Innovative NFC-based flexible sensing system for wireless and battery-free detection of H2S: A game-changer in real-time fresh food freshness evaluation

Worldwide, approximately 1.3 billion tons of food are wasted yearly, with food spoilage accounting for up to one-third of the total. However, there is no effective way to monitor the freshness of fresh food. Here, a flexible, high-sensitive, wireless NFC-based sensor system for real-time assessment of fresh food freshness was developed by detecting H 2 S concentration changes (ppb-level) via a smartphone. A threshold adjustment theory (TAT) was proposed and optimized to relate NFC-tag sensor readability to H 2 S concentration, providing a practical solution for monitoring fresh food quality throughout the supply chain. The NFC-tag sensors were integrated into salmon packages and successfully used to monitor the freshness of salmon for five consecutive days at 0–5 °C. The salmon exhibited a response of 115.4 % by day 4 and was judged to be spoiled. This low-cost, miniature, wireless NFC-tag sensor is easy to integrate into food packaging and offers a promising solution for combating food spoilage and reducing wastage globally.