Functional triboelectric nanogenerator based on shear stiffening gel for impact protection and self-powered motion monitoring

Aging often contributes to the atrophy of the plantar fat pad, diminishing its ability to effectively dissipate rebound impact force from the ground, which current wearable monitoring devices are insufficient for alleviating and susceptible to malfunction due to the damage of external power sources during a tumble. Herein, shear stiffening gel (SSG) and multi-walled carbon nanotubes (MWCNTs) were compounded to produce a composite (MSSG), which was encapsulated within the Ecoflex coating embedded with polytetrafluoroethylene (PTFE) particles. This resulting multifunctional composite, designated as MSSG@PEco, was subsequently interfaced with a copper sheet to construct a functional triboelectric nanogenerator (F-TENG). MSSG exhibits an improved thermal stability (T5% is increased from 219 degrees C to 276 degrees C) than SSG, while MSSG@PEco possesses excellent hydrophobicity (the water contact angle is 130.86 degrees). When experiencing the impact force, the MSSG@PEco dissipates over 90 % impact energy and its resistance responds timely, demonstrating exceptional anti-impact and mechanical-electrical coupling properties. The F-TENG, optimized for energy collection and conversion, generates a voltage of 74 V at a vertical contact-separation frequency of 5 Hz, efficiently powering 100 LEDs and charging a 1.0 mu F capacitor to 20 V within 14 s. The designed smart insole based on MSSG@PEco and F-TENG effectively outputs electrical signals corresponding to various human motions, highlighting its promising applications in novel energy-supplying, flexible wearable motion monitoring and safety protecting domains.