Burr- and etch-free direct machining of shape-controlled micro- and nanopatterns on polyimide films by continuous nanoinscribing for durable flexible devices

Polyimide (PI) is one of the most pragmatic polymers for highly durable flexible devices based on its micro- and nanopatterned structures, because of its excellent thermal and chemical stability. The conventional top-down patterning processes, typically involving materials removal and chemical etching, however, are often ineffective to fabricate micro- and nanopatterns on the PI film due to its high mechanical and chemical resistance. In this work, we develop a highly efficient and scalable PI patterning methodology by utilizing the burr- and etch-free direct mechanical deformation driven by continuous dynamic nanoinscribing. We systematically investigate that the micro- and nanopatterns can be cleanly machined on the PI film with tailored periods, depths, and shapes, by controlling several key nanoinscribing process parameters such as temperature and force. Among many potential applications that can benefit from the present study, we demonstrate the facile fabrication of metallic micro- and nanowires, either durably embedded in or etch-freely patterned on the PI surface, toward flexible and highly durable device systems.