As 3-D printing has become a mainstream technology, industry and academic researchers have been investigating printable structures that will fold themselves into useful three-dimensional shapes when heated or immersed in water.In a paper appearing in the American Chemical Society’s journal Applied Materials and Interfaces, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and colleagues report something new: a printable structure that begins to fold itself up as soon as it’s peeled off the printing platform.