Researchers at the University of Twente in the Netherlands have a new hobby—making tiny, self-folding, silicon nitride origami.
“While making 3D structures is natural in everyday life, it has always been extremely difficult to do so in microfabrication, especially if you want to build a large number of structures cheaply,” says leading author Antoine Legrain in an American Institute of Physics press release.
Credit: Discover Magazine; Youtube
The researchers made microscopic 3D structures—cubes, pyramids, bowls, and other geometric shapes—out of flat sheets of silicon nitride using only a droplet of water. Also, they printed shapes onto silicon wafers, etching the areas where they wanted the silicon to bend to create hinges. They then harnessed the capillary force of water to assemble the structures.
According to the press release, silicon origami has been accomplished before. Those previous feats added water to the system by hand, making it difficult to accurately control and scale the assembly process.
The new research, published in the Journal of Applied Physics, improves on those methods by adding water to the system through the channel in the wafer, affording both precision and control.
“The team also discovered that the final structures, which are about the size of a grain of sand, can be opened and closed up to 60 times without signs of wear, as long as they remain wet,” states the press release.
The tiny structures could have future biomedical and 3D sensor applications, and the team is next working to add conductive hinges to the structures.
The paper is “Controllable elastocapillary folding of three-dimensional micro-objects through-wafer filling” (DOI: 10.1063/1.4878460).
Feature image credit: A. Legrain, et al.; U. of Twente