An SMA artificial anal sphincter actuated by transcutaneous energy transmission systems

An application of shape memory alloys (SMAs) for artificial anal sphincters is presented. The artificial anal sphincter consists of two all-round shape memory alloy (ARSMA) plates as the main functional parts, and heaters attached on SMA plates for generating thermal cycles required for phase transformation accompanied shape changes of the plates. The SMA artificial sphincter could be fitted around intestines, performing an occlusion function at body temperature and a release function upon heating. For reducing the potential of infection, a transcutaneous energy transmission (TET) system is incorporated into the artificial anal sphincter, facilitating the complete implantation of the device. Investigation on the thermomechanical responses of the artificial sphincter has been conducted, with both the in vitro and in vivo experiments, showing great potential of practical uses. The relation between the values of applied power and the response times, and the thermocompatibility of the device are discussed.