Transcutaneous Energy Transmission Research Articles

Design and Optimization of Coil for Transcutaneous Energy Transmission System

This article presents a coil couple-based transcutaneous energy transmission system (TETS) for wirelessly powering implanted artificial hearts. In the TETS, the performance of the system is commonly affected by the change in the position of the coupling coils, which are placed inside and outside the skin. However, to some extent, the influence of coupling efficiency caused by misalignment can be reduced by optimizing the coil. Thus, different types of coils are designed in this paper for comparison. It has been found that the curved coil better fits the surface of the skin and provides better performance for the TETS. Various types of curved coils have been designed in response to observed bending deformations, dislocations, and other coupling variations in the curved coil couple. The numerical model of the TETS is established to analyze the effects of the different types of coils. Subsequently, a series of experiments are designed to evaluate the resilience to misalignment and to verify the heating of the coil under conditions of severe coupling misalignment. The results indicated that, in the case of misalignment of the coils used in artificial hearts, the curved transmission coil demonstrated superior efficiency and lower temperature rise compared to the planar coil.

Left ventricular assist devices: yesterday, today, and tomorrow.

The shortcomings of expense, power requirements, infection, durability, size, and blood trauma of current durable LVADs have been recognized for many years. The LVADs of tomorrow aspire to be fully implantable, durable, mitigate infectious risk, mimic the pulsatile nature of the native cardiac cycle, as well as minimize bleeding and thrombosis. Power draw, battery cycle lifespan and trans-cutaneous energy transmission remain barriers to completely implantable systems. Potential solutions include decreases in pump electrical draw, improving battery lifecycle technology and better trans-cutaneous energy transmission, potentially from Free-range Resonant Electrical Energy Delivery. In this review, we briefly discuss the history of LVADs and summarize the LVAD devices in the development pipeline seeking to address these issues.

Fundamental Study on Improvement of Transmission Efficiency by Applying α-Coil to Transcutaneous Energy Transmission System

Fundamental Study on Improvement of Transmission Efficiency by Applying α-Coil to Transcutaneous Energy Transmission System

Transcutaneous Pulsed RF Energy Transfer Mitigates Tissue Heating in High Power Demand Implanted Device Applications: In Vivo and In Silico Models Results.

This article presents the development of a power loss emulation (PLE) system device to study and find ways of mitigating skin tissue heating effects in transcutaneous energy transmission systems (TETS) for existing and next generation left ventricular assist devices (LVADs). Skin thermal profile measurements were made using the PLE system prototype and also separately with a TETS in a porcine model. Subsequent data analysis and separate computer modelling studies permit understanding of the contribution of tissue blood perfusion towards cooling of the subcutaneous tissue around the electromagnetic coupling area. A 2-channel PLE system prototype and a 2-channel TETS prototype were implemented for this study. The heating effects resulting from power transmission inefficiency were investigated under varying conditions of power delivery levels for an implanted device. In the part of the study using the PLE setup, the implanted heating element was placed subcutaneously 6–8 mm below the body surface of in vivo porcine model skin. Two operating modes of transmission coupling power losses were emulated: (a) conventional continuous transmission, and (b) using our proposed pulsed transmission waveform protocols. Experimental skin tissue thermal profiles were studied for various levels of LVAD power. The heating coefficient was estimated from the porcine model measurements (an in vivo living model and a euthanised cadaver model without blood circulation at the end of the experiment). An in silico model to support data interpretation provided reliable experimental and numerical methods for effective wireless transdermal LVAD energization advanced solutions. In the separate second part of the study conducted with a separate set of pigs, a two-channel inductively coupled RF driving system implemented wireless power transfer (WPT) to a resistive LVAD model (50 Ω) to explore continuous versus pulsed RF transmission modes. The RF-transmission pulse duration ranged from 30 ms to 480 ms, and the idle time (no-transmission) from 5 s to 120 s. The results revealed that blood perfusion plays an important cooling role in reducing thermal tissue damage from TETS applications. In addition, the results analysis of the in vivo, cadaver (R1Sp2) model, and in silico studies confirmed that the tissue heating effect was significantly lower in the living model versus the cadaver model due to the presence of blood perfusion cooling effects.

