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The development of wearable electronic devices has greatly stimulated the research interest of textile-based strain sensors, which can effectively combine functionality with wearability. In this work, the fabrication of highly stretchable and compressible strain sensors from weft-knitted spacer fabric was reported. Carbon nanotubes and polypyrrole were deposited on the surface of fabric via an in situ polymerization approach to reduce the electrical resistance. The as-fabricated WSP-CNT-PPy strain sensor exhibits high electrical conductivity and stable strain-sensing performance under different stretching deformations. The WSP-CNT-PPy strain sensor can be stretched up to 450% and compressed to 60% with a pressure of less than 50 KPa, which can be attributed to the unique loop and interval filament structures. The distinguishing response efficiency of WSP-CNT-PPy can effectively detect faint and strenuous body movements. In addition, the electrochemical behavior of WSP-CNT-PPy was also characterized to study the comprehensive properties. The electro-heating performance was also evaluated for feasible Joule heater applications. This work demonstrates the practicability of WSP-CNT-PPy strain sensor fabric for real-time monitoring in promising wearable garments. [ABSTRACT FROM AUTHOR]

A green approach was successfully developed to fabricate flexible sensors by utilizing carbonized waste cotton fabrics in combination with natural rubber latex. Waste cotton fabrics were firstly carbonized by heat treatment in the nitrogen atmosphere before they were combined with natural rubber latex using three methods, i.e., vacuum bagging, negative pressure adsorption and drop coating. After impregnation with natural rubber, the carbonized cotton maintained the fabric structure and showed good conductivity. More importantly, the electric resistance of the textile composites changed with the tensile strain. The cyclic stretching-releasing tests indicated that the prepared wearable flexible strain sensors were sensitive to strain and stable under cyclic loading. The flexible strain sensor also demonstrated the capability of monitoring human finger and arm motion. [ABSTRACT FROM AUTHOR]

[Display omitted] • A flexible and highly sensitive strain sensor was developed by using carbonized biomass Juncus effusus fiber. • The 3D fractal composite structure showed robust mechanical strength and excellent sensitivity. • Reliable sensing performance was achieved with mechanism revealed. • Potential applications include health care monitoring and human motion monitoring were demonstrated. • The promising potential of energy conversion and harvesting was demonstrated. Fabricating strain sensors with environmental-friendly, stretchable, and highly sensitive properties remains challenging. Nature has designed an abundance of biomaterials with distinctive biological structures, which may promote the development of ideal strain sensors. Herein, we present a carbonized Juncus effusus (CJE) fiber-based wearable electronic for strain sensing and energy harvesting. The CJE strain sensor demonstrated a combined superiority of large tolerable strain (over 80%), high sensitivity (GF 4.5–31.0), low detection limit (0.1% strain), fast response (within 100 ms), and excellent durability (3500 cycles), which benefit from the self-similar and homogenous three-dimensional (3D) networks of CJE fibers. Moreover, CJE-based woven fabrics exhibited enhanced sensing characteristics (GF up to 101.9, over 110% strain) and great application prospects as triboelectric nanogenerators (TENGs). Finally, the applications in detecting human activities and energy transformation were evaluated in detail. The structural advantages made CJE as a promising candidate for the feasible integration of flexible strain sensors and portable power source in wearable electronics. [ABSTRACT FROM AUTHOR]

• A core-sheath sensing yarns was fabricated via scalable friction spinning. • The yarn exhibited excellent heat resistance and stretchability simultaneously. • High-temperature alarm could be transmitted through stretching and thermosensation. Electronic textiles with functions of temperature monitoring and human motion detection have attracted considerable interest, especially those which can be operated under extreme conditions such as high temperature. However, the restricted working conditions and poor stretchability have limited the practical application of most reported electronic textiles. Herein, we report a facile and scalable strategy to fabricate flame-resistant sensing yarn with a core–sheath structure for temperature monitoring and strain sensor applications via a large-scale spinning technique. The hierarchical yarn comprises a spandex filament as the core, carbon nanotube (CNT)-coated aramid fibers as the middle layer, and aramid fibers as the sheath. The obtained spandex/CNT@Aramid/Aramid (SCAA) yarn exhibited stretchability up to 160 % with excellent thermal resistance, outstanding thermal insulation performance, and temperature monitoring ability within a wide-range of 50–400 °C. Additionally, SCAA-based textiles showed excellent strain sensing performance in a wide operating temperature range (0–300 °C). Based on the above, a SCAA-based textiles which can transmit high-temperature alarms through active (stretching) and passive (thermosensation) modes was designed, enabling temperature monitoring presenting at extremely high temperatures. We believe this work will contribute to the development of practical sensing e-textiles towards applications in harsh environment. [ABSTRACT FROM AUTHOR]

