Prior to the coronavirus spreading around the world, Jing Wang and his colleagues were researching sensors that could detect bacteria and viruses in the air. The concept of the sensor would not replace the established laboratory tests but could be used as an alternative method for a clinical diagnosis to measure virus concentration in air in real-time. The sensor could be used in busy places like train stations and hospitals.
The sensor features optical and thermal effects to detect the virus safely and reliably. It’s based on tiny structures of gold nanoislands on a glass substrate and DNA receptors that match specific RNA sequences of SARS-CoV-2 are grafted onto the nanoislands. The receptors on the sensor are complementary sequences to the coronavirus’s unique RNA sequences to help reliably identify the virus.
Wang and the researchers used localized surface plasmon resonance to detect the virus. The technology utilizes an optical phenomenon that happens in metallic nanostructures. They modulate incident light in specific wavelength ranges to create a plasmonic near-field around the nanostructure. Once molecules bind to the surface, the local refractive index in the plasmonic near-field changes.
The sensor’s plasmonic photothermal effect produces localized heat when the nanostructure on the sensor is excited with a laser of a certain wavelength.
To test the device, the researchers used the SARS-CoV virus, which broke out in 2003 and triggered the SARS outbreak, because the RNA on the two viruses differ only slightly, according to the researchers.
“Tests showed that the sensor can clearly distinguish between the very similar RNA sequences of the two viruses,” Wang said in a news release.
The researchers plan to develop the sensor further to measure the coronavirus concentration in air in places like Zurich’s main railway station. So far, the researchers plan to develop a system that draws in the air, concentrates the aerosols in it and releases the RNA from the viruses.
“This still needs development work,” Wang said.