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Conductive hydrogels have recently gained impressive attention in flexible sensing. However, their low sensing limit and poor interface matching have raised great concern during the practical application. Therefore, incorporating excellent stretchability and adhesiveness into conductive hydrogel is highly desirable but still be a huge challenge. In this study, we synthesized composite hydrogels with desired properties by utilizing the synergistic role of hemicellulose (HC) and conductive two-dimensional material MXene. As a result, the synthesized hydrogels showed good self-adhesion (3.12 KPa on the skin), great stretchability (>1700 %), and satisfactory electrical conductivity. These multifunctional hydrogels operated as adaptable sensors, adeptly capturing the nuanced signals emanating from an array of human motions. They exhibited an expansive strain tolerance, swift reactivity, and an enhanced acuity in detecting even the slightest deformations (GF = 2.1). Our research provides new insights for creating stretchable, self-adhesive, and functional hydrogels for sensing applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Stretchable and tough polysaccharide-based functional hydrogels have gained popularity for various applications. However, it still remains a great challenge to simultaneously own satisfactory stretchability and toughness, particularly when incorporating renewable xylan to offer sustainability. Herein, we describe a novel stretchable and tough xylan-based conductive hydrogel utilizing the natural feature of rosin derivative. The effect of different compositions on the mechanical properties and the physicochemical properties of corresponding xylan-based hydrogels were systematically investigated. Owing to the multiple non-covalent interactions among different components to dissipate energies and the strain-induced orientation of rosin derivative during the stretching, the highest tensile strength, strain, and toughness of xylan-based hydrogels could reach 0.34 MPa, 2098.4 %, and 3.79 ± 0.95 MJ/m 3 , respectively. Furthermore, by incorporating MXene as the conductive fillers, the strength and toughness of hydrogels were further enhanced to 0.51 MPa and 5.95 ± 1.19 MJ/m 3 . Finally, the synthesized xylan-based hydrogels were able to serve as a reliable and sensitive strain sensor to monitor the movements of human beings. This study provides new insights to develop stretchable and tough conductive xylan-based hydrogel, especially utilizing the natural feature of bio-based resources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Conductive hydrogels have attracted increasing attention for applications in wearable and flexible strain sensors. However, owing to their relatively weak strength, poor elasticity, and lack of anti-freezing ability, their applications have been limited. Herein, we present a skin-mimicking strategy to fabricate cellulose-enhanced, strong, elastic, highly conductive, and anti-freezing hydrogels. Self-assembly of cellulose to fabricate a cellulose skeleton is essential for realizing a skin-mimicking design. Furthermore, two methods, in situ polymerization and solvent replacement, were compared and investigated to incorporate conductive and anti-freezing components into hydrogels. Consequently, when the same ratio of glycerol and lithium chloride was used, the anti-freezing hydrogels prepared by in situ polymerization showed relatively higher strength (1.0 MPa), while the solvent-replaced hydrogels exhibited higher elastic recovery properties (94.6 %) and conductivity (4.5 S/m). In addition, their potential as strain sensors for monitoring human behavior was analyzed. Both hydrogels produced reliable signals and exhibited high sensitivity. This study provides a new horizon for the fabrication of strain sensors that can be applied in various environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

