Our research focuses on controlling materials at the 100-nanometer scale and investigating their size and shape-dependent properties. We have developed massively parallel, multi-scale nanopatterning tools to generate noble metal (plasmonic) structures that can manipulate visible light at the nanoscale. We are focusing on multi-scale, anisotropic, and 3D plasmonic materials for applications in imaging, sensing, and cancer therapeutics.
Strain-induced wrinkling of a stiff skin on a soft base layer is emerging as a powerful bottom-up method to realize ordered and disordered patterns across an entire surface. We have developed a memory-based, sequential wrinkling process that can transform flat polystyrene sheets into multi-scale, three-dimensional hierarchical textures. Multiple cycles of plasma-mediated skin growth followed by directional strain relief of the substrate resulted in hierarchical architectures with characteristic generational (G) features. Independent control over wrinkle wavelength and wrinkle orientation for each G was achieved by tuning plasma treatment time and strain-relief direction for each cycle. Lotus-type superhydrophobicity was demonstrated on three-dimensional G1-G2-G3 hierarchical wrinkles as well as tunable superhydrophilicity on these same substrates after oxygen plasma. Our new materials system provides a general approach for nanomanufacturing based on bottom-up sequential wrinkling that will benefit a diverse range of applications, and especially those that require large area (> 100 cm2), multi-scale, three-dimensional patterns.