Most matter isn’t very smart. But some exotic materials have memory: you can bend them, but when heated they return to their original shape. Engineers have tinkered with these materials for robotic and automotive applications, but polymer chemist Andreas Lendlein envisions their use in implantable therapeutic devices. In 1997, while working at MIT, Lendlein became the first to develop a biodegradable shape-memory polymer that responds to body temperature. A surgeon could insert a compressed polymer through a tiny incision; once inside the body it would expand. The payoff could be improved coronary stents to prop open blocked arteries, or scaffolds for growing new organs. A polymer with cells attached could be inserted to replace lost cartilage; triggered by the body’s warmth, the polymer would expand into the shape of the missing cartilage, then degrade as new tissue grew. Lendlein returned to his native Germany and cofounded mnemoScience, in Aachen, to commercialize his technology. MnemoScience’s researchers have successfully tested Lendlein’s materials in animals, and they hope to release their first medical product in a few years.