Researchers at USC's Information Sciences Institute produced this amazing pyramid, around 30 microns across, which may one day be used to deliver precise micro- or nano-doses of medication. The structures, dubbed "voxels" are made of silicon, cut into flats and then folded up and sealed to enclose tiny volumes of space inside. The team hasn't stopped at pyramids either— they've tried flat envelopes, cubes and partial dodecahedra, but these don't close together the way the pyramid does.
The flat shapes are first carved out of polysilicon sheets lying on a gold film using standard commercial techniques. The hinge areas are improved with some etching. Then they're electro-coated with permalloy, making them magnetic but leaving the hinges free. Folding and closing the shapes is the tricky part, requiring bending using magnetic fields, and then submersion in water. As the shapes dry capillary action draws the voxels closed. They plan on improving the folding precision and the strength of the bonds at each side of the voxel, which might be possible with carefully directed water jets.