Versatile Approach for Integrative and Functionalized Tubes by Strain Engineering of Nanomembranes on Polymers

Abstract

Flexible electronics, extremely sensitive sensors, strained-silicon technology, andmacromolecule separation, are only a few examples stimulating increasing interest in free-standing nanomembranes, which can be fabricated out of thin solid films, particle nanocomposites, organic layers, organic/inorganic networks, and even graphene sheets. Strain engineering offers an advanced strategy to deterministically rearrange such nanomembranes into threedimensional micro-/nanostructures including tubes, helices, rings, wrinkles and other advanced microarchitectures, all of which serve for applications in electronics, mechanics, fluidics, and photonics. The fabrication often requires a selective underetching procedure to release the nanomembranes from their substrate, which heavily constraints the number of desirable materials for exciting applications in, e.g., metamaterials or biomedical research. The material choice is limited, because the selective underetching not only removes the underlying sacrificial layer but also in many cases dissolves the nanomembrane material itself. We circumvent this problem for a broad range of materials and material combinations by a new approach outlined in Figure 1a. A pre-stressed inorganic nanomembrane deposited at low temperatures onto a polymer sacrificial layer (here: photoresist) is released from the substrate surface by removing