Smart materials are an innovation that has revolutionised the world of engineering over the last few decades. They've been dubbed smart because they interactwith their environment, responding to changes in temperature or moisture. From mobile phones that can be designed to pop open on request to biodegradable medical sutures, the applications of smart materials seem limitless. Quentin Cooper finds out more about these shape-shifters. Producer John Watkins Email: material.world@bbc.co.uk