Stretchable superhydrophobicity from monolithic, three-dimensional hierarchical wrinkles

Superhydrophobic surfaces that can also withstand mechanical deformation such as bending and stretching are important for applications such as robust self-cleaning, water-resistant electronics, and flexible microfluidics. We developed monolithic, multi-scale poly(dimethylsiloxane) (PDMS) nanowrinkles that can exhibit stretchable superhydrophobicity using high fidelity pattern transfer. The droplet impact dynamics revealed that droplet rebound depended strongly on the […]

Screening New Plasmonic Materials

Surface plasmon polaritons (SPPs) are responsible for exotic optical phenomena including negative refraction, surface enhanced Raman scattering, and nanoscale focusing of light. Although many materials support SPPs, the choice of metal for most applications has been based on traditional plasmonic materials (Ag, Au) because there have been no side-by-side comparisons of the different materials on […]

The Dark Side of Surface Plasmons

Plasmonic nanostructures concentrate optical fields into nanoscale volumes, which is useful for plasmonic nanolasers, surface enhanced Raman spectroscopy, and white-light generation. However, the short lifetimes of the emissive plasmons correspond to a rapid depletion of the plasmon energy, preventing further enhancement of local optical fields. Dark (subradiant) plasmons have longer lifetimes, but their resonant wavelengths […]

Superlatice Plasmons in Hierarchical Au Nanoparticle Arrays

Periodic metal nanoparticle (NP) arrays support narrow lattice plasmon resonances that can be tuned by changing the localized surface plasmons of the individual NPs in the array, NP periodicity, and dielectric environment. The high quality factors (100-200) of lattice plasmon resonances enabled NP arrays to function as nanocavities for surface-emitting lasers. We have developed optical […]

Controlled Three-Dimensional Hierarchical Structuring by Memory-Based, Sequential Wrinkling

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 […]

Real-time Tunable Lasing from Plasmonic Nanocavity Arrays

Plasmon lasers can support ultrasmall mode confinement and ultrafast dynamics with device feature sizes below the diffraction limit. However, most plasmon-based nanolasers rely on solid gain materials (inorganic semiconducting nanowire or organic dye in a solid matrix) that preclude the possibility of dynamic tuning. We developed an approach to achieve real-time, tunable lattice plasmon lasing […]

Hetero-oligomer Nanoparticle Arrays for Plasmon-Enhanced Applications

Plasmonic nanoparticles (NPs) arranged into assemblies can manipulate near-field profiles and modify far-field characteristics compared to a single NP. The ability to tune each nanoparticle in a plasmonic assembly can reveal new architectures for plasmon-enhanced applications. We developed a nanofabrication approach, Reconstructable Mask Lithography (RML), to achieve independent control over the size, position, and material […]

A Simple Method to Enhance Therapeutic Efficacy of Nanoconstructs

Apt-AuNS nanoconstructs composed of two primary components, an anisotropic gold nanostar (AuNS) core and a shell of secondary structure aptamer, AS1411, have shown great potential in cancer treatment. The high density of AS1411 that comprise the shell results in a high local concentration and enhances the therapeutic properties of the nanoconstructs. We have recently described […]

Nanowrinkles on polymer substrates

Nanotexturing polymeric surfaces changes their surface properties while their bulk properties remain unchanged. Wrinkles and folds can increase the efficiency and mechanical stability of optical and electrical devices. We have found a parallel method to create nanometer-scale textures over large areas with unprecedented control over wrinkle wavelength. Through reactive ion etching (RIE) we can create […]

Nanoconstructs for Cancer Therapeutics

Direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus is crucial for understanding the mechanism behind cancer cell death. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and were found to induce major changes in nuclear phenotype: near the site of the nanoconstruct, nuclear envelope invaginations […]