Characterization of ZnO Piezoelectric Nanowires in Energy Harvesting for Fiber-Reinforced Composites

Structural health monitoring can enhance reliability, increase safety, and decrease maintenance costs by detecting damage at an early stage. By taking advantage of the electromechanical coupling, piezoelectric materials have the potential to harvest energy from ambient vibration sources to provide low-power electricity for self-powered electronic devices. In comparison with other piezoelectric transducers, zinc oxide (ZnO) nanowires carry the added advantages of structural flexibility, lower cost, compactness, and lighter weight. In this study, the energy harvesting capabilities of nanoscale ZnO piezoelectric nanowires (NW) grown on the surface of glass fiber fabrics are investigated experimentally. A series of cantilevered carbon fiber beams containing a controlled amount of ZnO nanowires is evaluated. The absolute electrical energy dissipation is quantified by measuring the output power over a broad spectrum of known vibratory loads and frequencies. The maximum amount of power extracted is obtained by employing resistive impedance matching. Here, a maximum peak of ∼6.7 mV was generated when the beam containing ZnO nanowires was excited at 2.90g and connected to a 10 MΩ load. At that excitation level, a maximum of 20.0 pW was generated when an optimal resistor of 1 MΩ is connected. A tip mass of ∼0.6 gram added to the sample with ZnO NWs increased the peak-voltage by 2.21 mV and increased the peak-power by 13.3 pW. A series of DC voltage applied to the ZnO sample suggests the equivalence of poling treatment, where the dipole alignment of the ZnO NWs are disrupted. Here, a maximum peak-power of 45 pW is reported, showing promising potential of scaling-up to harvest ambient energy for low-powered electronics.