A research group led by Prof. LI Jia and Prof. YU Xuefeng from Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, along with Professor YANG Dexing from Northwestern Polytechnical University proposed a new strategy to realize highly responsive all-fiber humidity sensor with an ultrafast response time as fast as 7ms. 

Humidity is the concentration of water vapor present in the air, an important reference value in many aspects of life and production.

Fiber optics offers a significant photonic strategy for high-performance sensing effect. Apart from the inherent merits of fiber optics, such as compact size, light weight, immunity to electromagnetic interference, low cost, and high reliability, the fiber-based optical sensors promises high sensitivity, fast response, and in-line determination as well. 

In the physica status solidi (RRL) - Rapid Research Letters, the researchers developed a combination of black phosphorus (BP) with fiber optics, different from traditional transistor-based BP humidity sensors, herein, an all-fiber sensing strategy was proposed by integrating BP nanosheets with etched single-mode fiber (ESMF).

By combining the merits from both BP and fiber optics, to be more precise, directly coated BP nanosheets on the single mode fiber, the light passed through the fiber core and yielded an evanescent wave penetrated into BP coating, leaded to a strong light–matter interaction for moisture detection, thus accomplished highly responsive humidity sensor.  

The light passed through the fiber core and yielded an evanescent wave penetrated into BP coating, leaded to a strong light–matter interaction for moisture detection, and provided excellent sensing performance by combining the merits from both BP and fiber optics. 

"This device takes advantages of sensitivity and fast response of both fiber-optics and black phosphorus to environmental changes. We hope our work can provide an all-optical sensing platform not only for high-performance humidity sensing, but also for opening up new opportunities for many potential vapor/gas sensing applications in the fields of biomedical, chemical and environmental science,” said Prof. LI. 

Transmission path of light in BP-coated ESMF. (Image by Prof. LI Jia) 

Media Contact:
ZHANG Xiaomin
Email: xm.zhang@siat.ac.cn