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  Metamaterials & MRI: Intelligent Metamaterials for Enhanced MRI

Magnetic resonance imaging (MRI) stands as the gold standard in modern healthcare diagnostics, yet its complexity, high cost, and lengthy procedure times limit its universal accessibility. The quality of MRI images depends heavily on the signal-to-noise ratio (SNR), which directly affects image clarity. Importantly, SNR can often be traded for shorter scan times, thereby reducing procedure duration and alleviating key limitations such as cost and accessibility. The most direct way to enhance SNR is by increasing the magnetic field strength—but this also raises MRI complexity, cost, and potential risks to patients. How can we expedite MRI procedures without compromising imaging quality or significantly increasing costs? What if a simple material—crafted from plastic and copper wire—could address all these challenges, enabling MRI scans that are sharper, faster, more affordable, and safer?

Our material, known as a metamaterial, consists of an array of helical resonators—centimeter-tall structures made from 3D-printed plastic and coils of thin copper wire. These materials are not inherently extravagant, but when assembled, they form a flexible array that can seamlessly conform to the kneecap, abdomen, head, or any region requiring imaging. Its simplicity often surprises many. It's not a mystical material—rather, the power lies in its design and underlying concept. When positioned near the body, the metamaterial array interacts with the radiofrequency fields emitted during MRI image acquisition, enhancing the SNR without the need to increase the magnetic field strength.

Crucially, our metamaterials are "intelligent," comprising an array of closely packed metallic helical resonators integrated with a passive sensor. When relatively high-energy radio waves penetrate the patient during MRI, the metamaterial detects this energy level and automatically deactivates its resonance. Conversely, under low-energy radio excitation, the metamaterial activates its resonance, thereby amplifying the magnetic component of the radio wave. During this brief off-time—lasting only milliseconds—radiologists can use the metamaterial to enhance the energy returning to the MRI system, increasing the signal received from the patient. This also reduces the patient's overall exposure to radiofrequency radiation and mitigates potential safety concerns, supporting seamless integration into clinical imaging workflows. Our metamaterial improves SNR by more than 15-fold, significantly enhancing image quality, reducing scan times, and offering a cost-effective path to higher-performance MRI.

"You can keep your hat on (in the MRI). If I told you an MRI revolution was coming, you probably wouldn't expect it to come dressed like this." Taking our efforts further, we have developed a tunable, wearable metamaterial capable of dramatically improving brain scans. It may resemble a quirky bike helmet or a contraption straight out of Doc Brown's lab in Back to the Future, but despite its whimsical appearance, the device is a scientifically sophisticated metamaterial. The helmet consists of an array of metamaterial resonators—3D-printed plastic tubes wrapped in copper wire—assembled into an array and precisely positioned to manipulate the MRI's magnetic field. This dome-shaped device fits snugly over a person's head during a brain scan, enhancing MRI performance by producing sharper images that can be acquired at twice the usual speed. While its playful look evokes a mad scientist's lab, there is indeed method to the madness—and the potential applications of these metamaterials are far-reaching.

Undoubtedly, the prospect of simplifying MRI technology is highly appealing. From seamlessly integrating metamaterials with computer-aided embroidery for enhanced comfort to developing wireless, lightweight coils that conform to 3D body contours using coaxial cables, our recent breakthroughs are reshaping the future of MRI—blending comfort, precision, and affordability. While ultra-low-field MRI offers advantages such as portability and cost-effectiveness, its primary limitation lies in its inherently low SNR, which is inversely correlated with magnetic field strength. This is where our metamaterials play a critical role—enabling substantial improvements in MRI SNR. Leveraging metamaterials as a foundational platform, we are currently assembling a cost-effective, low-field MRI system tailored for brain imaging. With the performance gains enabled by our metamaterial technologies, we envision a clinically relevant, portable, and affordable diagnostic tool—poised to democratize MRI access for anyone, anywhere.

Representative Publications
(#denotes graduate students/postdocs supervised by X. Zhang; *denotes corresponding author by X. Zhang)

Metamaterial-enabled hybrid receive coil for enhanced magnetic resonance imaging capabilities
X. Zhu#, K. Wu#, S.W. Anderson, X. Zhang*
Advanced Science, 2025, 12(3): 2410907
Conformal metamaterials with active tunability and self-adaptivity for magnetic resonance imaging
K. Wu#, X. Zhu#, X. Zhao#, S.W. Anderson, X. Zhang*
Research, 2024, 7: 0560
A robust near-field body area network based on coaxially-shielded textile metamaterial
X. Zhu#, K. Wu#, X. Xie#, S.W. Anderson, X. Zhang*
Nature Communications, 2024, 15: 6589
Wireless, customizable coaxially shielded coils for magnetic resonance imaging
K. Wu#, X. Zhu#, S.W. Anderson, X. Zhang*
Science Advances, 2024, 10(24): eadn5195
Wearable coaxially-shielded metamaterial for magnetic resonance imaging
X. Zhu#, K. Wu#, S.W. Anderson, X. Zhang*
Advanced Materials, 2024, 36(31): 2313692
Computational-design enabled wearable and tunable metamaterials via freeform auxetics for magnetic resonance imaging
K. Wu#, X. Zhu#, T.G. Bifano, S.W. Anderson, X. Zhang*
Advanced Science, 2024, 11(26): 2400261
Helmholtz coil-inspired volumetric wireless resonator for magnetic resonance imaging
X. Zhu#, K. Wu#, S.W. Anderson, X. Zhang*
Advanced Materials Technologies, 2023, 8(22): 2301053
Auxetics-inspired tunable metamaterials for magnetic resonance imaging
K. Wu#, X. Zhao#, T.G. Bifano, S.W. Anderson, X. Zhang*
Advanced Materials, 2022, 34(6): 2109032
Nonreciprocal magnetic coupling using nonlinear meta-atoms
X. Zhao#, K. Wu#, C. Chen#, T.G. Bifano, S.W. Anderson, X. Zhang*
Advanced Science, 2020, 7(19): 2001443
Intelligent metamaterials based on nonlinearity for magnetic resonance imaging
X. Zhao#, G. Duan#, K. Wu#, S.W. Anderson, X. Zhang*
Advanced Materials, 2019, 31(49): 1905461
Boosting magnetic resonance imaging signal-to-noise ratio using magnetic metamaterials
G. Duan#, X. Zhao#, S.W. Anderson, X. Zhang*
Communications Physics − Nature, 2019, 2: 35

Ph.D. Dissertation
Magnetic field enhancement in metamaterials
Ke Wu, Ph.D. Dissertation, Boston University. (Advisor: Xin Zhang; March 2023)

Our Metamaterials in the Media (Media Logos, Quotes, Highlight Images, and Orginal Articles)


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