Ryan Hayward (UMass Amherst), Thomas Hull (Western New England University), and Junhee Na (UMass Amherst)

This print shows a magnification of a 1 mm-wide self-folded object. It is an origami design of a 3D octahedron-tetrahedron truss, independently discovered by many origamists, like David Huffman, Toshikazu Kawasaki, and Ron Resch. The sample shown here is made of a soft polymer gel layer that swells when placed in water bonded to stiff plastic layers. As the soft layer swells, it builds up stresses that cause the sheet to bend to defined angles at locations specified by patterning the stiff layers. This allows the sheet to fold itself simply by placing it in water. Here, the sheet is shown imaged by confocal microscopy, a technique that allows the full 3D structure to be reconstructed from a series of 2D fluorescence images.