Mapping Elevated Temperatures with a Micrometer Resolution Using the Luminescence of Chemically Stable Upconversion Nanoparticles

Abstract

The temperature-sensitive luminescence of nanoparticles enables their application as remote thermometers. The size of these nanothermometers makes them ideal to map temperatures with a high spatial resolution. However, high spatial resolution mapping of temperatures >373 K has remained challenging. Here, we realize nanothermometry with high spatial resolutions at elevated temperatures using chemically stable upconversion nanoparticles and confocal microscopy. We test this method on a microelectromechanical heater and study the temperature homogeneity. Our experiments reveal distortions in the luminescence spectra that are intrinsic to high-resolution measurements of samples with nanoscale photonic inhomogeneities. In particular, the spectra are affected by the high-power excitation as well as by scattering and reflection of the emitted light. The latter effect has an increasing impact at elevated temperatures. We present a procedure to correct these distortions. As a result, we extend the range of high-resolution nanothermometry beyond 500 K with a precision of 1–4 K. This work will improve the accuracy of nanothermometry not only in micro- and nanoelectronics but also in other fields with photonically inhomogeneous substrates.

Sustainable Smart Tags with Two‐Step Verification for Anticounterfeiting Triggered by the Photothermal Response of Upconverting Nanoparticles

“…Moreover, the 2 H 9/2 → 4 I 13/2 originated in the upper energy emitting level of Er 3+ is observed as a shoulder around 555 nm, consistent with recent reports in the literature. [ 48,49 ]…”

“…4 I 13/2 originated in the upper energy emitting level of Er 3þ is observed as a shoulder around 555 nm, consistent with recent reports in the literature. [48,49] To record the temperature using the photon upconversion of the obtained QR codes, the ratio between the integrated intensities of the 2 H 11/2 ! 4 I 15/2 (I H ) and 4 S 3/2 !…”

One ion to catch them all: Targeted high-precision Boltzmann thermometry over a wide temperature range with Gd3+

“…Luminescence (nano)thermometry has been demonstrated to be both a precise and accurate technique for probing fundamental thermodynamic phenomena at the micro- and nanoscale 27 – 29 and helps to assess the local temperature fluctuations in tissue 30 – 35 or in chemical reactors 36 – 40 . Currently, there has been observable progress on how to implement and standardize this technique for applications 41 – 45 , the connected limitations 46 , 47 , or how to couple temperature sensing with other functionalities such as single-molecule magnetism 48 , 49 and (meso-)porous materials 50 , 51 , e.g., theranostics 52 .…”

Self‐Referenced Temperature Imaging with Dual Light Emitting Diode Excitation and Single‐Band Emission of AVO4:Eu3+ (A=Y, La, Lu, Gd) Nanophosphors

“…Statistics in a uniform temperature region (5 mm by 1 mm) indicate a single pixel standard deviation of 1.5 °C for a spatial resolution of 160 μm, as determined from an image of a 1951 United States Air Force (USAF) resolution target with the same processing applied. Here the imaging system had a low magnification (0.3) as the emphasis was placed on measuring a wide temperature field to visualize the flame heating rather than achieving resolution in the submicrometer range as in impressive thermal imaging studies using scanning thermal microscopy, [ 38 ] confocal microscopy, [ 3 ] or a fiber scanning system. [ 39 ] Such a resolution yields 2D maps of 340 × 260 independent temperature measurements per image over a 34 mm by 26 mm region.…”

“…Often, remote temperature readout is the only way to provide temperature information with sufficient spatial and temporal resolution and without disturbing the system. Examples include imaging temperature in vivo or in vitro, [1] observing thermal mixing processes in fluids, [2] and monitoring the temperature of microelectronic components [3,4] or that of rotating parts, as in electric motors [5] or gas turbines. [6] Thermal imaging in the infrared range is a wellestablish remote sensing method but it relies on knowledge of object emissivity, which requires prior characterization and which may change, e.g., during thermal treatment.…”