Spotlight on Luminescence Thermometry: Basics, Challenges, and Cutting‐Edge Applications

Abstract

Luminescence (nano)thermometry is a remote sensing technique that relies on the temperature dependency of the luminescence features (e.g., bandshape, peak energy or intensity, and excited state lifetimes and risetimes) of a phosphor to measure temperature. This technique provides precise thermal readouts with superior spatial resolution in short acquisition times. Although luminescence thermometry is just starting to become a more mature subject, it exhibits enormous potential in several areas, e.g., optoelectronics, photonics, micro‐ and nanofluidics, and nanomedicine. This work reviews the latest trends in the field, including the establishment of a comprehensive theoretical background and standardized practices. The reliability, repeatability, and reproducibility of the technique are also discussed, along with the use of multiparametric analysis and artificial‐intelligence algorithms to enhance thermal readouts. In addition, examples are provided to underscore the challenges that luminescence thermometry faces, alongside the need for a continuous search and design of new materials, experimental techniques, and analysis procedures to improve the competitiveness, accessibility, and popularity of the technology

Toward Magneto‐Optical Cryogenic Thermometers with High Sensitivity: A Magnetic Circular Dichroism Based Thermometric Approach

“…This observation indicates the unsuitability of the presented approach for precise temperature sensing at higher magnetic fields. With that said, the possibility of implementing nine different thermometric parameters for the Ho III complex allows us to overcome the low sensitivity and high uncertainty under higher applied magnetic fields while enhancing the accuracy of the temperature read‐out [59] . As such, we can adopt the multiparametric thermal read‐out method in conjunction with a multiple regression approach, a novel technique introduced in recent work by Carlos and co‐workers [60] .…”

“…With that said, the possibility of implementing nine different thermometric parameters for the Ho III complex allows us to overcome the low sensitivity and high uncertainty under higher applied magnetic fields while enhancing the accuracy of the temperature readout. [59] As such, we can adopt the multiparametric thermal read-out method in conjunction with a multiple regression approach, a novel technique introduced in recent work by Carlos and co-workers. [60] In this approach, a multiple (linear or non-linear) regression can be applied to the different thermometric parameters, providing a self-calibrated readout, and increasing the precision of temperature measurement.…”

Luminescence Thermometry Beyond the Biological Realm

“…One potential source of artifacts is the optical instrumentation used to perform the luminescence measurements, such as spectral distortions caused by high numerical aperture objective lenses or noise from the CCD sensor used to record spectra. , The resulting temperature errors reported in these cases ranged from less than one degree up to tens of degrees. Optical misalignment can also introduce artifacts.…”

“…This review complements several other recent reviews on luminescence thermometry, some of which specifically focus on biological applications − and some of which also cover a subset of nonbiological applications. − ,− While a number of existing reviews provide excellent summaries of the different luminescent probes and signals that can be exploited for thermometry, here we largely focus on the applications enabled by these techniques. We also omit coverage of thermographic phosphors used primarily for combustion and industrial manufacturing applications, which are typically applied as paints or thin film coatings and have been reviewed elsewhere, , and focus on luminescent nanomaterial-based thermometry.…”

“…Finally, we discuss emerging areas such as the identification and mitigation of artifacts that can distort luminescence thermometry signals and the resulting temperature measurements, the application of advanced data analysis and machine learning (ML) methods to luminescence thermometry, and particle-to-particle uniformity of luminescence thermometry signals and the use of batch calibration procedures. Several of the emerging areas we cover were also highlighted in a very recent comprehensive review, 4 underscoring the growing importance of these topics within the luminescence thermometry community. We end by summarizing the current status of the field and offer a perspective on future research directions.…”