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Wearable strain transducers are poised to transform the field of healthcare owing to the promise of personalized devices capable of real‐time collection of human physiological health indicators. For instance, monitoring patients' progress following injury and/or surgery during physiotherapy is crucial but rarely performed outside clinics. Herein, multifunctional liquid‐free ionic elastomers are designed through the volume effect and the formation of dynamic hydrogen bond networks between polyvinyl alcohol (PVA) and weak acids (phosphoric acid, phytic acid, formic acid, citric acid). An ultra‐stretchable (4600% strain), highly conducting (10 mS cm−1), self‐repairable (77% of initial strain), and adhesive ionic elastomer is obtained at high loadings of phytic acid (4:1 weight to PVA). Moreover, the elastomer displayed durable performances, with intact mechanical properties after a year of storage. The elastomer is used as a transducer to monitor human motions in a device comprising an ESP32‐based development board. The device detected walking and/or running biomechanics and communicated motion‐sensing data (i.e., amplitude, frequency) wirelessly. The reported technology can also be applied to other body parts to monitor recovery after injury and/or surgery and inform practitioners of motion biomechanics remotely and in real time to increase convalescence effectiveness, reduce clinic appointments, and prevent injuries. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) are nanomaterials with engineered chemical structures, offering remarkable properties. However, their limited film‐formation capability hinders their integration into triboelectric nanogenerators (TENGs). This study proposes a simple yet effective solution to overcome this challenge by employing electrospinning techniques to integrate the zeolitic imidazolate framework (ZIF‐8) into an easy‐to‐use nanofibrous mat. ZIF‐8 has high surface potential, a unique cubical structure, and an easy fabrication process that makes it an ideal material for TENGs. By incorporating ZIF‐8 into the electrospinning solution, significant improvements are achieved in the electropositivity of the resulting nanofibers. It leads to notable changes in the shape, morphology, and roughness of electrospun fibers, consequently enhancing the overall performance of the TENG. The results indicate that utilizing the ZIF‐based electrospun mat as a tribo‐positive material can increase transferred charges between electrodes by more than 100%. Utilizing the MOF‐based nanofibrous mat, this study also introduces a novel rotary TENG that works based on a mode of TENG operation called rolling mode. The reliable charge generation by the proposed rolling system reveals that this mode of TENG operation could be a superb alternative for traditional TENG modes, like contact/separation or sliding, which cause high levels of mechanical stress due to harsh physical impact or friction. [ABSTRACT FROM AUTHOR]

Most mechanical energy harvesters produce only small amounts of electrical power from extremely low‐frequency input motions and immediately stop generating electricity when mechanical kinetic energy is exhausted. Here, a steady, long‐lasting and power‐boosted triboelectric nanogenerator is reported that can efficiently harvest from extremely low‐frequency irregular motions of less than 0.1 Hz by utilizing an escapement mechanism and frequency up‐conversion device. The escapement mechanism‐based triboelectric nanogenerator (EM‐TENG) consists of a mechanical energy storage spring, escapement mechanism and a torsional resonator for regular operation and frequency up‐conversion. In addition, the micro‐patterned alternating dielectric surfaces of Nylon and polytetrafluoroethylene (PTFE) and the comb‐type rotator significantly improve the output performance of the rotational EM‐TENG, increasing the current density level approximately 4.2 times compared to flat surfaces. Under an input frequency of 0.067 Hz, the EM‐TENG produces an open circuit voltage of 320 V and a short‐circuit current density of 0.59 mA m‐2. Most importantly, the EM‐TENG can produce long‐lasting and steady output power for 110 s (22 times) under only 5 s of input motion. Therefore, the EM‐TENG might pave the way to effectively harvest energy from extremely low‐frequency motions in nature, such as human motion, structural vibration and ocean waves. [ABSTRACT FROM AUTHOR]

The integration of bio-based materials into triboelectric nanogenerators (TENGs) for energy harvesting from human body motions has sparked considerable research attention. Here, a silanated cellulose nanofibril (SCNF) aerogel is reported for structurally reliable TENGs and reversely compressible Taekwondo scoring sensors under repeated impacts. The preparation of the aerogel involves silanizing cellulose nanofibers (CNFs) with vinyltrimethoxysilane (VTMS), following by freeze-drying and post-heating treatment. The SCNF aerogel with crosslinked physico-chemical bonding and highly porous network is found to exhibit superior mechanical strength and reversible compressibility as well as enhanced water repellency and electron-donating ability. The TENG having a tribo-positive SCNF layer exhibits exceptional triboelectric performances, generating a voltage of 270 V, current of 11 µA, and power density of 401.1 mW m -2 under an applied force of 8 N at a frequency of 5 Hz. With its inherent merits in material composition, structural configuration, and device sensitivity, the SCNF TENG demonstrates the capability to seamlessly integrate into a Taekwondo protection gear, serving as an efficient self-powered sensor for monitoring hitting scores. This study highlights the significant potential of a facilely fabricated SCNF aerogel for the development of high-performance, bio-friendly, and cost-effective Bio-TENGs, enabling their application as self-powered wearable devices and sports engineering sensors., (© 2024 Wiley‐VCH GmbH.)