Not many people would realize that cutting tiny disks into gold film would be the key to enhancing sensor detection, but Wei-Chuan Shih, assistant professor of electrical and computer engineering, did and now has this cutting-edge research published in Nanoscale, a nanoscience and nanotechnology peer-reviewed journal.
Shih’s lab has developed a material that will help scientists improve their standard Surface-enhanced Raman spectroscopy, a method of detection that uses a laser to refract different wavelengths of light off of certain functional groups of molecules, allowing the molecule to be identified by scientists.
This material — disks made of nanoporous gold film — has not only improved accuracy, but has also allowed Shih’s group to use as few as 1,000 molecules to detect said substance.
“Our contribution (to this study) is that we discovered (that) by patterning them into disks of this size, we can further the enhancement effect,” Shih said.
“We have to accurately estimate the total number of molecules that we are measuring, because for SERS, (our) EF — which stands for enhancement factor — is like the holy grail.”
The enhancement factor for standard SERS is 1 million, a UH press release said. His team has managed to achieve 100 million, displaying the relatively superior sensing capabilities. This increased sensitivity is because of an increase in surface area, Shih said.
“The molecule has to be on the surface (of the gold) in order to get plasmonically enhanced. If you have a flat surface, then maybe the first monolayer of molecules can be detected with SERS, but that decreases dramatically as you go away from the surface. Therefore, you have a larger surface area (and) a big advantage,” Shih said.
“As long as you get the thing you want to detect really close to the surface, the chances are that you will be able to detect it.”
The next step for Shih will be trying to detect and identify DNA molecules with his new surface material. He is doing interdepartmental research with Richard Willson, professor of chemical and biomolecular engineering.
“I’m working with Richard Willson in molecular engineering,” Shih said.
“We are attaching DNA onto it and trying to detect very low concentrations.”
