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• PBA and DMAA in ionogel offers abundant physical cross-linking. • Addition of [BMIM][TFSI] to ionogel provides environmental stability and adhesion. • The ionogel are prepared by a simple and convenient UV photoinitiation method. • Multifunctional ionogel are stretchable, electrically conductive, and self-healing. Conventional hydrogels integrated into sensor technologies face insufficient synergy between mechanical adaptability, conductive sensitivity, self-adhesion and self-healing. Therefore, we prepared an ionogel by photoinitiated polymerization using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonimide) salt ([BMIM][TFSI]) as the dispersing medium and ethyl 2-[[(butylamino)carbonyl]oxo]acrylate (PBA) and N,N-dimethylacrylamide (DMAA) as the monomers, which possess high stretching, high electrical conductivity, self-healing adhesion and remain very soft in extreme environments while being able to be twisted at will. The rich chemical cross-linking and physical cross-linking in the ionogel endows it with excellent fracture strength and elongation at break at room temperature, while its deformation durability is very strong, tensile/release cycling 5000 times still shows stable resistance change, and it has a good self-repairing ability, and its repairing efficiency can reach more than 90 % after 12 h of repairing at 20 ℃. In addition, the addition of fluorinated ionic liquids resulted in excellent environmental stability, virtually unchanged quality for 21 days in an 80 °C oven as well as strong adhesion to different substrates. The ionogel designed in this work have promising applications in wearable devices and electronics. [ABSTRACT FROM AUTHOR]

• DN hydrogel electrolytes based on CS-PAPILs are constructed via a green strategy. • Unique structural feature of CS-PAPILs endows the DN hydrogel with excellent antibacterial property and ionic conductivity. • The assembled supercapacitor exhibits high capacitance and long-term cycling stability at −50 °C. • The strain sensor well monitors various human motions. Polymeric conductive hydrogels have been highlighted for use in flexible electronics, and there is still a challenge to design and fabricate a high-performance hydrogel electrolyte with integrated and multiple properties, such as sustainability, stretchability and compressibility, ionic conductivity, antibacterial property, strain sensitivity, and low-temperature tolerance. Herein, chitosan (CS) derived poly(aprotic/protic ionic liquids) (CS-PAPILs) are facilely prepared by taking the structural and sustainable features of chitosan and betaine hydrochloride, which are used as a functional component for the fabrication of CS-PAPILs/polyacrylamide (PAM)/LiCl (CS-PAPILs/PAM/LiCl) double-network (DN) hydrogel electrolyte via an in situ polymerization of AM and then a soaking strategy in LiCl aqueous solution. The achieved DN hydrogels exhibit tunable mechanical performance (tensile strength of 70–900 kPa, elastic modulus of 31.5–484 kPa, high compressibility (4450 kPa at 80 % strain), superior low-temperature tolerance (freezing point < -85 °C), anti-dehydration performance, high ionic conductivity at 25/-50 °C (94.8/4.6 mS cm−1), and excellent antibacterial activity. As a proof of concept, an assembled flexible and anti-freezing supercapacitor by the as-prepared DN hydrogel electrolyte demonstrated a high specific capacitance of 108.4F/g (at 2 A/g) and impressive cycling stability over 50,000 cycles at temperature as low as −50 °C. Furthermore, a wearable strain sensor based on the DN hydrogel was also demonstrated, and the sensor can be successfully attached to the human joints to monitor various human motions. [ABSTRACT FROM AUTHOR]

[Display omitted] • PEDOT:PSS/PEG-UPy dispersion in water/isopropanol (IPA) as a "E-ink" suitable for flexible and folding film processing via drop coating, spin coating, blade coating and 3D printing. • PEDOT:PSS/PEG-UPy(10 wt%) film showing excellent mechanical, surface-interface and electrical performances with strong water (ultra-long > 150 days) and dirt resistance. • Embing supramolecular chain-expanding unit UPy into polyurethane molecular backbone, abundant hydrogen-bonded cross-linking interaction and "good" solvent effect of IPA to PEDOT:PSS enabling such electronic "paper" to make up for deficiencies of paper-based electronics and "E-paper" display technologies. Organic electrochromic conducting polymers (CPs) are at the forefront of flexible and ultra-thin display electronics. Solution processable poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) exhibits excellent electrical and electrochemical behavior in line with great processability, stability, and other promising properties. However, their uses are limited by the weak mechanical properties, wet instability, as well as inevitable conflicts among different functionalities and structural characteristics, etc. In this study, we designed and fabricated a high-mechanical-strength electronic "paper", PEDOT:PSS/PEG-UPy film, employed a thermoplastic polyurethane poly(ethylene glycol)-2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol (PEG-UPy) using diverse processing (drop coating, spin coating, blade coating and 3D printing) of its "electric ink (E-ink)" from the mechanical mixture of its isopropanol (IPA) solution with aqueous PEDOT:PSS dispersion. Compared to PEDOT:PSS film, the incorporation of supramolecular chain-expanding unit 2-amino-4-hydroxy-6-methylpyrimidine (UPy) into the PEG-UPy molecular backbone resulted into optimized self-supporting (substrate-free) film of PEDOT:PSS/PEG-UPy(10 wt%) which showed great flexibility, enhanced mechanical strength (elongation at break 47.08 %, tensile strength of 19.16 MPa, toughness 7.973 MJ m−3), considerable electrical properties (0.509 S cm−1), desirable physical properties including resistance to abrasion and solvent-wiping, and excellent surface-interface properties (e.g., hardness of 3H, adhesion of level 0, glossiness of 91). Its electrochromic capabilities include an optical contrast (ΔT) value of 67 %, a fast redox reaction (4 s and 3 s, respectively), and a coloring efficiency (722.19 cm2 C−1). Similar to paper, they can be easily tailored or folded into a variety of forms, but have greater advances on dense morphology, flat surface, considerable optical transparency (79.5 %), as well as robust resistance to mechanical damage (in the case of bending, stretching, and folding, etc.), water (immersing > 150 days), and dirt. The combined effect of molecular design of PEG-UPy, abundant hydrogen-bonded cross-linking interaction and "good" solvent effect of IPA to PEDOT:PSS play important roles in this system. This is the first work on solution processable PEDOT:PSS-based electrochromic "paper" being able to meet much comprehensive performance requirements for the application in practical complex working environment. [ABSTRACT FROM AUTHOR]

This work proposes a facile strategy of constructing gradient entanglement dual network (GEDN) hydrogel with high surface area and greatly improved mechanical/sensing performance. The prepared hydrogel strain/pressure sensors show great potential in body movement detection and character recognition. [Display omitted] Due to the advantages of high mechanical compliance and good biocompatibility, conductive hydrogels exhibit great application potential in flexible electronics. As the requirements in high sensitivity and high mechanical performance are increasing, the construction of patterned surfaces has been proven an effective approach, yet most of the common methods are complex and high-cost. Herein, we proposed a facile strategy to construct gradient entanglement dual network (GEDN) hydrogel with spontaneously patterned surface and consequent high surface area, which greatly enhances the sensitivity of hydrogel sensors. The strategy of high entanglement as well as the dual network in hydrogel achieved greatly improved mechanical performance. The prepared polyvinyl alcohol (PVA)/gradient entangled polyacrylamide (PAAm) DN and surface-patterned hydrogel possesses the advantages of excellent stretchability (681 %), high tensile strength (1.01 MPa), toughness (4.23 MJ/m3), and relatively low mechanical hysteresis. Meanwhile, it showed high sensitivity, wide detection range, and rapid response both as strain sensor (GF max = 10.96, detection range = 681 %, an average response time of 170 ms) and pressure sensor (S max = 0.17 kPa−1, detection range = 225 kPa, an average response time of 230 ms). In summary, it provides a new strategy for design of the multifunctional high-performance flexible devices, exhibiting great application prospects. [ABSTRACT FROM AUTHOR]

[Display omitted] • The HA@PPy composite film is developed via the in-situ loading of PPy onto the HA. • The HA@PPy film possesses remarkable tensile strength and exceptional toughness. • The HA@PPy film shows a preeminent EMI SE of 45.5 dB at a thickness of 26.3 µm. • The HA@PPy film has superior electro-/photothermal performance and fire retardancy. • High-performance HA@PPy film exhibits versatile applications. High-strength, ultratough, multifunctional polymer-based electromagnetic interference (EMI) shielding nanocomposite films have colossal application potential in artificial intelligence, 5G communications, and flexible electronics. In this work, a large-scale, high-strength, and ultratough heterocyclic aramid@polypyrrole (HA@PPy) composite film is developed via the in-situ loading of PPy onto the HA template. The synthesized films achieve remarkable mechanical properties and high electronic conductivity by using the template effect of HA to guide the assembly of conductive polymers. When the content of PPy is 45 wt%, the HA@PPy (HP45) film possesses excellent tensile strength (240.3 MPa), significant elongation at break (25.9 %), outstanding toughness (53.1 MJ m−3), and exceptional folding durability owing to strong hydrogen bond interaction between PPy and HA. Furthermore, thanks to the highly connected conductive paths formed by PPy, the HP45 film exhibits satisfactory EMI shielding effectiveness (EMI SE) of 45.5 dB and specific EMI SE of 14691.6 dB cm2 g−1 at an ultra-thin thickness (26.3 μm). The HP45 film also demonstrates excellent electromagnetic protection, electro-/photothermal deicing, thermal therapy, and flame retardancy applications. Therefore, high-performance and multifunctional HA@PPy films have substantial potential for widespread application in EMI shielding and thermal management. [ABSTRACT FROM AUTHOR]

