Raman skeleton key: Universal SERS substrate

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  • Published: Jul 1, 2015
  • Author: David Bradley
  • Channels: Raman
thumbnail image: Raman skeleton key: Universal SERS substrate

The universal

An ultrabroadband super-absorbing metasurface has been developed by researchers in China and the US. The system works as a universal SERS substrate for low cost and high performance sensing with much lower consumption of reagents as well as cutting overall measurement times for multiple experiments. Credit: University of Buffalo)

Commonly used substrates for surface-enhanced Raman spectroscopy (SERS) function only at specific excitation wavelengths; which means different substrates for different tasks consumes more biological/chemical materials, substrates, and measurement time. An ultrabroadband super-absorbing metasurface has been developed by researchers in China and the US. The system works as a universal SERS substrate for low cost and high performance sensing with much lower consumption of SERS substrates as well as cutting overall measurement times for multiple experiments.

For homeland security, drug detection, art authentication, food quality control and much more there is a sensor. But, no technology has attracted so much attention in recent years from a diverse range of analysts than surface-enhanced Raman spectroscopy (SERS). It is, of course, well known for its ability to identify a wide range of chemical and biological analytes, but commercial accessibility is often stymied by the need for expensive, consumable SERS substrates. An international research team led by scientists and engineers at the University at Buffalo, New York, USA, hopes to remedy that situation having devised a nanotechnology approach to SERS that simplifies its procedures and also cuts costs.

Random nano

Writing in the journal Advanced Materials Interfaces, the team describes a photonics advancement that introduces a universal SERS substrate. "The technology we're developing is a unique and, potentially, revolutionary feature," explains lead author Buffalo's Qiaoqiang Gan. "It allows us to rapidly identify and measure chemical and biological molecules using a broadband nanostructure that traps a wide range of light."

Working with Nan Zhang, Kai Liu, Haomin Song, Xie Zeng, Dengxin Ji and Alec Cheney as well as Suhua Jiang and Zhejun Liu of Fudan University in China, the Buffalo team has hit on a solution to the main problem with conventional SERS substrates: their being limited to a single, narrow, excitation band. This gives rise to the well-known issue of spectroscopists essentially requiring a different laser and different substrate for each type of test and analyte.

A universal SERS substrate would solve this problem because it could trap a wide range of wavelengths. The team's universal substrate comprises a thin film of silver or aluminium, which acts as a mirror, and a dielectric layer of silica or alumina. The dielectric material separates the mirror with tiny metal nanoparticles randomly spaced at the top of the substrate.

Raman skeleton key

"It acts [like] a skeleton key," says Nan Zhang. "Instead of needing all these different substrates to measure Raman signals excited by different wavelengths, you'll eventually need just one to open many doors." Kai Liu adds that, "The applications of such a device are far-reaching. The ability to detect even smaller amounts of chemical and biological molecules could be helpful with biosensors that are used to detect cancer, malaria, HIV and other illnesses." The same approach might also be used in identifying chemicals used in certain types of paint, for the detection of art fraud. It could also be applied to the detection of trace pollutants in the atmosphere, the water supply or other environments that give rise to causes for health concerns. It could even be used to detect explosives and chemical weapons.

"Our next step is to work with our industrial partner to pursue the commercialization potential," Gan told SpectroscopyNOW.

Related Links

Adv Mater Interfac 2015, online: "Ultrabroadband Metasurface for Efficient Light Trapping  and Localization: A Universal Surface-Enhanced Raman  Spectroscopy Substrate for “All” Excitation Wavelengths"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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