Lab-on-a-chip light analysis opens the door to widespread use of portable spectrometers

Scientists, including a materials researcher from the University of Oregon, have developed a better tool for measuring light, contributing to a field known as optical spectrometry in a way that could improve everything from smartphone cameras to environmental monitoring.

The study, published today in Scienceled by Finland’s Aalto University and came up with a powerful, ultra-tiny spectrometer that fits on a microchip and operates using artificial intelligence.

The research involved a relatively new class of ultrathin materials known as two-dimensional semiconductors, and the result is a proof of concept for a spectrometer that could easily be integrated into a variety of technologies—including quality control platforms, security sensors, biomedical analyzers and space telescopes.

“We have demonstrated a way to make spectrometers that are much smaller than those commonly used today,” said Ethan Minot, professor of physics in OSU’s College of Science. “Spectrometers measure the power of light at different wavelengths and are extremely useful in many industries and in all areas of science for sample identification and material characterization.”

Traditional spectrometers require bulky optical and mechanical components, while the new device could fit on the tip of a human hair, Minot said. The new research suggests that these components can be replaced with new semiconductor materials and artificial intelligence, allowing spectrometers to be dramatically reduced in size from today’s smallest ones, which are about the size of a grape.

“Our spectrometer does not require the assembly of separate optical and mechanical components or array designs to scatter and filter light,” said Hun Han Yoon, who led the study with colleague Zhipei Sun Yoon at Aalto University. “In addition, it can achieve high resolution comparable to benchtop systems, but in a much smaller package.”

The device is 100% electrically controllable in terms of the colors of light it absorbs, which gives it enormous potential for scalability and broad usability, the researchers say.

“Integrating it directly into portable devices like smartphones and drones could improve our daily lives,” Yoon said. “Imagine if our next generation of smartphone cameras could be hyperspectral cameras.”

These hyperspectral cameras could capture and analyze information not only from visible wavelengths, but also enable infrared imaging and analysis.

“It’s exciting that our spectrometer opens up possibilities for all kinds of new everyday gadgets and instruments to do new science as well,” Minot said.

In medicine, for example, spectrometers are already being tested for their ability to detect subtle changes in human tissue, such as the difference between tumors and healthy tissue.

For environmental monitoring, Minot added, spectrometers can detect exactly what kind of pollution is in the air, water or soil, and how much of it there is.

“It would be nice to have low-cost, portable spectrometers that do this job for us,” he said. “And in the educational setting, hands-on teaching of science concepts would be more effective with inexpensive, compact spectrometers.”

Applications also abound for science-minded hobbyists, Minot said.

“If you’re into astronomy, you might be interested in measuring the spectrum of light you collect with your telescope and having that information identify a star or a planet,” he said. “If geology is your hobby, you could identify gemstones by measuring the spectrum of light they absorb.”

Minot believes that as work with 2D semiconductors progresses, “we will quickly discover new ways to use their new optical and electronic properties.” Research into 2D semiconductors has only been going on in earnest for twelve years, beginning with the study of graphene, carbon arranged in a honeycomb lattice one atom thick.

“It’s really exciting,” Minot said. “I think we will continue to have interesting discoveries studying 2D semiconductors.”

In addition to Minot, Yoon and Sun, the collaboration included scientists from Shanghai Jiao Tong University, Zhejiang University, Sichuan University, Yonsei University and the University of Cambridge, as well as other researchers from Aalto University.