Investigating the Thermometric Performance of Inorganic Materials Doped with Nd<sup>3+</sup> under Infrared LED Excitation: An Alternative for Deep Tissue Luminescent Thermometry
André S. Laia,
Daniela A. Hora,
Marcos V. dos S. Rezende,
Maria A. Gomes,
Antônio C. Brandão-Silva,
Marcos A. C. dos Santos,
Noelio O. Dantas,
Anielle C. A. Silva,
José J. Rodrigues,
Mário E. G. Valerio,
Zélia S. Macedo,
Márcio A. R. C. Alencar
Affiliations
André S. Laia
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Daniela A. Hora
Grupo de Nanomateriais Funcionais (GNF), Departamento de Física, Universidade Federal de Sergipe, São Cristóvão 49100-000, SE, Brazil
Marcos V. dos S. Rezende
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Maria A. Gomes
Grupo de Nanomateriais Funcionais (GNF), Departamento de Física, Universidade Federal de Sergipe, São Cristóvão 49100-000, SE, Brazil
Antônio C. Brandão-Silva
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Marcos A. C. dos Santos
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Noelio O. Dantas
Laboratory of New Nanostructured and Functional Materials, Physics Institute, Federal University of Alagoas, Maceió 57072-900, AL, Brazil
Anielle C. A. Silva
Laboratory of New Nanostructured and Functional Materials, Physics Institute, Federal University of Alagoas, Maceió 57072-900, AL, Brazil
José J. Rodrigues
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Mário E. G. Valerio
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Zélia S. Macedo
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Márcio A. R. C. Alencar
Physics Department, Federal University of Sergipe (UFS), São Cristóvão 49100-000, SE, Brazil
Luminescent thermometers based on the luminescence intensity ratio between two thermally coupled levels have a strong appeal in the biomedical area due to the possibility of monitoring the temperature of deep tissues. In such procedures, it is necessary that the excitation and emission wavelengths are within the biological windows. Probes based on neodymium luminescence, with excitation and emission around 800 and 880 nm, are frequently proposed but have low relative sensitivity (0.2%.K−1) due to the small energy separation between the explored Stark sublevels. By changing the excitation wavelength to around 750 nm, it is possible to explore the thermal coupling between the 4F5/2 and 4F3/2 levels. However, lasers in this wavelength range are not common. An alternative is to use LEDs as an excitation source. As a proof of concept, we investigated the thermometric performance of three distinct Nd-doped luminescent probes under 730 nm LED excitation and 532 nm laser excitation: nanocrystalline Y2O3, LiBaPO4 microcrystals, and lithium-boron-aluminum (LBA) glass. The results indicated that the use of LEDs as an excitation source can be applied in nano-, micro- and macro-structured probes, as it does not compromise the thermometric performance of the systems, which exhibited relative sensitivities of approximately 2%.K−1.
