Quantitative multispectral biosensing and 1D imaging using quasi-3D plasmonic crystals

Abstract

We developed a class of quasi-3D plasmonic crystal that consists of multilayered, regular arrays of subwavelength metal nanostructures. The complex, highly sensitive structure of the optical transmission spectra of these crystals makes them especially well suited for sensing applications. Coupled with quantitative electrodynamics modeling of their optical response, they enable full multiwavelength spectroscopic detection of molecular binding events with sensitivities that correspond to small fractions of a monolayer. The high degree of spatial uniformity of the crystals, formed by a soft nanoimprint technique, provides the ability to image binding events over large areas with micrometer spatial resolution. These features, together with compact form factors, low-cost fabrication procedures, simple readout apparatus, and ability for direct integration into microfluidic networks and arrays, suggest promise for these devices in label-free bioanalytical detection systems.chemical sensing ͉ nanoimprint lithography ͉ surface plasmons ͉ optical transmission spectra

Coupling of plasmonic and optical cavity modes in quasi-three-dimensional plasmonic crystals

“…Here a two-dimensional plasmonic crystal, formed by the top gold coating, optically couples to an array of isolated disks of gold in the bottoms of the cylindrical depressions. Light transmitted through this 'quasi-3D' crystal via plasmonic coupling between the nanoholes and recessed disks 22 coherently reflects from the back mirror (that is, the layer of gold on glass) which in turn, influences the plasmonic resonances, constructively or destructively depending on the cavity length. Figure 1 shows a large area (5 mm×5 mm) optical image ( Fig.…”

Plasmonic gold mushroom arrays with refractive index sensing figures of merit approaching the theoretical limit

“…We also note that a closely related array structure has been reported recently, which consists of periodically perforated nanoscale holes in a gold film with a gold nanodisk at the bottom of each hole [42][43][44] . This structure can be thought of as an inverse one to our GMRA.…”

Soft lithography for micro- and nanoscale patterning

“…When combined with selective etching and lift-off, these nanostructures have been transferred into metals and then used as substrates for biosensing. The methods of detection have included optical diffraction 38 , surface plasmon resonance 39 , surface-enhanced Raman scattering 40 and electrochemistry 41 .…”