A wearable metasurface for high efficiency, free-positioning omnidirectional wireless power transfer

Wang, Hanwei; Chen, Yunsheng; Zhao, Yang

doi:10.1088/1367-2630/ac304a

Cited by 9 publications

(4 citation statements)

References 38 publications

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“…At the same transfer distance and larger receiver, the previous work in [ 31 ] obtained an efficiency of 20% with reconfigurable metamaterial. In [ 37 ], the achieved efficiency of the WPT system with metasurface for a receiver was 50.4% at a distance of 120 mm.…”

Section: Experiments Resultsmentioning

confidence: 99%

“…In addition, zero-permeability metamaterials can also be used to block magnetic fields to increase safety, as per a study by Lu et al [ 32 ]. Various configurations of metamaterials have been integrated into WPT systems, such as superconducting metamaterials, coding metasurfaces, side-place metamaterials, and wearable metasurfaces [ 33 , 34 , 35 , 36 , 37 ]. Most metamaterial structures integrated into WPT systems are in planar configurations with a rigid substrate, which limits practical applications.…”

Section: Introductionmentioning

confidence: 99%

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Flexible Magnetic Metasurface with Defect Cavity for Wireless Power Transfer System

et al. 2022

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In this paper, we present a flexible magnetic metamaterial structure for enhancing the efficiency of wireless power transfer (WPT) systems operating at 13.56 MHz. The metasurface between transmitter (Tx) and receiver (Rx) coils of the WPT system is constructed of a 3 × 5 metamaterial unit cell array with a total size of 150 × 300 mm2. Most metamaterial structures integrated into WPT systems are in planar configurations with a rigid substrate, which limits practical applications. The proposed metasurface is fabricated on an FR-4 substrate with a thin thickness of 0.2 mm; therefore, it can be bent with radii greater than 80 mm. A defect cavity is formed in the non-homogeneous metasurface by controlling the resonant frequency of the unit cell with an external capacitor. Simulation and measurement results show that the efficiency of the WPT system is significantly enhanced with metasurfaces. The performance of the WPT system can also be optimized with suitable bend profiles of metasurfaces. This proposed flexible metasurface could be widely applied to WPT systems, especially asymmetric, bendable, or wearable WPT systems.

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Section: Experiments Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flexible Magnetic Metasurface with Defect Cavity for Wireless Power Transfer System

et al. 2022

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“…Therefore, the aim of this paper is to develop a methodology to generalize and enhance the design of magnetic metasurfaces for WPT systems by considering arbitrarily conformal configurations. In the literature, different studies investigated conformal metasurface for WPT applications [37], [38], [39], [40], [41]. However, we presented a general formulation which can be applied to arbitrary shapes, thus allowing the realization of systems suitable for different geometries and facilitating the integration into existing electronic devices.…”

Section: Introductionmentioning

confidence: 99%

Arbitrarily Conformal Metasurfaces for Enhanced Wireless Power Transfer Systems

Dellabate,

Lazzoni,

Monorchio

et al. 2024

IEEE Access

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In this paper, design guidelines and unique features of arbitrarily conformal metasurfaces for Wireless Power Transfer (WPT) systems are discussed. In particular, we demonstrate the flexibility of conformal metasurfaces in achieving different behaviors by proposing two different applicative test cases: (i) magnetic field shielding in the region behind an RF coil, as typically required in automotive WPT scenarios, and (ii) wireless power transmission with a magnetic field distribution spatially focused by the metasurface, eventually useful for electromagnetic exposure and interferences reduction. In general, the metasurface design is performed by following an analytical method that allows controlling and tailoring its response even though the array is finite, conformal and near-field excited. For both the implementations, the analytical design was corroborated by accurate full-wave simulations and experimental measurements carried out at 13.56 MHz. In particular, the possibility to obtain a 8 dB shielding effectiveness of an RF coil magnetic field at distances larger than twice of its diameter was proved. Conversely, in the second implementation, the conformal metasurface was capable to guarantee a measured power transfer efficiency of 8% for a receiver placed in correspondence of the 4 cm diameter focusing spot, while drastically reducing the magnetic field everywhere else. The results demonstrated the excellent potentialities of conformal magnetic metasurfaces for WPT applications in ensuring the electromagnetic safety for operators while simultaneously achieving enhanced performance.

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“…Currently, various types of shapes and configurations of resonating spirals and other printed unit-cells have been studied to demonstrate metasurfaces' ability to enhance the mutual coupling between magnetic dipoles. Consequently, the inductive link power transfer efficiency, the working distance, and the misalignment robustness of WPT systems can be significantly improved 14,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] . In 42,46,47,[50][51][52] , it was also proved how metasurfaces could be employed to lower E-field peaks, therefore, accomplishing high safety standards for the WPT system while guaranteeing an enhanced power transfer efficiency level with respect to a conventional driver-receiver system.Typically, the design and analysis of metamaterials and metasurfaces are based on the classical electromagnetic theory where the slab is considered infinite, and uniformly excited by a normal incident plane wave 31 .…”

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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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A wearable metasurface for high efficiency, free-positioning omnidirectional wireless power transfer

Cited by 9 publications

References 38 publications

Flexible Magnetic Metasurface with Defect Cavity for Wireless Power Transfer System

Flexible Magnetic Metasurface with Defect Cavity for Wireless Power Transfer System

Arbitrarily Conformal Metasurfaces for Enhanced Wireless Power Transfer Systems

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

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