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Proceedings Paper

Design of plasmonic metamaterials for photothermal spectroscopy and application in molecular detection (Conference Presentation)
Author(s): Thu Le; Takuo Tanaka; Yukie Yokota

Paper Abstract

Micro/nanofluidics have attracted much attention as ideal platforms for bioanalysis. The interest in micro/nanofluidics has resulted in a high demand of non-label detections in ultra-small volume(aL-fL). Among existing optical detections in micro/nanofluidics, photothermal spectroscopy (PTS) is an important approach, which allows detection in non-label fashion. Its principle is based on the detection of refractive index change following the thermal relaxation when molecules absorb light. Many types of PTS have been developed for microfluidics, yet the sensitivity of PTS becomes an issue in sub-micrometer spaces where thermal diffusion is dominant. On the other hand, plasmonic metamaterials, which offers unique surface condition with tailored absorption properties and strong plasmonic enhancement is widely utilized to improve the sensitivity of absorption, fluorescence, Raman spectroscopies, etc. Recently, we proposed the integration of metamaterials to improve the sensitivity of PTS. However, the strong absorption of metamaterials itself is an obstacle for detection. In this study, we propose an idea of exploiting the electromagnetically induced transparence (EIT) phenomena to suppress the absorption in metamaterials. As the EIT peak is tailored to the absorption peak of detecting molecules or the excitation light, the absorption from metamaterials is negligibly small while the strong field enhancement can be achieved. The numerical calculation of absorption and PTS signals in case of metamaterials only, and under the existence of molecules were carried out by COMSOL. The results showed the improvement of signal-to-background ratio to 3-4 orders, while the sensitivity was improved to 2 orders. The experiments are ongoing to verify the calculation.

Paper Details

Date Published: 3 November 2016
PDF: 1 pages
Proc. SPIE 9925, Nanoimaging and Nanospectroscopy IV, 99250E (3 November 2016); doi: 10.1117/12.2237088
Show Author Affiliations
Thu Le, RIKEN Ctr. for Advanced Photonics (Japan)
Takuo Tanaka, RIKEN Ctr. for Advanced Photonics (Japan)
RIKEN (Japan)
Yukie Yokota, RIKEN (Japan)

Published in SPIE Proceedings Vol. 9925:
Nanoimaging and Nanospectroscopy IV
Prabhat Verma; Alexander Egner, Editor(s)

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