Transcutaneous Energy Transfer System Research Articles

Performance evaluation of an automatically controlled transcutaneous energy transfer system powering left ventricular assist device.

The survival rate of LVAD recipients may be improved by eliminating the infection failure mode at the percutaneous lead entry site. Wireless powering through a Transcutaneous Energy Transfer System (TETS) is a promising solution for achieving this. However, automatic controls need to be employed to compensate for the variations in efficiency and power transfer due to changes in load and coil-to-coil gaps. This article discusses the results of invitro and animal models performance evaluation of an automatically controlled TETS for powering a Left Ventricular Assist Device. It was found that power up to 20 W could be transferred at an axial gap of 30 mm. A 5% variation in speed and a 2% change in flow rate are observed with the change in tissue thickness, in porcine carcass model. The LVAD could be operated at the required RPM irrespective of the change in axial positions.

Design of Resonant Converter of Trans cutaneous Energy Transfer System to Power Artificial Heart

Wireless technologies have matured to recharge the batteries of consumer devices efficiently. The benefit of the technology is being used by mobile communication devices, personal computation devices, and wearable entertainment devices. The wireless energy transfer techniques employ the transfer of electrical energy between two-tesla coils in surface contact and not by electrical contact through the phenomenon of electromagnetic induction. Many international consortiums have made guidelines for designing and manufacturing these devices. However, for active implantable medical devices such as artificial hearts, a large amount of electrical energy usually in the range of 15W to 30W needs to be transferred across the skin at a depth of 10mm to 30mm. The design needs to be optimized for maximum power transfer with the highest possible efficiency. Any loss in power will be reflected as heat energy and cause burns and tissue death. A transcutaneous energy transfer system is such type of wireless energy transfer mechanism across the skin to power implanted life-saving devices. In this paper, the design of a resonant converter and its performance is investigated to wirelessly transfer electrical power up to a tissue thickness of about 25mm.

Design of a hybrid left ventricular assist device with a new wireless charging system.

The objective of this study was to design a new wireless left ventricular assist device (LVAD) that can be charged without using a conventional transcutaneous energy transfer system (TETS). Our new wireless LVAD was a hybrid pump operating in two different modes: magnetic and electric modes. The pump was driven wirelessly by extracorporeal rotating magnets in magnetic mode, whereas it was driven by electricity provided by an intracorporeal battery in electric mode. A magnetic torque transmission system was introduced to wirelessly transmit torque to the pump impeller. The intracorporeal battery was charged in magnetic mode making use of electromagnetic coils as a generator, whereas the coils were used as a motor in electric mode. To demonstrate the feasibility of our system, we conducted a bench-top durability test for 1 week. Our hybrid pump had shown sufficient pump performance as a LVAD, with a head pressure of approximately 80 mm Hg and a flow volume of 5.0 L/min, for 1 week. The intracorporeal battery was wirelessly charged enough to power electric mode for 2.5 h a day throughout the 1-week durability test. Our hybrid wireless LVAD system demonstrated the possibility of a wireless LVAD and has the potential to reduce medical complications of LVAD therapy.

Robust voltage-controlled transcutaneous energy transfer system for artificial anal sphincter.

The artificial anal sphincter (AAS) system has gained significant attention as a solution for treating fecal incontinence (FI). It relies on transcutaneous energy transfer (TET) as its primary energy source. However, changes in posture or biological tissue can cause misalignment of the coil, resulting in unstable power reception. Inadequate power affects charging efficiency, while excessive power leads to excessive heating at the receiver side. Consequently, achieving safe and constant voltage charging for the AAS becomes a complex challenge. To maintain a consistent charging voltage and overcome the issue of variations in load and coil coupling strength, this article proposes a wireless charging control system that utilizes an LCC-S-type resonant network and phase shift to adjust the transmitting voltage based on feedback charging voltage in real time. In particular, the PI controller and neural network are introduced to change the phase-shift angle swiftly. The dynamic performance is then evaluated under different misalignments and presented with comparative results. The results indicate that the multilayer perceptron control system outperforms the PI. Under the complex misalignment disturbance, the average error of receiver side load voltage is only 0.007 V, with an average settling time of 960 ms. Additionally, the average temperature at the receiver side is 40.4°C. The experiments demonstrate that the proposed system effectively addresses the misalignment issue in TET during the charging, ensuring constant voltage charging at the receiver side and thermal safety.

