Scalable Laser-Assisted Manufacturing of Chipless RFID Sensors on Metallized Films

The global food packaging industry, valued at 311.4 billion dollars in 2020 and projected to reach 456.6 billion dollars by 2027, is witnessing growing demands for improved food quality and safety. Monitoring the quality of packaged food plays a vital role in reducing spoilage and enhancing food safety. Key indicators like humidity levels, pH, and chemical changes in meat products necessitate sensors for effective monitoring. Current solutions, such as colorimetric sensors and active sensors, have limitations. While colorimetric sensors are cost-effective and suitable for transparent packaging, they cannot be used in non-see-through packages, requiring labor-intensive manual inspection. Active sensors, though automated, are expensive and may not always be biocompatible due to batteries and electronic chips.<br/> <br/>Battery-less chipless wireless sensors, due to their low cost and wireless capabilities, are becoming increasingly popular in food packaging. However, challenges in the commercialization of chipless sensors are associated with their manufacturing processes. Scalable manufacturing techniques like printing have been employed for chipless sensors in applications like moisture sensing, soil analysis, and identification. These techniques reduce the complexity and resources needed for sensor production but introduce challenges related to ink formulation, custom screens, and drying and sintering times.<br/> <br/>Our Scalable Laser-Assisted Manufacturing (SLAM) process offers a solution for large-scale, roll-to-roll production. It enables one-step patterning of a conductive aluminum layer on paper or PET sheets while concurrently creating high-surface-area Al2O3 nanoparticles within the laser-ablated regions, enhancing the sensitivity of the wireless sensor.<br/> <br/>This work presents a systematic investigation of different laser processing conditions on metalized paper films to optimize structures. These structures provide high-performance antennas while minimizing structural damage to the underlying paper substrate. Results demonstrate that optimized processing conditions yield concurrent patterning of the metalized film into desired antenna structures and high-surface-area metal oxide nanoparticles within the ablated region. This results in exceptional sensitivity (linear sensitivity of -87 kHz/RH in a relative humidity range of 0% to 85%), surpassing standard RFID sensors produced using conventional photolithography methods.<br/> <br/>The second part of this work demonstrates the post-functionalization of laser-patterned resonators and antennas to achieve responsive sensitivity to pH and hypoxanthine (HX), biomarkers relevant to food spoilage and fresh meat and fish produce. This technology opens new possibilities for scalable and cost-effective sensor production, paving the way for their implementation in smart packaging to address the challenges associated with food waste.