Two-Step Deformation Mechanism of Self-Forming Three-Dimensional Carbon Micro Structures

Abstract

We have developed a novel fabrication method for three-dimensional carbon micro structures using a carbon-microelectromechanical system (C-MEMS) and a thermomechanical deformation technique. Three-dimensional carbon micro structures could be fabricated as pyrolyzed SU-8 film with sputtered Au layer. The SU-8 film with sputtered Au layer was deformed autonomously by thermal deformation. Fabrication of three dimensional structures from two dimensional films is like origami structure. In this paper, we investigated deformation behaviour, including temperature-dependent deformation, shape-dependent deformation, and size-dependent deformation to design carbon structures. We found a two-step deformation. The SU-8 film with sputtered Au layer was deformed toward the Au-inside direction by thermal expansion at temperatures under 200 °C. However, it was deformed toward the Au-outside direction by the glass transition between 200 and 300 °C. Shape- and size-dependent deformations were also confirmed. This process could allow fabrication of various micro devices such as large surface area electrodes for micro fuel cells, microreactors, and microsensors.