[Display omitted] • Continuous high-strength hydrogel fibers were encapsulated with silicone rubber. • Amphiphilic stearic acid was embedded to enhance the interface bonding. • Composite hydrogel fibers have excellent anti-drying and anti-swelling properties. • The composite hydrogel fiber showed an excellent underwater sensing performance. Conductive hydrogel fibers with superior mechanical and electrical performance have been developed for flexible wearable electronics, but the inherent properties of hydrogels for dehydration in the atmosphere and underwater swelling limit its widespread application. In this work, a silicone rubber encapsulated hydrogel fiber with enhanced interface bonding, excellent mechanical and electrical properties was successfully developed, in which the core polyvinyl alcohol/sodium alginate hydrogel fiber was prepared by a continuous wet-spinning and the following freeze-thawing. The interlocking dual-network structure and the improved ion transport by negatively charged sodium alginate gave the core hydrogel fiber excellent strength of 4.15 MPa, elongation-at-break of 1531 % and electrical conductivity of 17.01 S·m−1. After encapsulation using a silicone rubber, the composite hydrogel fiber showed a low expansion rate underwater for 7 days of 1.00 ± 0.21 % and low weight loss in the air over 36 h of 38.67 ± 0.38 %. And the interface bonding of the core hydrogel fiber and silicone layer was enhanced by the bridging effect of amphiphilic stearic acid. Therefore, the composite hydrogel fiber demonstrated a great potential as a strain sensor for underwater communication to ensure the safety of individuals in an underwater environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanical and electrical performances remain stable for at least 22 months in the open air. • Ionogel can withstand 1,000,000 cycles of stretching even with a notch. • Thermoplasticity of ionogel enabled it to be easily reshaped into various forms and recycle. • Ionogel sensors exhibit sensitive sensing performance at various temperature. The longevity of flexible electronics substantially influences their viability for practical use. At present, the service life of pliable devices utilizing conductive gels is frequently compromised due to factors inclusive but not limited to solvent loss. Taking cues from the steadfast structure of human tissues, we hereby delineate a solvent-assisted strategy to fabricate ionogels, predicated on a supramolecular network of hydrogen bonds. Upon subjecting these ionogels to realistic operational environments, it has been empirically ascertained that they maintain a steadfast mechanical and electrical consistency for a minimum duration of 22 months. In terms of dynamic stretchability, they effortlessly endure one million stretch cycles, even when faced with a notch. The induction of a supramolecular structure within the ionogel not only confers exceptional mechanical attributes but also simultaneously enhances conductivity, a feat paralleled by few recent explorations. Furthermore, these ionogels boast of superior anti-freezing and adhesive characteristics, including a toughness extending up to 17.96 MJ/m3 at an ultra-low temperature of −50 °C, and an adhesive capacity permitting movement and bearing of items weighing over 10,000 times its own weight, the lap-shear strength can reach 30.2 kPa. Intriguingly, these gels demonstrate thermoplastic behavior, which facilitates their easy reshaping into diverse forms. Such compelling attributes amplify the potential of supramolecular ionogels, positioning them as formidable contenders for flexible electronics in stringent and challenging scenarios. [ABSTRACT FROM AUTHOR]

• 2D MXenes are systematically reviewed as flexible electrodes. • Printing methods are discussed. • Applications of 2D MXenes for printing energy storage devices are summarized. • Future research directions in MXenes for printing electronics are suggested. MXenes, as a prominent class of two-dimensional (2D) materials have gained significant attention in various research fields over the past decade. In recent years, MXene-based materials have emerged as promising candidates for conductive electrodes in printed electronics due to their unique properties, including high electrical conductivity, mechanical flexibility, stability, compatibility, and large surface area. These attributes make MXenes highly desirable for flexible printable electronics. MXenes have demonstrated great potential in energy storage systems, particularly in supercapacitors (SCs) and batteries. This review provides an overview of recent advancements in MXene synthesis and their significance in energy storage applications. Specifically, it summarizes the electrochemical performance of SCs and batteries utilizing MXene-based materials. Moreover,the review highlights current challenges associated with MXene inks and shedding light on new opportunities for integrating MXenes into diverse electronic devices and systems. [ABSTRACT FROM AUTHOR]

• High-performance flexible strain sensors based on scorpion-leg-inspired gradient crack arrays are achieved. • Gradient crack arrays controllably form in periodic thickness-gradient metal films on flexible substrates. • The cracks are progressively open under mechanical strain, behaving a unique sensing mechanism. • Applications for human activity monitoring and information encryption are demonstrated. Wearable flexible strain sensors based on conductive films have shown great application potential in many high-tech fields. They have high requirements for synergistic performances of sensitivity, flexibility, stability and durability. However, overcoming the trade-off between high sensitivity and high stretchability is still a great challenge in this research. Here we develop a facile strategy to prepare high-performance flexible strain sensors based on gradient crack arrays inspired by the gradient slits on scorpion legs. The gradient crack arrays with branched or hierarchical features controllably form in a periodic thickness-gradient metal film prepared by one-step masking technique on a flexible substrate. The cracks are progressively open from the thickest film region to the thinnest one under mechanical strain, behaving a unique sensing mechanism. As a result, the gradient crack-based strain sensors possess excellent comprehensive performances including high sensitivity (up to 21000), wide sensing range (∼70 %), low detection limit (0.02 %), quick response speed (below to 80 ms), excellent stability and durability (up to 15,000 cycles at 5 % strain). As demonstration of applications, the sensors are used to monitor various human activities and to express and encrypt information by bending bidirectionally. This work provides a novel way to fabricate highly sensitive, stretchable, robust, multifunctional, crack-based flexible strain sensors, which would greatly expand the applications in flexible electronics and wearable devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • A biobased, degradable and directional porous aerogel was prepared for piezoresistive pressure sensor. • The dual-conductive network by C-CNTs and MXene endowed the sensor with excellent sensing performances. • The superior degradability of the sensor was beneficial for environment protection and resource recycling. • The sensor was successfully applied for human motion detection and speech recognition of Chinese sentences. The rapid growth of wearable electronics, healthcare monitoring, and human–computer interaction has sparked growing interest in flexible piezoresistive pressure sensors, which in turn raised considerable concerns about the increasingly serious environmental pollution caused by electronic waste. Herein, a radial inward directional freezing-drying method was proposed to prepare biobased, degradable and directional porous carboxymethyl chitosan/lignosulfonate sodium aerogel with dual-conductive network constructed by carboxylated multiwalled carbon nanotubes (C-CNTs) and MXene for piezoresistive pressure sensor. Owing to the synergistic conductive network of C-CNTs and MXene as well as directional porous structure, the sensor exhibited high sensitivity (2.33 kPa−1 in 0–10 kPa, 1.04 kPa−1 in 10–31 kPa, 0.53 kPa−1 in 31–53 kPa), fast response (response/recovery time of 140/60 ms), and excellent repeatability (2,000 loading–unloading cycles). Moreover, the sensor was successfully applied for human motion detection, healthy monitoring, micro-expression identification, and speech recognition. In addition, the aerogel for sensor was able to be completely degraded within 70 h in 1 M hydrochloric acid solution or partially degraded in boiling water within 2.5 h for the recycling of conductive materials, which was beneficial for not only environment protection but also saving resource. Our findings conceivably stand out as a new strategy to prepare environmentally friendly and high-performance piezoresistive pressure sensor and will promote the further development and application of flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Janus film with tri-function is designed and fabricated by a facile electrospinning. • Film has obvious color switchable, reversible and stable thermochromic capability. • Macro + micro Janus structures avoid adverse effects to achieve superior tri-functions. • Film has superb thermochromism, high conductive anisotropy and intense fluorescence. • Film achieves working state visualization of conductive circuit in dark environment. Multi-functionalized thermochromic materials will greatly expand their application scopes. In this work, two functions of electrical conductivity and fluorescence are innovatively integrated into a thermochromic material by designing specific "macro + micro" Janus structures. Tri-functional thermochromic-anisotropic conductive-fluorescent thermochromic microcapsules-45 °C (TCM-45)/polymethyl methacrylate (PMMA) microfibers non-array&{[polypyrrole (PPy)/PMMA]//[Coumarin/PMMA] Janus microfibers array} up-down Janus film (named as TCFJAJF) is constructed by two-step electrospinning techniques of "single axis + parallel axis". The up layer of TCFJAJF is TCM-45/PMMA microfibers non-array film (defined as U-TCFJAJF, viz. thermochromic layer) and the down layer of TCFJAJF is [PPy/PMMA]//[Coumarin/PMMA] Janus microfibers array film (denoted as D-TCFJAJF, viz. anisotropic conductive-fluorescent layer). The macroscopic up-down Janus structure eliminates the mutual influences between D-TCFJAJF and U-TCFJAJF. U-TCFJAJF has excellent color conversion and fading/coloring performances, achieving a reversible and multiple colors conversion from blue to white upon heating from 25 to 45 °C. A new concept of "transient thermal printing" is proposed based on fast thermal coloring/fading conversion of thermally printed patterns on film. Meanwhile, the microscopic Janus microfiber structure of D-TCFJAJF largely alleviates absorption to the excitation light and emission light of Coumarin by PPy and influence of Coumarin on conduction of PPy, ensuring the intense fluorescence and high conductivity. Due to the ordered arrangement of Janus microfibers, D-TCFJAJF has excellent anisotropic conductivity. As a demo application, TCFJAJF as a conductor can light up LED bulbs in a microcircuit and emit bright blue fluorescence under UV light excitation, achieving the working state visualization of the conductive microcircuit in dark surroundings. The multi-functionalized thermochromic film will have huge application prospects in fields of temperature monitoring, transient information reading and displaying, flexible electronics, fluorescent labeling and thermal-fluorescent dual encryption anti-counterfeiting, etc. [ABSTRACT FROM AUTHOR]

