Application of Graphene Oxide-Based, Long-Period Fiber Grating for Sensing Relative Humidity

In this study, we proposed a Base S-type, long-period, fiber grating (Base S-type LPFG) coated with graphene oxide (GO) for sensing relative humidity based on the micro-electro-mechanical systems (MEMS) process and piezoelectric inkjet technology. The single mode optical fiber was etched to three different diameters (37, 42 and 60 μm) which were evaluated in the Base S-type LPFG. According to the experimental results, the diameter of 37 μm yielded the best sensitivity. Humidity sensor experiments showed that the Base S-type LPFG exhibited a high humidity sensitivity in a wide range from 20% RH to 80% RH. These experiments were repeated three times and the results showed that the average value of transmission loss sensitivity was -0.1824 dB/% RH and the average linear response had a correlation coefficient of 95.68%. The sensor exhibits good linearity, high stability, and reversibility in a wide working range. Therefore, the proposed graphene oxide-coated Base S-type LPFG humidity sensor has the potential for monitoring the relative humidity.