Bidirectional Soft Silicone Curvature Sensor Based on Off-Centered Embedded Fiber Bragg Grating

A compact bidirectional soft curvature sensor is achieved by embedding a fiber Bragg grating (FBG) off-centered in a silicone sheet. The proposed approach is capable to distinguish both the bending curvatures and bending directions through wavelength shift measurement of the FBG. Based on the pure bending model, the relationship between the FBG embedded position and the sensor sensitivity is studied and verified experimentally. Real-time curvature measurement of both positive and negative bending directions is experimentally achieved. The curvature sensor has a consistent performance and the results are highly repeatable with small variances. A linear relationship between applied curvature and FBG wavelength shift is obtained, with a large measurement range of up to ±80^-1 curvature.