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3D Mapping of the Structural Transitions in Wrinkled 2D Membranes: Implications for Reconfigurable Electronics, Memristors, and Bioelectronic Interfaces

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journal contribution
posted on 19.09.2019, 14:34 by Kaustubh S. Panse, Shan Zhou, Yingjie Zhang
Bending and wrinkling occur widely in thin membrane materials, such as biomembranes, optical coatings, and two-dimensional materials. Such deformed structures can exhibit distinct mechanical responses compared to flat membranes. However, to date, mechanical characterization of membranes is mainly limited to the macroscopic level. The microscopic structure–mechanics relationship, key for rational materials design, remains elusive. Here we bridge this gap by mapping out the nanomechanical response of a model membrane systemwrinkled monolayer graphene. Using an atomic force microscope (AFM), we perform force–distance spectroscopy at each nanoscale spot to obtain a microscopic map. We observe a significant restoring force as the AFM tip pushes on graphene nanowrinkles. When the indenting force is higher than a threshold (a few nanonewtons), the wrinkles locally snap onto the SiO2 substrate; after tip retraction, the wrinkles automatically restore their original shape. Through theoretical modeling and statistical analysis, we further find that nanoscale curvature enhances the effective stiffness and snapping threshold of atomically thin wrinkles. Our results can guide the rational design of mechanically reconfigurable materials and bioelectronic interfaces.