Angle-based fluorescence thermometry with high sensitivity and high resolution

Fluorescence-based thermometry offers non-contact, high-resolution temperature sensing, yet current methods face challenges in simultaneously achieving high sensitivity, stability and insensitivity to non-thermal perturbations. Here, a sensing paradigm is introduced that translates temperature variations into detectable shifts in the fluorescence emission angle via grating-modulated fluorescence emission. In a prototype device featuring a gold grating coupled with [Ru(phen)₃]Cl₂ fluorophores, an absolute sensitivity of 0.58 °/°C and a relative sensitivity of 81.34 %/°C at 79.36 °C are achieved, with a temperature resolution down to 0.01 °C. Unlike intensity-based methods, this angle-resolved strategy effectively isolates the thermal signal from excitation power fluctuations and environmental interferences and demonstrates robustness across broad humidity ranges (10-89% RH). Sustained operational stability is validated over 12-hour battery cycling, while real-time monitoring of a smartphone CPU enables early-warning capabilities against overheating. This promising and customizable approach establishes a pathway for thermal management in advanced engineering systems.