A general strategy is reported for efficiently fabricating high-performance stretchable conductive shape memory nanocomposites (SCSMNCs) based on the photo-mediated multiscale structural design. The combination of the high stretchability, high conductivity and excellent shape memory behavior provides SCSMNCs with long-range adaptive electrical performance and mechanical properties, which significantly promote the advanced applications of SCSMNCs for programmable electronics. [Display omitted] • The photo-mediated multiscale structural design is proposed to prepare stretchable conductive shape memory nanocomposites. • The rational design of photo reactions enables to construct a conjoined polymeric network in nanocomposites as fast as 68 s. • Metamaterial design provides increased stretchability without compromising other key properties of the nanocomposites. • The designed stretchable conductive shape memory nanocomposites can be used in function-programmable electronics. Conductive shape-memory nanocomposites are very promising in flexible electronics, soft robotics, wearable sensors, etc. However, achieving a balance between conductivity, shape-memory behavior, and stretchability is still challenging in this field. Here, we report stretchable conductive shape-memory nanocomposites (SCSMNCs) prepared through photo-mediated multiscale structural design (PMMSD). At a molecular level, we utilize highly efficient photo-mediated radical polymerization and hydrogen abstraction reaction to fast construct a conjoined polymeric network in one step (∼68 s). Hybrid nanofibers are, meanwhile, introduced to generate highly conductive networks. This rational design facilitates the fabrication of nanocomposites simultaneously exhibiting excellent shape-memory behavior, high conductivity, improved mechanical properties, and rapid gelation. Mechanics-guided metamaterial design can be then produced in macro-scale by additive manufacturing to further increase the stretchability of the nanocomposites without compromising other key properties. Consequently, benefitting from the PMMSD strategy, the stretching strain of SCSMNCs improves significantly by 19 times compared to the samples lacking network and structural design, with conductivity > 105 S/m, shape fixation ratio and shape recovery ratio > 95 %. Notably, the combination of the increased stretchability, high conductivity and excellent shape-memory behavior endows the SCSMNCs with adaptive electrical and mechanical properties over long ranges. Based on these advanced performances, we demonstrate the utility of the designed SCSMNCs as function-programmable electromagnetic interference shields and wearable sensors. We anticipate this study will pave a new way for the design and application of high-performance SCSMNCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible, air-permeable, and conductive non-woven silk fabric (nSF) was prepared. • A TPU-based honeycomb microporous structure was constructed within the silk fibers. • The conductive silk fabric shows stable humidity response and thermal response. • The conductive silk fabric displays reliable strain sensing ability. • The silk fabric shows effective EMI shielding performance and Joule heating management. Silk-based conductive composites have attracted much attention for applications in flexible smart electronics. However, silk-based conductive composites that combine high air permeability, Joule heat management, electromagnetic interference (EMI) shielding and multimodal responsiveness are still challenging. In this paper, flexible porous non-woven silk fabric (nSF)-based conductive composites with the aforementioned properties are designed and developed by a freeze-induced assembly and surface micro-dissolution adhesion (FASMA) process to introduce carbonyl carbon nanotubes (C-CNTs), MXene and thermoplastic polyurethanes (TPU) into the inter-fiber network structure of nSF, with the aim of constructing a high-performance multimodal sensing platform. Functioning as a flexible strain sensor, the nSF-based composite can detect strains as low as 0.05 % with rapid response and recovery time of 125 ms and 146 ms, respectively, and can be used to detect full-size human motion signals. The nSF-based composite has a good humidity response at 0–85 % relative humidity (RH) and a sensitive and reliable thermal response. In additionally, the nSF-based composites also have Joule heat management and EMI shielding functions. All these multi-functional applications demonstrate the advantages of the prepared flexible porous nSF-based composites in the field of flexible smart electronics. [ABSTRACT FROM AUTHOR]

Self-assembly polysaccharide network regulated hydrogel was obtained via one-step freeze–thaw process. the as-prepared PVA/ADSP hydrogel displayed great mechanical performance, environmental stability (water-retention and anti-freezing) and conductivity with the application in sensing and human–machine interaction. [Display omitted] • Self-assembly polysaccharide network regulated hydrogel was fabricated. • Physical cross-linked PVA/ADSP hydrogel exhibited the great mechanical property. • PVA/ADSP hydrogel presented anti-freezing and water retention performance. • Hydrogel was acted as sensor for health monitoring and human–machine interaction. Ionic conducting hydrogel acted as a promising candidate in flexible electronic device, however, the intrinsic properties of weak mechanical strength, conductivity and environmental instability still are the challenging task. Herein, an assembled polysaccharide network (acetylated distarch phosphate) regulated polyvinyl alcohol (PVA/ADSP) hydrogel is fabricated via one-step freeze–thaw method, the stress, elongation at break, elastic modulus, and toughness could reach 2.26 MPa, 818.60 %, 0.95 MPa, and 12.23 kJ/m3, respectively. At the same time, the binary solution interlocked structure and salt are introduced into the PVA/ADSP hydrogel realizing the great environmental stability (water-retention and anti-freezing) and conductivity (3.59 S/m). PVA/ADSP hydrogel act as strain sensor presenting the great responsibility (128 ms), strain sensitivity (GF=1.82 at 350–500 % of strain) and durability. On account of the excellent sensing characteristics, the PVA/ADSP hydrogel could reliably, accurately and consistently detect most of human exercises and subtle physiological activities (electrocardiography) in real-time. Moreover, PVA/ADSP hydrogel is also utilized to control robotic hand realizing the human–machine interaction. This work provides a novelty regulated approach for conducting hydrogel via self-assembled polysaccharide network, which contributes to the innovative advancement of flexible wearable electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The as-synthesized InHCF exhibits satisfied K+-storage performance. • DFT and experiment results reveal that the InHCF preferentially achieves K+ (de)intercalation rather than Zn2+. • The InHCF can deliver a high capacity of 60.6 mAh g−1 and prominent rate capability. • A novel single coaxially-fibrous K//Zn battery was successfully assembled with a high discharge plateau of 1.7 V. • The CFAR K//Zn battery shows high energy density, excellent weavability and mechanical flexibility. The design of eco-friendly fibrous aqueous rechargeable Zn-based batteries is important for the advancement of flexible electronics. But it is still remains extremely difficult to develop high-voltage fibrous Zn-based batteries on a single-fiber architecture that directly influence their energy density. Furthermore, the sluggish Zn2+ diffusion kinetics and tough electrostatic interaction seriously astrict to further move ahead for the Zn-based batteries. Herein, we demonstrate a high-voltage coaxially-fibrous aqueous rechargeable (CFAR) K//Zn battery based on open-framework indium hexacyanoferrate (InHCF) cathode. The resultant assembled CFAR K//Zn battery provides an eminent voltage of 1.70 V and a superhigh energy density of 197.88 mWh cm-3 at 170.4 mW cm-3. More importantly, our assembled CFAR K//Zn battery exhibits excellent mechanical steadiness with the capacity retention of 92.7 % by following bending at 90° for 4000 times. Therefore, the design of the new-style architecture in high-voltage CFAR K//Zn batteries provides a fresh strategy for economic, reliable, and high-energy-density wearable energy-storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of imidazolium ionic cellulose by modification with imidazolium ionic. • ILHPMC/PAA were prepared by imidazolium ionic cellulose with acrylic acid. • ILHPMC/PAA with high flexibility and excellent electrical conductivity. • The hydrogel has a tensile strength of 1.2 MPa, a high tensile strain of 683.4 %. • This provides a new strategy for ionic cellulose-based wearable conductive sensors. With the rapid development of the field of flexible electronics, it is necessary to develop more new flexible sensor materials with a high degree of flexibility, stretchability, biosafety, and good electrical conductivity to better achieve wearable with the human body. Cellulose hydrogels are promising building blocks for flexible sensors due to their renewability and excellent mechanical strength properties. In this study, we demonstrate an imidazolium ionic cellulose/polyacrylic acid hydrogel (ILHPMC/PAA) with high flexibility, antimicrobial properties and electrical conductivity. Firstly, epoxidized imidazole ionic liquids were synthesized using methyl imidazole as raw material, and imidazole ionic cellulose was prepared by grafting modified hydroxypropyl methyl cellulose (HPMC). Imidazolium ionic cellulose hydrogels were prepared by one-step cross-linking and forming a copolymeric bi-network with acrylic acid according to the principle of free radical polymerisation. This hydrogel has high flexibility, stretchability, biocompatibility, and desired electrical conductivity due to the introduction of imidazole ions, and the sensing sensitivity factor (GF) reaches 6.83. The tensile strength can be up to 1.2 MPa, and it also has excellent antibacterial properties, with an antibacterial zone diameter of up to 29.25 mm. This provides insights into the development of cellulose-based sustainable sensing hydrogel sensors for wearable ionic conductive sensing. [ABSTRACT FROM AUTHOR]

• Super-flexible, wearable, ultralight self-driven SBPD achieved through fabricating an a-Ga 2 O 3 film on different paper substrates (glossy, parchment, 75 GSM) with interdigitated Pt electrodes via magnetron sputtering. • The self-driven device exhibits an ultra-high responsivity of 20.96 mAW−1 and fast response speeds (65/67 ms) on a 75 GSM paper for 266 nm wavelength. • The device on 75 GSM paper demonstrates a UV-C/Vis rejection ratio exceeding ∼ 106, a high specific detectivity (∼1011 Jones), ultra-high responsivity (1.38 × 103 mAW−1), and an ultra-low NEP of 2.44 × 10-13 WHz−1/2 @ 5 V bias. • Exhibited exceptional flexibility, withstanding bending endurance (lo/l = 5) and maintaining stable performance throughout 600 bending cycles over two months. To address the growing demand for wearable optoelectronic devices in secure communication, environmental monitoring, biomedical, and military applications, the development of self-driven solar-blind photodetectors (SBPDs) is crucial. This work reports the fabrication of super-flexible, wearable, and ultralight self-driven SBPD based on an amorphous-Ga 2 O 3 film grown on various paper substrates (including glossy, parchment, and 75 GSM paper) with interdigitated Pt electrodes using a magnetron sputtering. The developed device on glossy, parchment, and 75 GSM paper exhibits superior responsivity of 8.30 mAW−1, 14.53 mAW−1, and 20.96 mAW−1, along with a fast response speed of 115/118 ms, 90/95 ms, and 65/67 ms for 266 nm light irradiation under self-driven conditions. Comparatively superior performance is recorded for 75 GSM paper-based device, owing to their surface roughness, porosity, and microfibrous structure, which enhance light absorption in the device. In addition, the developed device shows an ultraviolet C-to-visible rejection ratio of over ∼ 106, a high specific detectivity of 2.01 × 1011 Jones, a high responsivity of 1.38 × 103 mAW−1 and a low noise equivalent power of 2.44 × 10-13 WHz−1/2 at a 5 V bias on 75 GSM paper. The photocurrent remains close to its initial values even when bent to l o /l = 5, demonstrating outstanding flexibility, bending endurance, and deformability. The performance of the self-driven PD remains stable over two months and steady up to 600 bending cycles. Further, the fabricated device underwent thorough testing across various wearable applications, and the analysis demonstrates discernible alteration in its performance across real-world scenarios. This technique paves the way for developing self-driven paper-based SBPDs with high-performance, wearable, next-generation flexible optoelectronic device applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel photopolymerizable ink formulations based on conducting polymer were prepared. • DLP-based-3D printing of the formulation yields multi-functional hydrogels. • 3D-printed gels are mechanically robust and electrically conductive. • Printed gels resist freezing and maintain conductivity at sub-zero temperatures. • Gradient crosslinking of printed gels induces shape-morphing behavior. High-performance hydrogel-based electronic devices require conducting hydrogels. Conducting hydrogels that are stretchable, soft, and biocompatible are in much demand to fabricate human–machine interfaces, wearable devices, soft robotics, and many other applications. We present a new generation polymeric formulation to prepare hydrogels by digital light processing (DLP)-based three-dimensional (3D) printing technology with visible light that are anti-freezing, electrically conductive, tough, stretchable, and non-toxic. The printed conducting hydrogels have exceptional water-holding capability at atmospheric conditions and tolerance to freezing over a wide range of temperatures from − 80 to 45 °C. The inks are amenable to the manufacturing of four-dimensional (4D)-printed hydrogels that can elicit pre-programmed structural deformations. This work presents polymeric formulations for potentially designing ultrafast programmable electronic devices with printed hydrogel electronics in various biomedical applications, soft robotics, biosensors, flexible electronics, human–machine interfaces, and health monitors for use under extreme environmental conditions. [ABSTRACT FROM AUTHOR]

