric heterostructure avoids common nonessential adhesion and residue, facilitating operation. The intrinsic hydrophobicity of HSG also prevents water erosion, achieving reliable underwater adhesion and sensing. As a result, the assembled sensor based on HSG can stably monitor human motions and wirelessly transmit underwater information, exhibiting an enormous potential in wearable electronics. [ABSTRACT FROM AUTHOR]

Environmental concerns and climate protection are gaining increasing emphasis nowadays. A growing number of industries and scientific fields are involved in this trend. Sustainable electronics is an emerging research strand. Environmentally friendly and biodegradable or biobased raw materials can be used for the development of green flexible electronic devices, which may serve to reduce the pollution generated by plastics and electronics waste. In this work, we present cytocompatible, electrically conductive structures of nanocarbon water-soluble composites based on starch films. To accomplish this goal, potato starch-based films with glycerol as a plasticiser were developed along with a water-soluble vehicle for nanocarbon-based electroconductive pastes specifically dedicated to screen printing technology. Films were characterized by optical microscopy, scanning electron microscopy (SEM) mechanical properties and surface free energy. [ABSTRACT FROM AUTHOR]

Gallium‐based liquid metal (LM) is widely used in flexible electronics, optics, and green synthesis due to its excellent conductivity, flexibility, and self‐healing capabilities. However, LM's inherent fluidity and high surface tension greatly limit their practical applications. Therefore, there is a strong demand for developing LM composites that are easy to control and exhibit outstanding performance when used flexibly. In this work, the LM hydrothermal rheological modification method is proposed to synthesize Ga‐coated carbon microparticles, and the highly miscible rheological modification of LM is realized by mixing LM and Ga‐coated carbon microparticles. Including carbon microparticles in the LM improves the mechanical strength of the composite, thereby overcoming the limitation of the LM that has a low mechanical strength. By controlling the volume fraction of carbon microparticles in LM, electrical conductivity is increased by 30% and thermal conductivity by more than 2.0 times that of pure LM. In addition, the fundamental interfacial wetting behavior is demonstrated at the interface of LM and Ga2O3, and the rheological modification mechanism of LM is explained by carbon particles. This work presents a novel method for preparing high‐performance polymer materials and discusses their broad potential applications in thermal interface materials, wireless energy transfer, and flexible electronics. [ABSTRACT FROM AUTHOR]

The construction of mechanically responsive materials with reversible shape‐shifting, shape‐locking, and stretchability holds promise for a wide range of applications in fields such as soft robotics and flexible electronics. Here, we report novel thermoelastic one‐dimensional organic–inorganic hybrids (R/S‐Hmpy)PbI3 (Hmpy=2‐hydroxymethyl‐pyrrolidinium) to show mechanical responses. The single crystals undergo two phase transitions at 310 K and 380 K. When heated to 380 K, they show shape‐shifting and expansion along the b‐axis by about 13.4 %, corresponding to a larger deformation than that of thermally activated shape memory alloys (8.5 %), and exhibit a strong actuation force. During the cooling process, the stretched crystal shape maintains and a shape‐locking phenomenon occurs, which is lifted when the temperature decreases to 305 K. Meanwhile, due to the introduction of chiral ions, the thermal switching shows a 10‐fold second‐order nonlinear switching contrast (common values typically below 3‐fold). This study presents a thermoelastic actuator based on shape‐shifting and ‐locking of organic–inorganic hybrids for the first time. The dielectric and nonlinear optical switching properties of organic–inorganic hybrids broaden the range of applications of mechanically responsive crystals. [ABSTRACT FROM AUTHOR]

In recent years, there has been a significant increase in the prevalence of electronic wearables, among which flexible magnetoelectronic skin has emerged as a key component. This technology is part of the rapidly progressing field of flexible wearable electronics, which has facilitated a new human perceptual development known as the magnetic sense. However, the magnetoelectronic skin is limited due to its low sensitivity and substantial field limitations as a wearable electronic device for sensing minor magnetic fields. Additionally, achieving efficient and non-destructive delamination in flexible magnetic sensors remains a significant challenge, hindering their development. In this study, we demonstrate a novel magnetoelectronic touchless interactive device that utilizes a flexible giant magnetoresistive sensor array. The flexible magnetic sensor array was developed through an electrochemical delamination process, and the resultant ultra-thin flexible electronic system possessed both ultra-thin and non-destructive characteristics. The flexible magnetic sensor is capable of achieving a bending angle of up to 90 degrees, maintaining its performance integrity even after multiple repetitive bending cycles. Our study also provides demonstrations of non-contact interaction and pressure sensing. This research is anticipated to significantly contribute to the advancement of high-performance flexible magnetic sensors and catalyze the development of more sophisticated magnetic electronic skins. [ABSTRACT FROM AUTHOR]