Measurement of High-Frequency Patient Leakage Current From a Transmitting Coil in a Transcutaneous Energy Transmission System for Ventricular Assist Device

The transcutaneous energy transmission system (TETS) has been studied for wireless power supply in ventricular assist devices embedded in the body. To be approved as a medical device, it is necessary to measure the high-frequency patient leakage current ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> ) and to suppress it to a safety limit below 10 mA. However, it is difficult to suppress because the terminal voltage and the frequency of the transmitting coil are extremely high (500 V and 400 kHz). In this study, we propose an original measurement method for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> in TETS and measure the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> . Furthermore, the suppression method of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> is investigated using a high-frequency isolation transformer (HFIT) and an insulation sheet for transmitting coils. Consequently, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> of 17.14 mA is obtained when the HFIT without countermeasures and an insulation silicone sheet is used (Type A), whereas an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> of 7.68 mA is obtained when using two series-connected HFITs and an expanded polystyrene sheet with a thickness of 3.58 mm (Type B). Thus, it is possible to drastically suppress <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> below 10 mA. Additionally, we define the combined capacitance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Com</sub> based on the series connection of the capacitance of the insulation transformer <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C_p</i> and that of the insulation sheet <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C_c</i> and calculate the theoretical <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> . The theoretical <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> decreases from 20.8 mA for Type A to 5.6 mA for type B. The calculation results of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> are mostly in agreement with the measurement results, indicating that a reduction in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Com</sub> is important for suppressing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_p</i> of the TETS.

An Analysis of Mutual Interference Between Two Transcutaneous Energy Transmission Systems for Ventricular Assist Device When Two Wearers are Placed on Multiple Configuration Patterns:

Transcutaneous energy transfer system (TETS) for ventricular assist device (VAD) is a safe and effective technique that allows power to be delivered to implants wirelessly, avoiding the use of percutaneous wires. TETS is sensitive to mutual electromagnetic interference when multiple TETSs concentrate in the same location which may danger to device wearers. In this paper, two TETSs will be arranged in eight different configuration patterns to verify if it is possibility that mutual electromagnetic interference can enhance biological effects of human body by measured the internal electric fields (EINT) and TETS output voltages (Vout). The operating frequency of TETSs were fixed to 400 kHz. A novel four-layer human body simulation models consist of dry skin, wet skin, fat, and muscle were used as the TETS’s wearers. The results indicated that EINT was increased by 16.4% and Vout was increased by 15.5% in the worst case. To ensure that TETS can be used safely, the distance between wearers should be greater than 20 cm within the simulations.

2線アルキメデス螺旋コイルを用いた完全体内埋込型人工心臓用経皮エネルギー伝送システムへのプッシュプルE級増幅器の適用

2線アルキメデス螺旋コイルを用いた完全体内埋込型人工心臓用経皮エネルギー伝送システムへのプッシュプルE級増幅器の適用

The system of Transcutaneous Energy and Information Transmission for a Totally-Implantable Artificial Heart

For a totally-implantable artificial Heart (TIAH), the transcutaneous energy transmission system (TETS) and the transcutaneous communication system (TCS) are useful to reduce the risk of infection. Integration of TETS and TCS is expected to reduce patient’s burden, including miniaturizing the device. We have studied the two turns of the outer circumference of figure-eight coil for the integration of transdermal energy transmission and transdermal information transmission. In this study, a part of the two turns of the outer circumference of figure-eight coil is cut off to further reduce the effect of the magnetic field on information transmission by energy transmission. In addition, the magnetic field effects caused by the misalignment of the transdermal transformer are compared before and after cutting the circumstance of the coil in the information transmission system.

