  Origami design principles are scale invariant and enable direct
miniaturization of origami structures provided the sheets used for folding have
equal thickness to length ratios. Recently, seminal steps have been taken to
fabricate microscale origami using unidirectionally actuated sheets with
nanoscale thickness. Here, we extend the full power of origami-inspired
fabrication to nanoscale sheets by engineering bidirectional folding with 4 nm
thick atomic layer deposition (ALD) SiNx-SiO2 bilayer films. Strain
differentials within these bilayers result in bending, producing microscopic
radii of curvature. We lithographically pattern these bilayers and localize the
bending using rigid panels to fabricate a variety of complex micro-origami
devices. Upon release, these devices self-fold according to prescribed
patterns. Our approach combines planar semiconductor microfabrication methods
with computerized origami design, making it easy to fabricate and deploy such
microstructures en masse. These devices represent an important step forward in
the fabrication and assembly of deployable micromechanical systems that can
interact with and manipulate micro- and nanoscale environments.
