Recent progress in applications of in-fibre Bragg grating sensors

Abstract

In-fibre Bragg grating (FBG) sensor technology has become one of the most rapidly progressing sensing topics of this decade in the field of optical fibre sensors. FBG sensors are currently emerging from the laboratory to find practical applications. Rapid progress has been made in both sensor system developments and applications in recent years. This article presents a systematic review of recent progress in applications of FBG sensors in large composite and concrete structures, the electrical power industry, medicine, and chemical sensing.

Introduction

In-fibre Bragg grating (FBG) sensors have been subject to continuous and rapid development since they were first demonstrated for strain and temperature measurement about 10 years ago [1]. The main reason for this is because FBG sensors have a number of distinguishing advantages over other implementations of fibre-optic sensors, including potentially low-cost and unique wavelength-multiplexing capacity. The transduction mechanism is the modulation of the reflection wavelength of the sensing element, for example, thus avoiding the ambiguity of a phase measurement in an interferometric sensor or the requirement for referencing inherent in an interferometric one. FBG sensors seem to be ideal for realising so-called `fibre-optic Smart structures’ where fibre-optic sensors are embedded in (or attached to) the structure for achieving a number of technical objectives, such as health monitoring, impact detection, shape control and vibration damping, via the provision of real-time sensing information, such as strain, temperature and vibration [2]. The general aspects of the FBG sensor technology, including sensing principles, properties, fabrication, interrogation and multiplexing techniques, have been systematically reviewed by the author [3]; the present review concentrates on applications. In recent years, FBG sensors have been demonstrated for measurement of a wide variety of parameters; some FBG sensor systems have been installed in large-scale practical applications and a few FBG systems are commercially available. The applications of the FBG sensor cover a number of important fields. Generally speaking, the FBG sensor technology is approaching maturity after 10 years R&D, although there is still some potential for further improvement in terms of performance and functionality. Efforts are now engaged to realise cost effective FBG sensor systems and to explore more potential applications. Hence, it is considered useful to update the reader with the recent progress in applications of the FBG sensor technology. Several conference review articles on FBG applications with different emphases have been published previously [4], [5], [6], [7]. This article aims to provide a comprehensive overview of the FBG sensor technology in terms of recent progress in applications. Following the introduction, the applications of FBG sensors for large composite and concrete structures, the electrical power industry, medicine and chemical sensing, are provided in 2 Applications to large composite and concrete structures, 3 Applications in the electric power industry, 4 Applications to medicine, 5 Applications to chemical sensing, respectively. This article concludes in Section 6 with a brief discussion on some future developments of the FBG sensor technology.