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

Conductive hydrogels exhibit high potential in the fields of wearable sensors, healthcare monitoring, and e‐skins. However, it remains a huge challenge to integrate high elasticity, low hysteresis, and excellent stretch‐ability in physical crosslinking hydrogels. This study reports the synthesis of polyacrylamide (PAM)‐3‐(trimethoxysilyl) propyl methacrylate‐grafted super arborized silica nanoparticle (TSASN)‐lithium chloride (LiCl) hydrogel sensors with high elasticity, low hysteresis, and excellent electrical conductivity. The introduction of TSASN enhances the mechanical strength and reversible resilience of the PAM‐TSASN‐LiCl hydrogels by chain entanglement and interfacial chemical bonding, and provides stress‐transfer centers for external‐force diffusion. These hydrogels show outstanding mechanical strength (a tensile stress of 80–120 kPa, elongation at break of 900‐1400%, and dissipated energy of 0.8–9.6 kJ m−3), and can withstand multiple mechanical cycles. LiCl addition enables the PAM‐TSASN‐LiCl hydrogels to exhibit excellent electrical properties with an outstanding sensing performance (gauge factor = 4.5), with rapid response (210 ms) within a wide strain‐sensing range (1–800%). These PAM‐TSASN‐LiCl hydrogel sensors can detect various human‐body movements for prolonged durations of time, and generate stable and reliable output signals. The hydrogels fabricated with high stretch‐ability, low hysteresis, and reversible resilience, can be used as flexible wearable sensors. [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]

[Display omitted] • Organohydrogel with "island-bridge" conductive layer was prepared for strain sensor. • The special conductive layer is beneficial for balanced strain sensing performances. • The sensor shows good stability towards extreme external temperature environments. • The work opens a promising avenue for next-generation smart wearable electronics. Flexible conductive hydrogels (CHs) have received widespread attention in the field of wearable strain sensor, electronic skin, and artificial intelligence owing to their excellent stretchability, biocompatibility, and real-time sensing performance. However, it still remains a critical challenge to design and construct the satisfactory wearable strain sensor integrated with high sensitivity, wide sensing range, and environmental stability, especially at extreme temperatures. Herein, ionic conductive polyacrylamide/sodium alginate nanocomposite organohydrogel anchored with electronic conductive "island-bridge" microstructured carbon nanotubes (CNTs) conformal coating was designed and fabricated for high-performance strain sensor, of which the existence of "island-bridge" microstructured electronic conductive layer and its special structure evolution upon external stretching can significantly enhance the alternating current impedance response behavior of the sensor, featuring with a high sensitivity of 76.54 at 600 % strain, wide sensing range (0–600 % strain), fast responsiveness (110 ms), extremely low detection limit (0.1 %), and favorable stability and reproducibility of over 3200 cycles. Meanwhile, the resultant organohydrogel strain sensor can precisely detect and differentiate complicated human activities even at the environment temperatures of −30 °C and 50 °C, opening a promising avenue for next-generation smart wearable electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • A core-sheath composite fiber based on TPU and MWCNTs is obtained by wet spinning. • The unique dual conductive network structure is constructed by MWCNTs and RGO. • The"shoulder-peak" phenomenon is effectively weakened due to the dual conductive network structure. • The fiber-shaped strain sensor shows good response behavior in monitoring human motions. Flexible wearable strain sensor is a vital part of intelligent wearable systems due to their broad applications in human–machine interaction and smart clothes. Flexible strain sensor fabricated via conventional blending conductive polymer composites has some drawbacks, for example, low sensitivity, large hysteresis, and "shoulder-peak" phenomenon, which limit their practical applications greatly. Herein, we prepared a fiber-shaped strain sensor with a micro-porous, three-layer structure together with a dual conductive network based on reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs). The strain sensor demonstrates excellent response behaviors, including splendid stretchability (686 %), wide detection range (120 %), high sensitivity (gauge factor = 300), fast response time (300 ms) and excellent durability (over 9000 cycles). The unique dual conductive network structure endows the strain sensor with remarkable recoverability and reproducibility. The resistance of the strain sensor can recover to nearly initial conditions after the releasing process, exhibiting lower hysteresis. The "shoulder-peak" phenomenon has also been weakened based on the microstructure and conductive network design. Based on the high sensitivity and excellent response behavior, the fiber-shaped strain sensor performs real-time monitoring of breathing, finger bending, walking, and other human motions, providing a good candidate for its application in intelligent wearable devices. [ABSTRACT FROM AUTHOR]

