microscope slide

The glass microscope slide coating is made of gold and acrylic glass.

Coated Microscope Slides Able to Measure Temperatures

Published July 20, 2018

A study co-led by Ruogang Zhao, PhD, assistant professor of biomedical engineering, details a new technique that allows glass microscope slides to measure the temperature of mounted specimens.

Potential to Streamline Scientific Research

The advancement, made possible by a new transparent coating at the forefront of optics theory, has the potential to streamline and enhance scientific research worldwide, from clandestine government biology laboratories to high school chemistry classes.

It may also have implications in other industries — such as computers and electronics — whose products require measurement and control of heat in highly confined spaces.

“We have instruments that magnify incredibly small objects. And we have tools that measure heat, like infrared thermometers. But we haven’t been able to combine them in a low-cost and reliable manner. This new coating takes a big step in that direction,” says Zhao, the study’s co-lead author.

The biomedical engineering department is a multidisciplinary unit formed by the Jacobs School of Medicine and Biomedical Sciences and UB’s School of Engineering and Applied Sciences.

Zhao collaborated with researchers at the University of Pennsylvania, including co-lead author Liang Feng, PhD.

Coating Allows ‘Exceptional Points’ to Develop

For decades, researchers have tried to combine thermal imaging and microscopy. Images produced from systems that use thermocouples lack resolution and are often too coarse for modern science. Terahertz and infrared thermal mapping techniques interfere with the microscope’s lenses. Other techniques are expensive and time-consuming.

The new coating is made of a layer of acrylic glass (the same material used in most eyeglasses) that’s sandwiched between two layers of transparent gold. The gold is transparent because it’s only 20 nanometers thick; a typical sheet of paper is 100,000 nanometers thick.

Engineers fabricated the coating so that “exceptional points” — the sweet spots where unusual light behavior happens — can develop within the tri-layered structure.

illustration of glass slide

The illustration depicts the three-layered coating, in which acrylic glass is sandwiched between extremely thin layers of gold.

Seamless Integration With Most Microscopes

The coating, which significantly enhances the slide’s sensitivity to light detection, would be added to slides during the manufacturing process. Either the slide or cover slip could receive the coating.

To make use of the new coating, a laser is needed. Zhao says a common helium-neon laser, which can be seamlessly integrated with most microscopes, will do the job.

Common slides, which are often bought in bulk, typically cost around 5 cents apiece. The new coating would likely add a few pennies to the cost, Zhao says.

Study Published in Nature Communications

The study, “Exceptional Point Engineered Glass Slide for Microscopic Thermal Mapping,” was published May 2 in the journal Nature Communications.

Zhaowei Chen, a doctoral candidate in biomedical engineering, is a co-author from the Jacobs School.

Han Zhao, of the University of Pennsylvania, is a co-author.

The research is supported by funding from the National Science Foundation and the National Institutes of Health.