“Together, we are creating new classes of shape-shifting matter,” said Jennifer A. Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at Harvard. “Using an integrated design and fabrication approach, we can encode complex ‘instruction sets’ within these printed materials that drive their shape-morphing behavior.” Lewis is also a core faculty member of the Wyss Institute.
To create complex and doubly curved shapes — such as those found on a face — the team turned to a bilayer, multimaterial lattice design.
“The open cells of the curved lattice give it the ability to grow or shrink a lot, even if the material itself undergoes limited extension,” said co-first author Wim M. van Rees, who was a postdoctoral fellow at SEAS and is now an assistant professor at MIT.
To achieve complex curves, growing and shrinking the lattice on its own isn’t enough. You need to be able to direct the growth locally.
“That’s where the materials palette that we’ve developed comes in,” said J. William Boley, a former postdoctoral fellow at SEAS and co-first author of the paper. “By printing materials with different thermal expansion behavior in predefined configurations, we can control the growth and shrinkage of each individual rib of the lattice, which in turn gives rise to complex bending of the printed lattice both within and out of plane.” Boley is now an assistant professor at Boston University.