High Sensitive Molybdenum-diselenide-coated Micro-fiber For High Humidity Sensing

Humidity value is a vital monitoring parameter index in the fields of industrial and agricultural production,precision instrumentation and aerospace engineering.Compared with electronic humidity sensors,fiber optic humidity sensors have shown many advantages of long-distance transmission,anti-electromagnetic interference,corrosion resistance,distributed sensing,safety,economy and environmental protection,etc.Nowadays,the novel all-fiber sensors are tending to be more and more compact but without sacrificing its high performance.Among the category of optical fiber sensors,microfiber?MF?sensors have been widely used due to their excellent stabilization and optical characteristics.Thanks to its strong evanescent field,microfiber-based device in compact size can easily get interactions with external environmental factors to achieve high-performance detecting and sensing.Molybdenum diselenide?Mo Se₂?is a kind of two-dimensional transition metal dichalcogenides?TMDs?material with graphene-like layered structure.Mo Se₂ is widely employed in various photoelectric devices because of its excellent photoelectric properties provided by its special structure.By combining Mo Se₂ nanosheets and MF,a miniaturized high-performance MF humidity sensor is achieved in this paper.The MF is prepared by flame-brushing technique and the Mo Se₂ is combined to the MF by using natural evaporation method.The experimental results indicate that the Mo Se₂-based MF humidity sensor shows a highest sensitivity of 1.87 d B/%RH among the humidity range from83%RH to 97%RH.In aspect of response time,the Mo Se₂-based MF humidity sensor achieves a response time of 1 s and a recovery time of 2 s.Therefore,the Mo Se₂-based MF humidity sensor shows good application potential in the field of all-fiber humidity sensing technology due to its advantages of good working stability,reversibility,good repeatability.The finite element method?COMSOL multiphysics?is employed to analyze the sensing mechanism of this device.The refractive index of Mo Se₂ can be changed under the variation of external humidity,which will indirectly change the field strength of transmission mode of sensor.The calculation results indicate that the transmitted light characteristics of the device are enhanced with the rising external humidity,resulting in an increase in transmitted optical power accordingly.The agreement between the theoretical simulation results and the experimental results shows that the fabricated device has good linear sensitivity in the high humidity environment.Innovation in this paper:A fiber-optic humidity sensor combined with 2D Mo Se₂ and MF is proposed to realize high sensitivity?1.87 d B/%RH?monitoring and sensing in a high humidity environment?83%RH-97%RH?.