MIT Scientists Made a Shape-Shifting Material that Morphs Into a Human Face

An anonymous reader quotes Ars Technica:
The next big thing in 3D printing just might be so-called “4D materials” which employ the same manufacturing techniques, but are designed to deform over time in response to changes in the environment, like humidity and temperature. They’re also sometimes known as active origami or shape-morphing systems. MIT scientists successfully created flat structures that can transform into much more complicated structures than had previously been achieved, including a human face. They published their results last fall in the Proceedings of the National Academy of Sciences…

MIT mechanical engineer Wim van Rees, a co-author of the PNAS paper, devised a theoretical method to turn a thin flat sheet into more complex shapes, like spheres, domes, or a human face. “My goal was to start with a complex 3-D shape that we want to achieve, like a human face, and then ask, ‘How do we program a material so it gets there?'” he said. “That’s a problem of inverse design…” van Rees and his colleagues decided to use a mesh-like lattice structure instead of the continuous sheet modeled in the initial simulations. They made the lattice out of a rubbery material that expands when the temperature increases. The gaps in the lattice make it easier for the material to adapt to especially large changes in its surface area. The MIT team used an image of [19th century mathematician Carl Friedrich] Gauss to create a virtual map of how much the flat surface would have to bend to reconfigure into a face. Then they devised an algorithm to translate that into the right pattern of ribs in the lattice.

They designed the ribs to grow at different rates across the mesh sheet, each one able to bend sufficiently to take on the shape of a nose or an eye socket. The printed lattice was cured in a hot oven, and then cooled to room temperature in a saltwater bath.

And voila! It morphed into a human face.

“The team also made a lattice containing conductive liquid metal that transformed into an active antenna, with a resonance frequency that changes as it deforms.”