Demonstration of temperature monitoring of the curing process in resin transfer moulding using integrated phase-shifted Bragg grating sensors

Abstract

Composite materials have increased in use across multiple industries due to their low weight, thermal stability and design flexibility. As applications grow, the importance of accurate process-monitoring techniques grows, with various research teams investigating a variety of in situ cure-monitoring sensors. Photonic integrated circuits (PICs) can be a feasible solution in tracking curing cycles due to their resistance to harsh conditions and ease of integration into the production tool. This paper demonstrates the integration and performance evaluation of an embedded phase-shifted Bragg grating solution, instead of commonly used fiber sensors, based on 220 nm height silicon-on-insulator platform for in-situ monitoring of the RTM-6 resin curing process in a composite tool. The embedded optical sensor presents high sensitivity (75 pm/°C) and linearity (R2=0.995) up to 120 °C, enabling precise temperature measurements throughout the curing cycle. The experimental results show consistency with previously reported simulations, throughout the calibration, dry run characterization and the curing process, up to 120 °C, allowing for accurate monitoring of the curing process.