Multifunctional Self-Powered PVDF/TiO₂ Nanowire Platform for Energy Harvesting and Precision Vortex Flow Sensing

The precise detection of subtle fluid flow variations is essential for advanced applications ranging from environmental surveillance to real-time monitoring of oil and gas pipelines. In this work, we report a multifunctional piezoelectric nanogenerator (PENG) based on a poly(vinylidene fluoride) (PVDF) and titanium dioxide nanotube (TNT) composite, engineered via a confined phase-inversion technique. This nanostructured composite functions as a high-power energy harvester and a vortex flowmeter sensor. Notably, the growth of PVDF nanowires within the oriented TiO₂ nanotube template offers the additional advantage of inducing self-poling behavior, enhancing piezoelectric performance without external electrical poling. Under periodic mechanical excitation, the device delivers a remarkable open-circuit voltage of 48.6 ± 1.1 V and a power density of 0.93 ± 0.024 mW/cm², sufficient to charge a 30 μF capacitor. Integrated into a bluff-body flow setup, the system captures vortex-induced voltage signatures with high fidelity and enables flow detection at ambient wind speeds as low as 4.04 m/s, well below the detection limit of conventional flowmeters. The vortex frequency identified in computational fluid dynamics simulations closely matches the signal captured by our multifunctional nanogenerator. The synergistic integration of nanoscale material design and precision fluid dynamics positions this PVDF/TNT-based nanogenerator as a promising platform for next-generation, self-powered fluidic sensing networks.