Superhydrophobic conductive rubber band with synergistic dual conductive layer was designed and prepared for high-performance strain sensor, showing great potential for full-range monitoring of human motion and physiological signal, especially in the water environment. [Display omitted] Wearable electronic devices have received increasing interests because of their excellent flexibility, stretchability, and human friendliness. As the core components, flexible strain sensors integrated with wide working range, high sensitivity, and environment stability, especially in moisture or corrosive environments, remain a huge challenge. Herein, synergistic carbon nanotubes (CNTs)/reduced graphene oxide (rGO) dual conductive layer decorated elastic rubber band (RB) was successfully developed and treated with hydrophobic fumed silica (Hf-SiO 2) for preparing superhydrophobic strain sensor. As expected, stable entangled CNTs layer and ultrasensitive microcracked rGO layer endow the sensor with extremely low detection limit (0.1%), high sensitivity (gauge factor is 685.3 at 482% strain), wide workable strain range (0–482%), fast response/recovery (200 ms/200 ms) and favorable reliability and reproducibility over 1000 cycles. Besides, the constructed Hf-SiO 2 coating also makes the sensor exhibit excellent superhydrophobicity, self-cleaning property, and corrosion-resistance. As a proof of concept, our prepared high-performance strain sensor can realize the full-range monitoring of human motions and physiological signals even in the water environment, including pulse, vocalization, joint bending, running, and gesture recognition. Interestingly, it can also be knitted into a tactile electronic textile for spatial pressure distribution measurement. Thus, this study provides a universal technique for the preparation of high-performance strain sensors with great potential applications in the field of next-generation intelligent wearable electronics. [ABSTRACT FROM AUTHOR]

• A conductive fiber with synergistic conductive network is prepared for strain sensor. • The synergistic effect is beneficial for tunable and balanced sensing performances. • The sensor shows great potential for human motion monitoring and tactile sensing. • The fiber displays good photothermal performances even under 150% strain. With the rapid development of portable electronic products, smart wearable devices show great application potential in personalized motion monitoring, health monitoring and even in human-machine interaction. In particular, high-performance flexible fiber-shaped strain sensors are receiving more and more attention because they can be well integrated with clothes or human skin for real-time human activities monitoring. However, achieving improved sensitivity, wide detection range, diverse applications and easy operation of them remains a challenge. Here, we adopt a simple wet-spinning technique to prepare a porous fiber-shaped carbon nanotubes (CNTs)/silver nanoparticles (AgNPs)/thermoplastic polyurethane (TPU) fiber (CATF) for high-performance strain sensor, of which the synergistic conductive network of CNTs and AgNPs enables a wide detection range (∼248 %), high sensitivity (GF > 4295), fast response/recovery time (120 ms/140 ms) and excellent stability. Interestingly, strain sensing range and sensitivity of the sensor can be tuned by changing the AgNPs loading to make it suitable for different application scenarios. All the merits of the sensor make it capable for diverse human movements monitoring, pronunciation recognition, and gesture recognition. More importantly, our prepared CATF strain sensor can be easily weaved into wearable smart textiles, showing great potential for tactile sensing to realize multi-touch and pressure tracking. Finally, the CATF also displays efficient photothermal conversion capability even under different tensile strains up to 150 %, showing great potential in human body thermal management to improve the wearing comfort of wearable electronic fabric. [ABSTRACT FROM AUTHOR]

