Midfield Wireless Powering of Subwavelength Autonomous Devices

Kim, Sanghoek; Ho, John S.; Poon, Ada S. Y.

doi:10.1103/physrevlett.110.203905

Cited by 102 publications

(84 citation statements)

References 26 publications

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“…It can be shown that transfer is maximized by correctly setting (i) the resonant frequencies of the source ω S and receiver ω C and (ii) the rate of energy extraction by the load γ L . In the weak coupling regime, it can be shown that the impedance-matching conditions are simply ω = ω S = ω C and γ L = γ C , where ω is the operating frequency and γ C the rate of energy loss at the receiver structure [26]. In the strong-coupling regime, the matching conditions differ by a correcting term dependent on the coupling strength due to mode-splitting [19].…”

Section: Coupled Structuresmentioning

confidence: 99%

“…The design space, however, is too vast to exhaustively search with full-field electromagnetic simulations. To begin, the field equivalence principle can be invoked to reduce the dimensionality of the search space [26]. The principle is applied by drawing a plane between the surface of the body and the volume outside of the body where sources are allowed to exist.…”

Section: Optimal Energy Transfer Sourcementioning

confidence: 99%

“…The search for the optimal source can now be posed as an optimization problem maximizing f (|ψ ) over the space of all current sheets. Remarkably, this problem is in the form of the matched-filtering problem [26]. It is straightforward to show from the Cauchy-Schwarz inequality that the solution is…”

Section: Optimal Energy Transfer Sourcementioning

confidence: 99%

See 2 more Smart Citations

ENERGY TRANSFER FOR IMPLANTABLE ELECTRONICS IN THE ELECTROMAGNETIC MIDFIELD (Invited Paper)

Ho¹,

Poon²

2014

PIER

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Abstract-The wireless transfer of electromagnetic energy into the human body could power medical devices and enable new ways to treat various disorders. To control energy transfer, metal structures are used to generate and manipulate radio-frequency electromagnetic fields. Most systems for transfer across the biological tissue operate in the quasi-static limit, but operation beyond this regime could afford new powering capabilities. This review discusses some recent developments in the design and implementation of systems operating in the electromagnetic midfield, where transfer exploits wave-like fields in the body.

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Section: Coupled Structuresmentioning

confidence: 99%

Section: Optimal Energy Transfer Sourcementioning

confidence: 99%

See 1 more Smart Citation

ENERGY TRANSFER FOR IMPLANTABLE ELECTRONICS IN THE ELECTROMAGNETIC MIDFIELD (Invited Paper)

Ho¹,

Poon²

2014

PIER

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“…More recently, source structures that exploit the characteristics of the midfield to significantly improve the power transfer efficiency were analytically solved [7,8]. For the layered medium configuration shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…For the layered medium configuration shown in Fig. 1, the equivalence principle in electromagnetic theory ensures that the optimal efficiency obtained in [8] bounds the efficiency attainable by any physical realization of the source. The maximum efficiency was shown to be a function of the dielectric property of the tissue, distance between the source and receiver (z f ), and orientation (θ) of the receiver coil.…”

Section: Introductionmentioning

confidence: 99%

Non-Coil, Optimal Sources for Wireless Powering of Sub-Millimeter Implantable Devices

Kim¹,

Ho²,

Poon³

2017

PIER

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Abstract-This paper presents non-coil sources to improve the wireless power transfer efficiency for implantable device used in various medical applications -cardiovascular devices, endoscope in the small intestine, and neurostimulator in the brain. For each application, a bound on the power transfer efficiency and the optimal source achieving such bound are analytically solved. The results reveal that depending on the depth of the implantable devices, power can be transferred to a sub-millimeter scaled receiver with the efficiency ranging from −57 dB to −33 dB, which is up to 6.6 times higher than the performance of existing coil-based source systems. The technique introduced in this paper can be broadly applied to other medical applications.

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Metasurface Patch for Wireless Power Transfer in Implantable Devices

Lee

2023

Adv Funct Materials

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Wireless power transfer (WPT) systems enable the long‐term operation and miniaturization of implantable devices by eliminating the need for battery replacement and wired power supplies. Although wireless power transfer systems for implantable devices are extensively studied, their practical application is still challenging owing to the constraints and requirements of the human body, such as reflection loss owing to differences in the tissue dielectric properties, mm‐sized devices, and electromagnetic (EM) wave attenuation of the tissue. Here, a phase‐gradient metasurface patch is presented to achieve 5.8 GHz EM power focusing at a focal point of depth 10 mm in the tissue via EM wavefront modulation at the skin–air interface. The proposed metasurface patch is fabricated by arranging subwavelength‐thickness (<λ/10) unit cell structures composed of four metallic layers separated by dielectric substrates that exhibit high‐Q resonance properties and a sufficient phase modulation range with enhanced transmission. By applying the fabricated metasurface patch to a wireless power transfer system for implantable devices, it is experimentally confirmed that the transmission coefficient (S21) is improved by 6.37 dB compared with that of a wireless power transfer system without the metasurface patch. Furthermore, it is confirmed that the transmission coefficient can be maintained for an incident angle variation up to 30° from the transmitter to the metasurface patch, resulting in a stable power delivery of the proposed wireless power transfer system.

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Midfield Wireless Powering of Subwavelength Autonomous Devices

Cited by 102 publications

References 26 publications

ENERGY TRANSFER FOR IMPLANTABLE ELECTRONICS IN THE ELECTROMAGNETIC MIDFIELD (Invited Paper)

ENERGY TRANSFER FOR IMPLANTABLE ELECTRONICS IN THE ELECTROMAGNETIC MIDFIELD (Invited Paper)

Non-Coil, Optimal Sources for Wireless Powering of Sub-Millimeter Implantable Devices

Metasurface Patch for Wireless Power Transfer in Implantable Devices

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