Microscopes as Thermometers

A microscope system with the devised thermosensitive glass slide. While the white light source is for conventional microscopic imaging, the He-Ne laser is used as the incidence for thermal mapping. (Source: U. Buffalo)

A new kind of a micro­scope now enables scientists to see tiny objects while also measuring their tempera­ture. 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 labs 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 Ruogang Zhao, assis­tant professor in the Univer­sity at Buffalo depart­ment of biome­dical engi­neering. Zhao collaborated with researchers at the Uni­versity of Pennsyl­vania, Liang Feng, assistant professor of materials science and engi­neering, and electrical and systems engi­neering.

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 that’s sandwiched between two layers of trans­parent gold. The gold is trans­parent because it’s only 20 nm thick.

Engineers fabri­cated the coating so that excep­tional points can develop within the trilayered structure. 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. The new coating would likely add a few pennies to the cost, Zhao says. (Source: U. Buffalo)

Reference: H. Zhao et al.: Exceptional point engineered glass slide for microscopic thermal mapping, Nat. Commun. 9, 1764 (2018); DOI: 10.1038/s41467-018-04251-3

Link: Dept. of Biomedical Engineering, The State University of New York at Buffalo, Buffalo, USA

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