Transcutaneous Energy Transmission System for Ventricular Assist Device with Transmission Distance of 2 cm:

Transcutaneous Energy Transmission System for Ventricular Assist Device with Transmission Distance of 2 cm:

Measurement of Patient Leakage Current from Air-core Transcutaneous Energy Transmission System with High-frequency Isolation Transformer

Measurement of Patient Leakage Current from Air-core Transcutaneous Energy Transmission System with High-frequency Isolation Transformer

Transcutaneous Energy Transmission for Ventricular Assist Device with a Couple of Air-core Transcutaneous Transformers

Transcutaneous energy transmission systems that supply power to the ventricular assist device implanted in the human body have been studied. The magnetic field radiated from a transcutaneous transformer exceeds the limit set by the international standard CISPR 11. Therefore, we proposed a magnetic-field-reduction method using both 0° and 180° phase-shift transformers. In this study, we measured the magnetic field both in the case of using a single transcutaneous transformer (Type A) and in the case of using a couple of transcutaneous transformers (Type B). The receiving power of the load resistance was fixed at 14.4 W. As a result, the magnetic field became 59.0 dBµA/m in Type A, and 49.3 dBµA/m in Type B. Furthermore, the transmission efficiency was 57.2% in Type A and it was 45.2% in Type B when the distance between the couple of transcutaneous transformers was 30 cm. These results indicated the effectiveness of our method in magnetic-field reduction.

Transcutaneous Energy Transmission: Can we do it now?

The percutaneous driveline used in contemporary LVADs presents a continuous risk of infection for the duration of support. Minimizing infection in durable mechanical circulatory support systems requires total implantation of all components and energy transfer by means other than percutaneous drivelines. A novel coplanar energy transfer (CET) system, similar to the original transcutaneous energy transfer (TET) design, is unique by incorporating two large rings with coil-within-the-coil topology to ensure strong resonance power. The CET system consists of an internal integrated controller, a battery coupled with an internal thoracic coil ring, and the LVAD pump. External equipment includes a power transmission belt with an external controller, a battery, and wristwatch monitor. The CET system is adaptable to multiple LVAD designs, though the Jarvik 2000 (Jarvik Heart, Inc., New York, NY) with postauricular power cable was used in the initial clinical cases. Two male patients, ages 51 years and 24 years, underwent implantation of the CET/Jarvik 2000 system for the bridge to transplant indication. One patient experienced a stroke and device thrombosis which led to termination of LVAD support while the patient waited for transplantation. The second patient underwent successful transplant after two months of support. The CET functioned as intended in both patients. Larger, multicenter, controlled clinical trials are necessary to determine the long-term safety and efficacy of the CET technology.

Neural Implants Without Electronics: A Proof-of-Concept Study on a Human Skin Model.

Objective: Chronic neural implants require energy and signal supply. The objective of this work was to evaluate a multichannel transcutaneous coupling approach in an ex vivo split-concept study, which minimizes the invasiveness of such an implant by externalizing the processing electronics. Methods: Herein, the experimental work focused on the transcutaneous energy and signal transmission. The performance was discussed with widely evaluated concepts of neural interfaces in the literature. Results: The performance of the transcutaneous coupling approach increased with higher channel count and higher electrode pitches. Electrical crosstalk among channels was present, but acceptable for the stimulation of peripheral nerves. Conclusions: Transcutaneous coupling with extracorporeal transmitting arrays and subcutaneous counterparts provide a promising alternative to the inductive concept particularly when a fully integration of the system in a prosthetic shaft is intended. The relocation of the electronics can potentially prevent pressure sores, improve accessibility for maintenance and increase lifetime of the implant.