• A conductive nanofiber composite is successfully fabricated by in situ reduction Ag NPs. • The conductive TPU nanofiber composite demonstrates good stability in harsh conditions. • The nanofiber composite sensor possesses a high sensitivity and broad working range. • The sensor was able to detect full range detection of human body motions. Flexible strain sensors have received wide attention due to their potential applications in wearable devices. However, the development of strain sensors with higher stretchability, and larger workable strain range still remains a challenge. Here, a conductive nanofiber composite with a hierarchical silver nanoparticles (Ag NPs) shell and thermoplastic polyurethane (TPU) nanofiber core microstructure are constructed via depositing Ag NPs on TPU nanofiber mats surface with the aid of tannic acid (TA) and hydrolysable 3-aminopropyltriethoxysilane (APTES) hybrid coating (TA-APTES coating). The prepared strain sensor demonstrates high stretchability with maximum strain of 565% and high sensitivity with a gauge factor (GF) of about 6886. In addition, the TPU@(TA-APTES)@Ag NPs composite strain sensor can be applied to detect human motions. [ABSTRACT FROM AUTHOR]

• Implementing in situ hydrothermal growth of Cu NPs on textiles. • Introducing polydopamine as a template to facilitate growing nanoparticles. • Fibrous structure has been preserved with nanoparticles deposited on fibers. • Durable and highly-flexible textile based wearable sensor was developed. Incorporating conductive components into fibrous structure for wearable applications has attracted research attention recently. However, utilizing the flexibility and wearability of textiles to maintain a stable and durable wearable performance is a big challenge, as the intrinsic properties of textiles and the conductivity of the incorporated components have to work synergically in the fibrous system without compromising. In this work, polydopamine-templated PET fabrics were prepared to grow copper nanoparticles (Cu NPs) on the surface of the knitted PET fabrics. The surface morphology, chemical composition and crystalline structure of the Cu NP-coated PET fabrics were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The results showed that Cu NP layer was successfully deposited onto the polydopamine-templated PET fabrics. The fabrics showed excellent electrical conductivity due to the loading of Cu NPs. The unique knitted structure together with the durable deposition of Cu NPs resulted in negative change in electrical resistance of the fabrics under strains, granting the fabrics the potential in wearable applications. The Cu NP-coated PET fabrics were demonstrated to be applicable as wearable strain sensors and electrical heaters. [ABSTRACT FROM AUTHOR]

With fiber-based wearable electronics being developed and widely used in various fields, the safety and durability of nanomaterials in fibrous system become big concerns due to the leakage of nanomaterials and possible failure in functionality. To date, it is still challenging to fabricate wearable strain sensors with sensitivity and durability. Herein, we report a simple strategy for large-scale fabrication of core-sheath nanocomposite yarn (CSCY) based wearable sensor with high sensitivity and superior durability. By dispersing aqueous CNT ink into braided composite yarns as the core (BYs-CNT) and electrospun polyurethane (PU) nanofibers as the sheath, a unique core-sheath micro-nanofibrous structure was fabricated to grant the yarn with extremely high sensing sensitivity (maximum GF up to 980), long-term stability and great durability (against washing and dilute hydrochloric acid). The as-developed CSCY strain sensor was demonstrated to monitor real-time subtle and vigorous human activities. The present work provides insights for developing reliable and stable, highly sensitive, flexible and durable wearable electronics with potential applications in different areas. Image 1 [ABSTRACT FROM AUTHOR]