Wheels Image
The chemical immobilized on the sheet decomposes hydrogen peroxide in the host solution to lighter products (water and oxygen), thereby producing spontaneous fluid flows. These fluid flows drive the 2D flexible sheet to pop up at the center, forming an ideal 3D structure that rotates in the clockwise direction. (Credit: A. Laskar)

University of Pittsburgh researchers have utilized a catalytic reaction that causes a two-dimensional, chemically coated sheet to spontaneously “morph” into a three-dimensional gear.

The findings indicate the potential to develop chemically driven machines that do not rely on external power but simply require the addition of reactants to the surrounding solution.

Catalysts are placed on a two-dimensional sheet resembling a wheel with spokes, with heavier nodes on the sheet’s circumference. The flexible sheet, approximately a millimeter in length, is then placed in a fluid-filled microchamber. A reactant is added to the chamber that activates the catalysts on the flat “wheel,” causing the fluid to flow. The inward fluid flow drives the lighter sections of the sheet to pop up, forming an active rotor that catches the flow and rotates.