Fibre Sensing System Based on Long-Period Gratings for Monitoring Aqueous Environments

Thus, environmental monitoring is a crucial factor in the ecosystems health. Actually, methods for measuring salinity are mainly based on the mobility of ions in water (Zhao et al., 2003) changing the refractive index. However, these methods are inherently electrical and can be affected by any kind of electromagnetic interference. An alternative is the use of sensors based on optical technology, in particular, long-period fiber gratings (LPG) which are intrinsically sensitive to the external refractive index. These gratings devices have the advantage of being immune to electromagnetic interference and having small size, nonintrusive nature, flexible geometry, high speed of response and excellent salt water corrosion resistance.