Evolutionary Design and Prototyping of Single Crystalline Titanium Nitride Lattice Optics

Plasmonic metasurfaces—structured materials with subwavelength units—are of interest for applications ranging from high resolution imaging to 3D holography. Integrated devices, however, are challenging to achieve because traditional plasmonic materials such as Ag or Au are not compatible with semiconductor processing. Recently, TiN has received attention as an unconventional plasmonic material because of its potential CMOS […]

Multiscale, Hierarchical Patterning of Graphene by Conformal Wrinkling

Patterning three-dimensional (3D) structure into two-dimensional (2D) graphene is important for applications in flexible electrodes, stretchable electronics and energy storage devices. We have demonstrated a conformal wrinkling process that can generate hierarchical graphene architectures. Multi-scale graphene patterning is achieved by sandwiching a soft fluoropolymer skin layer between as-synthesized graphene and pre-strained polystyrene substrates. Because the […]

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 […]