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Quantum-limit-approaching chemical sensing SERS chip

21 January 2021 | News
by Ian Michael

A new study has improved a chemical sensing chip based on surface-enhanced Raman spectroscopy (SERS) that aims to identify drugs and other trace chemicals quickly and accurately.

University at Buffalo researchers have reported an advancement of a chemical sensing chip based on surface-enhanced Raman spectroscopy (SERS) that could lead to handheld devices that detect trace chemicals. The chip, which may have uses in food safety monitoring, anti-counterfeiting and other fields where trace chemicals are analysed, is described in a study that was published in Advanced Optical Materials.

“There is a great need for portable and cost-effective chemical sensors in many areas, especially drug abuse”, says the study’s lead author Qiaoqiang Gan, professor of electrical engineering in the UB School of Engineering and Applied Sciences. The work builds upon previous research Gan’s lab led that involved creating a chip that traps light at the edges of gold and silver nanoparticles. While effective, the earlier chip wasn’t uniform in its design. Because the gold and silver were spaced unevenly, it could make scattered molecules difficult to identify, especially if they appeared on different locations of the chip.

Gan and a team of researchers—featuring members of his lab at UB and researchers from the University of Shanghai for Science and Technology in China, and King Abdullah University of Science and Technology in Saudi Arabia—have been working to remedy this shortcoming. The team used four molecules (BZT, 4-MBA, BPT and TPT), each with different lengths, in the fabrication process to control the size of the gaps in between the gold and silver nanoparticles. The updated fabrication process is based upon two techniques, atomic layer deposition and self-assembled monolayers, as opposed to the more common and expensive method for SERS chips, electron-beam lithography.

The result is a SERS chip with unprecedented uniformity that is relatively inexpensive to produce. More importantly, it approaches quantum-limit sensing capabilities, says Gan, which was a challenge for conventional SERS chips

“We think the chip will have many uses in addition to handheld drug detection devices”, says the first author of this work, Nan Zhang, PhD, a postdoctoral researcher in Gan’s lab. “For example, it could be used to assess air and water pollution or the safety of food. It could be useful in the security and defence sectors, and it has tremendous potential in health care.”

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