Fiber Optic Sensor with an Optically Transparent Electrode for Monitoring CaCO3 Scale Formation in Geothermal Water

Herein, we present a fiber optic sensor with an optically transparent electrode for monitoring calcium carbonate scale formation in geothermal water. The proposed sensor was fabricated by coating indium tin oxide onto the surface of an unclad multimode fiber core. The surface charge of the sensor could be controlled by applying potentials. The transmittance change for scale formation varied as a function of the applied potential. The proposed sensor was used to monitor the scale formation in natural geothermal water at Matsushiro, Japan.