Conductive hydrogels are gaining significant attention as promising candidates for the fabrication materials for flexible electronics. Nevertheless, improving the tensile properties, hysteresis, durability, adhesion, and electrochemical properties of these hydrogels remains challenging. This work reports the development of a novel semi‐interpenetrating network poly(ionic liquid) hydrogel named PATV, via the in situ polymerization of acrylamide, N‐[Tris(hydroxymethyl)methyl] acrylamide, and 1‐vinyl‐3‐butylimidazolium tetrafluoroborate. The density functional theory calculations reveal that the poly(ionic liquid) in the hydrogel network acts as physical cross–linking points to construct hydrogen‐bond networks. Furthermore, the hydrogen‐bond networks dissipate energy efficiently and quickly, and thus stress concentration and hysteresis are avoided. The prepared hydrogel has a low hysteresis (9%), high tensile properties (900%), fast response (180 ms), high sensitivity (gauge factor = 10.4, pressure sensitivity = 0.14 kPa−1), and wide sensing range (tensile range: 1–600%, compression range: 0.1–20 kPa). A multifunctional sensor designed based on the designed hydrogel enables real‐time, rapid, and stable response‐ability for the detection of human movement, facial expression recognition, pronunciation, pulse, handwriting, and Morse code encryption. Furthermore, the assembled triboelectric nanogenerator displays an excellent energy harvesting capability, thus highlighting its potential application in self‐powered flexible wearable electronic devices. [ABSTRACT FROM AUTHOR]

High mechanical strength, excellent toughness, low hysteresis, and robust resilience are of great importance for stretchable conductive hydrogels (CHs) to heighten their reliabilities for self‐powered sensing applications. However, it still remains challenging to simultaneously obtain the mutually exclusive performances. Herein, an intrinsically conductive and adhesive hydrogel is fabricated by one‐step radical polymerization of acrylamide (AAm), three hydroxy groups together clustered‐N‐[tris(hydroxymethyl)methyl]acrylamide (THMA), and cationic 1‐Butyl‐3‐Vinylimidazolium Bromide (ILs) dissolved in core‐shell structurally dispersed PEDOT:PSS (PP) solution. Owing to abundant clustered hydrogen bonds, electrostatic interactions between PILs chains and anionic PSS shells, and polymer chain entanglements, the CHs feature superior mechanical properties with a high tensile strength (0.25 MPa), fracture strain (1015%), fracture toughness (1.22 MJ m‐3), fracture energy of 36.5 kJ m‐2 and extremely low hysteresis (5%), and display excellent resilience and fatigue resistance. As a result, the CHs indicate excellent sensing properties with a gauge factor up to 10.46, a broad sensing range of strain (1‐900%) and pressure (0.05‐100 kPa), and fast responsive rate, thus qualifying for monitoring reliably and accurately large and tiny human movements in daily life. Moreover, the hydrogel‐assembled triboelectric nanogenerators (TENGs) exhibit excellent and stable electrical output performances, which are greatly promising in self‐powered flexible wearable electronics. [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]

The development of flexible electronics technology has led to the creation of flexible energy storage devices (FESDs). In recent years, flexible self‐supporting cathodes have gained significant attention due to their high energy density, excellent mechanical performance, and strong structural plasticity among various cathode materials. Flexible self‐supporting cathodes enable larger active material loading capacity and conductive networks for electrodes, thereby perfectly meeting the mechanical and electrochemical performance requirements of FESDs. Currently, the focus of flexible self‐supporting cathodes lies in exploring flexible substrates or novel binders to enhance the flexibility of conventional cathode materials. However, the flexibility of cathode poses challenges as they are primarily composed of transition metal oxides, resulting in limited research on their flexibility. A comprehensive review and prospective analysis are of utmost importance to effectively advance the progress of flexible self‐supporting cathodes and propel their development forward. Herein, the present discourse delves into the latest advancements concerning flexible self‐supporting cathode, focusing on synthesis methodologies, structural design approaches, and characterization parameters. Examining the current progress, the inherent advantages, existing challenges, and potential prospects of these materials are comprehensively elucidated and emphasized. [ABSTRACT FROM AUTHOR]

