Surface-enhanced Raman spectroscopy using linearly arranged gold nanoparticles embedded in nanochannels

Abstract

A micro/nanofluidic device containing linearly arranged gold nanoparticles embedded in nanochannels was developed for highly sensitive and highly efficient surface-enhanced Raman spectroscopy (SERS). The Si nanochannel array was fabricated using a photolithography-based process. The nanochannel width was controlled from 100 to 400 nm. Synthesized particles of mean diameter 100 nm were arranged linearly in the nanochannels, using a nanotrench-guided self-assembly process. We developed a process for integrating linearly arranged nanoparticles and micro/nanofluidic components. The particle geometry provided significant Raman enhancement. Furthermore, efficient Raman analysis was possible by scanning a laser spot, because the particles were arranged in one direction. The fabricated structures were evaluated for SERS using 4,4$-bipyridine molecules at concentrations of 1 mM and 10 µM. The Raman peaks was obtained from a few hot spots. The Raman spectra showed that the molecule-specific Raman intensities were correlated with the number of hot spots in the nanochannel.

Exploring Anomalous Fluid Behavior at the Nanoscale: Direct Visualization and Quantification via Nanofluidic Devices

“…These emerging nanoconfinement-assisted synthesis/assemblies require clear fundamental understanding from controlled experiments. The combination of LPTEM and other methods (e.g., Raman spectroscopy) with purpose-built nanofluidic devices could serve these future experimental needs uniquely well.…”

“…54 These emerging nanoconfinement-assisted synthesis/assemblies require clear fundamental understanding from controlled experiments. The combination of LPTEM and other methods (e.g., Raman spectroscopy 55 ) with purpose-built nanofluidic devices could serve these future experimental needs uniquely well. In summary, with the advancement of nanofabrication and measurement techniques, it is foreseeable that nanofluidic devices with well-controlled dimensions and surface properties will not only shed light on fundamental nanoscale fluid research but also significantly advance across disciplines such as physics, chemistry, and materials science.…”

Single-molecule surface-enhanced Raman spectroscopy of 4,4′-bipyridine on a prefabricated substrate with directionally arrayed gold nanoparticle dimers

“…It is fabricated by nanotrench-guided self-assembly with a high yield. [16][17][18] It enables us to utilize the effect of polarization on the enhancement for single-molecule SERS. Although electron beam (EB) lithography or focused ion beam (FIB) has been used for fabricating orderly nanostructures, it cannot be used for fabricating a nanogap of around 1 nm, which shows a marked electromagnetic enhancement.…”

Characterization method for relative Raman enhancement for surface-enhanced Raman spectroscopy using gold nanoparticle dimer array

“…A particle dimer is fabricated by drying-based nanotrench-guided self-assembly. [15][16][17][18][19] Particle surfaces are covered by citrate, acetonedicarboxylic acid, acetoacetic acid, and intermediate products after chemical synthesis using a citrate reduction method. [20][21][22] During the drying process in the self-assembly, the adsorbed molecule layer acts as a spacer between particles, forming a nanogap between particles.…”

“…Before the SERS analysis for target molecules in the solution, the adsorbed molecules were removed. Although electron beam (EB) lithography or focused ion beam (FIB) has been used for fabricating orderly nanostructures, [15][16][17][18][19] one cannot fabricate a nanogap of around 1 nm, which shows a marked electromagnetic enhancement. 24,25) We confirmed that the proposed structures enable us to perform an ultrasensitive and rapid SERS analysis.…”