Optical fiber sensor layer embedded in smart composite material and structure

A composite structure health monitoring system with optical fiber sensors is an important development in smart materials and structures. But it is difficult to embed a network of distributed optical fiber sensors in a smart composite structure, and the most effective method would be integrating the network of sensors with the polyimide film as a layer, called the optical fiber sensor layer, and then embedding the layer with optical fiber sensors in the composite material. This paper introduces three methods of making a distributed optical fiber sensor layer with polyimide. The first is to sandwich optical fiber sensors in two polyimide films. The second is to deposit the network of sensors in polyimide solution, and dry the polyimide solution. The last is to build thin-film optical waveguides and optical sensors by using fluorinated polyimide, which is expected to have high integration and high reliability. Some tests indicate that there is a little influence on the mechanical performance of the structure; however, optical fiber sensor built-in polyimide films work very well.