Inspired by the extraordinary functionality of biological systems that assemble anisotropic nanostructures, there is growing interest in designing multiscale ordered materials to modulate bio-based micro- and nanoscale assemblies for high performance and exceptional functionality. Current strategies for magnetic field-induced alignment of cellulose nanofibers face limitations, often relying on ultra-high magnetic fields or yielding poor orientation with microspherical magnetic particles. This study proposes an ordered assembly of cellulose nanofibers decorated with magnetic nanorods, induced under low magnetic fields. The resulting cellulose films exhibit an orientation parameter greater than 0.8. It demonstrates that the mechanism behind the magnetic field-induced alignment of magnetic nanorods with cellulose nanofibers results from a combination of magnetic torque-induced alignment of the rods and shear orientation driven by radial flow. This highly aligned, magnetically flexible, multiresponsive film achieves a dielectric constant elevated from 8.67 to 15.21. Simply by regulating the cellulose structure, the TENG output performance is improved to 971%. Compared with other complex modified cellulose film methods, the output performance is only enhanced to 760%. This method provides new insights into anisotropic assembly, with potential applications in flexible electronics and self-powered sensors.
Polyvinylidene difluoride (PVDF) and its copolymers are commonly used in triboelectric nanogenerators (TENGs) due to their flexibility and good mechanical–electrical properties. In this study, poly[(vinylidene fluoride)-co-trifluoroethylene] [P(VDF-TrFE)] composites were fabricated by embedding polydopamine (PDA)-coated cobalt ferrite nanorods (RCFO). A stripe-like microstructure was formed by applying a magnetic field during the curing process. The TENG was built with a polytetrafluoroethylene (PTFE) film as the negative friction material. Due to the enhanced micro–nano structure of the P(VDF-TrFE) films, the increased charge transfer occurred between the RCFO@PDA/P(VDF-TrFE) composite film and the PTFE film. Good triboelectric performance was realized, with an open-circuit voltage of 33.20 V, a short-circuit current of 1.20 μA, and a transferred charge of 13.17 nC at a frequency of 5 Hz and a vertical contact force of 15 N. Additionally, a peak power density of 32.5 μW cm −2 was achieved when connected to an external load resistor of 20 MΩ. In practical applications, the TENG could directly illuminate a series of 36 connected light-emitting diodes without the need for capacitors. The device's ability to capture stray magnetic fields was also demonstrated. A wireless transmission-based remote security system was demonstrated as the self-powered sensor in a noncontact mode.
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