Application of a shape memory alloy for internal artificial organs

Abstract

Shape memory alloy (SMA) is an actuator with high efficiency, and for this reason, SMA is suitable for totally implantable artificial internal organs. We have thought about the various possible applications, and one is an artificial sphincter. Many patients with cancer have a stoma, with which control of excretion is, of course, difficult. It limits the quality of life (QOL) of patients with stomata. If there is a sphincter for the stoma, control becomes possible. Therefore, an artificial anal sphincter was developed. Energy will be supplied by the use of a transcutaneous energy transmission system (TETS). The energy is used to raise the temperature and this becomes the drive energy in the SMA. This system can achieve very high efficiency; therefore, this actuator may be suitable for artificial internal organs. This system is currently in the stage of animal experimentation. By opening and shutting an artificial anal sphincter, excretion becomes possible. Application of this totally implantable system to artificial myocardium is considered in this article. SMA thread was sewn together, and the artificial myocardium was applied to the outside of a heart. For improvement of the cooling time, Peltier elements were adopted in this artificial myocardium. By the use of Peltier elements, rapid cooling becomes possible. Using this artificial myocardium, cardiac contraction may be assisted. In this way, various applications of the SMA are being considered in Tohoku University.