Disposable gold coated pyramidal SERS sensor on the plastic platform

Abstract

In this paper we investigate suitability of arrays of gold coated pyramids for surface-enhanced Raman scattering (SERS) sensing applications. Pyramidarrays composed of 1000 nm pit size with 1250 nm pitch lengthwerereplicated on a plastic substrate by roll-to-roll (R2R) ultraviolet (UV) embossing. The level of SERS enhancement, and qualitative performance provided by the new substrate is investigated by comparing Raman spectrum of benzenethiol (BTh) test molecules to the benchmark Klarite SERS substrate which comprises inverted pyramid arrays(1500 nm pit size with 2000 nm pitch length) fabricated on a silicon substrate. The new substrate is found to provide upto 11 times increase in signal in comparison to the inverted pyramid (IV-pyramid) arrays fabricated on an identical plastic substrate. Numerical simulation and experimental evidence suggest that strongly confined electromagnetic fields close to the base of the pyramids, are mainly responsible for the Raman enhancement factor, instead of the fields localized around the tip. Unusually strong plasmon fields are projected upto 200nm from the sidewalls at the base of the pyramid increasing the cross sectional sensing volume.

Self-Assembled Plasmonic Pyramids from Anisotropic Nanoparticles for High-Efficient SERS

“…2d-i, we can identify two main trends as the measuring position shifts from the pyramid tip towards the bottom base: (1) the scattering spectra exhibited a spectral blue shift as the position moves away from the peak. This phenomenon is similar to those obtained via simulation studies reported for pyramidal pits, in which strong coupling and strong field maximum at the pyramid tips are attributed to the lightning rod effect [29,[42][43][44]. (2) The scattering intensity is at its maximum when measuring position is located in the middle of each pyramid-*30 and *40 to 50% distance to the top along the edges and sides of the pyramid, respectively.…”

“…The relative standard deviation of Raman intensities for 1074 cm -1 peak from tip-to-tip was calculated to be 1.6, 2.6 and 3.4% for RD-, OH-and NS-based pyramidal substrates, respectively. These values are much lower than those reported for gold pyramidal arrays (22%) [44], Klarite (10%) [21], silver pyramidal arrays (9%) [43] and gold nanopillar films (7%) [52], confirming the good reproducibility of our self-assembled pyramid film substrates. Fig.…”

“…This can be explained by the fact that the plasmon resonance of the RD-pyramid (*680 nm) matches more closely with the excitation wavelength of 785 nm, resulting in additional resonance effect that provides significant local electromagnetic field confinement on the plasmonic nanostructure [2,50]. Notably, our pyramids demonstrated better or comparable SERS performance to those reported for gold-coated polymer and silicon pyramid (*10 4 to 10 6 ) [29,44], Ag-deposited pyramids (*10 7 ) [43], triangular multi-layered superstructure assemblies (*10 7 ) [34] and commercially available Klarite (*10 6 ) [20,51]. In addition to superior signal enhancement, signal reproducibility is also an important factor which determines the efficacy of a SERS substrate.…”

Fabrication of gold-coated PDMS surfaces with arrayed triangular micro/nanopyramids for use as SERS substrates

“…The micro/nanostructures of a blue butterfly wing were used as a template, and a SERS substrate was produced and utilized to detect rhodamine dye for the elimination of organic pollutants [ 19 ]. Additionally, pyramidal array structures on conventional Klarite substrates [ 22 ] were fabricated as specifically engineered structures with an apex angle of 70.5° that can also be used as a template. The SERS substrate can then be achieved via a ultraviolet (UV) embossing process by transferring these structures to a plastic substrate.…”

Fabrication of copper substrates for surface-enhanced Raman scattering using the microscratching method

“…Nowadays, active substrates of surface-enhanced Raman scattering (SERS) have attracted considerable attentions due to the ability of detecting molecules and inspecting the interaction between molecules and metal surfaces. [1][2][3] Some chemical methods, [4][5][6] including chemical/electrochemical deposition, 4 electrochemical etching, 5 and hydrothermal process 6 are often employed to fabricate SERS substrates. However, the uniform distribution of materials at different positions on the generated SERS-active substrate is difficult to be controlled and localized, and the ''hot spots'' for SERS enhancements cannot be easily reproduced.…”