Tunable acoustic energy harvester using Helmholtz resonator and dual piezoelectric cantilever beams

Abstract

A tunable acoustic energy harvester consisting of dual piezoelectric cantilever beams and a Helmholtz resonator with a perforated backplate is proposed. The tunability of the operation frequency band can be achieved not only via simply adjusting the radius (r) of the aperture due to the strong dependence of resonance frequencies of the Helmholtz resonator on the acoustic impedance affected by r, but also by changing the distance (d) between piezoelectric cantilever beams because of their magnetic force interaction. Experimental results show that as r (or d) increases from 0 (or 1.4) to 1.0 (or 3.4) cm, the frequency band is broadened and varies from 175.5~198 (or 175.5~213) Hz to 170.5~221 (or 161~203) Hz. The average ratio of the adjusted frequency bandwidth to r (or d) can reach 28 (or 2.25) Hz/cm over the range of 125~250 Hz.

Analytic model for ultrasound energy receivers and their optimal electric loads

“…which should be used, instead of the loss-less wave-speed v p defined in equation (7), to define the stiffened acoustic impedance of the piezoelectric material Z p st in equation (14) as…”

“…In the usual approach, the power source is a distant emitter that sends waves towards the receiver, which is commonly made of piezoelectric material and can adopt many different construction forms On the one hand, receivers built as piezo-beams [7], diaphragms [8], horns [9] or Helmholtz resonators [10] can be found in literature. On the other hand, receivers with more basic cylindrical or disc geometric forms and composed solely of piezoelectric material are another common approach.…”

Acoustic Metamaterials: A Review of Theories, Structures, Fabrication Approaches, and Applications

“…Similarly, Yang et al. [ 65 ] combined a Helmholtz resonator with cantilever beams constructed with dual piezoelectric ceramics to achieve sound energy conversion. Meanwhile, a 2D unit cell, consisting of three adjacent Helmholtz resonators with different heights (shown in Figure 4d), that exhibited multiband and multifunctional acoustic characteristics was developed by Zhu and Assouar.…”

Eigenfrequency Shift of Piezoelectric Backplate in Vibro-Acoustic Energy Harvesting

“…As a consequence, acoustic energy harvesting research is vital and has the potential to expand in the future. Acoustic energy harvesting is defined as the technique of collecting continuous acoustic waves from the environment using an acoustic resonator tube and converting them into electrical energy using a transducer mechanism [3], [16], [28]. As acoustic waves propagate longitudinally in the medium element, an acoustic resonator tube is required to magnify the incident acoustic wave at a specific frequency, and standing resonant waves within the resonator stimulate the transducer mechanism [6], [8], [16], [29].…”

“…𝑐𝑚 −2 . Most previous studies focused on harvesting acoustic energy at relatively high frequencies ranging from a few hundred to kHz and MHz [1], [3], [4], [7], [8], [28], [30]- [32] using an HR as an acoustic resonator. Meanwhile, Bin, Li et al [29], [33], [34] focused on low-frequency acoustic sources using multiple piezoelectric in the rigid quarter wavelength resonator.…”