Real‐Time Thermal Imaging based on the Simultaneous Rise and Decay Luminescence Lifetime Thermometry

Abstract

The most reliable technique of remote temperature sensing considers either the rise or the decay transient of a luminescent temperature probe. Here, real‐time visible (Vis) and near‐infrared (NIR) thermal imagings based on the simultaneous measurement of the emission rise and decay of transition or lanthanide metal activator are described. A single pulse time‐gated detection method that allows the real‐time mode of the temperature measurement, the emission detection at its highest temporal intensity, and the tunability of the emission detection in terms of time delay and gate width is proposed. Cr‐ZnGaGeO4/ZnGa2O4; Er, Ho, Yb–Y2O3 and Er, Ho, Yb–β‐NaYF4 nanoparticles that display luminescence in the Vis to NIR range (450–1200 nm) with timescales varying from 10 to 100 ms are selected. Maximum relative temperature sensitivity in Vis to Vis and NIR to NIR imaging which exceeds up to a factor of two the values obtained by the standard average lifetime method is achieved. This method applies to any lifetime‐based luminescent thermometer, opening a new avenue in designing accurate and straightforward lifetime thermal imaging systems operating in the Vis to NIR range.

Luminescence Thermometry Beyond the Biological Realm

“…Luminescence lifetime thermometry measurements are one of the more common time-resolved techniques, given the signal's robustness to variations in parameters such as particle size, morphology, and emitter concentration. 163 The lifetimes of most emitters decrease with increasing temperature due to the higher probability of phonon-assisted, nonradiative decay processes at elevated temperatures. Lifetime measurements typically involve a pulsed excitation laser and a time-gated photon monitor such as a camera or a photodetector.…”

“…As a result, studies pertaining to heat dissipation in microelectronics and other nanoscale heating applications can greatly benefit from sensitive thermometry techniques with high spatial and temporal resolution. Luminescence lifetime thermometry measurements are one of the more common time-resolved techniques, given the signal’s robustness to variations in parameters such as particle size, morphology, and emitter concentration . The lifetimes of most emitters decrease with increasing temperature due to the higher probability of phonon-assisted, nonradiative decay processes at elevated temperatures.…”

“…(a) Major components for a time-resolved luminescence thermometry measurement. Reprinted with permission under a Creative Commons CC BY 4.0 license from ref Copyright 2021 John Wiley and Sons. (b) Schematic of a single-particle luminescence thermometry measurement utilizing a spectrometer to record luminescence spectra.…”

“…163,169 Because the transitions that give rise to UCNP luminescence are parity forbidden, UCNPs have long lifetimes on the order of hundreds of μs to ms, limiting the temporal resolution of UCNP-based lifetime thermometry. Luminescence lifetime thermometry using Mn 3+ and Mn 4+ codoped 170 and Cr 3+ -doped 163 nanoparticles with lifetimes on the order of ms and tens of ms, respectively, has also been reported. Other emitters intrinsically have much faster lifetimes, enabling higher temporal resolution measurements.…”

“…Lifetime thermometry has been demonstrated using a number of UCNP compositions, including NaYF 4 :Yb 3+ ,Er 3+ , ,− other Yb 3+ and Er 3+ codoped hosts, ,, and compositions involving other dopants such as Tm 3+ and Ho 3+ . , Because the transitions that give rise to UCNP luminescence are parity forbidden, UCNPs have long lifetimes on the order of hundreds of μs to ms, limiting the temporal resolution of UCNP-based lifetime thermometry. Luminescence lifetime thermometry using Mn 3+ and Mn 4+ codoped and Cr 3+ -doped nanoparticles with lifetimes on the order of ms and tens of ms, respectively, has also been reported. Other emitters intrinsically have much faster lifetimes, enabling higher temporal resolution measurements.…”