High-sensitivity tapered fiber relative humidity sensor based on PDMS and GO films

A new tapered fiber relative humidity (RH) sensor based on polydimethylsiloxane (PDMS) and graphene oxide (GO) film coatings is proposed and demonstrated. Tapered fiber is fabricated in single mode fiber by the tapering machine. The PDMS film is coated on the surface of the fiber using the hydroxide flame sintering technique, while the GO film is deposited using the physical deposition technique. This structure can achieve strong interference effect by the smaller range of tapering process. In the RH measurement experiment, the humidity sensitivity of the sensor is measured to be as high as 0.371 dB/%RH within the RH range of 35% to 90%. The experiment investigates the impact of different numbers of PDMS coating on sensitivity. As the number of PDMS coatings increases, the RH sensitivity of the sensor also increases and reaches the highest sensitivity when coated with 10 layers of PDMS film. The sensor has high sensitivity to RH, good stability and mechanical strength, which also shows great performance in both moisture absorption and desorption. These advantages make the sensor suitable for the wide range of humidity sensing applications.