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Download fileSurface-Enhanced Infrared Absorption: Pushing the Frontier for On-Chip Gas Sensing
journal contribution
posted on 2017-12-21, 00:00 authored by Xinyuan Chong, Yujing Zhang, Erwen Li, Ki-Joong Kim, Paul R. Ohodnicki, Chih-hung Chang, Alan X. WangSurface-enhanced
infrared absorption (SEIRA) is capable of identifying
molecular fingerprints by resonant detection of infrared vibrational
modes through the coupling with plasmonic modes of metallic nanostructures.
However, SEIRA for on-chip gas sensing is still not very successful
due to the intrinsically weak light-matter interaction between photons
and gas molecules and the technical challenges in accumulating sufficient
gas species in the vicinity of the spatially localized enhanced electric
field, namely, the “hot-spots”, generated through plasmonics.
In this paper, we present a suspended silicon nitride (Si3N4) nanomembrane device by integrating plasmonic nanopatch
gold antennas with metal–organic framework (MOF), which can
largely adsorb carbon dioxide (CO2) through its nanoporous
structure. Unlike conventional SEIRA sensing relying on highly localized
hot-spots of plasmonic nanoantennas or nanoparticles, the device reported
in this paper engineered the coupled surface plasmon polaritons in
the metal–Si3N4 and metal–MOF
interfaces to achieve strong optical field enhancement across the
entire MOF film. We successfully demonstrated on-chip gas sensing
of CO2 with more than 1800× enhancement factors by
combining the concentration effect from the 2.7 μm MOF thin
film and the optical field enhancement of the plasmonic nanopatch
antennas.