Encapsulation of Fiber Optic Sensors in 3D Printed Packages for Use in Civil Engineering Applications: A Preliminary Study

Fiber optic sensors have considerable potential for measuring strains in the challenging environment posed by today's civil engineering applications. Their long-term reliability and stability are particularly important attributes for assessing, with confidence, effects such as cracking and response to normal (and abnormal) loads. However, given the fragile nature of the bare fiber, the sensors must be packaged to achieve adequate robustness but the resulting increased cost of installation can frequently limit the number of sensors which can be installed or their use may have to be ruled out altogether due to these financial constraints. There is thus potential for the development of a more affordable type of packaging and this paper describes work undertaken to produce a cost-effective and easy-to-use technique for encapsulating fiber optic sensors in resin, taking advantage of 3D printing techniques which are widely available and at low cost. This approach can be used to produce a robust, inexpensive packaged sensor system which is seen as being suitable to be extended to a wider range of uses including installation in concrete structures prior to casting. To evaluate this approach, several such 3D printed package types and geometries are described and their behavior is assessed from a programme of laboratory trials, the results of which are presented in this paper. This proof-of-concept testing has demonstrated the considerable potential which 3D printed packages have and the scope for further development and consequent use in civil engineering applications. Areas showing promise and potential, which have been identified from the work undertaken, are discussed.