• A new class of cross-linked poly(glycerol-co-δ-valerolactone) urethane substrates are developed for flexible and wearable electronics. • A cost-effective synthetic method was developed for these substrates, utilizing a cross-linking reaction between poly(glycerol-co-δ-valerolactone) triol and a specific diisocyanate on a glass mold. • The substrates exhibited exceptional properties, including high transparency (∼90 %), high stretchability (∼673 %), biodegradability, and thermal stability (∼300 °C). • Transparent conducting electrodes (TCEs), characterized by mechanical robustness and high stretchability, were fabricated from these sustainable substrates. The fabrication process incorporated novel steps, such as using polyvinyl alcohol (PVA) as a wet film leveling agent and a heat and pressure-based nano-welding technique. • The TCEs were applied in various sensor applications, including strain, pressure, curvature sensors, and heaters, showcasing their broad utility. • Pressure sensors effectively monitored human motion in real-time, while heaters were evaluated for their performance in low-temperature conditions. Substrates form the backbone of most flexible electronic devices. This study reports sustainable substrates based on a new class of cross-linked poly(glycerol-co-δ-valerolactone) urethanes for flexible and stretchable electronic devices. A cost-effective method is described for preparing these substrates via thermal cross-linking polymerization of poly(glycerol- co -δ-valerolactone) triol with diisocyanates on a glass mold. The developed substrates display high flexibility, stretchability (∼673 %), transparency (∼90 %), thermal stability (∼300 °C), and degradability, essential for next-generation flexible devices. Using synthesized polymers as substrates, we develop stretchable transparent conducting electrodes (TCEs). An innovative fabrication technique involves applying a thin electrospun polyvinyl alcohol (PVA) nanofiber mat as wet film leveling agent to enhance the adhesion and even distribution of sprayed silver nanowires. Through heat and pressure-based nanowelding of silver nanowire junctions, we create TCEs with uniform conductivity, low sheet resistance (∼40 Ω sq−1), and good transparency (∼70 %). To demonstrate the versatility of stretchable TCEs, we fabricated flexible devices like capacitive sensors, curvature sensors, strain sensors, and heaters. The TCE strain sensor exhibits low creep and consistent performance from 5–45 % strain, maintaining signal stability for over 200 cycles at 10 kPa. The fabricated pressure sensor responds to pressures from 0.5–300 kPa with a maximum sensitivity of 2.43 kPa−1 and stability for at least 2600 cycles. The curvature sensor shows increased capacitance at curvatures up to 600 m−1. The flexible heater reaches 85 °C in under 10 s with 5.5 V and responds rapidly under 0–35 % strain. These devices effectively detect human motion, serving as wearable sensors and heaters in cold conditions, demonstrating real-life applicability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SP-PENG possesses the excellent output voltage up to 49.2 V, which is 11.7 times higher than the PVDF-PENG. • It is confirmed that the low-resistivity SnO 2 filler has an enhancing effect on the local electric field strength of the SP composite fibers, thereby promoting electrostatic polarization. • A self-powered wireless sensing-monitoring system is realized by the integrating circuit with SP-PENG. Furthermore, PENG's potential for motion recognition with a deep learning model is demonstrated. A recognition accuracy of 100% is achieved through handwriting letters A, B, C, and D. With the rapid development of the Internet of Things and flexible electronics, piezoelectric nanogenerators (PENGs) based on polyvinylidene fluoride (PVDF) have demonstrated a wide range of potential applications in wearable devices. However, there are still challenges in developing high-performance PENGs, which affect their potential applications in more scenarios. Herein, we propose a SnO 2 -PVDF (SP)-PENG based on low-cost and environment-friendly SnO 2 nanoparticles modulated via electrospinning, achieving outstanding piezoelectric output performance. The piezoelectric output of SP-PENG is up to 49.2 V, which is 11.7 times higher than that of pure PVDF-PENG. From the theoretical perspective, the enhanced electrostatic polarization is achieved by the strengthened local electric field due to the presence of low-resistivity SnO 2 in the SP fibers. The mechanism of enhanced electrostatic polarization is also declared by COMSOL simulation. Moreover, the SP-PENG exhibits excellent durability (41,600 cycles) and long-term stability (8 months). A self-powered wireless sensing-monitoring system is realized by combining SP-PENG with circuit design. The motion recognition system is accomplished by integrating an assistance of a 1D CNN-LSTM joint learning model, which is verified by an alphabetic handwriting recognition with a classification accuracy up to 100 %. This study provides significant insights for enhancing the performance of PENGs and offers valuable guidance for exploring the application of PENGs in flexible electronics and artificial intelligence. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile process yields flexible, high-performance ammonia sensors. • Uniquely, the method achieves unprecedented CNT-loading in NRL composite. • Enhanced strength from a mesh-like structure offers sensor stability. • Reversible sensing of ammonia, even at low concentrations, was achieved. • Radiation cross-linking stabilizes sensors while maintaining NRL properties. • PALS and SEM confirm encapsulation of NRL with CNT. Ammonia vapor sensors are indispensable for a wide range of applications, from industrial monitoring to medical diagnosis. However, the development of flexible and standalone ammonia sensors has remained a significant challenge. This study presents a novel, low-cost, and facile approach for fabricating ammonia sensors that exhibit high sensitivity, flexibility, and standalone functionality, with immense potential for applications in the rapidly expanding field of flexible electronics. The sensors were fabricated using a new approach: localized coalescence of Natural Rubber Latex (NRL) onto carbon nanotubes (CNTs), which leads to exceptionally high carbon nanotube loading along with complete flexibility and mechanical integrity, surpassing the limitations of conventional methodologies. The localized coalescence (NRL@CNT) of the CNTs resulted in a mesh-like structure that significantly improved the stiffness and strength of the composite. Radiation cross-linking was employed to further stabilize the CNT network architecture, ensuring high conductivity even under deformation, while preserving the intrinsic properties of the NRL, as confirmed by dynamic mechanical analysis and positron annihilation lifetime spectroscopy. Sensors fabricated on the spot by piercing two gold-plated steel pins in compression-molded thin films of gamma radiation processed NRL@CNT demonstrated broad-range sensitivity and high selectivity for ammonia vapors, exhibiting a linear response within the 8–500 µmol/L range with an impressive correlation coefficient of 0.99 and a low detection limit. This fabrication method is straightforward, scalable, and environmentally benign, offering a wide range of potential applications in fields such as healthcare, environmental monitoring, and flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] Eutectogels are emerging as attractive soft conductors for flexible wearable electronics and next-generation human–computer interaction devices owing to their inherent environmental stability and high ionic conductivity. However, it remains a challenge to achieve efficient multifunctional integration of flexible wearable sensors through a convenient and environment-friendly approach. Herein, the eutectogel with excellent mechanical properties, self-healing, environmental tolerance, reversibly fluorescent and high conductivity was prepared via a facile UV-initiated one-step polymerization. Abundant hydrogen bonds and multiple dynamic interactions impart the eutectogel with excellent tensile strength (1.99 MPa), high stretchability (>1500 %), high toughness (20.85 MJ/m3), strong self-adhesion (192 kPa), and autonomously self-healing (>92 %) capabilities. Due to the dynamic photochemical reaction of the anthracene groups, the eutectogel exhibits tunable and reversible fluorescence. The eutectogel-based flexible wearable devices and wireless interaction systems can be used for non-contact information writing and transmission, motion monitoring, wireless communication, and human–computer interaction, which achieves the working modes of digital and visual signals complementing each other as well as efficient multifunctional integration. Therefore, this simple and environment-friendly design concept can provide new ideas for the development of multifunctional integrated portable flexible sensing devices and wireless interactive systems. [ABSTRACT FROM AUTHOR]

• A skin-beyond multifrequency camouflaging system. • The multispectral camouflage skin (MCS). • The obtained RAL exhibits high transparency in visible region, broadband absorption in the microwave region, and angular insensitivity. • An adaptive processing unit (APU). Camouflage technology could enhance the safety and security of desirable targets by concealing their signatures from the microwave, vision, infrared detection methods. However, conventional single-band camouflage fails to align with the current trends toward multi-band compatibility and intelligent adaptation. Here a bioskin-inspired multifrequency camouflaging system, including an artificial multispectral camouflage skin and an adaptive processing unit, was designed to simultaneously achieve infrared, radar, and adaptive visual stealth. This skin adopts a vertically stacked structure and utilizes a square patterned indium tin oxide for infrared stealth, a sector-box nesting silver nanowire-graphene (AgGr) metasurface for radar stealth, and a light-controlled AgGr heater to drive thermochromic displays for visible stealth. The system achieves multiband compatible properties with ultralow infrared emissivity of 0.24, high and broad microwave absorption in the 10 GHz-37.5 GHz region, and highly self-adaptive discoloration in response to background-color changes. Our work provides a reliable all-in-one design in flexible smart optoelectronics for future camouflage skin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative ionogel synthesis enhances sensitivity and flexibility. • Ionogels display superior mechanics and transparency. • Exceptional temperature sensitivity with high linearity over a broad range. • Integrated manufacturing enhances robust sensor fabrication. In the realm of modern flexible electronics, temperature sensors are pivotal, driving transformative advancements in electronic skins, healthcare monitoring systems, and intelligent firefighting technologies. However, impediments such as diminished temperature sensitivity, the dichotomy of rigidity versus flexibility, and compromised long-term stability hinder their full potential, adversely affecting sensor efficacy and reducing device longevity. In this research, we propose an innovative methodology for synthesizing P(HFA-co-SBMA)/[LI-BMIM] ionogels via a meticulously engineered ionic liquid system. This technique engenders temperature sensors with unparalleled sensitivity and adaptability, boasting tailor-made mechanical properties that achieve a harmonious balance between stiffness and malleability, alongside enhanced environmental tolerance. The fabricated ionogels, distinguished by their intrinsic conductivity, demonstrate superior mechanical performance, evidenced by a Young's modulus of 44.74 MPa, high strength (7.79 MPa), and elevated toughness of 7.36 MJ/m3, coupled with notable transparency (∼90.7 %). These sensors display remarkable environmental endurance and remarkable temperature sensitivity (−9.81 % °C−1 and a B -value of 3894.6 K), achieving a high linear correlation coefficient (R 2 = 0.997) across a broad operating spectrum. Leveraging density functional theory (DFT) analyses, we unravel the enhanced ion transport dynamics, validating the efficacy of our approach. By integrating 3D printing, mold casting, and in-situ polymerization techniques, we streamline the custom fabrication of miniaturized flexible ionogel sensors, enhancing the design, development, and production of sensors endowed with ideal characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • A self-healing and reprocessable biobased NIPU elastomer was designed and synthesized. • The elastomer showed high healing efficiency of 97.5 % after healing at room temperature for 24 h. • The tensile strength of the elastomer after three reprocessing cycles reached 136.1% of the original one. • The elastomer-based flexible strain sensor was successfully applied for human motion detection. Owing to the nontoxicity of monomers, non-isocyanate polyurethane elastomers have attracted considerable attention, yet the synthesis and functionalization are still challenging. Herein, self-healing and reprocessable biobased non-isocyanate polyurethane (NIPU) elastomers with dual dynamic covalent adaptive network (DDCAN) by disulfide bonds and dynamic imine bonds were synthesized as substrate for the construction of flexible strain sensor with MXene as conductive substance. The tensile strength and elongation at break of the NIPU elastomer were 3.22 MPa and 234 %, respectively. Thanks to the formation of DDCAN, the NIPU elastomer showed high healing efficiency of 97.5 % after healing at room temperature for 24 h. Interestingly, the NIPU elastomer possessed superior reprocessing capability and the tensile strength after three reprocessing cycles reached 136.1 % of the original one, which was attributed to the increase of crosslinking points caused by topological rearrangement. In addition, the NIPU elastomer-based flexible strain sensor exhibited fast response (response time = 60 ms) and excellent repeatability (1000 bending-releasing cycles) and was successfully applied for human motion detection and speech recognition. The findings in this work conceivably stand out as a new methodology for the preparation of biobased and functional elastomers, which will greatly promote the sustainable development and application of flexible electronics. [ABSTRACT FROM AUTHOR]

