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Flexible wearable strain sensors with excellent sensing performance have received widespread interest due to their superior application capability in the field of human-computer interaction, sports rehabilitation, and disease diagnosis. But at present, it is still a considerable challenge to exploit a flexible strain sensor with high sensitivity and wide sensing range that is easily manufactured, low-cost, and easily integrable into clothing. MXene is a promising material sensitive enough for flexible sensors due to its superior conductivity and hydrophilicity. The warp knitting weft insertion textile structure gives the fabric excellent elasticity, making it suitable as a flexible, stretchable substrate. Therefore, utilizing a polyester elastic fabric with a warp knitting weft insertion structure, a fabric strain sensor with high sensitivity and wide sensing range prepared by layer-by-layer self-assembly of polyvinyl alcohol layers and MXene layers is reported in this study. The strain sensor exhibits high sensitivity (up to 288.43), a wide sensing range (up to 50%), fast response time (50 ms), ultra-low detection limit (a strain of 0.067%), excellent cycle stability (1000 cycles), and good washability. Besides, affixing the MXene/polyvinyl alcohol/polyester elastic fabric strain sensor on the joints can detect the movement of limbs. Therefore, the MXene/polyvinyl alcohol/polyester elastic fabric strain sensor demonstrates potential application opportunities in smart wearable electronic devices, and the researcher can also apply this method in the production of other flexible, intelligent wearable devices.

One-dimensional high-performance yarns with excellent conductivity and flexibility are of considerable interest in the energy and aerospace industries. However, how to achieve highly conductivity, excellent flexibility, extreme condition durability and high mechanical performance in one fiber material is still a great challenge using economically viable materials and synthesis technologies. Herein, we report electrically conductive yarns (modified polyimide (M-PI)/reduced graphene oxide (RGO) yarns) consisting of RGO coated on the surface of nitrogen plasma M-PI yarns, which are fabricated by combining the N2 plasma pre-treatment and repeated dip-coating and reducing technique. N2 plasma treatment is used to roughen the surface of the PI yarn and introduce functional groups, contributing to improve wettability, which can provide a stronger adhesion of the graphene coating. The dip-coating and reducing process was repeated 10 times to enhance the loading mass of RGO on the PI yarns, then M-PI/RGO yarns with better conductivity property can be obtained. The effects of N2 plasma treatment power and time on the M-PI yarns and M-PI/RGO yarns are investigated and discussed. The results demonstrate that the graphene layer is uniformly and densely coated on the PI yarn when being treated at 200 W for 8 min, and the conductivity of the M-PI/RGO yarn reaches 1.51 × 102 S/m. The M-PI/RGO yarn combine the advantages of RGO and PI yarns, retaining the mechanical properties and thermal stability of PI yarn while exploiting the conductive property of RGO. In addition, the enhanced adhesion between the PI yarn and graphene coating endows the composite yarns with excellent fastness and superior flexibility. This work describes an environmentally friendly, controllable and facile method to develop flexible and conductive functional graphene-coated PI yarns with high-performance properties.

Soft robots are those that can move like living organisms and adapt to the surrounding environment. Compared with traditional rigid robots, the advantages of soft robots, in terms of material flexibility, human–computer interaction, and biological adaptability, have received extensive attention. Flexible actuators based on light response are one of the most promising ways to promote the field of cordless soft robots, and they have attracted the attention of scientists in bionic design, actuation implementation, and application. First, the three working principles and the commonly used light-responsive materials for light-responsive actuators are introduced. Then, the characteristics of light-responsive soft actuators are sequentially presented, emphasizing the structure strategy, actuation performance, and emerging applications. Finally, this review is concluded with a perspective on the existing challenges and future opportunities in this nascent research frontier.

Fiber supercapacitors have attracted significant attention owing to the relevancy in textile electronics. However, the key challenge is to achieve a high output voltage and performance in fiber supercapacitors, while maintaining the high flexibility as fibers. Here, we present a particular type of fiber supercapacitors, based on an overlaid tree topological configuration, by braiding sub-fiber supercapacitor units in an asymmetrical series connection. The tree-like topology-based asymmetric fiber supercapacitors (TTAFSCs) simultaneously achieved a high energy density (22 mWh cm-3 at a power density of 444 mW cm-3) and voltage output, while maintaining outstanding mechanical properties (>1000 bending cycles, capable of loading an object of ~200 g). By continuous braiding of a 6-unit TTAFSC (28 cm length), we were able to achieve a tunable output voltage as high as 9.6 V, which is superior to that achieved by most state-of-the-art fiber supercapacitors. Furthermore, TTAFSCs of ~8 cm long are capable of lightening light-emitting diodes, driving a watch, and powering a display, even at the bent and twisted state. The design of TTAFSCs and fabrication technology acquired represent a genuine breakthrough in textile electronics.

Summary Fiber supercapacitors have attracted significant attention because of the relevance for textile electronics. However, the key challenge is to achieve high output voltage and performance of fiber supercapacitors while maintaining the high flexibility of the fibers. Here, we present a fiber supercapacitor, based on an overlaid tree topology configuration, by braiding sub-fiber supercapacitor units in an asymmetrical series connection. The tree-like topology-based asymmetric fiber supercapacitors (TTAFSCs) achieve a high energy density (0.022 Wh cm−3 at a power density of 0.444 W cm−3) with an extendable high voltage output (>9.6 V) while maintaining outstanding mechanical properties (>1,000 bending cycles, capable of loading an object of ∼200 g). TTAFSCs of ∼8 cm in length are capable of lighting light-emitting diodes, driving a watch, and powering a display, even in a bent and twisted state.