CARD7: Design of a Hybrid Wireless Left Ventricular Assist Device with a New Charging System

Drivelines of the current left ventricular assist devices (LVADs) have some problems such as acting as a source of infection and Drivelines of the current left ventricular assist devices (LVADs) have some problems such as acting as a source of infection and limiting the outside activities of patients, thereby reducing the quality of life of patients. Transcutaneous Energy Transfer Systems (TETSs) have been developed to solve these problems but they have other problems such as malposition between coils and burn injury due to sending high-power transmission. In a previous study, we proposed a new concept of wireless LVAD, which consisted of magnetic and electric pumps, to improve the current problems of conventional wireless LVAD. However, implanting two different pumps in the body could occupy more space than a single pump. In addition, two extracorporeal devices on the skin, an external coil for TETS and extracorporeal rotating magnets for the magnetic pump, were possibly confusing to patients. Moreover, the distance limitation between the extracorporeal magnets and intrathoracic pump remained a fundamental problem of the magnetic pump. To solve these problems, we developed a single hybrid pump driven by either magnetic or electric force and charged wirelessly without an external coil. Our new wireless LVAD was a hybrid pump operating in two different modes: magnetic and electric modes. The pump was driven wirelessly by extracorporeal rotating magnets in magnetic mode, whereas it was driven by electricity from an intracorporeal battery in electric mode. Magnetic torque transmission system was introduced to efficiently transmit magnetic torque to the impeller. The intracorporeal battery was charged in magnetic mode making use of electromagnetic coils as a generator, which operated as a motor in electric mode. Our hybrid pump performed a flow rate and a head pressure of approximately 5.0 L/min and 80 mm Hg, respectively, in a bench-top test. The charging rate of the intracorporeal battery in magnetic mode was around 2.5 W, which enabled the hybrid pump to operate in electric mode 3 hours a day. Magnetic torque transmission system shortened the distance between the extracorporeal and intracorporeal magnets and achieved downsizing the magnets. Our hybrid wireless LVAD solved the potential problems of our previous wireless LVAD and demonstrated a new wireless charging system without an external coil. It has the potential to reduce the problems relating to drivelines and to realize high quality of life of patients with LAVD. Our future prospect is to conduct an in vivo test with our device.Figure 1. Prospective configuration of our hybrid LVAD system: (A) intracorporeal components, (B) positional relationship between the hybrid pump and extracorporeal device.Figure 2. (A) Top view of the impeller, (B) Bottom view of the impeller, (C) Pump housing, (D) Hybrid pumpFigure 3. (A) Front view of the test loop, (B) detailed view of the hybrid pump and extracorporeal magnets

Design of an Innovative Wireless Left Ventricular Assist Device Driven by either Extracorporeal Magnets or an Intracorporeal Battery Pack.

This study aimed to design a new wireless left ventricular assist device (LVAD) that solved the driveline problem of current LVADs and the heat problem of the transcutaneous energy transfer system (TETS). Our new wireless LVAD consisted of two blood pumps capable of driving using extracorporeal magnets and an intracorporeal battery pack. When one pump was driven, the other pump was stopped. The battery pack was wirelessly and slowly charged using TETS with low-power transmission, whereas the magnetic pump was driven wirelessly by extracorporeal magnets. We demonstrated the feasibility of our system in a bench-top durability test for 7 days. The distance between the extracorporeal magnets and the magnetic pump was 27.5 mm. Our LVAD system had steadily provided sufficient pressure and flow volume (approximately 108 mmHg and 5.0 L/min, respectively) to the test loop for 7 days. Although loss of synchronism occurred once during the test, it recovered within a few minutes. The results demonstrate the feasibility of the proposed wireless LVAD system. Further technical improvements are required in our system, such as downsizing the electric devices inside the body, to conduct an in vivo test for the next step.

