A Directional Curvature Sensor Using Excentric Heterogeneous Fiber Filled PDMS With Spherical Structure

Abstract

A directional curvature sensor using excentric heterogeneous fiber (EHF) filled polydimethylsiloxane (PDMS) with spherical structure is proposed and prepared. The main structure of the sensor is an EHF cascaded with two spherical structures made of single-mode fibers (SMFs), and the EHF cladding and eccentric core are corroded and filled with PDMS. The asymmetry of the sensor structure causes it to transmit asymmetric modes. It produces different spectral shift effects for bending in different directions, so it can be used for curvature detection in multiple directions. Experimental results show that in the curvature range of 0–0.73 m−1, the spectrum is red shift when the bending direction is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}$ </tex-math></inline-formula> , and the maximum curvature sensitivity is 15.88 nm/m−1. When the bending direction is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-{x}$ </tex-math></inline-formula> , the spectral is blue shift and the maximum curvature sensitivity is 20.66 nm/m−1. When the bending direction is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${y}$ </tex-math></inline-formula> , the spectrum is red shift and the maximum curvature sensitivity is 22.14 nm/m−1. This sensor has a simple structure and high sensitivity and can be used for precision equipment, intelligent robots, large building structure health monitoring, and other areas of curvature detection.