Magnetic metasurfaces properties in the near field regions

Brizi, Danilo; Monorchio, Agostino

doi:10.1038/s41598-022-07378-y

Cited by 19 publications

(3 citation statements)

References 41 publications

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“…In the literature, several works have been carried out to characterize the analytical model of passive SRs [26], [27], [28], [29], [30]. Conventionally, the equivalent circuit of a planar SR can be modeled as an RLC series resonator, and these lumped parameters could be accurately determined following the extraction procedure described in [28].…”

Section: Analytical Modelmentioning

confidence: 99%

Millimetric Inclusion Detection Through a Contactless Microwave Spiral Sensor for Biomedical Applications

2023

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This article introduces the design and fabrication of a microwave contactless sensor used to detect the presence of millimetric inclusions in a biological medium for biomedical applications. The hardware system comprises a self-resonant planar spiral resonator (SR) (sensing element) inductively coupled to an external concentric single-loop probe (reading probe), working at 648 MHz. The microwave sensor configuration relies on the Q-factor maximization of the spiral coil, that is, the sensing element, through an optimization process, to obtain a stronger sensitivity and, thus, a millimeter resolution for the inclusions' detection. The detection is achieved by recording both the amplitude variation and the frequency shift of the input impedance of the reading probe. To validate the proposed solution, full-wave simulations have been performed to design and preliminary evaluate the radiating system performance in detecting millimetric biological inclusions. As an applicative example, we focus on air bubbles detection in hemodialysis procedures; in particular, we carried out the experimental verification by employing an agar phantom to replicate the dielectric characteristics of the blood tissue and polylactic acid (PLA) samples of various sizes to represent the air inclusions. We proved that the theoretical assumptions were in excellent agreement with both the numerical and experimental results, encouraging further analysis of the potential use of such sensors in biomedical applications. Indeed, the radiating device can be very helpful for all operations where it is necessary to detect the presence of undesired and dangerous contaminants in a contactless way, making the procedure safer for patients.

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Section: Analytical Modelmentioning

confidence: 99%

Millimetric Inclusion Detection Through a Contactless Microwave Spiral Sensor for Biomedical Applications

2023

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“…In this work, a response-controlled passive magnetic metasurface acts as a filter of the magnetic field distribution generated by an active RF coil, achieving ultra-high focusing capability. In particular, the possibility of rapidly designing and configuring a passive metasurface allows us to obtain the desired magnetic field distribution, almost in an arbitrary way [ 86 , 87 ]. The described metasurface consisted of a 5 × 5 matrix of single loops, each having a 3 cm diameter and placed 1 cm apart from the others.…”

Section: Technical Approaches For Magnetic Field Shaping and Focusingmentioning

confidence: 99%

Shaping and Focusing Magnetic Field in the Human Body: State-of-the Art and Promising Technologies

Rotundo

Brizi

Flori

et al. 2022

Sensors

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In recent years, the usage of radio frequency magnetic fields for biomedical applications has increased exponentially. Several diagnostic and therapeutic methodologies exploit this physical entity such as, for instance, magnetic resonance imaging, hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation. Within this framework, the magnetic field focusing and shaping, at different depths inside the tissue, emerges as one of the most important challenges from a technological point of view, since it is highly desirable for improving the effectiveness of clinical methodologies. In this review paper, we will first report some of the biomedical practices employing radio frequency magnetic fields, that appear most promising in clinical settings, explaining the underneath physical principles and operative procedures. Specifically, we direct the interest toward hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation, together with a brief mention of magnetic resonance imaging. Additionally, we deeply review the technological solutions that have appeared so far in the literature to shape and control the radio frequency magnetic field distribution within biological tissues, highlighting human applications. In particular, volume and surface coils, together with the recent raise of metamaterials and metasurfaces will be reported. The present review manuscript can be useful to fill the actual gap in the literature and to serve as a guide for the physicians and engineers working in these fields.

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“…In particular, achieving a satisfying magnetic field spatial homogeneity is the key factor to overcome the misalignment issue. By making use of the analytical circuit model described in 58 , 59 , the response of a magnetic metasurface can be arbitrarily manipulated and controlled, to obtain the desired field distribution. Specifically, in 58 , the authors designed a radio-frequency (RF) solenoid exciting a passive metasurface to validate the analytical model.…”

Section: Introductionmentioning

confidence: 99%

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Lazzoni

Brizi

Monorchio

2023

Sci Rep

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In this paper, we present the design of spatial filtering magnetic metasurfaces to overcome the efficiency decay arising in misaligned resonant inductive Wireless Power Transfer systems. At first, we describe the analytical framework for the control of currents flowing on a finite-size metasurface, avoiding classical truncation effects on the periphery and opportunely manipulating, at the same time, the spatial magnetic field distribution produced by the closely placed RF driving coil. In order to validate the theoretical approach, we conceive a numerical test case consisting of a WPT system operating at 12 MHz. By performing accurate full-wave simulations, we prove that inducing a uniform current in the metasurface results in a more robust WPT system in terms of misalignment with respect to conventional configurations, also including standard metasurfaces. Therefore, while the use of metasurfaces in WPT systems has been already demonstrated to be beneficial in terms of efficiency enhancement, we confirmed that a proper control of the metasurfaces field filtering response can be advantageous also for the misalignment issue. Notably, the free space wavelength at the operating frequency (12 MHz) is 25 m, whereas the proposed metasurface dimensions are only 0.0024λ × 0.0024λ. Despite the extremely reduced dimensions, the spatial magnetic field distribution produced by the closely placed RF driving coil can be nevertheless opportunely manipulated. Finally, experimental measurements conducted on fabricated prototypes validated the numerical results, demonstrating the effectiveness of the proposed approach. These achievements can be particularly helpful in WPT applications where the position of driving and receiving coils frequently changes, as in consumer devices and biomedical implants.

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Magnetic metasurfaces properties in the near field regions

Cited by 19 publications

References 41 publications

Millimetric Inclusion Detection Through a Contactless Microwave Spiral Sensor for Biomedical Applications

Millimetric Inclusion Detection Through a Contactless Microwave Spiral Sensor for Biomedical Applications

Shaping and Focusing Magnetic Field in the Human Body: State-of-the Art and Promising Technologies

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

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