Inspired by the ancient needling process in textiles, a kind of nanopaper of ultrahigh stable conductance enabled by a reinforcement structure containing cellulose aerogel and liquid metal is reported. Such a reinforcement structure can improve the interlaminar strength of the nanopaper by 94.8%, and the interlaminar strength of the modular connection by 39.2%. The nanopaper exhibits unique pressure-insensitive behavior (ΔR/R0 < 0.02) up to 0.9 MPa. The nanopapers show excellent performances as the heater, conductor and self-powered sensor. [Display omitted] • The nanopaper shows pressure-insensitive behavior (ΔR/R 0 < 0.02 up to 0.9 MPa). • The nanopaper exhibits remarkable conductivity which is comparable with metals. • The reinforcement structure increased the interlaminar strength of nanopaper by 94.8%. • The temperature can be raised to 58 °C when the nanopaper serves as electric heater. • The nanopaper can realize the function of sensing as a triboelectric nanogenerator. Conductors with high conductivity and flexibility are critical components of smart wearable electronics. However, the substrates of most reported flexible conductors are typically non-renewable and non-biodegradable, derived from petroleum-based synthetic polymers. Inspired by the ancient needling process in textiles, needling technology was introduced into the preparation of nanopaper-based sensors for the first time, a modular composite nanopaper-based electronic (MCPE) with an interlayer performance-enhancing structure was prepared by combining cellulose aerogel and liquid metal. Such a reinforcement structure can improve the interlaminar strength of the MCPE by 94.8 %, and the interlaminar strength of the modular connection by 39.2 %. The service life of the MCPE is greatly improved and its practical application scenarios are expanded. The MCPE has long-term durability (>6000 pressing/releasing cycles) and good initial conductivity (9.6 × 103 S cm−1). The MCPE exhibits unique pressure-insensitive behavior (Δ R / R 0 < 0.02) up to 0.9 MPa. In addition, as a wearable sensor, MCPE can respond to pressure and deformation through a self-powered mode. When the MCPE is used as an electric heater, the temperature can reach 58 °C at 0.8 V. This nanopaper-based sensor with a reinforcement structure demonstrates unique pressure-insensitive behavior and provides a direct path to flexible electronics. [ABSTRACT FROM AUTHOR]

• The universal strategies of graphene films interfacial modification are concluded. • The research results adhering to "simplicity" concept have been importantly focused. • Strategies to precisely manipulate the interlayer spacing and channels is discussed. • The well-aligned GO films with regularized mass-transfer channels are emphasized. • Potential application and future direction in flexible energy devices are discussed. The advancement of flexible electronics relies heavily on the progress in flexible energy storage device technology, necessitating innovative design in flexible electrode materials. Among numerous potential materials, graphene-based composite films emerge as promising candidates due to their capacity to leverage the superior electrochemical and mechanical properties of graphene flakes. However, the influence of strong van der Waals forces often leads to inevitable agglomeration and self-stacking of adjacent graphene flakes. Consequently, achieving an elaborate control over the interlayer structure of graphene-based composite films becomes imperative to improve their structural stability in electrolytes and enhance charge/electron transfer efficiency. Herein, this review provides a comprehensive overview of diverse interfacial functional modification strategies for graphene and graphene oxide nanoflakes, thereby facilitating the assembly of graphene-based composite films. Additionally, it encompasses a discussion on the universal designs of micro-nanostructures within interlayers. Particularly, the technologies to manipulate, stabilize and orientate the interlayer channels and interlayer spacing are highlighted. These insights serve as an informative reference for the engineering of interlayer structures in graphene-based composite films. Furthermore, the review addresses the potential applications of flexible graphene-based composite films in wearable applications, current challenges, and future directions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Revealing the independent correlation of photochromism and PersL in the same material. • Achieving the largest coloration contrast and multicolor photochromism in inorganics. • Demonstrating application of the light-responsive materials in flexible electronics. Photochromism and persistent luminescence (PersL) are two fascinating light-responsive effects in phosphors, both of which have found widespread applications in optical switching, optical anticounterfeiting and information storage. However, the relationship between photochromism and PersL has not been clarified, thus greatly limiting the use and design of the light-responsive materials in multifunctional applications. Herein, taking BaMgSiO 4 :Eu2+, TM (TM = transition metal: Fe, Co and Cr) as model materials, we first reveal that photochromism and PersL could be two independent photophysical effects, although they are both related to the charge carrier trapping/detrapping processes. Notably, photochromism and PersL show have different responses to light wavelengths, and the depth of traps involved in the two effects is also quite different. Moreover, by codoping different transition metal elements, we obtain the largest reflectance difference of ∼71 % among inorganic photochromic materials reported thus far, and demonstrate interesting multicolor photochromism, including magenta, golden and pink. Based on their distinct response to light and temperature, a multi-functionalized optical anticounterfeiting technology is proposed, which may open up a new avenue for applying the light-responsive materials in flexible electronics and wearable devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-based nanomaterials enabled inkjet-printed MSC with pseudocapacitance of 900 F‌/g. • Flexible MSCs employ highly stable ink on AgNW-modified paper with detailed pattern. • The areal capacitance of 35.7/23.6 mFcm−2 is achieved in symmetric/asymmetric device. • Robust cyclic and mechanical stability shows the potential for wearable electronics. Cobalt-based nanomaterials are among the most noticed candidates for manufacturing supercapacitive electrodes. Inkjet-printing is an emerging technique for fabricating miniaturized devices. In this work, highly flexible microsupercapacitors (MSCs) are manufactured, using a pseudocapacitive (C = 900 F‌ g−1 at 1 A g−1) Co-oxide-hydroxide water-based and ultra-stable (up to 12 months) ink on paper. The synthesized capacitive active material consists of cobalt-oxide nanocubes and cobalt-hydroxide hexagonal nanoflakes. Conductive (R s = 13 Ω/□) silver nanowire networks serve as current collectors, and the morphology of cobalt oxide-hydroxide structures and the developed ink features, allow for printing well-detailed and homogeneous patterns. The inkjet-printed symmetric and asymmetric devices show notable areal specific capacitances of 35.68 mF cm−2 and 23.60 mF cm−2 at a current density of 0.1 mA cm−2, respectively. The asymmetric devices deliver impressive energy and power densities of 2.76 μW h cm−2 (4.10 W h kg−1) and 646 μW cm−2 (959 W kg−1), respectively. A thorough study on the cyclic and mechanical stability of the flexible devices resulted in perfect capacitance maintenance of 94.3 % after 10,000 charge and discharge cycles and retention of over 80 % even after 1000 cycles of successive bending and folding. The extensive study of capacitance retention following folding under various obtuse and reflex angles, which can be regarded as an important step toward characterizing flexible devices suitable for being utilized in wearable electronics, is carried out for the first time to the best of our knowledge. The findings of this study clearly illustrate the prospects of using the inkjet-printing technique to fabricate high-performance MSC devices appropriate for integration with flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

