Cost-effective load measurement system for health monitoring using long-period grating as an edge filter

Abstract

Abstract A low-cost real time load measurement system employing fiber Bragg grating as a strain sensor and long-period grating as an edge filter for structural health monitoring is being reported in the present work. The shift in Bragg wavelength due to applied load on a prototype bridge is converted to corresponding change in optical power using edge filter technique. Further, this change in the optical power is converted to voltage using a pigtailed photodiode and a trans-impedance amplifier. This voltage is fed to an Arduino Uno and transmitted via Bluetooth to a mobile for continuous monitoring of the load on the bridge beam from a remote location. The performance of the system is found to be linear with a coefficient of linearity 0.983 and sensitivity of −0.0024 mV/gr for applied loads up to 3 kg. A standard error of +50 g is observed, which confirms ability of the proposed system in field applications.