The inherent low thermal conductivity, low cost, and flexibility of polymeric materials make them potential candidates for thermoelectric applications. Their eco-friendliness and mechanical flexibility are useful for the design of portable and flexible self-powered electronics. However, the heat-to-electrical power conversion efficiency, also known as the figure-of-merit (ZT), of polymer TE materials is low. Research efforts are in progress to enhance the thermoelectric performance of polymers and to find new kinds of polymer composites. Recent research innovations, such as chemical doping of polymers, development of nanocomposites and hybrid composites, and nanostructuring have significantly changed the thermoelectric properties of the polymeric materials. In this article, we summarize the recent developments and achievements in polymer materials for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Organic memory devices have attracted attention because they promise flexible electronics, low manufacturing costs, and compatibility with large–scale integration. A series of new D−A architectures were synthesized employing different donor groups and the isatin moiety as the acceptor through Suzuki–Miyaura coupling reactions. Strong intramolecular interactions were observed in the synthesized compounds, further corroborated by an optimal bandgap. The SEM investigation confirmed good molecular ordering and superior thin film surface coverage. All the compounds demonstrated notable binary Write–Once–Read–Many–Times (WORM) memory behaviour. The threshold switching voltage for these D−A systems ranged from −0.79 to −2.37 V, with the compound having isobutyl substituent showing the lowest threshold voltage and maximum ON/OFF ratio of 102, thus outperforming others. The combined effects of charge transfer and charge trapping are responsible for the resistive switching mechanism prevailing in these systems. The alterations in D−A molecules that affect molecular packing, thin film morphology, and, finally, the memory performance of the active layer are highlighted in this work. [ABSTRACT FROM AUTHOR]

In this paper, we present an optimization of the planar manufacturing scheme for stretch-free, shape-induced metal interconnects to simplify fabrication with the aim of maximizing the flexibility in a structure regarding stress and strain. The formation of trenches between silicon islands is actively used in the lithographic process to create arc shape structures by spin coating resists into the trenches. The resulting resist form is used as a template for the metal lines, which are structured on top. Because this arc shape is beneficial for the flexibility of these bridges. The trench depth as a key parameter for the stress distribution is investigated by applying numerical simulations. The simulated results show that the increase in penetration depth of the metal bridge into the trench increases the tensile load which is converted into a shear force Q(x), that usually leads to increased strains the structure can generate. For the fabrication, the filling of the trenches with resists is optimized by varying the spin speed. Compared to theoretical resistance, the current–voltage measurements of the metal bridges show a similar behavior and almost every structural variation is capable of functioning as a flexible electrical interconnect in a complete island-bridge array. [ABSTRACT FROM AUTHOR]

Flexible electronics have revolutionized the field by overcoming the rigid limitations of traditional devices, offering superior flexibility and adaptability. Conductive ink performance is crucial, directly impacting the stability of flexible electronics. While metal filler-based inks exhibit excellent conductivity, they often lack mechanical stability. To address this challenge, we present a novel conductive ink utilizing a ternary composite filler system: liquid metal and two micron-sized silver morphologies (particles and flakes). We systematically investigated the influence of filler type, mass ratio, and sintering process parameters on the composite ink's conductivity and mechanical stability. Our results demonstrate that flexible wires fabricated with the liquid metal/micron silver particle/micron silver flake composite filler exhibit remarkable conductivity and exceptional bending stability. Interestingly, increasing the liquid metal content results in a trade-off, compromising conductivity while enhancing mechanical performance. After enduring 5000 bending cycles, the resistance change in wires formulated with a 4:1 mass ratio of micron silver particles to flakes is only half that of wires with a 1:1 ratio. This study further investigates the mechanism governing resistance variations during flexible wire bending. Additionally, we observed a positive correlation between sintering temperature and pressure with the conductivity of flexible wires. The significance of the sintering parameters on conductivity follows a descending order: sintering temperature, sintering pressure, and sintering time. Finally, we demonstrate the practical application of this technology by integrating the composite ink-based flexible wires with conductive polymer-based strain sensors. This combination successfully achieved the detection of human movements, including finger and wrist bending. [ABSTRACT FROM AUTHOR]

