Wafer‐Scale Polymer‐Based Transparent Nanocorals with Excellent Nanoplasmonic Photothermal Stability for High‐Power and Superfast SERS Imaging

Abstract

Polymer‐based surface‐enhanced Raman spectroscopy (SERS) substrates offer distinctive advantages such as low‐cost and high optical transparency which allows direct detection of trace chemicals on target surfaces and easy microfluidic integration. However, incident‐laser‐induced localized surface plasmon resonances can generate heat that deform the polymer and significantly reduce the intensities of recorded SERS signals. Herein, a novel wafer‐scale polymer‐based transparent nanocoral (WTNC) SERS substrate with 3D electromagnetic “hotspots” is presented. Its fabrication is simple and lithography‐free. The novel SERS substrate demonstrates excellent nanoplasmonic heat resistance, high SERS sensitivity, and unmatched SERS signal uniformity with a relative standard deviation of ≈6% across 80 mm. Excellent photothermal stability is achieved by highly crosslinking SU‐8, a negative epoxy photoresist, raising its initial degradation temperature to ≈230 °C, much higher than the glass transition temperature of state‐of‐the‐art thermalplasts used in SERS substrates, including polyethylene terephthalate and poly(methyl methacrylate). The WTNC substrate can withstand very high laser irradiance of up to 300 kW cm−2, enabling superfast SERS imaging of analytes in extremely small quantities. A high resolution SERS image containing 10 201 spectra of ≈44 amol trans‐1,2‐bis(4‐pyridyl)ethylene is obtainable in <5 min. The WTNC substrate pushes the state‐of‐the‐art in polymer‐based SERS substrates and has great potential for rapid routine analyses.

Gold nanoplasmonic particles in tunable porous silicon 3D scaffolds for ultra-low concentration detection by SERS

“…The Enhancement Factor (EF) is an important criterion to evaluate quantitatively the performance of SERS substrates 34,35 . As discussed in the literature, there are several ways to determine the EF [58][59][60] . In this work, we adopted an approach that defines it as EF = I SERS /N SERS I RS /N RS 61 .…”

Toward Sensitive and Reliable Surface-Enhanced Raman Scattering Imaging: From Rational Design to Biomedical Applications

“…Better stability and biocompatibility of Au enable it to be the most widely used SERS-active material for in vivo application. 23 Except for the basic nanosphere and nanorod, considerable research has been dedicated to developing substrates with high performance of signal amplification, such as nanotube, 24 nanostar, 25 nanocage, 26 nanoflower, 27 nanomushroom, 28 nanocoral, 29 etc., as shown in Figure 1. These specially shaped structures form sharp points or spikes on the surface of the nanoparticles, generating additional hot spot regions and enhancing SERS signals with the local electromagnetic field.…”

Quantifying Optical Absorption of Single Plasmonic Nanoparticles and Nanoparticle Dimers Using Microstring Resonators

“…Note that for the rest of the paper, all the experimental heating ratios are obtained using this method. Next, a more complex plasmonic system is probed -an AuNS dimer, which is important for applications such as trace molecule detection using SERS 38,39 and photothermal plasmon-assisted cancer surgery. 9 A single AuNS dimer shown in Figure 3A (right) is probed using the same partially polarized nm HeNe laser in two orthogonally different polarizations -along and perpendicular to the dimer axis, and using four incident laser powers.…”