An MRI Compatible RF MEMs Controlled Wireless Power Transfer System

Byron, Kelly; Winkler, Simone Angela; Robb, Fraser; Vasanawala, Shreyas S.; Pauly, John M.; Scott, Greig

doi:10.1109/tmtt.2019.2902554

Cited by 18 publications

(12 citation statements)

References 24 publications

(22 reference statements)

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“…The reported four‐channel array is slim, lightweight, and comfortable, illustrating the broader vision of wearable MRI detectors that are unobtrusive and adapt to the patient rather than the other way around. Towards full implementation of wearability, arrays of this sort could be combined with miniaturized on‐body digitization 44,45 and digital optical 44‐47 or wireless 48‐52 data transfer, as well as wireless power supply 53 …”

Section: Discussionmentioning

confidence: 99%

Elastomer coils for wearable MR detection

Port

Luechinger

Brunner

et al. 2021

Magnetic Resonance in Med

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Funding information Nano-Tera.ch, project: WearableMRI Purpose: To explore the use of conductive elastomer for MR signal detection and the utility of this approach for wearable detector arrays. Methods: An elastomer filled with silver microparticles was used to form stretchable radiofrequency coils for MR detection. Their electrical performance in terms of the Q unloaded and Q ratio was assessed in the relaxed state and under repeated strain up to 40%. In a phantom imaging study, the signal-to-noise ratio yield of conductive elastomer coils was compared with that of a reference copper coil. Four elastomer coils were integrated with a stretchable textile substrate to form a wearable array for knee imaging. The array was employed for multiple-angle and kinematic knee imaging in vivo. Results: The elastomer coils proved highly stretchable and mechanically robust. Upon repeated stretching by 20%, a medium-sized coil element settled at Q unloaded of 42 in the relaxed state and 32 at full strain, reflecting sample-noise dominance. The signal-to-noise ratio of elastomer coils was found to be 8% to 16% lower than that achieved with a conventional copper coil. Multiple-angle and kinematic knee imaging with the wearable array yielded high-quality results indicating robustness of detection performance against stretching and warping of the array. Conclusion: Conductive elastomer is a viable material for MR detection. Coils made from this material reconcile high stretchability and adequate electrical performance with ease of manufacturing. Conductive elastomer also offers inherent restoring forces and is readily washable and sanitizable, making it an excellent basis of wearable detector front ends. K E Y W O R D S conductive elastomer, knee imaging, wearable array 1 | INTRODUCTION In the design of MRI receiver coils, one of the key goals is to maximize signal sensitivity. To this end, coils and coil arrays are traditionally made from excellent conductors, predominantly copper, which minimizes detection noise caused by coil losses. Along with superior conductivity, copper offers ease of manufacturing, favorable chemical properties, and mechanical strength. The latter is helpful in forming robust, rigid coil setups as commonly used for both clinical and research uses of MRI. However, rigidity is arguably ambivalent. Receiver setups should be applicable in a range of patients with anatomies of varying size and shape. Rigid coils will then inevitably be too large for some subjects, at the How to cite this article:

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Section: Discussionmentioning

confidence: 99%

Elastomer coils for wearable MR detection

Port

Luechinger

Brunner

et al. 2021

Magnetic Resonance in Med

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“…RF WPT implies the construction of a dedicated system consisting of primary (e.g., in the patient table) and secondary (close to the receive coil) loops for the sole purpose of power delivery by inductive coupling. Byron et al [78,79] propose an MRcompatible WPT system operating at 10 MHz transferring up to 13 W over a few centimeters' distance in a 1.5 T system.…”

Section: Wireless Power Transfermentioning

confidence: 99%

Perspectives in Wireless Radio Frequency Coil Development for Magnetic Resonance Imaging

et al. 2020

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This paper addresses the scientific and technological challenges related to the development of wireless radio frequency (RF) coils for magnetic resonance imaging (MRI) based on published literature together with the authors' interpretation and further considerations. Key requirements and possible strategies for the wireless implementation of three important subsystems, namely the MR receive signal chain, control signaling, and on-coil power supply, are presented and discussed. For RF signals of modern MRI setups (e.g., 3 T, 64 RF receive channels), with on-coil digitization and advanced methods for dynamic range (DR ≥ 16-bit) and data rate compression, still data rates > 500 Mbps will be required. For wireless high-speed MR data transmission, 60 GHz WiGig and optical wireless communication appear to be suitable strategies; however, on-coil functionality during MRI scans remains to be verified. Besides RF signals, control signals for on-coil components, e.g., active detuning, synchronization to the MR system, and B 0 shimming, have to be managed. Wireless power supply becomes an important issue, especially with a large amount of additional on-coil components. Wireless power transfer systems (>10 W) seem to be an attractive solution compared to bulky MR-compatible batteries and energy harvesting with low power output. In our opinion, completely wireless RF coils will ultimately become feasible in the future by combining efficient available strategies from recent scientific advances and novel research. Besides ongoing improvement of all three subsystems, innovations are specifically required regarding wireless technologies, MR compatibility, and wireless power supply.

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“…We propose a wireless power transfer (WPT) system based upon resonant inductive coupling and explore the adaptations of WPT in terms of electromagnetic coupling, physical deployment and noise emissions for compatibility with MRI. This work expands upon our initial feasibility tests of [22]–[24]. The system uses RF gating to minimize the impact on the MR image by gating the WPT system off during the MRI receive time.…”

Section: Introductionmentioning

confidence: 98%

“…This work expands upon our initial feasibility tests of. [22][23][24] The system uses RF gating to minimize the impact on the MR image by gating the WPT system off during the MRI receive time. A 10 mF storage capacitor is used to continuously deliver power while the system is gated on and off.…”

Section: Introductionmentioning

confidence: 99%

An RF‐gated wireless power transfer system for wireless MRI receive arrays

Byron

Robb²,

Stang³

et al. 2017

Concepts Magn Reson

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In MRI systems, cable-free receive arrays would simplify setup while reducing the bulk and weight of coil arrays and improve patient comfort and throughput. Since battery power would limit scan time, wireless power transfer (WPT) is a viable option to continuously supply several watts of power to on-coil electronics. To minimize added noise and decouple the wireless power system from MRI coils, restrictions are placed on the coil geometry of the wireless power system, which are shown to limit its efficiency. Continuous power harvesting can also cause a large increase in the background noise of the image due to diode rectifier up-conversion of noise around the frequency of the transmitted power. However, by RF gating the transmitted power off during the MRI receive time while continuing to supply power from a storage capacitor, WPT is demonstrated to have minimal impact on image quality at received power levels up to 11 W. The integration of WPT with a 1.5T scanner is demonstrated.

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An MRI Compatible RF MEMs Controlled Wireless Power Transfer System

Cited by 18 publications

References 24 publications

Elastomer coils for wearable MR detection

Elastomer coils for wearable MR detection

Perspectives in Wireless Radio Frequency Coil Development for Magnetic Resonance Imaging

An RF‐gated wireless power transfer system for wireless MRI receive arrays

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