This work reports a highly‐strain flexible fiber sensor with a core–shell structure utilizes a unique swelling diffusion technique to infiltrate carbon nanotubes (CNTs) into the surface layer of Ecoflex fibers. Compared with traditional blended Ecoflex/CNTs fibers, this manufacturing process ensures that the sensor maintains the mechanical properties (923% strain) of the Ecoflex fiber while also improving sensitivity (gauge factor is up to 3716). By adjusting the penetration time during fabrication, the sensor can be customized for different uses. As an application demonstration, the fiber sensor is integrated into the glove to develop a wearable gesture language recognition system with high sensitivity and precision. Additionally, the authors successfully monitor the pressure distribution on the curved surface of a soccer ball by winding the fiber sensor along the ball's surface. [ABSTRACT FROM AUTHOR]

Electrical and mechanical integration approaches are essential for emerging hybrid electronics that must robustly bond rigid electrical components with flexible circuits and substrates. However, flexible polymeric substrates and circuits cannot withstand the high temperatures used in traditional electronic processing. This constraint requires new strategies to create flexible materials that simultaneously achieve high electrical conductivity, strong adhesion, and processibility at low temperature. Here, an electrically conductive adhesive is introduced that is flexible, electrically conductive (up to 3.25×105 S m−1) without sintering or high temperature post‐processing, and strongly adhesive to various materials common to flexible and stretchable circuits (fracture energy 350

Smart healthcare solutions are crucial for early diagnosis, real‐time health monitoring, and personalized therapy. Essential to these advancements are flexible wearable devices and medical robotics, which incorporate a range of elements, including soft sensors, therapeutic modules, human‐machine interfaces, actuators, and systems for communication, computation, and power. Liquid metal‐based materials are rapidly emerging as one of the key elements for these innovations. This review will delve into the latest breakthroughs in liquid metal (LM) functionalization innovation and the applications in healthcare‐related wearables and soft robotics. Firstly, techniques to modify LM are explored, emphasizing strategies to enhance properties such as electromechanical, thermal, electromagnetic, biochemical, self‐healing, and magnetic capabilities. Next, the authors shed light on contemporary wearable sensors, therapeutic on‐skin devices, and other flexible device innovations. They finally conclude by highlighting the challenges and charting the path forward for LM‐driven healthcare advances. [ABSTRACT FROM AUTHOR]

Traditional circuit board fabrication schemes are not directly applicable to the production of flexible, multi‐material circuits. This article reports a technique, microfluidic directed material patterning, which combines soft microfluidic stamps and low‐temperature solution‐phase deposition to generate multi‐material circuits on flexible, non‐planar polymeric supports. Specifically, metallic and semiconductive traces are combined on commodity plastic films to yield functional photosensitive circuits that can be used in the spectrophotometric detection and concentration measurement of microdroplets on 3D “e‐plates.” The photoresistive material cadmium sulfide is used in these circuits because it is suitable for visible light detection and it can be deposited directly from aqueous solutions following established bath deposition procedures. This method can produce colorimetric devices capable of quantifying micromolar concentrations of Allura Red in microdroplets of Kool‐Aid. This technique presents the opportunity for producing single‐use or low‐use disposable/recyclable devices for flexible 3D sensors and detectors following a convenient, low‐waste fabrication scheme. The general capabilities of this approach, in terms of substrate geometry and device layout (e.g., the number, area, and pattern of photoresistive elements), can be applied to the design and manufacture of more intricate, multiplexed devices supportive of advanced and/or specialized functions that go beyond those reported in this initial demonstration. [ABSTRACT FROM AUTHOR]