Transcutaneous Energy Transmission System for Ventricular Assist Device with Transmission Distance of 2 cm

Transcutaneous Energy Transmission System for Ventricular Assist Device with Transmission Distance of 2 cm

Design of Two Turns of the Outer Circumference of Figure-eight Coil for Transcutaneous Energy and Information Transmission for a Totally-Implantable Artificial Heart

Design of Two Turns of the Outer Circumference of Figure-eight Coil for Transcutaneous Energy and Information Transmission for a Totally-Implantable Artificial Heart

Air-core Transcutaneous Energy Transmission System for Ventricular Assist Device with High-frequency Isolation Transformer:

Transcutaneous energy transmission systems (TETS) that supply power to ventricular assist devices have been developed. The air-core transcutaneous transformer is coated with insulating materials, however, the high-frequency leakage current (HFLC) flows because capacitive coupling may be electrically connected between the air-core transcutaneous transformer and the human body. We proposed that high-frequency isolation transformer as a way to suppress HFLC. In this study, attenuation rate of HFLC was measured according to the change of the number of turns of the high-frequency isolation transformer (HFT). As a result, HFLC was 4.2-6.9 mA when the number of turns HFT was 6 turns. TETS which uses 6 turns of HFT satisfies the restriction value of JIS T 0601-1. However, in the 3 turns HFLC was increased to 13 mA and the temperature rise of the HFT was 20 degrees because of the core loss due to high magnetic flux density. It was confirmed that our HFT is compact, lightweight, low heat generation, and is suitable for TETS for ventricular assist device.

Wireless Power Transmission to Implantable Monitoring Devices for Gastroesophageal Reflux Disease

This paper proposes a wireless energy transmission system for implanted devices for monitoring gastroesophageal reflux disease. One of the wireless energy transmission systems is transcutaneous energy transmission system (TETS). We developed a wireless power transmission system that uses a planar-type transmitting coil to send power to a planar-type receiving coil implanted deep inside the body. To obtain higher transmission efficiency, the transmission frequency and number of turns of the receiving and transmitting coils were modified. The relative performance of two methods of wireless power transmission, i.e., series compensated transmitting and receiving (SS method) and series compensated transmitting and parallel compensated receiving (SP method), was analyzed. The calculation result revealed that the maximum transmission efficiency of SP method was 0.8%, when the number of turns of receiving coil was 15 and that of transmitting coil was 22 at 0.9 MHz.

Left Ventricular Assist Devices: Challenges Toward Sustaining Long-Term Patient Care.

Over the last few decades, the left ventricular assist device (LVAD) technology has been tremendously improved transitioning from large and noisy paracorporeal volume displacement pumps to small implantable turbodynamic devices with only a single transcutaneous element, the driveline. Nevertheless, there remains a great demand for further improvements to meet the challenge of having a robust and safe device for long-term therapy. Here, we review the state of the art and highlight four key areas of needed improvement targeting long-term, sustainable LVAD function: (1) LVADs available today still have a high risk of thromboembolic and bleeding events that could be addressed by the rational fabrication of novel surface structures and endothelialization approaches aiming at improving the device hemocompatibility. (2) Novel, fluid dynamically optimized pump designs will further reduce blood damage. (3) Infection due to the paracorporeal driveline can be avoided with a transcutaneous energy transmission system that additionally allows for increased freedom of movement. (4) Finally, the lack of pump flow adaptation needs to be encountered with physiological control systems, working collaboratively with biocompatible sensor devices, targeting the adaptation of the LVAD flow to the perfusion requirements of the patient. The interdisciplinary Zurich Heart project investigates these technology gaps paving the way toward LVADs for long-term, sustainable therapy.

補助人工心臓用体外結合型経皮エネルギー伝送システム

補助人工心臓用体外結合型経皮エネルギー伝送システム

フレキシブルコイルを用いた人工心臓用磁界共振結合経皮電力伝送システムのファントムによる評価

A conventional power supply method using a drive line for a ventricular assist device causes infection diseases, which decreases patient’s quality of life and survival rate. A possible solution is to use a transcutaneous energy transmission system utilizing electromagnetic induction. However, it is necessary for the coil to be located on the body surface accurately because of short transmission distance. In order to avoid infection diseases as well as increase the transmission distance, we proposed the new system utilizing magnetic resonant coupling that embedded flexible coils into clothes to transfer energy. In this paper, we evaluated the influence of the electric characteristics of the human body on the transmission efficiency by using both phantom and pork. The measured transmission efficiency with a gap of 30 mm was 67 % in phantom and 70 % in pork while that in air was 80 %.