Improvement of the transcutaneous energy transmissoin system utilizing ferrite cored coils for artificial hearts

Heart transplantation is currently the best treatment for end-stage heart failure. There is a large disparity between the number of available donor hearts and the number of people who need them. Total artificial hearts and ventricular assist devices have been developed as alternatives to the transplantation. Percutaneous leads should be avoided in long-term implantations due to the risk of infection and the restraint on patients´ activities. Transcutaneous energy transmission systems transmit electric power across intact skin by electromagnetic induction with a pair of coils. Our system has thin ferrite cores, which increase the magnetic coupling factor and self-inductance. In addition MOSFET synchronous rectifier using a digital PLL technique can reduce forward voltage drops. These features result in high energy transmission efficiency. Also the core has a roll of magnetic shield. This effect made it possible to mount the synchronous rectifier circuit board on the back of the coil. In animal experiments, the output voltage of the TETS decreased when the primary coil shifted from the normal position. Local elevations of temperature at the ICs that consume relatively high power caused heat injuries. Also pressure necroses were seen in the circumference of the secondary coil.