Thermal Analysis of a Transcutaneous Energy Transfer System for a Left Ventricular Assist Device

Thermal Analysis of a Transcutaneous Energy Transfer System for a Left Ventricular Assist Device

Coupling and maintaining link efficiency ultrasonics in transcutaneous energy transfer systems

We present on the development of a 12.8 mm diameter ultrasonic transcutaneous energy transfer system for powering implanted hearing devices. The system was based on two custom 8mm diameter PMN-PT 1-3 composite transducers operating at 1.25MHz and featured three significant innovations. First, to ensure long-term biocompatibility and reliability of the implanted portion of the link and to ensure robust attachment to bone, the implanted transducer was designed into a 12.8 mm diameter, 3.5 mm thick hermetically sealed titanium package in an easy-to-implant form factor. The transducer was designed to deliver sound efficiently through the casing walls using a mass-spring acoustic matching technique. Second, for the external unit a “dry” acoustic coupling system based on a silicone pressure sensitive adhesive was designed that combined efficient acoustic coupling, robust adhesion to skin and that was comfortable to wear. The external unit was aligned with the internal unit using a magnetic alignment system. Third, we developed and demonstrated an efficient Class E transmit amplifier and receive electronics that incorporated compensation for changes in acoustic separation between the transducer to maintain robust, high efficiency power transmission. The system achieved 33% DC-to-DC electrical conversion efficiency through 5mm of water and 19% DC-to-DC efficiency through 5mm of porcine tissue.

Effects of Electromagnetic Fields Generated from Transcutaneous Transformer:

Transcutaneous energy transfer system (TETS) is one of the methods to supply electric power to an assisted heart. In this study, we analyzed the effects of electric fields in the body on biological tissues around the TETS. Using an electromagnetic field simulator, biological tissue models consisting of Dry-Skin, Wet-Skin, Fat, and Muscle were fabricated. When the frequency was fixed at 400 kHz and the transmission distance at 20 mm, the analysis was conducted by changing the transmitting coils from 2 to 4 layers and the receiving coils from 1 to 4 layers in order to suppress the electric field strength inside the body. The results showed that the lowest internal electric field was observed at 2 layers of transmitting and 4 layers of receiving coils, and the maximum internal electric field was 77.07 V/m. This result was below the occupational of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guideline.

空芯偏平型経皮トランスから発生させる電磁界の生体影響

Transcutaneous energy transfer system (TETS) is one method of supplying electric power to a ventricular assist device. In this study, we analyzed the effects of internal electric fields on biological tissues around the TETS. The transmission frequency was fixed at 400 kHz, the transmission distance at 20 mm, the transmitting and receiving coils at 3 layers, and the output power at 15 W. The distance between the transmitting coil and the body surface was varied from 0.5 to 4.0 mm, and the output voltage was simulated at 24 V, which is the rated voltage of the VAD, and 14 V to suppress the internal electric field. The results showed that the internal electric field was the lowest when the distance was 4.0 mm and 14 V, and the maximum value was 18.68 V/m. This value was lower than the occupational exposure value of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines.

