New light-trapping sensor promises improved drug, bomb detection
The new device uses infrared absorption spectroscopy – an approach that looks at how light interacts with trace amounts of matter. While not a new technology, attempts are still underway to make it more sensitive, inexpensive, and versatile to make it feasible for more applications.
The UB researchers claim to have made progress on all three fronts with their sensor. “This new optical device has the potential to improve our abilities to detect all sorts of biological and chemical samples,” says Qiaoqiang Gan, PhD, associate professor of electrical engineering in the School of Engineering and Applied Sciences at UB, and the lead author of a paper on the study.
Using the non-visible light spectrum used in most remote controls, night-vision, and other applications, the device itself comprises two layers of metal with an insulator sandwiched in between. Gaps in the metal layers, measuring less than five nanometers, enable the sensor to absorb up to 81% of infrared light, while similar devices absorb only 3%, say the researchers.
The device acts as a substrate, or surface, for the materials being examined, in a process called surface-enhanced infrared absorption (SEIRA) spectroscopy, where infrared light trapped by the gaps in the metal surface can be used to detect trace amounts of matter. According to the researchers, their sensor boosts the sensitivity of such devices to detect molecules at 100 to 1,000 times greater resolution than previously reported results.
This advancement could be useful in any scenario that calls for finding traces of molecules, says Dengxin Ji, the first author of the paper and a PhD candidate in Gan’s lab. Potential applications include – but are not limited to – drug detection in blood, bomb-making materials, fraudulent art, and tracking diseases, he says.
Researchers next plan to continue the research and examine how to combine their SEIRA advancement with cutting-edge surface-enhanced Raman spectroscopy (SERS), an approach that measures light scattering as opposed to absorption. For more, see “Efficient Mid-Infrared Light Confinement within Sub-5-nm Gaps for Extreme Field Enhancement.”
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