Optical Signals for Quantitative and Qualitative Monitoring of Temperature‐Sensitive Products

Abstract Monitoring the real‐time quality and validity of thermo‐sensitive foods during storage and transportation can be achieved with time‐temperature indicators (TTIs). However, the available TTIs still need to be improved in terms of accuracy, recoverability, environmental tolerance, and quantitative monitoring. Here, a novel TTI based on the optical signals originating from the as‐explored Sr 3 Y 2 Ge 3 O 12 : Mn 2+ , Er 3+ (SYGO: Mn 2+ , Er 3+ ) phosphor is developed. Thanks to the fact that the release of the captured carriers is tightly related to the storage time and ambient temperature, distinct optical signals of the as‐obtained TTI under multi‐stimulus (980 nm laser irradiation, thermal stimulation, and mechanical force) can be distinguished to judge the validity of temperature‐sensitive products. This work reveals the promising potential of SYGO: Mn 2+ , Er 3+ phosphors with cryogenic optical storage properties as advanced TTIs, especially for packaged products in cold chain logistics.