Self-healing materials span diverse application fields, including flexible electronics, soft robotics, and energy devices. However, conventional self-healing materials pose a challenge in achieving the delicate balance between flexibility and electrical conductivity. Moreover, they also suffer from prolonged healing times, incomplete healing, and high manufacturing costs. Liquid metals possess excellent self-healing capabilities owing to their unique combination of fluidic and metallic properties, high surface tension, and reversible solid-liquid phase change at room temperature, offering an intriguing material option for addressing the challenges associated with flexibility and electrical conductivity. In this review article, we comprehensively examine the domain of self-healing liquid metals from the standpoint of typical mechanisms underlying self-healing processes, as well as practical strategies employed for achieving such rejuvenation. Additionally, we explore representative applications that showcase the potential of these materials while aiming to provide a valuable reference for advancing and enhancing the field of self-healing materials. Future prospect along this direction is made. [ABSTRACT FROM AUTHOR]

Flexible electronics are striving in modern society, and they impose harsh and urgent requirements for flexibility on electronic package substrates. However, traditional materials, including ceramics, metals, or polymers are lack of flexibility. Herein, a polyurethane named PU‐D1Q1VF1 is proposed via incorporating carefully selected biobased units and synergistic dynamic bonds, and the PU‐D1Q1VF1 not only meets the basic requirements of flexibility but also possesses properties of self‐heal, UV‐protection, reprocessability, and degradability. The polycaprolactone diol (PCL diol) was employed as the soft segment, and the bis(2‐hydroxyethyl) disulfide (HEDS) and lignin derived model monomer hydroquinone were selected as chain extenders. Moreover, carefully synthesized bio‐based monomer (E)‐4‐(((furan‐2‐ylmethyl)imino)methyl)‐2‐methoxyphenol (VF) was used as the capping agent, which could facilitate the self‐healing process of the PU‐D1Q1VF1. [ABSTRACT FROM AUTHOR]

The piezoelectric effect refers to a physical phenomenon where piezoelectric materials generate an electric field when subjected to mechanical stress or undergo mechanical deformation when subjected to an external electric field. This principle underlies the operation of piezoelectric sensors. Piezoelectric sensors have garnered significant attention due to their excellent self-powering capability, rapid response speed, and high sensitivity. With the rapid development of sensor techniques achieving high precision, increased mechanical flexibility, and miniaturization, a range of flexible electronic products have emerged. As the core constituents of piezoelectric sensors, flexible piezoelectric composite materials are commonly used due to their unique advantages, including high conformability, sensitivity, and compatibility. They have found applications in diverse domains such as underwater detection, electronic skin sensing, wearable sensors, targeted therapy, and ultrasound diagnostics for deep tissue. The advent of flexible piezoelectric composite materials has revolutionized the design concepts and application scenarios of traditional piezoelectric materials, playing a crucial role in the development of next-generation flexible electronic products. This paper reviews the research progress on flexible piezoelectric composite materials, covering their types and typical fabrication techniques, as well as their applications across various fields. Finally, a summary and outlook on the existing issues and future development of these composite materials are provided. [ABSTRACT FROM AUTHOR]

Strategies for synthesis and processing of silicone rubber materials in three-dimensional (3D) structures are of significant interest based on their exceptional potential in many applications including flexible electronics and biomedical devices. Here, we present a synthetic approach of crosslinked polydimethylsiloxane (PDMS) exhibiting dynamic siloxane bond exchange for sufficient stress relaxation capability to enable versatile processabilities including reprocessing, remolding, self-healing, and hot-melt extrusion 3D printing. Considering the significant potential of recyclable silicone materials and their 3D structures, presented approaches enabled by dynamic exchangeable PDMS can provide a new pathway to replace conventional unrecyclable silicone used in diverse industrial sectors. [ABSTRACT FROM AUTHOR]

Over the past several years, atomically thin two‐dimensional carbides, nitrides, and carbonitrides, otherwise known as MXenes, have been expanded into over fifty material candidates that are experimentally produced, and over one hundred fifty more candidates that have been theoretically predicted. They have demonstrated transformative properties such as metallic‐type electrical conductivities, optical properties such as plasmonics and optical nonlinearity, and key surface properties such as hydrophilicity, and unique surface chemistry. In terms of their applications, they are poised to transform technological areas such as energy storage, electromagnetic shielding, electronics, photonics, optoelectronics, sensing, and bioelectronics. One of the most promising aspects of MXene's future application in all the above areas of interest, we believe, is reliably developing their flexible and bendable electronics and optoelectronics by printing methods (henceforth, termed as printed flexible MXetronics). Designing and manipulating MXene conductive inks according to the application requirements will therefore be a transformative goal for future printed flexible MXetronics. MXene's combined property of high electrical conductivity and water‐friendly nature to easily disperse its micro/nano‐flakes in an aqueous medium without any binder paves the way for designing additive‐free highly conductive MXene ink. However, the chemical and/or structural and hence functional stability of water based MXene inks over time is not reliable, opening research avenues for further development of stable and conductive MXene inks. Such priorities will enable applications requiring high‐resolution and highly reliable printed MXene electronics using state‐of‐the art printing methods. Engineering MXene structural and surface functional properties while tuning MXene ink rheology in benign solvents of choice will be a key for ink developments. This review article summarizes the present status and prospects of MXene inks and their use in inkjet‐printed (IJP) technology for future flexible and bendable MXetronics. [ABSTRACT FROM AUTHOR]

