Auxetics-Inspired Tunable Metamaterials for Magnetic Resonance Imaging.
Auxetics-Inspired Tunable Metamaterials for Magnetic Resonance Imaging.
复制标题
磁性共振成像的辅助启发式可调节材料。
DOI：
10.1002/adma.202109032
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发表时间：
2022-03
期刊：
影响因子：
--
通讯作者：
Zhang X
中科院分区：
文献类型：
--
作者：
Wu K;Zhao X;Bifano TG;Anderson SW;Zhang X
物理学是指具有负泊松比的结构或材料，从而能够表现出违反直觉的行为。本文中，利用拉胀结构来设计在兆赫兹（MHz）频率下操作的平面和半球形配置中的机械可调谐超材料，针对它们在磁共振成像（MRI）中的应用进行了优化。特别地，所报道的可调谐超材料由具有金属螺旋的相互连接的单位单元阵列组成，使得具有负泊松比的拉胀图案成为可能。超材料的可展开变形通过单位单元之间的电磁相互作用的所得修改产生相对于频率可调谐性的附加自由度。超材料使用3D打印技术制造，并且在变形期间实现谐振模式的~20 MHz频移。在临床（3.0特斯拉）MRI中进行实验验证，证明超材料在共振匹配条件下能够显著提高射频（RF）场强，最终大幅提高MRI的信噪比（SNR）（~ 4.5倍）。本文提出的可调谐超材料提供了一种新的途径，使超材料在MRI中的实际利用，以及一系列其他新兴的应用。几何学是指由负泊松比确定的结构或材料，并表现出反直觉的几何行为。受拉胀学的启发，提出了在兆赫频率下工作的平面和半球形结构的机械可调磁性超材料，其用于增强局部磁场并在其应用于磁共振成像（MRI）时提高信噪比（SNR）（~ 4.5倍）。
Auxetics refers to structures or materials with a negative Poisson's ratio, thereby capable of exhibiting counter-intuitive 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 inter-jointed 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 a ~20 MHz frequency shift of the resonance mode is enabled during deformation. Experimental validation is performed in a clinical (3.0 Tesla) MRI, demonstrating that the metamaterials enable a marked boost in radiofrequency (RF) field strength under resonance matched conditions, ultimately yielding a dramatic increase in the signal-to-noise ratio (SNR) (~ 4.5X) of MRI. The tunable metamaterials presented herein offer a novel pathway towards 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 counter-intuitive 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 (SNR) (~ 4.5X) in their application to magnetic resonance imaging (MRI).
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