"The three of us work for companies on this technological frontier, building devices that take advantage of developments in low-power implantable sensors and embedded signal processing. In this article we’ll describe three devices that respond to the flux of biology within the body. Because these devices rely on data related to the processes they influence, we call them “closed-loop” systems, but you could also call them the next step in a bionic model of medicine. In this new paradigm, engineered systems composed of chips, wires, and batteries can replace or supplement biological systems that malfunction." - Todd Hoff