Central OC Times

University of California, Irvine scientists have developed a one-dimensional nanoscale material capable of changing color with temperature variations. The findings were published in Advanced Materials.

"We found that we can make really small and sensitive thermometers," said Maxx Arguilla, UC Irvine professor of chemistry whose research group led the study. "It's one of the most applied and translatable works to come out of our lab."

Arguilla compared these thermometers to "nano-scale mood rings," which change color based on body temperature. He noted that unlike mood rings, the color changes in these materials "can be calibrated and used to optically take temperature readings at the nanoscale."

"The need to measure temperature is important because a lot of biological and industrial processes depend on tracking minute changes in temperature," Arguilla added. "We may now have thermometers that we could try poking into cells."

Dmitri Cordova, a postdoctoral scholar in Arguilla’s group, stated that these optical thermometers could potentially measure temperatures and assess efficiencies in micro- and nano-electronics, including circuits and data storage devices. While industries currently use optical thermometers for fabricating computer components, the new material is “at least an order of magnitude more sensitive,” according to Cordova.

The breakthrough occurred when Cordova and colleagues grew crystals resembling helical “slinkies” at nanometer scales. Initially grown to test heat stress disintegration points, they noticed systematic color shifts from yellow to orange depending on the temperature.

Precise measurements showed light yellow colors corresponded to temperatures around -190 degrees Celsius, while red-orange colors matched approximately 200 degrees Celsius.

"We spent a lot of effort trying to make sure the measurements were precise," Arguilla said.

To retrieve nanoscale samples, the team used adhesive tape on bulk-scale crystals and transferred them onto transparent substrates.

“We can peel off these structures, and we can use them as nanoscale thermometers that can be transferred, reconfigured and coupled with other materials or surfaces,” explained Arguilla.

This discovery marks an initial step towards finding new materials for taking temperature readings at nanometer scales. Future plans include testing other nanoscale materials for broader temperature range measurements.

“We’re now trying to hack the materials design rules to make even more sensitive materials,” Arguilla stated. “We’re trying to open the toolbox for optical thermometry from the bulk scale down to the nanoscale.”

Co-authors include Yinong Zhou, Griffin M. Milligan, Leo Cheng, Tyler Kerr, Joseph Ziller, and Ruqian Wu. Funding was provided by the National Science Foundation through UC Irvine MRSEC's Center for Complex and Active Materials (Award No. DMR-2011967).

UC Irvine’s Brilliant Future campaign aims to raise awareness and support for university initiatives by engaging alumni and securing philanthropic investments totaling $2 billion.

Founded in 1965, UC Irvine is ranked among the nation’s top 10 public universities by U.S. News & World Report. It has produced five Nobel laureates and offers 224 degree programs with over 36,000 students enrolled.

For more information about UC Irvine or its latest news updates visit www.uci.edu or news.uci.edu.

###