Assistant Professor and lead author So Nagashima,
Assistant Professor Andrej Košmrlj, Donald R. Dixon '69 and Elizabeth W. Dixon Professor Howard A. Stone, and Principal Research Scientist Myoung-Woon Moon discussed the paper they and their co-authors published in
Proceedings of the National Academy of Sciences. "I think that the most challenging aspect of devising our method for utilizing a thin skin template that responds to water by dynamically changing its surface morphology was finding the conditions where the wrinkle-to-fold transition occurs," Moon tells
Phys.org. "The critical conditions as a function of the applied strain, initial wrinkle geometries, and thickness of the skin layer determined by oxygen plasma treatment duration were difficult to find." Moon adds that the observation technique for the dynamic transition was limited to only optical microscopes whose highest optical resolution falls between 100 to 1000 nm in the width of nanowires, this being due to the dynamic transition taking place at the submicron scale.
When inducing a template surface wrinkle-to-fold transition by exploiting the capillary forces of water containing DNA molecules, Stone points out, the observation that water changes the wrinkle-to-fold transition is new. "As far as we know, ours is the first study to show this effect, as is demonstrating one use of such folds for the alignment of DNA. Moreover, control of surface tension or resultant capillary forces and the area for fold formation is relatively hard—and by adding DNA molecules to water, it appears that the surface tension is changed, so the fold transition length was shorter."
Read more at: https://phys.org/news/2017-06-wrinkles-wires-capillarity-induced-skin-spontaneously.html#jCp
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