Communications of the ACM
Knowing When to Fold: Engineers Use 'nano-Origami' to Build Tiny Electronic Devices
Massachusetts Institute of Technology researchers are developing nano-origami, a new technique that enables engineers to fold nanoscale materials into simple three-dimensional (3D) structures. Nano-origami could be used to build motors and capacitors and lead to better computer memory storage, faster microprocessors, and new nanophotonic devices. The MIT team used conventional lithography tools to create a nanoscale two-dimensional pattern in materials, and then folded the material into predetermined 3D shapes.
The researchers have already demonstrated a 3D nanoscale capacitor. The capacitor currently has only a single fold, but as more folds are added, its ability to store energy will increase. Additional layers also would promote faster information flow, similar to how the folds in a human's brain may allow for faster communication between brain regions, says graduate student Nader Shaar.
The researchers have developed several ways to induce folding, including depositing metal onto the surface where a fold should be, which causes the material to curl upward. Directing a beam of helium ions onto the desired fold imprints a pattern that causes the material to fold once it is removed from the surface. High-energy beams accumulate at the bottom, causing a downward fold, and low-energy beams accumulate at the top for downward folds.
A third technique uses embedded gold wires and a current that interacts with an external magnetic field, creating a Lorentz force that lifts the material's face. The folded shapes can be fabricated in several materials, including silicon, silicon nitride, and a soft polymer known as SU-8.
From MIT News
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