Editors: | F. Kongoli, A. G. Mamalis, K. Hokamoto |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2018 |
Pages: | 352 pages |
ISBN: | 978-1-987820-88-1 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
The physical entity that has an effect on even the tiniest elements of daily life and is involved in a broad spectrum of human activities is temperature. Accurate and reliable measurement of temperature with high spatial resolution of many special inaccessible objects is a challenging task. The conventional methods of temperature measurements are not companionable with the current nano/bio technologies, as they demand precise thermometry down to the nanoscale regime. Optical temperature sensing using nanomaterials is a promising method to achieve it. This is the only thermometry that works in non-contact mode and has high resolution and sensitivity. A range of versatile materials have been utilized to fabricate luminescence-based optical thermometers to achieve high sensitivity and wide working range. This review article focuses on the gradual advances in luminescence-based optical temperature sensors and highlights the wide range of materials used to fabricate them. The article covers the importance of temperature sensors and their applications, followed by the overview of various types of thermometry and their mode of operations with detailed description of optical thermometry, particularly luminescence based sensors. Later section deals with different detection modes for the analysis of the luminescent sensors. The subsequent section will discuss a number of materials and their structures used for fabrication of luminescence based temperature sensor; viz. (a) Metal Organic Frameworks, (b) Quantum Dots (QDs), (c) Rare Earth Doped Phosphors and (d) Nanocomposites. In all, the article compares different thermometers in the basis of mechanism, constituting materials, and their performance parameters. Among all the device parameters, sensitivity and temperature range are the most concerned issues. To the best of our knowledge, highly luminescent rare earth doped phosphors<sup>1</sup> could achieve the maximum sensitivity as 7% K<sup>-1</sup> and a temperature range of 20-500K. However, our group has reported a relative sensitivity of 8.4 K<sup>-1</sup> and the widest temperature range of 20-560K using CdS:SiO<sub>2</sub> nanocomposite<sup>2</sup>. Further improvement in these parameters by doping of Ag in CdS:SiO<sub>2</sub> nanocomposite system will be discussed in this article. The review features a comprehensive summary on challenges and new direction in designing luminescence based temperature sensor.