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 Sr3Y2Ge3O12: Mn2+, Er3+ (SYGO: Mn2+, Er3+) 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: Mn2+, Er3+ phosphors with cryogenic optical storage properties as advanced TTIs, especially for packaged products in cold chain logistics.

Nonstoichiometry-Induced Self-Activated Phosphors for Dynamic Anti-counterfeiting Applications

“…Besides, the electron paramagnetic resonance (EPR) spectra for oxygen are recorded, as shown in Figure d. The EPR signal of oxygen vacancies ( g = 2.0020) of the Zn 2.2 GeO 4 sample is significantly enhanced in comparison to that of Zn 2 GeO 4 , further supporting that the increase of Zn 2+ induces the increased concentration of oxygen vacancies . Accordingly, the defect modulation mechanism based on the nonstoichiometry could be summarized as follows: The increase of the Zn 2+ ion content within the Zn 2 GeO 4 matrix modifies the local lattice coordination environment, leading to the creation of lattice defects.…”

The Development of a Cold-Chain-Packaging Risk Management Model Based on Fuzzy Bayesian Network

“…Temperature indicators utilize the inversible color change of physicochemical responses through microbial growth, solid state reactions, polymerizations, diffusion, etc. [22]. Gao et al (2020) developed a new temperature excursion indicating material based on the mixture of a phase-change material with photochromic spirogyra compounds that can change color once the temperature reaches 8 • C [21].…”