Quite possibly, thanks to a collaboration of scientists from Fudan University in China and the University at Buffalo (UB), New York. This new low-cost chemical sensing chip is the kind of thing that police authorities have been wanting for years. Just like breathalyzers, this chip could be integrated into a portable device ready for drug testing via blood, breath, urine, or spit. The study was published just last week in the journal Small Methods.

The chip was originally designed to detect cocaine and can do so in a matter of minutes. But moving forward the team is hopeful it can be used for testing other drugs in the system such as marijuana or opioids. It can be produced using low-cost raw materials and low-cost fabrication techniques. All together it would cost around 10 cents to produce one of these chips, which is hardly anything.





The way the chip’s designed it’s able to trap light along the edges of silver and gold nanoparticles. Anytime a chemical or biological molecule lands on the surface of the chip some of the light is captured and dispersed into new energy light. This light acts as a sign that’s individual to every chemical. And by using special technology the researchers are able to reveal information about what compounds are present in each chemical. The name of this sensing method is surface-enhanced Raman spectroscopy (SERS).

“SERS holds a lot of promise for rapid detection of drugs and other chemicals, but the materials required to perform the sensing are usually quite expensive,” explains Nan Zhang, first author on the study and a Ph.D. candidate at UB. “The chips used for SERS are typically fabricated using expensive methods, such as lithography, which creates specific patterns on a metal substrate. We created our chip by depositing various thin layers of materials on a glass substrate, which is cost-effective and suitable for industrial-scale production.”





The new chip looks similar to that of a layer cake with layer stacked upon layer and is a structure known as a metasurface. It’s essentially a sheet of dielectric material that’s placed between a silver mirror and some form of hybrid material that’s made up of silver and gold nanoparticles. It’s a setup that works very well in conjunction with SERS as cocaine or other drug molecules falls into the gaps in between the chips nanoparticles. Then, upon exposure to light, the dielectric layer and the silver mirror work together manipulating the light in such as way that it increases the number of photons present on the surface of the chip.

Even after sitting a year in storage, this technology proved to work well. Part of the reason for its long shelf life is due to its surface design. The gold nanoparticles help in shielding the silver nanoparticles from the air. This prevents the chip from degrading, oxidizing, or tarnishing. “With our structure. we can realize both high performance and stable performance over time,” says Qiaoqiang Gan, Ph.D., a first author on the study, and an associate professor of electrical engineering in the UB School of Engineering and Applied Sciences.

Moving forward the team will look to integrate the chip into some form of a portable testing device. It would work by first extracting specific molecules such as cocaine or other drugs from blood, breath, urine, or spit through a purification process. Then any chemicals that were detected during this method would be transferred to the chip for further analysis.





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