Transcutaneous Energy Transfer System for Cardiac-Assist Devices by Use of Inhomogeneous Biocompatible Core Material

A novel magnetic liquid silicone rubber composite core design applicable to wireless power transfer (WPT) for medical applications is presented. As a case study, the integration of WPT, including the proposed cores for the coils, with ventricular-assist devices (VADs) was investigated. This facilitates transferring 4.6 W of power wirelessly through the skin layer, which, thus, allows to disposal of the transcutaneous cable that connects the extracorporal batteries to the implanted blood pump. To enhance the coupling coefficient and consequently increase the WPT efficiency, the geometry of the cores was optimized. This reduces the temperature increase in the implant area. The field and thermal simulations were carried out with CST software. The electrical properties of the proposed design as obtained by simulation were validated by measurements. The simulation results perfectly coincide with the measured results. Finally, a new optimized design with additional high permeability core inserts is introduced to further increase the coupling coefficient. The results indicate that the coupling coefficient is increased from 0.31 to 0.52 with the optimized design compared to the case without cores. Moreover, by fixing the initial temperature as 37 °C, the maximum temperature is decreased from 38.19 °C to 37.27 °C while keeping the transferred power fixed. Its high magnetic conductivity, biocompatibility, low-loss property, flexibility, and Qi-standard compatibility make the proposed WPT design an excellent candidate for the wireless powering of heart-assist devices, such as VADs.

Transcutaneous Energy Transmission System for a Totally Implantable Artificial Heart Using a Two-Wire Archimedean Spiral Coil.

This paper describes the application of a proposed spiral coil to the transformer of a transcutaneous energy transfer system for a totally implantable artificial heart. To reduce the number of rectifier components in the power receiving circuit, the shape of the power receiving transformer was reviewed. The results indicated that the power transmission efficiency between the transformers was almost the same as that of the receiving transformer with the same shape. In addition, the calculations indicated that the power transmission efficiency including that of the power receiving circuit was increased, and the number of components in the power receiving circuit was reduced.

Biocompatibility and Biosafety Analysis of Transcutaneous Energy Transfer System of Artificial Anal Sphincter

Biocompatibility and Biosafety Analysis of Transcutaneous Energy Transfer System of Artificial Anal Sphincter

The Effect of the Operating Frequency on the Output Characteristics of a Wireless Transcutaneous Energy Transfer System Based on a Class E Power Amplifier with Tunable Capacitors

The Effect of the Operating Frequency on the Output Characteristics of a Wireless Transcutaneous Energy Transfer System Based on a Class E Power Amplifier with Tunable Capacitors

An artificial anal sphincter based on a novel clamping mechanism: Design, analysis, and testing.

An artificial anal sphincter is a device to help patients with fecal incontinence rebuild the ability to control the excrement through the anus. In this article, an artificial anal sphincter based on a novel clamping mechanism (AASNCM) is proposed to improve the safety and reliability. The AASNCM, which is powered by a transcutaneous energy transfer system, consists of a novel clamping mechanism, a receiving coil and a control unit. According to design requirements, the novel clamping mechanism model was established. After that, its kinematics and dynamics were analyzed. The results of force tests on the prototype AASNCM show that the maximum values of clamping force and expanding force are 15.859 and 31.029 N, respectively. Comparing the experimental results with theoretical analysis, a good match can be concluded. Finally, in vitro experiments were conducted, and have verified the safety and reliability of the proposed AASNCM.

Tuning of Class E Power Amplifier for Compensating the Effect of the Receiver Coil Implantation Depth on the Operation of a Wireless Transcutaneous Energy Transfer System

A method is proposed for compensating the effect of the receiver coil implantation depth on the output power of a wireless system for transcutaneous energy transfer via inductive coupling. A class E power amplifier is used in the transmitting part of the system. The proposed method is based on determining the rated values of the shunt and series capacitances used in the amplifier load circuit that would provide the required output power. The rated values of the capacitances providing the output power of 1.6 W were determined for a set of wireless energy transfer systems with the implantation depth of the receiver coil varying from 5 to 20 mm. For the selected system parameters the energy transfer efficiency was found to vary within the range of 56-93% depending on the receiver coil implantation depth.

Thermal evaluation of a hermetic transcutaneous energy transfer system to power mechanical circulatory support devices in destination therapy.