The research results and evaluation of the applicability of the original composition of hybrid paper based on silver nanowires (AgNWs), cellulose pulp (CP), and carbon nanotubes (CNTs) are presented and discussed. The material tested was used to manufacture sensors for mechanical deformation resulting from external influences or related to human activity interactions. The sensors were fabricated using an AgNWs + CP suspension and additives by the vacuum filtration method. The substrate obtained was machined and then laminated with a layer of poly(dimethylsiloxane) (PDMS). The recorded responses to selected types of imposed mechanical interactions in the form of changes in the relative resistance of the sensor throughout the tests showed a close cause-and-effect relationship. The response of the tested systems when applying an alternating magnetic field was also observed. The results indicate that the proposed solutions can find application in the monitoring of mechanical interactions resulting from the dynamic behavior of physical objects, as well as derived from selected human vital functions. [ABSTRACT FROM AUTHOR]

Miniaturization and flexibility are becoming the trend in the development of electronic products. These key features are driving new methods in the manufacturing of such products. Printed electronics technology is a novel additive manufacturing technique that uses active inks to print onto a diverse set of substrates, realizing large-area, low-cost, flexible and green manufacturing of electronic products. These advantageous properties make it extremely compatible with flexible electronics fabrication and extend as far as offering revolutionary methods in the production of flexible electronic devices. In this paper, the details of a printing process system are introduced, including the materials that can be employed as inks, common substrates, and the most recently reported printing strategies. An assessment on future setbacks and developments of printed flexible electronics is also presented. [ABSTRACT FROM AUTHOR]

As a functional material, polyurethane elastomers have found different applications in a variety of fields such as flexible electronics and smart coatings, but due to the damage during use, they are often endowed with self‐healing properties. However, conventional intrinsically self‐healing polyurethanes often don't balance excellent mechanical and self‐healing properties, so it has become crucial to prepare polyurethane elastomers with excellent self‐healing properties and high mechanical properties. In this study, a self‐healing waterborne polyurethane elastomers (IP‐DTDAx‐BAy‐WPU‐n) was synthesized based on 4, 4‐diaminodiphenyl sulfide (DTDA) boronic acid (BA). The disulfide bond has high motility at low temperatures and induces molecular‐level healing at the damaged interface, contributing to good repair under mild conditions. The borate ester bond limits intermolecular chain slippage and improves the mechanical properties as a dynamic cross‐linking point, while its dynamic reversible effect can synergistically improve the self‐healing ability. The results show that the synthesized elastomer films have good mechanical properties (strength 23.21 MPa, elongation at break 1259.08%, toughness 83.28 MJ m−3), good elastic recovery and self‐healing properties (93%). Furthermore, a composite conductors (IP‐DTDAx‐BAy‐WPU/AgNWs) with self‐healing properties was prepared by compositing AgNWs nanowires with polyurethane elastomers, which laid the foundation for its application in flexible electronic devices and wearable sensing devices. [ABSTRACT FROM AUTHOR]

