Characterization of Flexible Copolymer Optical Fibers for Force Sensing Applications

Marek Krehel,Lukas Scherer,René Rossi,Gian-Luca Bona

doi:10.3390/s130911956

Abstract

In this paper, different polymer optical fibres for applications in force sensing systems in textile fabrics are reported. The proposed method is based on the deflection of the light in fibre waveguides. Applying a force on the fibre changes the geometry and affects the wave guiding properties and hence induces light loss in the optical fibre. Fibres out of three different elastic and transparent copolymer materials were successfully produced and tested. Moreover, the influence of the diameter on the sensing properties was studied. The detectable force ranges from 0.05 N to 40 N (applied on 3 cm of fibre length), which can be regulated with the material and the diameter of the fibre. The detected signal loss varied from 0.6% to 78.3%. The fibres have attenuation parameters between 0.16–0.25 dB/cm at 652 nm. We show that the cross-sensitivies to temperature, strain and bends are low. Moreover, the high yield strength (0.0039–0.0054 GPa) and flexibility make these fibres very attractive candidates for integration into textiles to form wearable sensors, medical textiles or even computing systems.

Highlights

Optical fibres-based sensors have numerous advantages compared to electrical or chemical devices, e.g., insensitivity to electromagnetic fields, water and corrosion resistance, compact size and light weight [1,2]
To implement optical fibre based pressure sensors into textile fabrics, the fibres should be highly flexible, which is not the case for glass-based fibres most often used for fibre Bragg grating based sensors
The force sensor is based on the losses in light transmission along the light guides when the fibres are compressed

Summary

Introduction

Optical fibres-based sensors have numerous advantages compared to electrical or chemical devices, e.g., insensitivity to electromagnetic fields, water and corrosion resistance, compact size and light weight [1,2]. Due to these benefits, optical fibre based sensors are used in numerous applications to detect changes in chemical and/or physical parameters [1,3,4,5,6]. Sensors based on fibre Bragg gratings have to be single mode and are dependent on temperature, strain and pressure simultaneously and require compensation of some of the parameters in order to sense one of them [15,16]

Methods

Results

Conclusion