An Intensity-Variation RI Sensor for Multi-Variant Alcohol Detection with Twisted Structure Using Polymer Optical Fiber

This research introduces an RI sensor for detecting various alcohol species with a designed twisted polymer optical fiber (POF) sensor. The sensor is developed via a straightforward twisting technique to form an effective coupling mechanism. The sensor works on intensity variation where coupled intensity varies when different types of alcohol are added. The structure relies on the twisting of two fibers, where one fiber is used as the illuminating fiber and the other fiber is used as the receiving fiber. Five different types of alcohol are tested (methanol, ethanol, propanol, butanol, and pentanol) as a substant. The experimental results reveal that the sensor is able to detect all five distinct substants effectively by optical power intensity variation. Moreover, the sensor’s sensitivity is analyzed with different factors such as the influence of the bending radius and the coupling length, which reveals that the sensing parameters could be customized depending on specific requirements. The sensor demonstrated consistent responses in repeatability tests, with minimal variation across multiple measurements, highlighting its stability. Additionally, the study explores temperature’s influence, revealing a sensitivity shift for every degree Celsius of change. This POF-based alcohol sensor represents a significant leap forward in optical sensing technology.