Implementation of a Fiberoptic Sensor to Detect Change in Liquid Level and Change in Concentration of Solute in a Water Reservoir

Abstract

Liquid level detection is a crucial research topic from the perspective of a riverine and flood-prone country like Bangladesh. Typical electronics based liquid level detectors carry the risk of accidents which are hazardous and costly as they are prone to electrical short-circuits. As optical fibers do not carry electricity and can operate a fair distance from the transceiver, they are safer to use as the main sensor material. In this work, an optical fiber liquid level measurement sensor is designed and analyzed. The sensor operates on the principle of fiber optic bending loss (FOBL). As the liquid level increases, so does the bending loss; resulting in a gradual decrease of the output signal on the receiving end. The bending loss for measuring water level (0-15 cm) resulted in a power output ranging from -26.79 dBm to 8.2 dBm. The water characteristic sensor gave power outputs ranging from 37-39 dBm, 38-40 dBm, 39-44 dBm for freshwater, Saltwater and muddy water respectively. The results are then used in a simple application of automating a 12 V DC powered pump to model a water pump automation in everyday household requirements. The sensor is also useful in detecting a change in medium based on the relationship of refractive index change. This makes it successful in detecting a change in the water quality that is present in the tank.