Bidirectional Self-Folding with Atomic Layer Deposition Nanofilms for Microscale Origami

TL;DR

This paper demonstrates a novel method for creating microscale origami structures using bidirectional self-folding of atomic layer deposition nanofilms, enabling complex microdevices with potential applications in micromechanical systems.

Contribution

It introduces a new approach to microscale origami by engineering bidirectional folding with 4 nm ALD bilayer films, combining microfabrication with origami design.

Findings

Successful fabrication of complex micro-origami devices

Self-folding behavior driven by strain differentials in bilayers

Potential for mass production of deployable microstructures

Abstract

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.