Development of a low invasive FBG based temperature and strain sensor for aerospace systems management

In engineering systems development, particularly in mechanical and aerospace applications, there is a great demand for minimally invasive sensors capable of measuring various physical parameters while operating in harsh environments. Optical fiber sensing technology is well-suited to meet the stringent requirements imposed by the operational environment in space. This work describes the conceptualization, development, fabrication and testing phases of an integrated temperature and strain sensor based on Fiber Bragg Grating (FBG) optical sensors. The minimal invasiveness of the final product makes it ideal for a wide range of applications, both for surface measurements and for direct integration into the manufacturing process of the component. The sensor is based on the use of two gratings integrated into different layers of metallic and polymeric materials. This configuration provides a primary FBG directly bonded to the structure, making it sensitive to strain, local temperature and strain induced by temperature changes. Additionally, the proposed design includes a secondary FBG, positioned very close to the first but mechanically isolated from the structure, ensuring a purely thermal measurement. The fabrication of the complete sensor and the subsequent testing phase demonstrated the sensor's high sensitivity along with excellent capability in decoupling thermal and mechanical parameters.