Most adhesives lose adhesion in the presence of sweat. A sweat-adaptive adhesive hydrogel was developed here through dynamic hydrogen bond networks. The sodium chloride released during sweating functions as the salting in effect which decouples hydrogen bonds of the polymer network exposing more polar groups which contributes to enhanced interfacial adhesion, enabling higher adhesion energy at the hydrogel-tissue interface. [Display omitted] • The enabling sweat-adaptive adhesive hydrogel via dynamic hydrogen bond networks. • Cellulose contributes a lot to adhesive properties of the hydrogel. • The hydrogel combines high interfacial toughness and adhesion strength. • Tough bioadhesion toward advanced bioelectronics for EMG monitoring upon sweating. Adhesive hydrogels offer an appealing way to the demand for flexible epidermal electronics. Despite the significant advances of adhesive hydrogel electronics, the unavoidable degradation of adhesion and associated diminished detection on sweaty skin are two long-standing bottlenecks for their practical applications. Herein, we present a sweat-adaptive adhesive poly(acrylamide)/cellulose (PAAm/Cel) hydrogel electronic via dynamic hydrogen bond networks. Increased sweat promotes the decoupling of hydrogen bonds within the hydrogel between PAAm and cellulose, leading to enhanced skin-hydrogel interfacial adhesion due to the strong binding of exposed abundant polar groups to the skin. The resulting PAAm/Cel hydrogel exhibits robust bioadhesion on sweating skin, with 268.3 J m−2 in interfacial toughness, 201.7 kPa in tensile strength, and 31.7 kPa in shear strength. Furthermore, the conformable and adhesive PAAm/Cel hydrogel electronics are demonstrated to produce high-quality and stable electromyogram (EMG) signals worked on persistent sweating skin. We believe that our designed adhesive hydrogel with dynamic hydrogen bond networks coupled with sweat is promising for tough bioadhesive electronics and enables bioadhesive technologies with high-level adaptivity in daily activities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Masked spray deposition enables thick, free-standing electrodes for M-ZSCs. • M-ZSC achieves an ultrahigh areal capacitance of 226.5 mF/cm2 and an energy density of 80.5430 µWh/cm2. • M-ZSC is adaptable for deployment in flexible electronics and on-chip applications. • M-ZSC exhibits a remarkable 95% capacitance retention and stable performance over time. The ubiquity of conventional micro-fabrication techniques has encountered impediments in constructing cost-effective micro-devices, thereby constraining their broad deployment. Concurrently, the suboptimal energy density inherent to supercapacitors exacerbates this challenge. This study presents a straightforward assembly methodology for the fabrication of a mechano-electrochemically efficient micro-zinc ion hybrid supercapacitor (M−ZSC), alongside the introduction of an innovative polymeric current collector. The M−ZSC is fabricated through a process involving masked spray deposition of a novel adhesive current collector and the electrode materials, and electroplating of zinc nanosheets onto the anode finger, creating an electrochemically performant and mechanically robust device. The resulting M−ZSC exhibits a notable areal capacitance of 52.2 mF/cm2 and an energy density of 18.5 µWh/cm2 for the normal mass-loading of 3.6 mg/cm2, which is amongst the highest reported values for energy storage. The masked spray deposition/hot pressing technique enabled us to fabricate free-standing thick electrodes with a loading density of up to 56.1 mg/cm2, facilitating the achievement of an ultrahigh areal capacitance of 227 mF/cm2 and an energy density of 80.5 µWh/cm2. Furthermore, the M−ZSC exhibits a robust retention of 95 % capacitance at 1 mA/cm2. Critical to its flexibility, the device is constructed using purely additive deposition methods on flexible substrates and is therefore well-tailored for deployment in flexible electronics and on-chip applications. These micro-devices are well-poised for seamless integration within a singular electronics package or chip architecture. [ABSTRACT FROM AUTHOR]

A series of liquid crystal elastomer-based printed electronic devices has been innovatively crafted through modifying screen-printing patterns. [Display omitted] • A printed liquid crystal elastomer soft actuator with multi-stimuli responsiveness and self-sensing capabilities is achieved. • A printed liquid crystal elastomer near-infrared light array sensor is fabricated. • A series of printed functional devices are fabricated through simple modifications of the printing patterns. Liquid crystal elastomers (LCEs) are valuable in soft actuators, sensors and other emerging fields. However, it is still a huge challenge to build high-performance LCE-based functional devices in a simple and fast way to achieve the orderly and patterned integration of multiple functional layers and LCE. Herein, screen-printing technology is used to realize the multi-layer pattern deposition of silver fractal dendrites conductive ink (with excellent Joule heating effect and strain-sensing function) and carbon black conductive ink (with photothermal conversion ability) on the surface of LCE. A series of LCE-based electronic devices are prepared through customized printing patterns. The as-obtained actuator possesses excellent electric actuating performance (bending angle of 102° at 200 mA) and self-sensing function (maximum relative resistance changes of −55.0%), and also exhibits NIR light-driven self-sensing bending actuation behavior (bending angle of 81° at 1.43 W/cm2), which can be used to control the robotic arm. The as-printed NIR light sensing array system can accurately sense the intensity, spot size and position of NIR light, showing good application potential in the field of unmanned aerial vehicle flight safety. This work provides a new strategy for the efficient preparation of LCEs-based flexible electronics. [ABSTRACT FROM AUTHOR]

Schematic diagram of the components of the sandwiched soft actuator. The actuator could both achieve a variety of complex movements from one to three dimensions under the stimulation of NIR light and could be deformed under electric or optical heat or direct heating to achieve the role of switching, which could be regarded as a novel soft actuator with multiple stimulus responses and multi-function. [Display omitted] • A novel molecule was synthesized to the use of self-healing behavior. • Multi regulation of the deformation mode of the liquid crystal elastomers by polymerization method. • A novel and generally coating method for the preparation of functional layer. • Dual-responsive photothermally and electrothermally liquid crystal elastomers. • Self-healing and reusable and anti-fatigue soft actuator. Due to the great potential in many applications, multi-responsive soft actuators as a kind of smart materials have attracted great interest from the scientific community. Liquid crystal elastomers (LCEs) are gradually becoming their preferred candidate matrix because of their unique mesogenic anisotropy and polymer elasticity. Here, we designed and synthesized a new disulfide-bonded aromatic molecule (named DSAC), which was used to endow the LCE matrix with a self-healing effect to extend the service life. The large conjugate structure greatly reduces the bond energy of the disulfide bond, thus allowing self-healing to occur at a lower temperature. Furthermore, the LCE matrix was coated with a novel type of functional layer with photothermal and conductive properties to make it be driven by multi-modes. Based on the above, we have prepared a healable and dual-driving mode soft actuator enabled by disulfide-bonded liquid crystal elastomers with multiple stimulus–response properties, which shows great potential in flexible electronics, artificial muscles and soft robots. [ABSTRACT FROM AUTHOR]

• A dual function flexible sensor was developed. • The sensor shows independent and sensitive pressure and temperature sensing, with no need of signal decoupling. • The independent sensing is a result of different sensing mechanism and the employment of bionic structures. Temperature and pressure sensing are two primary goals of bionic electronic skin. In this work, we developed a dual function flexible sensor, which achieved independent temperature and pressure sensing, with easy fabrication and without complicate signal decoupling. For this sensor, two flexible films with conductively bionic microstructure on the surface are combined face to face, which were replicated from rose petal and mulberry leaf. Ti 3 C 2 T x nanoflakes were mixed with PEDOT: PSS as conductive layer and thermoelectric layer, and the performance of which can be optimized by regulating the concentration of Ti 3 C 2 T x. The principles for temperature and pressure sensing are thermoelectric and piezo-resistive respectively, which are isolated by structure design. The change of contact area and resistance between the two micro-structured layers upon pressure determines the pressure response of the device. The thermoelectric response in one layer realizes the temperature sensing. The metallic conductivity of Ti 3 C 2 T x is insensitive to temperature, leading to the invariable electric response to pressure upon varied temperature. The microstructure buffers most of the pressure, which keeps the substrate unchanged and results in the independent thermoelectric response upon varied pressure. This dual function sensor shows robust and repeatable response, and exhibits great application potential in flexible electronics. [ABSTRACT FROM AUTHOR]

The review systematically discusses the progress made in stretchable ionogels in terms of both structural design and toughening mechanisms. In addition, this review categorizes these ionogels for flexible stretchable wearable electronic devices into several key application areas, including ionic skin, human motion detection, human–machine interactions and flexible energy storage devices. Finally, the challenges and prospects of stretchable ionogels are summarized, providing forward-looking strategies for further applications in wearable electronics. [Display omitted] • Ionogels can be classified into four categories based on various toughening methods. • The mechanism of ionogels toughening is systematically and comprehensively reviewed. • The applications of ionogels in the field of wearable electronics are fully summarized. • Thoroughly presented are the serious challenges and future developments of ionogels wearable applications. Based on the fact that flexible electronic devices have the property of sensing human movement and monitoring physiological signals, this will pave the way for the development of wearable electronic devices that can be stretched. Ionogels have become a focal point in the field of flexible and stretchable wearable electronics by combining carefully selected chemical properties of ionic liquids with superior physicochemical properties. To accommodate with the application environment of flexible electronics, researchers' interest in toughening ionogels continues to increase. Consequently, this review systematically discusses the advancements made in stretchable ionogels from both structural design and toughening mechanism perspectives. Moreover, this review classifies these ionogels for flexible stretchable wearable electronic devices into several key application areas, including ionic skin, human motion detection, human–machine interactions and flexible energy storage devices. Finally, the challenges and prospects of stretchable ionogels are summarized, providing forward-looking strategies for further applications in wearable electronics. This review aims to emphasize the benefits of stretchable ionogels for wearable electronic devices and to provide feasible solutions for designing efficient wearable electronic devices. [ABSTRACT FROM AUTHOR]

• SE-tattoo is conformable, sweat permeable, and imperceptible on hairy skin. • Design a biocompatible water-based conductive ink for spray fabrication method. • SE-tattoo shows high adhesiveness, high conductivity, and fast curing ability (<20 s) • Reliable and versatile solution for bidirectional human–machine interaction. Biopotential signals recorded by skin surface electrodes reflect the state of the body and corresponding organ functions. These signals are commonly utilized in clinical diagnosis, health monitoring, sports training, and human–computer interaction. However, the utilization of conventional electrodes on hairy skin causes a number of issues, including suboptimal skin compliance, obstructed sweat secretion and impaired tactile perception, making it difficult to obtain long-term and high-fidelity biopotential recordings. Here, we propose an imperceptible spray-on electrode tattoo (SE-tattoo) with sweat-permeability, high adhesiveness, high conductivity, and fast curing ability (<20 s). The water-based conductive ink is sprayed directly on the hairy skin to form a conformable conductive tattoo that neither affects nor is affected by the skin hair. We demonstrate it for heart health monitoring, sports training, electro-tactile display and close-loop teleoperation control. The SE-tattoo offers a reliable and versatile solution to biopotential recordings and serves as a promising platform for bidirectional human–machine interaction. One-Sentence Summary: Imperceptible sweat-permeable SE-tattoo enables high-fidelity biopotential recordings for bidirectional human–machine interaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible and ultra-thin liquid metal/elastomer composite film is fabricated by facile scraping and mechanical sintering process. • The film exhibits outstanding specific SE value and strain-invariant EMI-shielding and Joule-heating behavior. • The film can be followed by structural design and achieves tunable EMI SE by locally activating the conductive pathways. With the development of flexible electronics towards sophistication and miniaturization, the demand for stretching-stable ultra-thin electromagnetic interference (EMI) shielding films is increasing. Liquid metal (LM) with metallic conductivity and extreme fluidity is a satisfactory choice for preparing stretchable EMI shields. However, manufacturing high-efficiency flexible LM-based EMI shields with ultra-thin thickness and strain-stable shielding effectiveness (SE) through a facile strategy remains challenging. Herein, we proposed fabricating flexible and ultra-thin LM and polydimethylsiloxane (PDMS) composite films by facile scraping and mechanical sintering process. The resultant film with only ∼24 vol% LM and ∼150 μm thickness could show specific SE (SSE = SE T /thickness) of ∼298 dB/mm and exhibit strain-invariant EMI-shielding behavior and higher SSE up to ∼400.9 dB/mm at 75 % strain, which almost ranks at the top of SSE values compared to formerly reported LM-based polymer composites. Moreover, the PDMS/LM film can be followed by structural design, and the potential of the designed film for directionally tunable EMI shielding is demonstrated by locally activating the conductive pathways and rotation. Furthermore, the stable conductive network provided relatively stable Joule-heating performance during stretching. This work develops a simpler strategy to construct a flexible conductive film for strain-invariant EMI shielding and Joule heating, and it also shows great potential for application in designable EMI shields. [ABSTRACT FROM AUTHOR]

