Auxetics‐Inspired Tunable Metamaterials for Magnetic Resonance Imaging

Auxetics refers to structures or materials with a negative Poisson's ratio, thereby capable of exhibiting counterintuitive behaviors. Herein, auxetic structures are exploited to design mechanically tunable metamaterials in both planar and hemispherical configurations operating at megahertz (MHz...

Full description

Saved in:
Bibliographic Details
Published in:Advanced materials (Weinheim) 2022-02, Vol.34 (6), p.e2109032-n/a
Main Authors: Wu, Ke, Zhao, Xiaoguang, Bifano, Thomas G., Anderson, Stephan W., Zhang, Xin
Format: Article
Language:English
Subjects:
auxetics
Deformation
Electromagnetic interactions
Field strength
Frequency shift
Helices
magnetic coupling
Magnetic resonance imaging
Metamaterials
Poisson's ratio
Radio frequency
signal‐to‐noise ratio
Three dimensional printing
tunable metamaterials
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Auxetics refers to structures or materials with a negative Poisson's ratio, thereby capable of exhibiting counterintuitive behaviors. Herein, auxetic structures are exploited to design mechanically tunable metamaterials in both planar and hemispherical configurations operating at megahertz (MHz) frequencies, optimized for their application to magnetic resonance imaging (MRI). Specially, the reported tunable metamaterials are composed of arrays of interjointed unit cells featuring metallic helices, enabling auxetic patterns with a negative Poisson's ratio. The deployable deformation of the metamaterials yields an added degree of freedom with respect to frequency tunability through the resultant modification of the electromagnetic interactions between unit cells. The metamaterials are fabricated using 3D printing technology and an ≈20 MHz frequency shift of the resonance mode is enabled during deformation. Experimental validation is performed in a clinical (3.0 T) MRI system, demonstrating that the metamaterials enable a marked boost in radiofrequency field strength under resonance‐matched conditions, ultimately yielding a dramatic increase in the signal‐to‐noise ratio (≈4.5×) of MRI. The tunable metamaterials presented herein offer a novel pathway toward the practical utilization of metamaterials in MRI, as well as a range of other emerging applications. Auxetics refers to structures or materials identified by a negative Poisson's ratio and exhibiting a counterintuitive geometrical behavior. Inspired by auxetics, mechanically tunable magnetic metamaterials in both planar and hemispherical configurations operating at megahertz frequencies are proposed, which serve to enhance local magnetic fields and increase signal‐to‐noise ratio (≈4.5×) in their application to magnetic resonance imaging.
ISSN:0935-9648
1521-4095
1521-4095
DOI:10.1002/adma.202109032