Graphene oxide-coated microbottle resonators for relative humidity sensing

Graphene oxide (GO) is a 2D coating material used to improve fiber optics sensors’ response to relative humidity. Microbottle resonators (MBRs) have garnered more attention as sensing media structures. An MBR with a 190 µm diameter was coated with GO. Then, tapered fiber light coupling was used to investigate the relative humidity sensing performance in the range of 35–70%RH at 25 °C. The MBR showed a higher Q factor before and after GO coating. The sensitivity of 0.115 dB/%RH was recorded with the 190 µm GO-coated MBR sample compared to a sensitivity of 0.022 dB/%RH for the uncoated MBR sample. These results show that the MBR can be used in fiber optic sensing applications for environmental sensing.