• A conductive sponge Ppy/PDMS with gradient porous structures was developed. • The conductive sponge Ppy/PDMS exhibits compressibility and mechanical robustness. • The sensor has a wide strain range from 0 % to 70 %, high sensitivity (S = 31.4). • The Ppy/PDMS sponge sensor can accurately monitor and analyze complex actions. Flexible pressure sensors based on porous conductive composites have potential applications in electronic skin, healthcare due to their pressure-responsive electrical conductivity. However, simultaneously enhancing sensitivity and expanding the working range remains a formidable challenge. In this work, we propose a bioinspired polypyrrole (Ppy)/polydimethylsiloxane (PDMS) sponge, which was fabricated using a one-step emulsion ice template process. This approach allows for the creation of a gradient pore structure along the thickness direction by adjusting the solid content of the latex solution and incorporating renewable carboxymethyl cellulose (CMC) additive. The technique effectively eliminates the issues associated with template residues, chemical pollutants, and multiple processes, thereby meeting the requirements for the sustainable development of flexible electronics in the future. The as-prepared Ppy/PDMS sponge exhibits a gradient modulus from top to bottom due to its gradient pore structure, thereby resulting in a combination of enhanced compressibility arising from larger pores and excellent stress adaptation characteristics originating from smaller pores. The Ppy/PDMS sponge based sensor exhibits a remarkable strain sensitivity of 31.4, a broad strain range from 0 % to 70 % and exceptional durability even after undergoing ∼ 10000 compression-release cycles. Additionally, the sensor can be utilized for health monitoring, human motion detection, and human–machine interfaces. Furthermore, an array of our sensors possesses the capability to collect spatiotemporally resolved signals for the purpose of monitoring and analyzing intricate actions. These advantages make our Ppy/PDMS sponge a highly promising candidate for flexible pressure sensor. [ABSTRACT FROM AUTHOR]

• The liquid metal (LM) based electronic materials were printed by a pioneering direct ink writing 3D printing strategy. • LM-based electronic 2D/3D structures were printed by cellulose nanofibrils and water-based polyurethane. • The bimolecular interpenetrating network structure solves the problem of LM leakage and enhances the flexibility. Ultra-flexible liquid metal (LM) composites have significant potential in various applications, including soft robotics, wearable electronics, and human–machine interactions. This burgeoning field necessitates mass production at a critical scale alongside highly accurate and fully automated technology. In this study, a direct ink-writing (DIW) 3D all-printing strategy was developed, integrating cellulose nanofibrils (CNF), water-based polyurethane (WPU), and LM to fabricate high-performance LM-based electronic films, circuits, and diverse 2D or 3D structures. The stable ternary interface system was investigated, and bimolecular interpenetrating network system of CNF/WPU significantly enhanced the flexibility, reducing LM damage, mitigation, and leakage. Moreover, the systematic control of the DIW all-printing process facilitated high-resolution and excellent printability. The super-flexibility and precise electrical conductivity were demonstrated by investigating bending deformation and recyclable electrical signals. Electronics based on ultra-flexible LM, with a high LM content (78.0%), exhibited an accurate electrical response to bending deformation, extraordinary flexibility, and recyclable durability (up to 500 cycles). Notably, the all-printed system facilitates the complete automation, complex structuring, and precise moulding of various appliances. DIW 3D all-printing of LM has the potential to create complex conductive architectures for programmable and multi-material LM-based electronics, meeting high-precision, large-scale, and automated production requirements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel multifunctional ionogels with tailoring performance were prepared. • API50 sensors exhibited high sensitivity and whole-strain range linearity. • API50 sensors showed versatile applications in electronic devices. • The shape memory API10 ionogel can be used to fabricate temperature alarm devices. • The ionogel-based TENG showed application prospect in self-powered sensors. Ionogels with high stretchability, conductivity, self-healing and self-adhesive performances have shown great application potential in flexible electronics. In this study, a dual-crosslinked ionogel, denoted as APIx, was synthesized, showcasing versatile functionalities contingent on the ionic liquid (IL) content. Notably, API50, featuring high IL content, exhibited exceptional flexibility (1418 %) and conductivity (0.31 S m−1), which conferred upon it exemplary strain-sensing performance, manifesting in rapid responsiveness (50 ms), heightened sensitivity (GF = 3.38), and whole-strain range linearity (R2 = 0.998 at strains ranging from 10 % to 900 %). Leveraging these properties, the API50-based sensor was successfully integrated into an integrated circuit to fabricate diverse electronic devices for applications such as smart switches, signal transmission, and human–machine interaction. Conversely, ionogels with lower IL content displayed noteworthy shape memory characteristics, providing thermal responsiveness suitable for temperature alarm devices. Furthermore, these ionogels were employed to fabricate a triboelectric nanogenerator (API-TENG) exhibiting exceptional electrical output performance (134 V and 1.26 W m−2). This underscores their potential in sustainable power sources and self-powered sensors for monitoring human motions. Collectively, this research introduces a novel strategy to advance the utilization of ionogels in human–machine interaction, energy harvesting devices, human healthcare, and wearable electronic devices. [ABSTRACT FROM AUTHOR]

• Developing a wireless charging flexible in-situ optical sensing for food monitoring. • Realizing the non-destructive and in-situ wireless monitoring for food quality. • Building a partial least squares regression based prediction model for food monitoring. • Improving the visualization and transparency of food in supply chain. Food safety is an important public health issue, real-time monitoring and identification of food freshness is essential to ensure food quality and consumer health. This study presents a wireless charging flexible in-situ optical sensing system (FIOS). FIOS integrates visible (VIS)/near-infrared (NIR) spectral sensors, electronic components, and microcontrollers into flexible circuits by flexible electronic technology, and obtains energy through wireless charging to solve the problem of battery replacement and frequent charging of electronic systems. FIOS exhibits excellent flexibility and bendability which can be attached well to the surface of the food for efficient, accurate, non-destructive, and in-situ monitoring. A prediction model between food quality and spectral data was established by chemometrics to achieve accurate prediction of food quality. It can obtain the spectral information of the food in real-time and transmit the data wirelessly to a cloud platform, which enables the visualization of food quality and facilitates quality traceability. FIOS is characterized by simple craft, low cost, and real-time monitoring, and can be widely deployed as an Internet of Things (IoT) node in food transportation, storage, and sales to improve the transparency of food at all stages and ensure the quality and safety of food. The FIOS has the advantages of portable and non-destructive monitoring, which improves the accuracy of food quality monitoring and provides a new technological program in the field of food quality monitoring. It is expected to promote the development of food quality and safety monitoring in the future and provide consumers with a more reliable guarantee of food quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • An alternating layered structure of CNT and GaInCu alloy (GCLA) is proposed. • Fibers with wrinkled GCLA layer show extremely high stretchability and conductivity. • Wrinkled GCLA layer enables fiber to achieve stable conductivity during stretching. • The GCLA structure can be patterned on hydrophilic and hydrophobic substrates. Liquid metal (LM) composites, known for their excellent conductivity and fluidity, hold great promise in the fields of printed electronics and wearable technology. However, their high surface tension and fluidity can lead to circuit instability, such as leakage during deformation, resulting in short circuits. Therefore, additional methods are necessary to enhance the stability of LM within composite material systems. In this paper, Carbon nanotube (CNT) was introduced as a transition layer to enhance the adhesion of gallium-indium-copper-alloy ink (GCLA) on different elastic substrates and to obtain interface fusion conductive layers. The modified GCLA conductive fibers achieved high conductivity (conductivity up to 3.13 × 105 S/m), ultra-stretchability (1580 % of ultra-large deformation, the resistance changes less than 3 Ω), and ultra-stability (within 200 % of large deformation, the change of resistance less than 1 Ω). In addition, we also demonstrated the operability of GCLA in forming patterns on hydrophilic and hydrophobic substrate surfaces and obtained conductive patterns through printing, transfer printing, and hand drawing, making it a promising candidate for flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass LS was transformed into nanohybrids with PBA through coordination. • PBA-LS/XNBR composites as flexible substrates were prepared by latex compounding. • PBA-LS was in-situ decomposed into metal-doped porous carbon on substrates by DLW. • Stretchable rubber-based SC was fabricated by "island-bridge" structure design. • The rubber-based SC could work under stretching for powering small devices. With the advent of the Internet-of-Things (IoT) era, flexible supercapacitors (F-SC) have emerged as one of the most promising power sources for wearable devices. However, the rapid fabrication of F-SC with high energy density and stretchability remains a challenge. In this study, an intrinsically stretchable rubber-based supercapacitor, for the first time, was fabricated from Co-Fe Prussian blue analogous (Co-Fe PBA)/sodium lignosulfonate (LS) nanohybrids (PBA-LS) reinforced carboxylated nitrile rubber (XNBR) by direct laser writing (DLW) technology. Under the transient photothermal action of programable high-energy laser irradiation, biomass-derived LS among PBA-LS nanohybrids was directly transformed into patterned porous graphitized carbon on the surface of PBA-LS/XNBR substrates (PLX), while Co-Fe PBA was pyrolyzed into bimetallic compound nanoparticles as pseudocapacitive materials embedded into the carbon framework. Benefiting from the in-situ doping of the bimetallic compounds within the LS-derived carbon framework on flexible PLX substrates, the rubber-based electrode showed an excellent electrochemical activity, reversibility and stability. Accordingly, symmetric interdigitated F-SCs could be rapidly fabricated by DLW, showing high areal capacitance of 479.08 mF cm−2 and energy density of up to 80.07 μWh cm−2. To achieve their stretchability, "island-bridge" structured stretchable F-SCs (SF-SC) were fabricated through Kirigami technology and liquid metal linkage. The rubber-based SF-SC demonstrated high voltage window and energy density as well as excellent electromechanical stability for powering small devices. This work provided new insights into the scalable fabrication of flexible energy storage devices by DLW, and it was of significant importance for the development of rubber-based flexible electronics and the valorization of biomass LS. [ABSTRACT FROM AUTHOR]

