An Intensity-Variation Technique for Dual-Point Liquid Level Measuring Sensor Utilizing Polymer Optical Fiber

The present study designed the dual-point liquid level measuring sensor using the polymer optical fiber (POF). The sensor measures the liquid level variation based on the optical power intensity variation. The sensor structure is based on the twisting of two fibers and introduces cascading to achieve a dual-point detection. In our work, two liquid-level sensors are combined in series to form a dual-point liquid level sensor. Meanwhile, the system relies on a single input source, and the outputs of both sensors are individual. The individual output source of each sensor independently measures the liquid level variation that does not require any decoupling technique to extract the sensing information. The liquid level variation is sensed by dual-point sensor by the change in the refractive index due to medium change. The increasing liquid level led to change in medium from air to water, where the power coupling varies due to the change in liquid level. For present study, we achieved the liquid level detection in the range of 0-12 cm. The overall both sensors have the liner response of coupled optical power with respect to change in liquid level. The R-squared value of both sensors (Sensors-A and -B) is measured as 0.9924 and 0.9925. At repeated times, both sensors have a close response curve. The dual-point liquid level sensor is capable to response for continuous and discontinuous liquid level variations.