LF RFID Capacitive Sensors for Curing Monitoring of Glass Fiber Reinforced Polymers

In recent years, glass fiber reinforced polymers (GFRPs) have gained widespread adoption across various industrial sectors due to their advantageous properties. As a result, ensuring the production quality of GFRP components and enhancing manufacturing efficiency have become critical priorities to meet the growing demand and performance standards of fiber-reinforced composites. Wireless passive radio frequency identification (RFID) sensing technology has emerged as a valuable tool for monitoring the curing process of GFRP. However, the practical application of this technology is often hindered by the bulkiness of the devices and their susceptibility to interference, which limits their effectiveness in real-world scenarios. In this article, an low-frequency (LF) RFID capacitive sensor, which can be embedded in the GFRP, is proposed for monitoring GFRP curing. The sensor not only monitors subtle changes in electrical properties during the curing of GFRP but also integrates RFID technology for material tracking. This dual approach enhances the reliability of the curing process and ensures consistent high-quality production. The communication and sensing principles of the LF RFID capacitive sensor are described, and the feasibility of the method is analyzed using an equivalent circuit. A interdigital capacitive (IDC) sensor is printed on a flexible circuit board and connected to an RFID tag. The response of the LF RFID capacitive sensor during the curing process of the GFRP was investigated and compared with the measurement results of the dielectric analysis (DEA) method. The experimental results demonstrate the sensor’s effectiveness in monitoring the curing process of GFRP, highlighting its potential for real-time assessment in composite manufacturing.