• An all-cellulose ionogel was prepared using directly cracked wood. • The ionogel exhibits superior performance in both mechanical properties and ionic conductivity. • The ionogel shows excellent self-healing properties and is fully biodegradable. • Flexible printed electronic circuits, sensors and flexible supercapacitors are well served by the ionogel. For thousands of years, wood has been utilized as a natural, abundant, and sustainable material for structural construction and furniture. To enhance its value, we have developed a simple process that can directly convert low-value wood (including cracked wood, chips, shives, and other wood residues) into high-performance all-cellulose ionogels. This process involves delignification, in situ dissolution of cellulose, and self-assembly of molecular cellulose chains. The resulting ionogel exhibits excellent properties such as high ion conductivity (∼60 mS/cm), mechanical strength (∼6 MPa), and self-healing capability (∼10 min). Notably, it also demonstrates exceptional freeze tolerance, withstanding temperatures as low as −50 °C while maintaining high ion conductivity (∼6.4 mS/cm). The ionogel is a versatile substrate for flexible electronic circuits. We have developed a sensor utilizing this ionogel that is breathable, flexible, and highly responsive to temperature, humidity, and strain. Furthermore, we have used it as a gel electrolyte to create supercapacitors with exceptional performance even in low-temperature conditions. The ionic liquid can be reused, with an all-cellulose framework that breaks down naturally in moist soil within 15 days. This sustainable method of producing high-performance ionogels from low-value wood has immense potential in shaping the next generation of soft, intelligent devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanostructured MnOx/MoS 2 electrode facilitates capacitance change of all-fiber ITSs. • Cotton fibers boost ionic distribution to enhance mechanical stability. • Rapid response and exceptional sensitivity under high pressure. • Monitoring of human movement and physiological signals for sensors are achieved. • Integration with motion recognition technology enhances rehabilitation assessment. Interfacial capacitance sensing technology shows great potential in the fields of flexible electronics and healthcare. However, further advancements are necessary to enhance the sensitivity and mechanical stability of all-fiber iontronic tactile sensors (ITSs), especially under high pressure. This study addresses these challenges by optimizing the electrode structure and composition, incorporating hydrophilic cotton fibers as the dielectric layer framework. As a result, the ITSs exhibit ultrahigh sensitivity (58853 kPa−1), rapid response times (below 2 ms), and improved mechanical stability, enduring 10,000 cycles at 195.2 kPa. Moreover, these sensors have proven effective in detecting human motion and physiological signals in both air and aquatic environments. Integration into a motion state recognition system demonstrates potential applications in sports injury recovery, stroke rehabilitation, and chronic pain management. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous sponge has ant-nest-like interior channels and reliable breathability. • MXene ink-printed interdigitated electrode-coated electrospun film was prepared. • The sensor shows high sensitivity, wide sensing range, and great stability. • The sensor exhibits facile biodegradability and EMI shielding performance. Flexible wearable electronic sensors are regarded to facilitate revolutionary changes in human's daily life for their great promise in multifunctional artificial electronic skins, personalized healthcare monitoring, and smart human–machine interaction. However, there remains great challenges to simultaneously achieve high sensitivity, broad sensing range and robust cyclic stability for high-performance personal diagnostic healthcare monitoring, excellent breathability for comfortable wearing, as well as environmentally friendly biodegradability for reducing electronic wastes. Herein, bioinspired by three-dimensional network structure of ant nest with high specific surface area, interconnected channels, and robust ventilation, a wearable, breathable, and biodegradable electronic sensor is prepared from facile face-to-face assembly of breathable biodegradable MXene-coated poly(1,8-octanediol- co -polycaprolactone citrate) elastomer sponge (MXene@POPLC), and an MXene ink-printed interdigitated electrode-coated breathable electrospun film. The as-obtained flexible electronic sensor exhibits high sensitivity (up to 246.3 kPa−1), broad sensing range (up to 333.3 kPa), reliable cycling stability (∼20,000 cycles), fast response (10 ms)/recovery time, robust breathability, excellent biocompatibility, facile biodegradability, and wireless wearable human–machine interfacing. Therefore, this line of research work opens up a novel avenue for the preparation of multifunctional wearable, breathable, and biodegradable electronics to hold great promise in smart healthcare monitoring, intelligent human–machine interaction, smart personal protection and next-generation artificial skin. [ABSTRACT FROM AUTHOR]

• An ultra-tough bio-organogel with supramolecular-zipper nanostructure was designed. • Covalent/noncovalent synergistic network was optimized by mimicking wood cell wall. • MD simulation verified enhanced effect of sliding crosslink-assisted chain alignment. • The conventional tradeoff between strength and toughness of material was overcame. • Organogel showed outstanding overall performance as multifunctional soft electronic. Soft electronics have garnered significant interests owing to their distinctive qualities. However, their practical utilizations are still limited by their generally poor mechanical properties, environmental concerns, and incompatibility. Here, we present a unique hierarchical nanoarchitectural design of dynamic noncovalent supramolecular zipper to achieve synergistic enhancement of both mechanical strength and toughness in organogels. By building lignin-carbohydrate complexes nanoparticles (LCCNPs)-based sliding zippers within the interpenetrating polymer networks (IPN) formed by in-situ regenerated cellulose nanofibrils (CNFs) and polyvinyl alcohol (PVA) molecular chains, the lignocellulosic organogels demonstrated excellent mechanical properties, shape recovery performances, and strain-stiffening behaviors. The ultimate tensile strength increased by 11-fold, reaching 8.29 MPa, while the toughness also had an increase of 24-fold, reaching 23.8 MJ/m3 at the same time, comparing to those of the PVA hydrogel. These novel organogels also exhibited exceptional anti-freezing (<-150 °C), anti-dehydration, transparency, UV-shielding, and biodegradable properties. The assembled wearable sensor using the organogels were able to monitor human motion status and physiological signals with a tunable conductivity (up to 5.14 S/m), a high sensitivity (a maximum gauge factor of 5.62) and long cyclic stability (2000 cycles). This novel nano-structural design approach showcases a facile and versatile platform for constructing the next-generation high performance bio-based soft electronics. [ABSTRACT FROM AUTHOR]

• The ionogel with multi-function characteristics is used asflexible stress, strain and temperature sensors. • Ionogels has many excellent properties under the coordinated control of ionic liquid and hydroxypropyl cellulose. • The designed ionogels can be used asan encryption device with a temperature alarm. Conductive gels are promising soft ionic conductors for stretchable and flexible electronics. However, the integration of multiple functions into one gel remains a great challenge, as the tailoring of these properties is mutually exclusive. In this paper, a simple photopolymerization method is designed to prepare polyacrylic acid/ionic liquid /hydroxypropyl cellulose (PIH) ionogels, which have high transparency (89 %), and superior electrical conductivity (0.379 mS/cm). Owing to the dynamic and reversible nature between the polymer chains, the ionogel possesses good self-healing capability (79.6 %) and self-adhesive properties (242.32–742.76 kPa, typical substrate at room temperature). At the same time, the excellent chemical stability of ionic liquids ensures that PIH ionogels still have good temperature sensitivity (-30 ∼ 110 °C) in extremely harsh environments. Wearable strain sensors based on PIH ionogels can sensitively detect and distinguish body movements, such as limb bending, pronunciation, and pulse. When PIH ionogels are used as a temperature sensor, a cryptographic device with a temperature alarm and an externally stimulated UV switch is designed by using the excellent transparency and temperature response of PIH ionogels. It is believed that the designed ionogel will show great prospects in wearable devices and flexible encryption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photosensitive ionic liquids employed as precursor solutions for DLP 3D printing. • 3D printing of ionic skin sensors that mimic the interlocking layers of human skin. • The ionic skin sensor exhibits high sensitivity over a pressure range of 0–144 kPa. Conductive ionoelastomers (CIEs) have become a reliable alternatives to gel-based ionic conductors, attracting widespread attention in the field of flexible sensors. However, it remains a challenge to develop CIEs with an appealing combination of performance, including high self-healing efficiency, temperature resistance, degradability, and 3D printability. In this study, a novel photosensitive ionic liquid (polymerizable deep eutectic solvent) was designed as a precursor solution for UV-curable 3D printing. Subsequently, CIEs synthesized through UV-curing demonstrated good ionic conductivity (0.23 S m−1). The abundant hydrogen bond interactions within the elastomer network endowed the CIEs with outstanding stretchability (565 %), remarkable self-healing efficiency (99 % at room temperature), degradation capability, and the ability to maintain conductivity and self-healing across a wide temperature range (–23 to 50 °C). Following this, Digital Light Processing (DLP) 3D printing was employed to fabricate CIEs with microstructures mimicking the interface between the epidermis and dermis layers of human skin. And the 3D printed components were assembled into highly sensitive ionic skin to monitor small deformations in real time. These features indicate that the well-rounded performance and feasible manufacturing make the developed CIEs promising for a wide range of applications in the field of flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Prepared new conductive MXene-based hydrogel. • Improved the oxidative stability and preventing accumulation of MXene. • Composite hydrogel exhibits high stretchability, skin-like softness and high toughness. • Monitor weak electrophysiological signals and achieve sign language translation and eye tracking. Epidermal sensors capable of monitoring various physical signals are vital in wearable healthcare applications. MXene-based conductive hydrogels have become promising candidates as skin-attachable sensors for these purposes. However, due to the easy oxidation and weak combination of MXene nanosheets with network matrix, it remains challenging to construct a mechanically tough, highly conductive and skin-conformal hydrogel for reliable signal recording (especially weak electrophysiological signals). Herein, a new conductive MXene-based hydrogel is fabricated through introducing silk fibroin (SF)-modified MXene (MXene-SF) into polyacrylamide (PAM) network. It is demonstrated that the encapsulation of SF on MXene surfaces greatly improves its stability, and meanwhile induces the formation of multiple noncovalent interactions between MXene-SF and PAM chains. The resulting hydrogel exhibits high stretchability (1560 %), remarkable toughness (165 kJ/m3), high conductivity (0.25 S/m) and self-adhesion. This hydrogel is high-sensitive in a large strain range for detecting various human motions. Especially, the high conformal adhesion and low interface impedance make the hydrogel bioelectrodes precisely monitor weak electrophysiological signals (e.g. electromyogram and electrooculogram), successfully achieving sign language translation and eye tracking. Additionally, the hydrogel has great thermosensitive capacities for body temperature monitoring. This study provides a general strategy for designing MXene-based hydrogels with tailored functionalities as flexible electronics. [ABSTRACT FROM AUTHOR]