INTRA-FASCICULAR NERVE ELECTRODE AIMING AT THE NEW CONTROL METHOD OF THE TOTAL ARTIFICIAL HEART USING NERVE SIGNALS

Abstract

The various control methods of the total artificial heart (TAH) have been tried over decades. Nevertheless, the method using the autonomic nerve signals has not been achieved yet. Using the nerve signals, the TAH could be controlled directly based on the body demand. For this aim the nerve electrode must be developed, therefore the short lifetime of the current electrodes has been improved in this study. To overcome the drift of the electrode position on the fascicle, we made the cylindrical cuff completely covering the nerve fascicle. Inside the cuff, the needle-shaped stainless electrodes projected inward and stuck into the fascicle. In addition, the silicone gel was filled in the clearance between the fascicle and the cuff for further fixation. These refinements minimized the position drift, and then realized the stable measurement of the signal. To evaluate the performance of the newly developed intra-fascicular newe electrode, it was implanted into rabbits. As a result, the cervical vagal nerve activity was successfully measured for 3 weeks. Compared to our extra-fascicular nerve electrode developed previously, the signal-to-noise ratio was improved from 1.6 to 2.0. At present, we are devising this electrode adopting the flexible needle made of the polyimidefilm to decrease the damage to the nerve fibers and achieve still longer lifetime for sensing the signal in the TAH goat.