Abstract: Aiming at the shortcomings of the complicated manufacturing process and the high cost of the existing curvature sensors, a flexible curvature sensor based on fiber grating is proposed. Using the wavelength division multiplexing characteristics of fiber Bragg grating (FBG), it is cascaded with multiple taper fiber curvature sensors to realize the flexible curvature of multi-point taper fiber. This enables simultaneous sensing of the curvature information at multiple points. Experimental results show that the film-like PDMS has good flexibility, allowing synchronous bending of the tapered fiber and the PDMS film. The bending sensitivity is about 0.593 48~0.606 96 dB/m^-1. The flexible curvature sensing of multi-point taper fiber based on FBG exhibits strong anti-crosstalk ability and can sense the curvature information of multiple points at the same time. Further, the flexible sensor is used to monitor human activity at the throat and wrist. Experimental results show that the sensor can not only detect small muscle changes in the human body but also capture larger movements, which suggests promising prospects for development.

Key words: fiber Bragg grating (FBG), single-mode tapered fiber, curvature sensing, polydimethylsiloxane (PDMS)