• • The Rb2Ge4O9:0.002 Mn4+ fluorescent film achieves a relative sensitivity of 17.03% K−1 at 330 K in time-resolved thermometry, the highest within the physiological temperature range, enabling precise thermal monitoring in biomedical applications.
• • A practical temperature resolution of 0.08 K at 325 K is demonstrated, allowing detection of minute temperature variations critical for microelectronics thermal management.
• • The film encapsulated in PDMS exhibits enhanced chemical stability, addressing the degradation issue of bare phosphors in humid or reactive environments, thus extending operational lifetime.
• • Temperature imaging of a 20 μm nickel circuit under varying currents reveals clear microstructure and temperature gradients, validating the technique for high-resolution thermal mapping in integrated circuits.