A New Transcutaneous Energy Transmission System With Hybrid Energy Coils for Driving an Implantable Biventricular Assist Device

Abstract

We have developed a new transcutaneous energy transmission (TET) system for a totally implantable biventricular assist device (BVAD) system in the New Energy and Industrial Development Organization (NEDO) artificial heart project. The TET system mainly consists of an energy transmitter, a hybrid energy coil unit, an energy receiver, an internal battery system, and an optical telemetry system. The hybrid energy coil unit consists of an air-core energy transmission coil and an energy-receiving coil having a ferrite core. Internal units of the TET system are encapsulated in a titanium alloy casing, which has a size of 111 mm in width, 73 mm in length, and 25 mm in height. In in vitro experiments, the TET system can transmit a maximum electric energy of 60 Watts, and it has a maximum transmission efficiency of 87.3%. A maximum surface temperature of 46.1 degrees C was measured at the ferrite core of the energy-receiving coil during an energy transmission of 20 Watts in air. The long-term performance test shows that the TET system has been able to operate stably for over 4 years with a decrease of energy-transmission efficiency from 85% to 80%. In conclusion, the TET system with the hybrid energy coil can overcome the drawback of previously reported TET systems, and it promises to be the highest performance TET system in the world.

A Novel Low Temperature Transcutaneous Energy Transfer System Suitable for High Power Implantable Medical Devices: Performance and Validation in Sheep

“…Both these coils are considerably larger in size compared to the coils that we have designed. Furthermore, at 20 W power transmission, the maximum surface temperature of the internal coil is 46.1°C, and this was measured at the ferrite core (9). This high temperature is a major disadvantage of the use of ferrites in the system.…”

Improvement of the Coupling Factor of Litz-Wire Coil Pair With Ferrite Substrate for Transcutaneous Energy Transfer System

“…In order to reduce the risk of postoperative infection and patient discomfort, transcutaneous energy transfer system (TETS) is widely applied to wireless powering of implantable biomedical devices, such as left ventricular assist devices (LVAD) [1], artificial anal sphincters [2,3], artificial retinas [4], and wireless neurostimulators [5]. The performance of TETS largely depends on the high power transfer efficiency (PTE), which is imperative to minimize the size of the external drive source, heating of the tissue, and interference with other devices.…”

“…This kind of coil is suitable for applications with requirements of significant power but less size constrains. As described in [1], TETS with Litz-wire coils can transmit electric energy 20 W with a tissue thickness of 5 mm∼15 mm at an efficiency of over 85%. In addition, ferrite components have been successfully used to constrain flux to desired paths in order to improve coupling between coils and consequently prevent excessive loss of surrounding materials caused by magnetic field leakage [9,10].…”

Externally-coupled transcutaneous energy transmission for a ventricular assist device-Miniaturization of ferrite core and evaluation of biological effects around the transformer

“…However, most of the commercially available VASs transfer energy by means of wires penetrating the abdomen or chest from an external source [1]. We have developed a transcutaneous energy transmission (TET) system, which transfers energy via electromagnetic induction between two coils of a transcutaneous transformer placed on each side of the skin over the pectoralis major muscle [2][3][4]. As one of several possible methods, the externally-coupled transcutaneous transformer (ECTT) is studied in this paper [5][6][7].…”