Rollup fabrication of microtubular structures by mechanically stretching/compressing thin films

This paper presents a new method to fabricate microtubes. The stress mismatch between two layers of a single (or different) material thin film is created by a mechanical stretcher. When the thin film is released from the substrate, it rolls up automatically to form the microtubes. Different types of materials are tested including magnesium, aluminum and parylene. The result shows that by changing the applied mechanical stress and the thickness of the thin film, the radius of rolled-up microtube could range from tens to thousands of microns. As model applications, the fabricated microtubes are examined for bubble trapping showing strong enough to trap air bubbles without collapse when submerged into water. When the acoustic field is applied, the bubble could oscillate and generate the microstreaming, therefore successful propelling motions are achieved. In addition, the biodegradable ability of magnesium microtube is tested. This fabrication method may be extended to make more complex three-dimensional microstructures in the future.