Long period optical fiber grating outcladding overlaid sensors: A versatile photonic platform for health and bio applications

Long period fiber gratings with suitable thin film overlayers can constitute a strong platform for the development of versatile and multi-functional sensing devices for serving diverse Biological and Health monitoring applications. Herein, we present three cases of thin film overlaid long period gratings that can find direct application in health related applications: the first example refers to a humidity sensing device utilizing PEO/CoCl₂ overlayers, and, the second refers to a simple radiation dose sensor utilizing spiropyran doped PMMA overlayers. In the final case, a vapor detection probe is demonstrated utilizing a zinc oxide (ZnO) nanorods coating. The proof of principle of these devices is presented, in conjunction with experimental results on their performance, while their application in health related applications is projected and discussed.