Fluorescence-Based Thermometry:Principles and Applications

The temperature-sensitive nature of molecular fluoresence provides the basis for designing optical detection systems whereby changes in fluorescent intensity, peak position, or other spectral attributes can provide a local measurement of temperature. This review details the underlying photophysics responsible for the effects of temperature, compares their relative utilities for temperature sensing, and provides an overview of the instrumentational requirements for performing multi-dimensional temperature sensing. The requisite integration of chemistry and optics for this application helps define the desired properties for the fluorescent probe. In particular, bichromophoric fluorophores offer notable advantages by providing an internal reference for fluorometric temperature sensing. The review focuses its description on the operation and properties of this class of fluorescent compounds and summarizes the reported probes and their operating ranges. A model one-dimensional system for measuring spatial and temporal changes in temperatures using a bipyrenyl fluorophore is presented as demonstration of the ability to perform remote detection using a bichromophoric fluorescent probe. The selection of light source and detector are highlighted as are specific designs employing lasers and CCD cameras for expanding the ability of fluorometric sensing to produce three-dimensional profiles of temperature.