A team of researchers has developed a flexible, inkjet-printed loop antenna sensor that provides real-time, non-invasive assessments of meat freshness, marking a significant breakthrough in food safety.
Study: A High-Sensitivity Inkjet-Printed Flexible Resonator for Monitoring Dielectric Changes in Meat. Image Credit: Microgen/Shutterstock.com
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Published in the journal Sensors, the study highlights how this innovative sensor detects changes in dielectric properties over time, offering a reliable alternative to traditional methods that often rely on subjective judgment and are prone to human error. As consumer demand for safer, high-quality food continues to grow, this advancement aligns with modern needs for efficiency and accuracy in food quality management.
Ensuring food safety throughout the meat supply chain is crucial, as spoilage can lead to significant health risks. This study highlights dielectric properties—specifically permittivity—as reliable indicators of freshness and spoilage in perishable foods.
As meat deteriorates, its chemical composition changes, leading to measurable shifts in its dielectric properties. Advanced sensor technologies can detect these variations, improving food safety protocols. Existing monitoring systems are often costly and rely on rigid substrates, limiting their practicality. The introduction of a flexible sensor addresses these challenges, making integration into smart packaging and wearable systems a viable option for real-time food safety monitoring.
The Study
This study focuses on the design and implementation of a flexible loop antenna-based sensor, created using inkjet printing on a polyimide substrate. Operating within the 2.4 GHz ISM band, the sensor is designed for food safety monitoring, particularly in detecting quality changes in meat. Its sensing mechanism is based on tracking shifts in resonance frequency, which occur due to variations in the meat’s dielectric properties over a six-day storage period.
To optimize sensitivity and accuracy, the sensor design was refined using CST Microwave Studio 2024. The experimental setup involved five identical beef samples stored under different conditions, with resonance frequency measurements collected using a Vector Network Analyzer (VNA). Results showed a progressive frequency shift from an initial 2.14 GHz on Day 0 to 1.29 GHz by Day 5. By systematically analyzing these shifts, the study effectively correlates resonance changes with spoilage levels, demonstrating the sensor's potential to enhance food safety monitoring.
Results and Discussion
The findings revealed a steady decline in resonance frequency as the meat aged, directly correlating with increased permittivity due to spoilage. Throughout the six-day monitoring period, the sensor demonstrated an average sensitivity of 0.173 GHz per day, proving its capability to detect even minor changes in meat quality.
Resonance frequency measurements aligned closely with theoretical predictions, reinforcing the sensor’s reliability for real-time food safety applications. Beyond Day 6, no significant frequency shifts were observed, suggesting the sensor had reached its detection limit—highlighting the critical six-day window for monitoring meat freshness.
The study also confirmed the sensor’s reproducibility, as results remained consistent across multiple samples. This reliability strengthens its potential for commercial use, where accurate and consistent quality assessments are essential. Given the increasing emphasis on food safety, such advancements in sensor technology could play a key role in modernizing food quality management. The flexible design further enhances its applicability, allowing integration into smart packaging or wearable monitoring systems for real-time freshness assessments.
Conclusion
This study presents a practical and effective solution for improving food safety monitoring through a flexible loop antenna-based sensor designed to assess meat freshness in real time. By detecting dielectric property changes, the sensor provides measurable and accurate indicators of spoilage, addressing key limitations of traditional monitoring methods.
Beyond its immediate application in meat quality assessment, this innovation lays the groundwork for broader research into monitoring other perishable foods. The potential integration of such sensors into Internet of Things (IoT) systems could further enhance food safety management, offering greater control over food quality and strengthening consumer trust. As food safety concerns continue to evolve, this study contributes valuable insights into the development of next-generation monitoring technologies tailored to an increasingly quality-conscious market.
Journal Reference
Abounasr J., Gharbi M.E., et al. (2025). A High-Sensitivity Inkjet-Printed Flexible Resonator for Monitoring Dielectric Changes in Meat. Sensors 25(5):1338. DOI: 10.3390/s25051338, https://www.mdpi.com/1424-8220/25/5/1338