The technology (depicted above) consists of a thin film of silver or aluminum that acts as a mirror and a dielectric layer of silica or alumina. The dielectric separates the mirror with tiny metal nanoparticles randomly spaced at the top of the substrate. Credit: Qiaoqiang Gan.
SERS is a sensing technique with the ability to identify chemical and biological molecules in a wide range of fields. However, the current technology relies on a substrate that is consumed during the SERS workflow. This substrate is often a thin film of aluminum, silver, or gold deposited onto a silicon wafer. Unfortunately, this substrate is expensive and complicated to fabricate. Talk about inefficient.
As a laser forces chemical and biological molecules to interact, molecules begin to vibrate and produce inelastic or Raman scatterings of light. These photons, which make up the scattered light, have a different frequency from the laser. These frequencies are weak and difficult to read without a powerful laser.
SERS addresses these problems by utilizing a nanopatterned substrate that enhances the light field at the surface and intensifies Raman scattering. Unfortunately, traditional substrates are typically designed for only a very narrow range of wavelengths.
This is problematic because different substrates are needed if scientists want to use a different laser to test the same molecules. In turn, this requires more chemical molecules and substrates, increasing costs and testing time.
Universal Substrates and Nanotechnology
Described in a recent research paper in Advanced Materials Interfaces, the universal substrate “is a unique and, potentially, a revolutionary feature,” says Qiaoqiang Gan, University at Buffalo (UB) assistant professor of electrical engineering and the study's lead author.
The universal substrate traps a wide range of wavelengths with a thin film of silver or aluminum and a dielectric layer of silica or alumina. Squeezing the wavelengths into small gaps to create an enhanced light field, the dielectric separates the mirror with tiny metal nanoparticles randomly spaced at the top of the substrate.
"It acts similar to a skeleton key,” says Nan Zhang, UB PhD candidate in electrical engineering and co-author of the study. “Instead of needing all these different substrates to measure Raman signals excited by different wavelengths, you'll eventually need just one.”
Not only does it open doors, but the universal substrate can help detect smaller amounts of chemical and biological molecules than previously possible, at even faster rates.
Next-generation SERS technology is able to detect trace amounts of molecules in the air, in water and on surfaces. This ability could revolutionize various technologies from the smoke detectors in our homes, to community water purification systems, to new military defense technologies.
To learn more, visit buffalo.edu.