기계적 변형이 가능한 능동 플라즈모닉 기반 표면증강라만분광 기판 Optical Society of Korea Winter Annual Meting 강민희, 김재준, 오영재, 정기훈 바이오및뇌공학과, KAIST Stretchable Active-Plasmonic Substrates for Surface-enhanced Raman Spectroscopy

Contents Motivation. Working Principle. Experimental Details. Characterization -Plasmon Resonance Tuning by Membrane Deformation -SERS Enhancement by Active Tuning Summary and Conclusion. Optical Society of Korea Winter Annual Meting 2012

Biological imaging Plasmon Cancer therapy Excited nanoshells Tumor Healthy tissue gold silica Bio-sensor SERS Localized Surface Plasmon Resonance Charge density oscillation confined to metallic nanoparticles w/o matched w/ matched Plasmon resonance makes electric dipole moment which leads to large electric field enhancement near the metal nanostructures.

Selecting the Localized Surface Plasmon Resonance for SERS Selecting the plasmon resonance is necessary to optimally enhance SERS signal.

Surrounding’s Dielectric constant Inter-particle distance Tuning the Plasmon Resonance Inter-particle distance change allows active tuning of the plasmon resonance. G. J. Phys. Chem. B(2006) X. Nano Lett.(2011) X. Nano Lett.(2005)

Deformable Nanoplasmonic Membrane Circular membrane deformation is employed to change the inter-particle distance in a way of tuning the plasmon resonance. scattered light Incident light SERS signal

X X (a)Small gap  Strong dipole interaction  Low Resonance Frequency (b) Large gap  Weak dipole interaction  High Resonance Frequency E-field intensity and plasmon resonance correspond to dipole-dipole interaction of metal dimers.

Design & Fabrication Procedures C4F8C4F8 PDMS Silver Glass wafer Maximum deflection Radius of curvature Strain vs. applied pressure Strain can be calculated by w o of the distensible circular membrane and radius of curvature R s. Silver nano-islands ∆ P<0 Pneumatic control Ref. pressure sensor i. Substrate preparation ii. Silver nano- islands formation iii. Membrane transfer

200nm Adjusting Nano-islands Size by Annealing Condition The control of the annealing time allowed control of the size and density of the metal islands. D=18nm D=20nm D=34nm D=18nm D=20nm D=34nm

Dynamic Tuning of Plasmon Resonance 0% 20% D=18nm D=20nm D=34nm D

SERS exploit unique vibrational characteristic of molecules, each peak is related with chemical bonding and vibrational mode. Experimental Details for SERS Raman Scattering & SERS ω stoke

SERS Signal Behavior SERS signal enhancement is observed when the λ LSPR position is at the window that includes both λ ex and the λ vib. 932cm cm -1

Active plasmonic substrates by employing dynamic deformation of membrane. The plasmon resonance was actively tuned by varying the strain applied nanoplasmonic membrane. To find optimal condition for SERS enhancement, SERS signal behavior was studied. Summary & Conclusion Increase Strain Extinction (a.u.) Wavelength (nm) This work was supported by the National Research Foundation of Korea (NRF)(No , No , No ) grant funded by the Korea government, IT R&D program(No. KI ) and (No ) of MKE/KEIT. 0% 20%