Roll-to-roll fabrication of three-dimensional self-folding microstructures

Self-folding technology offers a promising alternative to conventional microfabrication techniques. It utilizes controlled and imbalanced stresses to transform specific patterns of flat materials into pre-determined three-dimensional (3D) structures for diverse applications. However, current production methods of self-folding structures are mostly limited to lab-scale production. In this study, a novel roll-to-roll (R2R) production setup is developed to address the limited scalability of self-folding technology. The R2R setup continuously stretches and bonds a pre-cured PDMS (polydimethylsiloxane) film to another PDMS film attached to a stiff PET (polyethylene terephthalate) carrier layer. This creates a bilayer PDMS film with imbalanced stress, causing it to self-fold into pre-determined 3D shapes upon patterning and releasing from the PET carrier layer. The R2R setup achieves a production rate of 96 cm² min^-1, significantly surpassing our previous method based on spin-coating and baking. This demonstrates the potential of R2R technology for industrial-scale production of self-folding microstructures.