FlexBrite revolutionizes liquid composition analyzation

ECE ILLINOIS alumnus Zhida Xu (MS ’11, PhD ’14) and ECE Associate Professor Gang Logan Liu have introduced a revolutionary method of molecule detection that can easily answer what substances, and how much of each, are in a liquid.

Zhida Xu’s paper (Nanoscale, 2016,8, 6162-6172), co-written with Jing Jiang, Xinhao Wang, Kevin Han, Abid Ameen, Ibrahim Khan, Te-Wei Chang, and Associate Professor Gang Logan Liu, details the development of a substrate they named FlexBrite that, for the first time, combines naked-eye colorimetry and surface-enhanced Raman spectroscopy (SERS) on one sensor.

At first glance, FlexBrite is a thin, bendable, plastic-based wafer that shines purple in the light. At the nanoscale, however, it’s crisscrossed with tiny bumps. Xu calls these structures “nano-mushrooms,” which bend the light reflected off them and account for FlexBrite’s color-changing properties, allowing researchers to analyze liquids much more efficiently.

“We can use it for food safety detection and environmental detection,” Xu said. “And the good thing about this sensor is it’s the first time we displayed both qualitative and quantitative at a very low cost, because it can be detected by the naked eye without the need of very sophisticated equipment.” FlexBrite can be used to tell what’s in the liquid and how much of each substance there is, even down to trace amounts if a spectrometer is used.

Along with a handheld spectrometer, FlexBrite’s qualitative properties are done through a process called surface-enhanced Raman spectroscopy, an analytical technology which can detect the Raman spectrum of substance with super high sensitivity and speed. Generally speaking, it can detect trace amount of suspect substances within seconds.

FlexBrite’s quantitative properties refer to the color change the device makes when the concentration of the substance in liquid changes. The quantity of a substance in the liquid can be determined by the shift of the color through a process called colorimetry. The color change is so drastic that it can be seen by the naked eye and measured by a cell phone camera. Xu’s research team was able to use the technique to find trace amounts of the narcotic methamphetamine in samples of water.

For their unique discovery, the team had their research published in Nanoscale. Xu said that having his team’s work published represented a culmination of two years’ worth of laborious research. Because of how important this device can be to help determine water safety and oil quality, the research team hopes to see FlexBrite commercialized in the years to come.

“The research took a lot of effort before we were able to publish our findings,” Xu said. “We performed many experiments, designed the structure and also did theoretical studies by simulation. So the contents of this paper are very rich, and it meant a lot to have it recognized in this publication.”