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Researchers develop cheap chip that detects illicit drugs

A low-cost chemical sensing chip has been developed that sniffs out cocaine in minutes, offering a promising alternative to drug monitoring.

Researchers at the University at Buffalo School of Engineering and Applied Sciences have developed technology that they hope can be incorporated in a handheld, portable device for detecting all kinds of drugs in biological samples of blood, breath, urine or spit. The findings were published Monday in the journal Small Methods.

"Currently, there is a great demand for on-site drug testing," Dr. Qiaoqiang Gan, associate professor of electrical engineering in the University at Buffalo School of Engineering and Applied Sciences, said in a press release. "The high-performance chip we designed was able to detect cocaine within minutes in our experiments. It's also inexpensive: It can be produced using raw materials that cost around 10 cents, and the fabrication techniques we used are also low-cost."

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Current biological tests are slower and costlier, the researchers say, making their development a potentially important one.

"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," Buffalo Ph.d. candidate Nan Zhang said.

The new chip, a structure known as a metasurface, has horizontal layers of material sitting atop one another. A sheet of dielectric material, such as silicon dioxide or aluminum oxide, is sandwiched between a silver mirror at the base of the chip, with a hybrid nanomaterial made from gold and silver nanoparticles as the chip's active surface.

The method is called surface-enhanced Raman spectroscopy.

"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," Zhang said. "The chips used for SERS are typically fabricated using expensive methods, such as lithography, which creates specific patterns on a metal substrate."

The method traps light at the edges of gold and silver nanoparticles. Some of the captured light interacts with the molecules when they land on the chip's surface and they are "scattered" into light of new energies. This displays what chemicals are presents much like how recognizable patterns are revealed in fingerprints, the researchers said.

The researchers said the chip can last after a year in storage because gold nanoparticles, which are deposited last, help to shield the silver nanoparticles from the air and then oxidization, degradation and tarnishing.

"In the future, we are hoping to also use this technology to detect other drugs, including marijuana," Gan said. "The widening legalization of marijuana raises a lot of societal issues, including the need for a system to quickly test drivers for drug use."
By Allen Cone

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