With the development of wearable devices, the fabrication of strong, tough, antibacterial, and conductive hydrogels for sensor applications is necessary but remains challenging. Here, a skin-inspired biomimetic strategy integrated with in-situ reduction has been proposed. The self-assembly of cellulose to generate a cellulose skeleton was essential to realize the biomimetic structural design. Furthermore, in-situ generation of silver nanoparticles on the skeleton was easily achieved by a heating process. This process not only offered the excellent antibacterial property to hydrogels, but also improved the mechanical properties of hydrogels due to the elimination of negative effect of silver nanoparticles aggregation. The highest tensile strength and toughness could reach 2.0 MPa and 11.95 MJ/m 3 , respectively. Moreover, a high detection range (up to 1300%) and sensitivity (gauge factor = 4.4) was observed as the strain sensors. This study provides a new horizon to fabricate strong, tough and functional hydrogels for various applications in the future., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Hydrogels containing renewable resources, such as hemicellulose, have received a lot of attention owing to their softness and electrical conductivity which could be applied in soft devices and wearable equipment. However, traditional hemicellulose-based hydrogels generally exhibit poor electrical conductivity and suffer from freezing at lower temperatures owing to the presence of a lot of water. In this study, we dissolved hemicellulose by employing deep eutectic solvents (DESs), which were prepared by mixing choline chloride and imidazole. In addition, hemicellulose-based DES hydrogels were fabricated via photo-initiated reactions of acrylamide and hemicellulose with N, N′-Methylenebisacrylamide as a crosslinking agent. The produced hydrogels demonstrated high electrical conductivity and anti-freezing properties. The conductivity of the hydrogels was 2.13 S/m at room temperature and 1.97 S/m at −29 °C. The hydrogel's freezing point was measured by differential scanning calorimetry (DSC) to be −47.78 °C. Furthermore, the hemicellulose-based DES hydrogels can function as a dependable and sensitive strain sensor for monitoring a variety of human activities. [ABSTRACT FROM AUTHOR]

Magnetic hydrogels have been widely utilized in the fields of biomedical devices, flexible electronics, and soft robotics. Unfortunately, current strategies to synthesize magnetic hydrogels are difficult to achieve high mechanical properties. Herein, we have presented a biomimetic strategy to synthesize a strong, tough and elastic cellulose enhanced magnetic hydrogel (CEMH). The cellulose skeleton containing magnetic nanoparticles was first generated by self-assembly of cellulose chains as the enhancement filler, while elastic polyacrylamide formed by in situ polymerization functioned as the elastic matrix. The mechanical and physicochemical properties of CEMH, as well as the effect of Fe3O4 and acrylamide concentration on the performance, were systematically investigated. The highest tensile strength and toughness of CEMH could reach 1.1 MPa and 2.9 MJ/m3, respectively. Furthermore, CEMH showed a high elastic recovery of 94.5% (10th cycle), accompanies by a certain swelling resistance ability. All these advantages were accomplished mainly owing to the synergetic contribution of biomimetic design and enhanced non-covalent interactions. [ABSTRACT FROM AUTHOR]

• Nature cellulose is utilized as supramolecular fibers to mimic skin-like hydrogels. • The synthesized hydrogels displayed excellent mechanical properties. • It can be used as a stable and sensitive strain sensor to monitor the human behavior. The soft electronics industry is booming. To integrate with soft tissues (e.g. skin), the materials must possess skin-like properties in terms of stretchability, toughness, elasticity, softness, self-stiffness, swelling resistance, and conductivity. Herein, a biocompatible cellulose biomimetic hydrogel (CBH) showing the characteristics of the skin is fabricated. The first step is the regulation of cellulose self-assembly to form a porous non-swelling supramolecular fiber skeleton. Then, the elastic polymers generate within the pores of skeleton. This design mimics the skin's structures by utilizing the crystallization behavior of cellulose. Importantly, the cellulose supramolecular network has significantly strengthened the resultant hydrogels with over a 45-fold increase in toughness, and it could reach 4.3 MJ/m3. Moreover, it shows enhanced properties in terms of stretchability, modulus, self-stiffness and elasticity. Investigation on the swelling resistance shows that the utilization of non-swelling porous cellulose skeleton can limit the swelling of CBH. Finally, the fabrication of conductive CBH is performed through the in-situ polymerization of aniline within CBH. It can retain the mechanical features due to the tunable swelling, and also be used as a sensitive and stable strain sensor to monitor human motions, even under an aqueous environment. The gauge factor within the range of 90% to 600% was 1.7. This study highlights the significance of utilizing original cellulose features and provides a new avenue to prepare high-performance strain sensors. [ABSTRACT FROM AUTHOR]