Comparison of strain sensitivities of free and attached FBG strain sensors

The strain sensitivity of FBG-based strain sensors that had been inscribed into three different types of optical fibers were determined for both conditions, for fibers that were glued on a specimen and for free, bare fibers, i. e. fibers that were not bonded to a structure at the location of the FBG. The influence of the gluing technique on the strain sensitivities of the FBG sensor elements was investigated by comparing the strain sensitivities of a multitude of attached and free sensor elements on a statistical basis. A good agreement between the strain sensitivities of free and attached fibers was achieved, which shows the high quality of the gluing method employed.