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Title: Compact acoustic rainbow trapping in a bioinspired spiral array of graded locally resonant metamaterials
Authors: Zhao, Liuxian
Zhou, Shengxi
Keywords: Acoustic Rainbow Trapping
Artificial Cochleae
Issue Date: 2019
Source: Zhao, L., & Zhou, S. (2019). Compact acoustic rainbow trapping in a bioinspired spiral array of graded locally resonant metamaterials. Sensors, 19(4), 788-. doi:10.3390/s19040788
Series/Report no.: Sensors
Abstract: Acoustic rainbow trappers, based on frequency selective structures with graded geometries and/or properties, can filter mechanical waves spectrally and spatially to reduce noise and interference in receivers. These structures are especially useful as passive, always-on sensors in applications such as structural health monitoring. For devices that face space and weight constraints, such as microelectromechanical systems (MEMS) transducers and artificial cochleae, the rainbow trapping structures must be compact as well. To address this requirement, we investigated the frequency selection properties of a space-saving design consisting of Helmholtz resonators arranged at sub-wavelength intervals along a cochlear-inspired spiral tube. The height of the Helmholtz resonators was varied gradually, which induced bandgap formation at different frequencies along the length of the spiral tube. Numerical simulations and experimental measurements of acoustic wave propagation through the structure showed that frequencies in the range of 1–10 kHz were transmitted to different extents along the spiral tube. These rainbow trapping results were achieved with a footprint that was up to 70 times smaller than the previous structures operating at similar bandwidths, and the channels are 2.5 times of the previous structures operating at similar bandwidths.
ISSN: 1424-8220
DOI: 10.3390/s19040788
Rights: © 2019 The Authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Fulltext Permission: open
Fulltext Availability: With Fulltext
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