Deciphering the sensory landscape: a comparative analysis of fiber Bragg grating and strain gauge systems in structural health monitoring

Structural Health Monitoring (SHM) is essential for engineering structure safety and durability. This study compares Fiber Bragg Grating (FBG) and Strain Gauge Systems (SGS), the two prominent sensing technologies used in SHM. Through this study, we aim to elucidate the sensory mechanisms, advantages, and limitations of each system, providing a comprehensive understanding of their applications in monitoring the structural integrity of various constructs. An attempt has been made to assess the superiority of FBG sensors over traditional transducer systems such as SGS. A real-time experiment is performed with a cantilever beam embedded with an SGS with a few tens of grams of force applied. The wavelength variation of the FBG sensor is strain-dependent, and an experiment is performed to show the reflectivity with applied force. With the same applied force, the FBG has linear behavior, while the strain gauge has a deviation of 15%. Further, we determined the R2 coefficient of deviation (COD) 0.84 for the SGS and 1 for the FBG sensor. With the FBG sensor, we obtained a superior strain sensitivity of 1.20 pm/μɛ and a Full Width at Half Maximum (FWHM) of 0.00136 µm. The SGS exhibits a self-heating characteristic and is inherently corrosive. In contrast, the FBG sensor has negligible electromagnetic interference, operates in the tetra-hertz frequency range, and exhibits an exceptional strain response.