Benefitting from the wearability, ductility and portability, flexible and stretchable strain sensors display a more extensive field of applications than traditional sensors in terms of medical diagnosis, smart home, environmental monitoring and so on. However, the critical sensing performances, such as sensitivity, sensing range, stability and detection limit of flexible strain sensors still need to be improved. Microstructural optimization has been considered as an efficient strategy for tuning the performances. In this work, a carbon nanotubes (CNTs)/carbon black (CB)/thermoplastic polyurethane (TPU) fibrous film (CCTF) is prepared through electrospinning, spraying and ultrasonic anchoring technique. Synergetic conductive layers by combining CNTs/CB and CB are constructed on both sides of CCTF. In virtue of the optimization of microstructures and the synergetic conductive network, the obtained CCTF possesses an ultrawide response range (up to 500 % strain), high sensitivity (gauge factor, GF up to 1516), short response/recovery time (80/80 ms), low detection limit (0.05 % strain), favorable sensing stability and long-term durability. CCTF with excellent strain sensing performances is assembled as a strain sensor, which accounts for full range human biological signal acquisition, including joint movements, muscle tension, and facial micro-expressions. This paper provides a certain reference significance for the preparation and fabrication of next-generation flexible strain sensors with high performances. A flexible strain sensor based on carbon nanotubes (CNTs)/carbon black (CB)/thermoplastic polyurethane (TPU) film (CCTF) is fabricated through electrospinning, spraying and ultrasonic anchoring technologies. CCTF possesses excellent sensing performance due to the optimization of the microstructure, achieving a wide sensing range (up to 500 % strain), high sensitivity (GF up to 1516), low detection limit (0.05 % strain), and short response/recovery time (80/80 ms). [Display omitted] • A fibrous strain sensor with synergetic conductive networks of CNTs/CB and CB is fabricated. • The sensor possesses both a wide sensing range (500 % strain) and high sensitivity (GF up to 1516). • Low detection limit (0.05 % strain) and short response/recovery time have also been achieved. • The sensor is demonstrated to precise full range human biological signal acquisition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Breathable electronic skin with 3D skeleton and microcrack structures is designed. • High sensitivity and wide working range are realized for the strain sensor. • The strain sensor can accurately distinguish various human movements. • The device has photo-thermo-electric and self-powered sensing applications. With the rapid development of wearable electronic, electronic skin with excellent performance for human motion detection have been widely investigated recently. In this work, a multifunctional electronic skin with three-dimensional conductive network skeleton was prepared based on synergistic conductive filler (carboxylated multi-walled carbon nanotubes (C-MWCNT) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS)) decorated breathable thermoplastic polyurethane (TPU) electrospinning fibrous membrane. Then, microcrack structure was constructed via pre-stretching and the strain sensitivity of the resultant C-MWCNT/PEDOT:PSS/TPU (CPT) conductive fibrous membrane could be effectively adjusted by changing the microcrack density. Due to the three-dimensional conductive network skeleton, microcrack structure and the bridging effect of C-MWCNT between the adjacent crack fragments, ethylene glycol treated CPT (mass ratio of C-MWCNT and PEDOT:PSS is 9/1) (e-CPT 9/1) strain sensor exhibited high sensitivity (6008.3), wide response range (680 %), fast response/recovery time (200 ms/200 ms), low detection limit (0.5 %), excellent durability and repeatability (6000 cycles). The excellent strain sensing performances enables it to accurately monitor motion activities and physiological signals, and can also be used as a smart sensing glove to identify different letters gesture and numeric gestures. Furthermore, owing to the photothermal conversion ability and thermoelectric effect of C-MWCNT and PEDOT:PSS, the obtained e-CPT 9/1 device also displayed efficient "light-thermal-electric" conversion ability and showed the great potential as self-powered strain sensor. [ABSTRACT FROM AUTHOR]

Personalized rehabilitation training provides maximum help to stroke patients to alleviate the after-effects and restore the body to normal function. However, available monitoring devices have the disadvantages of being large, requiring professional guidance, and lacking intuitive signal display capabilities. Herein, a bio-inspired wearable high-performance strain sensor with a simple structure can simultaneous electrical signals and optical visualization in response to external stimuli. The sensor comprises a conductive layer with significant electromechanical behaviors of cellulose nanocrystals (CNC)/carbon nanotubes (CNTs)/MXene nanohybrid network, and a stretchable elastomer layer consisting of thermoplastic polyurethane and fluorescent agent. Benefiting from the designed microcracks and fluorescent material, the strain sensor exhibits ultra-high sensitivity (476800), ultra-low detection limit (0.005%), low response time (60 ms), wide working range (0–100%), and enables strain visualization for applications in visually rehabilitation training monitoring. Based on these sensing characteristics, the sensor shows great advantages in human motion and sound monitoring, with the integration of digital signals and visual images makes it show great potential in visually personalized rehabilitation training monitoring. [Display omitted] • Cellulose nanocrystals are introduced to modulate the sensitivity of the strain sensor. • CCMTPF has ultrahigh sensitivity of 476800 and ultralow detection limit of 0.005%. • CCMTPF achieves electric signals and visualization of optical images responses under strain. • CCMTPF has been demonstrated for visual rehabilitation training monitoring in real time. [ABSTRACT FROM AUTHOR]

• PTFE template with micro-cavity was prepared by micromilling. • As-prepared PTFE templates have the advantages of easy demoulding and reusability. • A facile and low-cost method to fabricate microgroove-crack-based strain sensor. • Such strain sensor exhibits high sensitivity and low detection limit. • Detect body motion underwater and sound vibration with different frequencies. Strain sensor is a crucial component of high-performance wearable electronic devices. Crack-based sensor has attracted much attention due to its high sensitivity that allow an extensive application for wearable electronic devices. However, facile, efficient and cost-effective fabricating crack-based sensors is still a challenge. Herein, a facile, highly efficient, and low-cost approach was proposed to fabricate stretchable microgroove-crack-based strain sensor whose highest sensitivity is 27818.5 and low detection limit is 0.01%. Moreover, it can be pasted on human body to detect motion both in air and underwater conditions. Furthermore, it can recognize the recorded vibration spectrum of different musical scores. This study offers a facile and efficient approach for fabricating stretchable microgroove-crack-based strain sensor, showing tremendous potential in future wearable electronic devices production. [ABSTRACT FROM AUTHOR]

