(235b) Plasmon-Enhanced Nanoscale Metamaterial Sensors

Plasmon-enhanced Nanoscale Metamaterial
Sensors

Presenting Author: D. Keith Roper. University of Arkansas,
dkroper@uark.edu

Nano Bio Photonics Lab, Chemical Engineering, http://comp.uark.edu/~dkroper/

Microelectronics/Photonics Graduate Program, http://microep.uark.edu/

Coauthors: Phillip Blake; Gyoung Jang; Braden Harbin

Nanoscale
metamaterials exhibit coupling between plasmon-active elements that creates
strong, local electromagnetic fields.  These fields enhance sensitivity more
than 10-fold relative to localized surface plasmon (nanoparticle) or plasmon polariton
(BIACore) sensors.   Plasmons are oscillating free electrons confined to
metal surfaces excited by incident electromagnetism at specific wavelengths (l).
 But sensitivity gains from plasmon field enhancements are in limited
regions of the electromagnetic spectrum and only occur in close
proximity to plasmon-active nanostructures.  These limitations arise from the
wavelength-specificity and nanometer-scale localization of plasmon resonances,
respectively.  Metamaterials, whose tunable electromagnetic functionality
derives from three-dimensional (3D) structuring of suitable condensed-matter
composites, can provide delocalization of plasmon effects as well as
tunability across the electromagnetic spectrum to permit far-field, broad-spectrum,
plasmon enhancement.  However, progress in developing plasmon-active nano-scale
metamaterials for sensing is limited by (1) lack of comprehensive, multi-scale models
to evaluate plasmon-exciton coupling and design ordered plasmon-active, 3D
metamaterial nanostructures; (2) limited availability of inexpensive, bottom-up
methods to fabricate plasmon-active metamaterials for sensing applications; and
(3) scant analytic and experimental evaluation of plasmon-active nanoscale metamaterials
sensing. We present the first sensor data from nanoscale metamaterials
fabricated using inexpensive, scale-able methods guided by solutions of Navier
Stokes[1]
and Maxwell-Stefan equations.  We characterize sensor properties using TEM,
SEM, T-UV, and Raman spectroscopy.  Data corresponds to theoretical sensor results
based on analytic and finite difference time domain (FDTD) solutions to Maxwell's[2] equations.  A new,
refined metric is introduced to compare sensitivity of nanoscale metamaterials
with nanoparticle and BIAcore sensors on an equivalent basis.