Optical Fiber Fabry–Perot Interferometric CO2 Gas Sensor Using Guanidine Derivative Polymer Functionalized Layer

In this paper, a polymer polyhexamethylene biguanide (PHMB) based Fabry-Perot (FP) interferometric optical fiber sensor for carbon dioxide gas detection at atmospheric pressure is investigated and experimentally demonstrated. The absorption and release of CO2gas molecules lead to the refractive index change of the PHMB. The length of CO2sensitive FP cavity can be easily controlled by using the Czochralski method. The real-time measurement result shows that CO2gas concentration with a sensitivity of 12.2 pm/ppm in a 0-700 ppm range can be achieved.