Current generation left ventricular assist devices (LVADs) are powered by a percutaneous driveline. The high prevalence of driveline infections has motivated the development of transcutaneous energy transfer (TET) systems which eliminate driveline associated complications by wirelessly delivering power across the skin. Destination therapy (DT) requires long-term reliable operation of the TET electronics suggesting the use of hermetic packaging techniques as used in all other chronically implanted devices. TET coils dissipate heat during operation and in order for the technology to be suitable for patient use, sufficient power must be delivered while maintaining temperatures at levels deemed safe. The heating of a TET system designed for DT which uses hermetic packaging technology was evaluated in silico and in vivo. A numerical model was used to evaluate the temperature of the TET coils. The TET system was fabricated and assessed in vivo using an ovine model. The receiving coil was implanted subcutaneously in a sheep and the transmission coil placed in contact with the skin and concentric to the implanted coil. Temperatures of the system were measured using sensors fixed to the surface of the coils. Numerical modeling indicated that the maximum temperatures of the primary and secondary coil surfaces were 38.13°C and 38.41°C, respectively, when delivering 10W continuously. Stable temperatures were observed in vivo after 70minutes and the maximum skin and implant surface temperatures were 37.73°C and 38.31°C, respectively. This study showed that a hermetic, chronically implantable TET system is thermally safe when continuously delivering 10W of power, sufficient to power modern LVADs.

First human use of a wireless coplanar energy transfer coupled with a continuous-flow left ventricular assist device

The drive-line to power contemporary ventricular assist devices exiting the skin is associated with infection, and requires a holstered performance of the cardiac pump, which reduces overall quality of life.Attempts to eliminate the drive-line using transcutaneous energy transfer systems have been explored but have not succeeded in viable widespread application. The unique engineering of the coplanar energy transfer system is characterized by 2 large rings utilizing a coil-within-the-coil topology, ensuring robust resonance energy transfer while allowing for a substantial (>6 hours) unholstered circulatory support powered by an implantable battery source. Herein we report the first known human experience with this novel technology, coupled with a continuous-flow assist left ventricular assist device, in 2 consecutive patients evaluated with the primary end-point of system performance at 30 days post-implantation.

A novel power supply system for puborectalis‐like artificial anal sphincter

Puborectalis-like artificial anal sphincter (PAAS) is an innovative new type of artificial anal sphincter (AAS). It overcomes many drawbacks and inadequacies of various previous AASs, and it has successfully been implanted in vivo for almost 3 weeks. During in vivo testing, PAAS shows its ability to retain continence with low risk of ischemia necrosis, and somehow truly helps to remodel rectal perception. However, there are still many defects that influence the long-term implantation of PAAS, especially in the power supply system (PSS). This article presents a new designed PSS which includes a new transcutaneous energy transfer (TET) system, a heat reduction system, and a safety usage system. The new PSS reduces the total size of PAAS by at least 30%. Newly designed TET system can satisfy the Qi standard, and render a power of 3W to fulfill the requirement of fast charging and normal use of PAAS at the distance of 15.5mm when frequency of TET system is 110 kHz, which previous TET systems can hardly achieve. Heat reduction system helps to reduce the heat generated during TET charging. It can reduce heat by 40% during the same period of time of TET charging. Safety usage system helps the user control PAAS more properly which can reduce the rate of failure of PAAS system.

Experimental Determination of the Maximum Permissible Coil Misalignment in Adaptive Transcutaneous Energy Transfer Systems

The effect of the symmetrical coil couple geometry on the value of lateral coil misalignment that corresponds to zero coupling in inductive energy transfer systems was studied. It was shown that the distance between coil turns and the number of coil turns have rather small effect on the zero-coupling distance. Increasing the outer diameter of the coils was shown to be the only way to increase the zero-coupling distance at given parameters of the system. It was found that changes in the outer diameter of the coils had more significant effect on the zero-coupling distance when the outer diameter was more than twice as great as the inner diameter.