We obtained 3D nanoflowers of MoS2 (3D-MoS2) with an average size of 1–3 µm synthesized by a one-step hydrothermal method, the "flower-shape" being composed of several petal-like sheets with a thickness of about 19 nm. The 3D nanoflowers underwent functionalization with diethyl[2-hydroxy-2-(thiophen-3-yl)ethyl]phosphonate and 2-tiophene carboxylic acid. P3HT/MoS2 composites were synthesized by Grignard metathesis using a 2,5-dibromo-3-hexylthiophene/MoS2 weight ratio of 1:0.05. As a reference, the P3HT/MoS2 composites were also synthesized with unfunctionalized 3D-MoS2. The P3HT/MoS2 composites were characterized by FTIR, XRD, TEM, 1H NMR, UV–Vis, TGA, and cyclic voltammetry. We studied the influence of 3D-MoS2 nanoflowers functionalized with phosphonic and carboxyl groups on the properties of the P3HT/MoS2 composites. The addition of functionalized 3D-MoS2 in the P3HT/MoS2 composites improved the percentage of HT dyads and the definition of shoulders in the dyad signal, indicating a better arrangement of the polymeric chains in the P3HT/3D-MoS2 functionalized composites. In addition, the functionalization of the 3D-MoS2 white phosphonic group increased the conjugation length, the percentage of crystallinity, and the conductivity. Likewise, the P3HT/MoS2 functionalized composites showed a decrease in the energy gap compared to P3HT. The functionalization of the 3D-MoS2 was successfully carried out, and a close interaction between the P3HT and 3D-MoS2 was determined. We achieved the in situ synthesis of P3HT/MoS2 composites by Grignard metathesis using functionalized 3D-MoS2 obtained by the hydrothermal method. We compared two functionalization groups with 3D-MoS2 and their subsequent polymerization with P3HT. Our work provides evidence for a better performance in composites functionalized with a phosphonate group because a phosphonic anchor provides strong electronic coupling with the 3D-MoS2. The above makes this material suitable for applications in flexible electronics photosensors, electrochromic devices, photocatalysis, and harvesting energy material in solar cells. [ABSTRACT FROM AUTHOR]

Conductive hydrogels have emerged as fascinating materials for flexible electronics because of their integrated conductivity, mechanical flexibility, and the possibility to introduce several smart functions. However, the swelling of hydrogels in aqueous environments significantly reduces their applicability where contact with water is unavoidable. In this study, a physically cross‐linked composite hydrogel is proposed, that is transparent, highly stretchable, anti‐swelling, capable of autonomous self‐healing, adhesive, and anti‐freezing. The hydrogel is synthesized through a simple one‐step photopolymerization in a novel deep eutectic solvent (DES)/water system. Dynamic physical interactions, including hydrophobic interaction, hydrogen bonding, and electrostatic interactions, confer remarkable transparency (92%), self‐healing capability (up to 94%), good adhesion to a wide array of substrates (91 to 199 kPa), high toughness (1.46 MJ m−3), excellent elongation at break (up to 2064%), and resistance to swelling in water (equilibrium swelling ratio of 3% in water for 30 days) even in solutions at different pH (pH 1–11), and in other solvents. The incorporation of a DES contributes to exceptional anti‐freezing performance. The transparent sensor achieves multifunctional sensing and human motion detection with high sensitivity and stability. Notably, the sensor demonstrates information transmission underwater through stretching and pressing, showcasing its immense potential in underwater flexible devices. [ABSTRACT FROM AUTHOR]

Multistable structures have widespread applications in the design of deployable aerospace systems, mechanical metamaterials, flexible electronics, and multimodal soft robotics due to their capability of shape reconfiguration between multiple stable states. Recently, the snap-folding of rings, often in the form of circles or polygons, has shown the capability of inducing diverse stable configurations. The natural curvature of the rod segment (curvature in its stress-free state) plays an important role in the elastic stability of these rings, determining the number and form of their stable configurations during folding. Here, we develop a general theoretical framework for the elastic stability analysis of segmented rings (e.g., polygons) based on an energy variational approach. Combining this framework with finite element simulations, we map out all planar stable configurations of various segmented rings and determine the natural curvature ranges of their multistable states. The theoretical and numerical results are validated through experiments, which demonstrate that a segmented ring with a rectangular cross-section can show up to six distinct planar stable states. The results also reveal that, by rationally designing the segment number and natural curvature of the segmented ring, its one-or multiloop configuration can store more strain energy than a circular ring of the same total length. We envision that the proposed strategy for achieving multistability in the current work will aid in the design of multifunctional, reconfigurable, and deployable structures. [ABSTRACT FROM AUTHOR]

