A Low‐Frequency Energy Harvester from Ultralong, Vertically Aligned BaTiO₃ Nanowire Arrays

Abstract

growth of ultralong, vertically aligned BaTiO 3 NW arrays and demonstrated in a high sensitivity NEMS accelerometer. [ 19 ] In this communication, a novel NEMS energy harvester is fabricated using this newly developed process for ultralong, vertically aligned BaTiO 3 NW arrays which has a low resonant frequency (below 200 Hz) and its AC power harvesting capacity from low amplitude base vibrations is demonstrated. The design and fabrication of low resonant frequency vibrational energy harvesters has been challenging in the fi eld of MEMS/ NEMS since the high stiffness of the structures results in resonant frequency often greater than 1 kHz. [ 20 ] However, ambient mechanical vibrations usually exist in the 1 Hz to 1 kHz range and thus high aspect ratio nanostructures are benefi cial to enable effi cient energy conversion. Through the use of this new process for the growth of highly compliant, ultralong (≈40 µm long) BaTiO 3 NW arrays, it is shown that NW based energy harvesters capable of harnessing this low frequency ambient energy can be constructed. Resistive impedance matching at the device's resonant frequency is used to identify the peak root mean square (rms) value of AC power and peak power density observed from the long BaTiO 3 NW array energy harvester that is driven by an rms sinusoidal base acceleration of only 0.25 g.Ultralong (≈40 µm) vertically aligned BaTiO 3 NW arrays are grown on an oxidized Ti substrate using an inexpensive two-step hydrothermal process that allows for control over the aspect ratio of the resulting NW arrays by tuning the reaction parameters in the synthesis procedure. BaTiO 3 NW arrays are synthesized via temperature assisted Ba 2+ ion diffusion into single crystal vertically aligned sodium titanate NW arrays that act as templates during the second hydrothermal reaction. Figure S1 (Supporting Information) shows the detailed X-ray diffraction (XRD) pattern of all materials utilized in the synthesis of long BaTiO 3 NW arrays. The dimensions of the BaTiO 3 NWs are controlled using reaction parameters so that the NW arrays are suffi ciently rigid to avoid wicking on the top surface from capillary forces during the drying process after synthesis. [ 21 ] The resulting NWs have a length of ≈40 µm and a diameter of ≈630 nm. A detailed analysis of the microstructure of the aligned array of NWs is performed using a scanning electron microscope (SEM) as shown in Figure 1 a. The crystallographic structure of the NWs is analyzed using X-ray diffraction (XRD) and the XRD pattern from the NWs match with BaTiO 3 (JCPDS No. 5-0626) as shown in Figure 1 b. Next, the BaTiO 3 NW based energy harvester is fabricated through the removal of the as-synthesized vertically aligned BaTiO 3 NW arrays from the oxidized Ti substrate that was used for their growth. The assynthesized BaTiO 3 NW arrays' surface can be easily released from the original growth substrate after immersing in dilute HCl solution and drying in room temperature after washing Mechanical vibrations are an abundantly available renewable ...

Self-powered flexible inorganic electronic system

“…However, general piezoelectric ceramics are brittle and bulky with limited capacity for flexible deformation. Although several efforts have been made to develop NWs-based perovskite nanogenerators, bottom-up approaches have the drawbacks of difficult synthesis and low performance [36][37][38][39].…”

One‐Dimensional Ferroelectric Nanostructures: Synthesis, Properties, and Applications

“…Similar BaTiO 3 NW-based NGs were also demonstrated, but where much longer (40 mm) NWs were used, facilitated by converting extremely high aspect ratio sodium titanate NWs. [ 145 ] These ultralong NWs were shown to produce an output of 390 mV and 1.86 nA, with 192 nW cm −3 on a load of 100 MΩ using an acceleration of only 0.25 g.…”

A Scalable Nanogenerator Based on Self‐Poled Piezoelectric Polymer Nanowires with High Energy Conversion Efficiency

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nanowires, [ 7 ] PbZr x Ti 1x O 3 nanowires [ 8 ] and nanoribbons [ 9,10 ] and poly(vinylidene fl uoride) (PVDF) nanofi bers [ 11 ] have all revealed promising energy harvesting performance. There has since been an ongoing concerted effort in developing this relatively new research fi eld, connecting nanotechnology with the fi eld of energy.

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