Transcutaneous Energy Transfer System Performance Evaluation

Abstract

A transcutaneous energy transfer (TET) system has been developed to power implantable devices such as artificial hearts, defibrillators, and electrical stimulators. Transcutaneous coupling of power to these implanted de‐vices remains a favorable alternative as percutaneous lines are avoided in order to eliminate the potential of infection and allow patient mobility. In vitro, in vivo, ex vivo, and human cadaver studies of the electrohydraulic ventricular assist device TET have demonstrated that power can be transmitted over a range of skin thicknesses of 3–15 mm and can tolerate radial misalignments of up to 20 mm. Sensitivity to coil separation and radial misalignment variations has been addressed by the development of an auto‐tuning TET. The system has only a 10% attenuation in secondary coil voltage when metallic objects are in contact with the primary coil. The system has demonstrated a power transfer efficiency of 60–80% for power demands from 5 to 70 W. The TET secondary coil will provide an output voltage of 10–25 V for current demands from 0.5 to 4.0 A. TET chronic studies in porcine models have demonstrated no adverse effect to the tissue when up to 40 W of power can be delivered to an implanted load without the tissue‐contacting surface of the coil exceeding 42°C. In conclusion, the TET is a feasible alternative for tether‐free power transmission.

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

“…An earlier performance evaluation of a TET system using a porcine model by Mussivand et al. (13) demonstrated no adverse effects to tissue when up to 40 W of power was delivered to an implanted load without the tissue contacting surface on the implanted coil exceeding 42°C. In our TET study, no attempt was made to reduce the conduction of heat from the primary coil into the body.…”

“…The LionHeart system requires a minimum of 14 W, and the system also contains an internal rechargeable battery that allows for 20 min of operational time without the TET system (12). The HeartSaver TET system designed by Mussivand et al consists of a primary coil measuring 58 mm in diameter by 30 mm in height and weighing 75 g, and the secondary implanted coil measuring 70 mm in diameter by 20 mm in height, and weighing 125 g. It demonstrates a power efficiency of 60-80% for power demands of 5-70 W (13). The primary and secondary coils that were designed for the presented system were smaller in size, lighter in weight, and tolerant to misalignment without heavily compromising power efficiency compared to previously developed TET systems (13).…”

Preclinical development of SMA artificial anal sphincters

“…Power transmitted to the heaters is provided by a transcutaneous energy transmission (TET) system. A typical setup of TET system consists of an AC power supply connected with a primary coil for providing an alternating magnetic field, and a secondary coil in which AC current could be induced and transmitted to a load (15)(16)(17)(18). In our design, the secondary coil was electrically connected to the foil heaters.…”

In Vivo Comparison of Two Enteric‐Pouch Power Transformers for Circulatory Support

“…This was tested in only one of the publications reviewed. The Ottawa device showed a 10% attenuation of secondary output with a metal object of unspecified mass in contact with the primary coil (11). No testing involved the more ominous concern that an effective short circuit of the input (primary circuit) power by the induced eddy currents could precipitously drain portable battery packs during, for instance, recreational outings.…”

“…At least 2 devices have been subjected to rigorous experimental trial for over 15 years and are approaching clinical use (8,9). Several modifications extend efficiency and adaptability (10)(11)(12)(13)(14)(15)(16)(17)(18). This has been achieved, however, with air cored, high frequency (160 kHz to 1 MHz) devices.…”