Autonomous Implants.

With the increasing aging population, more implants are being used in the body. However, these implants often fail, and they suffer from a lack of integration or proper function. Efforts have been made to generate implants by employing bioactive materials, adding cellular components, and integrating smart characteristics such as self-healing properties. The vision is, however, to develop an implant that can mimic native tissues in their way of doing things, responding to challenges and remodeling. Such automated implants require the integration of advances made in various fields of science. Although early, there are good steps taken in this way, e.g., the development of stimuli-responsive, self-powering, self-actuating, self-healing, self-regenerating, self-aware implants. Attempts to combine more than one smart property into these implants are still at the beginning, e.g., the integration of such special characteristics requires a new set of skills and thinking, which presents new challenges that warrant exploration and investment. Such an implant evolution is expected to be in stages, where the first implant will be able to communicate with doctors and hospitals; then, in the next stage, with patients, and later, they will be independent, sense any disturbances and aberrations from normal early on, and correct themselves before damage becomes irreversible. This forward-looking review looks at the research done thus far in this direction and efforts to assemble individual aspects of smart implants into multifunctional implants in the future. The stages of material, in vitro, and in vivo testing and clinical application, if any, are critically reviewed. In addition, the challenges facing the development of autonomous smart implants are discussed, and research directions and ideas are suggested.