uThaw: Ultra-Wideband Wireless Solid–Liquid State Transition Sensor to Detect Thawing of Food

Abstract

This letter explores the potential use of ultra-wideband (UWB) wireless sensors in detecting the transition of food items from a frozen state to thawed state (or vice versa), marking a significant advancement in monitoring the thawing process. By exploiting the drastic change in complex permittivity at microwave frequencies (we use frequencies close to 4 GHz) during the solid–liquid state transition, this letter introduces a novel approach in ensuring frozen food safety and in enhancing the efficiency of the frozen food industry and cold chain transportation. The developed system, capable of operating through food packaging, offers a noninvasive, cost-effective solution for real-time monitoring, addressing the limitations of conventional temperature-based and timing-based methods widely used today in household and professional cooking and in the food industry. Our findings from the raw UWB channel impulse responses and computed similarity scores indeed show significant promise and validate the feasibility of the proposed system with various real-world applications.