Nowadays, hydrogel-based sensors have drawn great attention owing to the growing demand for wearable devices. However, tailoring the property of the hydrogel sensor through a facile approach remains a great challenge. In this work, inspired by natural plants, a stretchable, adhesive and conductive hydrogel was prepared via the coordination between gallic acid (GA) and Zn2+ and chemical cross-linking. The dynamic crosslinking provided greater structural integrity for the polyvinyl alcohol / polyacrylamide (PVA/PAM) double network, endowing the hydrogel with high mechanical performance (0.25 MPa at 910% tensile strain, and 1.21 MPa at 70% compressive strain). Meanwhile, the presence of GA enabled the hydrogel with excellent repeatable adhesive performance, which greatly solved the problem of signal loss caused by poor adhesion. Moreover, the addition of ZnCl 2 enhanced the ionic conductivity and gauge factor of the hydrogel. Besides, the conductive hydrogel exhibited successively stable changes of resistance signals under different external stimuli (5–500% strains and 80–200 mm/min rates) and superior durability (over 500 cycles). The hydrogel-based wearable sensors demonstrated excellent sensing performance in detecting various human motions. The multifunctional PVA/PAM/GA-Zn2+ hydrogel has significant applications in soft robots and healthcare monitoring as the flexible strain sensor. [Display omitted] • The hydrogel was prepared via the coordination and chemical cross-linking. • The prepared hydrogel has excellent mechanical properties performance. • Plant-derived GA makes the hydrogels have good adhesion properties. • the hydrogel exhibited successively stable changes of resistance signals [ABSTRACT FROM AUTHOR]

• Waterproof conductive fiber with microcracked synergistic conductive layer was designed. • High sensitivity and wide working range were achieved for the conductive fiber strain sensor. • Tunable sensing performance was achieved for the conductive fiber strain sensor. • The sensor can precisely distinguish various human movements and physiological signals. With the rapid development of wearable smart electronic devices, flexible strain sensors with high sensitivity in a wide working range are urgently demanded. Meanwhile, good self-cleaning and anti-corrosion properties are also essential for daily use. Herein, a waterproof conductive spandex fiber strain sensor with microcracked synergistic Ag nanoparticles (AgNPs)-carbon nanotubes CNTs conductive layer was designed and fabricated via the solvent swelling, non-solvent-induced phase separation (NIPS), and low surface energy treatment process. Benefiting from the stable synergistic conductive network and the ultrasensitive microcrack structure, the sensor exhibits excellent overall strain sensing performances, including high sensitivity (gauge factor is 48,310 within 335–400% strain), wide working range (0–400%), ultralow detection limit (0.1%), fast response/recovery time (80 ms/100 ms), and long-term fatigue resistance over 10,000 cycles, making it reliably and precisely distinguish both violent human movements and subtle physiological signals. More importantly, strain sensing range and sensitivity of the sensor can also be effectively tunned through changing the AgNPs loading in the synergistic conductive network, enabling it to be applicable for different application scenarios. What's more, the waterproof surface with good self-cleaning and anti-corrosion properties also endows the sensor with great potential for real-time body motion monitoring under humid and underwater environments without being interfered. This study provides a facile one-step method for the fabrication high-performance flexible strain sensor. [ABSTRACT FROM AUTHOR]

Stretchable strain sensors with integrated attributes of flexibility and robustness are urgently required owing to their promising applications in healthcare monitoring and environment detection. Herein, we achieved a highly stretchable thermoplastic polyurethane (TPU) mat (PUM) through electrospinning, then decorated with polyaniline (PANI) nanoparticles bridged by reduced graphene oxide (rGO) nanosheets by in-situ polymerization and ultrasonication. The rGO/PANI/TPU mat (GPTM) was then assembled as the strain sensor (GPTSS), showing a wide sensing range of 0.1%–300% strain, high gauge factor (GF) of 3000.2, favorable sensing stability, short response time (90 ms) and excellent long-term durability after 10000 stretching/releasing cycles, which endows the strain sensor with high discernibility for detecting intricate human motions. The GPTSS shows the capacity to precisely monitor ammonia gas (as low as 5 ppm), which can be used to detect harmful gases. The integrated capabilities of strain sensing and environmental monitoring promote the progress of high-performance electronics. [Display omitted] [ABSTRACT FROM AUTHOR]