The flexible electronic sensor is a critical component of wearable devices, generally requiring high stretchability, excellent transmittance, conductivity, self‐healing capability, and strong adhesion. However, designing ion‐conducting elastomers meeting all these requirements simultaneously remains a challenge. In this study, a novel approach is presented to fabricate highly stretchable, transparent, and self‐healing ion‐conducting elastomers, which are synthesized via photo‐polymerization of two polymerizable deep eutectic solvents (PDESs) monomers, i.e., methacrylic acid (MAA)/choline chloride (ChCl) and itaconic acid (IA)/ChCl. The as‐prepared ion‐conducting elastomers possess outstanding properties, including high transparency, conductivity, and the capability to adhere to various substrates. The elastomers also demonstrate ultra‐stretchability (up to 3900%) owing to a combination of covalent cross‐linking and noncovalent cross‐linking. In addition, the elastomers can recover up to 3250% strain and over 94.5% of their original conductivity after self‐healing at room temperature for 5 min, indicating remarkable mechanical and conductive self‐healing abilities. When utilized as strain sensors to monitor real‐time motion of human fingers, wrist, elbow, and knee joints, the elastomers exhibit stable and strong repetitive electrical signals, demonstrating excellent sensing performance for large‐scale movements of the human body. It is anticipated that these ion‐conducting elastomers will find promising applications in flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

Ionic thermoelectric (i‐TE) gels have attracted widespread attention in flexible electronics due to their flexibility, leakage‐free, low toxicity, and converting low‐grade waste heat into electricity. For practical application, it is strongly desirable to fabricate negative‐thermopower (n‐type) i‐TE gels with excellent mechanical performances, which is still a big challenge. Herein, a multi‐hierarchical network structure is proposed to simultaneously improve the TE and mechanical performance. Such structure including hierarchical hydrogen bonds, coordination bonds, and dense polymer chains is realized via the synergy of the coordination effect of polymer to cations and the Hofmeister effect of anions to polymer. As a result, the optimized gel exhibits not only negative thermopower up to −3.69 mV K−1 with a conductivity of 0.15 S m−1 at room temperature, but also outstanding tensile strength (>6.7 MPa), elongation at break (>1100%), and toughness (>43 MJ m−3), which is the toughest n‐type i‐TE gel reported to date. In addition, these n‐type i‐TE gels present good freeze tolerance (−58.53 °C) and dry resistance. Furthermore, the application potentials of the i‐TE device are proven in converting human thermal power into electricity. These findings provide a new way to obtain high‐performance n‐type i‐TE materials by synergistic anion and cation action on polymers. [ABSTRACT FROM AUTHOR]

The emergence of cutting‐edge cross‐disciplines has motivated the rapid development of wearable technology and flexible electronics. The flexibility and tunable properties of organic materials enable organic flexible electronics to adapt to complex surface deformations and achieve sensitive detection of physiological signals. The cost‐effectiveness of organic materials in mass production offers additional possibilities for the practical and commercialization of e‐skin technology. However, how to ensure stability and long‐term reliability while maintaining a highly sensitive, flexible, and stretchable is a challenge for e‐skins. In this review, the research progress and development trend of e‐skin is systematically summarized, especially the latest breakthroughs and innovations in the frontier of organic flexible electronics, and systematically review the applications of e‐skin in sensors, physiological monitoring, and energy supply. In addition, the review further discusses the prospects and current challenges for the application of organic flexible electronics in e‐skin, which provides a one‐stop reference for the development of e‐skin. [ABSTRACT FROM AUTHOR]

The state-of-the-art technology of fabricating printed copper electronics is focussed largely on thermal sintering restricting transition towards heat sensitive flexible substrates. Herein we report a pioneering technology which eliminates the need for conventional sintering. Biopolymer-stabilised copper particles are prepared such that they can be compressed at room temperature to generate air-stable films with very low resistivities (2.05 – 2.33 × 10−8 Ω m at 20 °C). A linear positive correlation of resistivity with temperature verifies excellent metallic character and electron microscopy confirms the formation of films with low porosity (< 4.6%). An aqueous ink formulation is used to fabricate conductive patterns on filter paper, first using a fountain/dip pen and then printing to deposit more defined patterns (R < 2 Ω). The remarkable conductivity and stability of the films, coupled with the sustainability of the approach could precipitate a paradigm-shift in the use of copper inks for printable electronics. [ABSTRACT FROM AUTHOR]