Rum adulteration detection using an optical fiber sensor based on multimodal interference (MMI)

In this work, we propose and demonstrate the fabrication of an optical fiber sensor based on multimode interference effects (MMI) for rum quality control. The operation of the sensor relies on the fact that when rum is adulterated, which can be done either with ethanol or ethylene glycol, the refractive index (RI) of the adulterated rum will be different as compared to the original rum. Since the white rum (Bacardi®) has a RI close to 1.345 and the highest RI of the contaminant is 1.412 (ethylene glycol), the RI of the adulterated rum will increase as the volume of the contaminant is increased. Therefore, considering that the MMI sensor exhibits a sensitivity of 258.06 nm/RIU for liquids with RI ranging from 1.318 to 1.4203, we can accurately determine if a rum sample is free of contaminants or adulterated with other liquid, which is typically performed using ethanol or toxic elements like ethylene glycol. Although the sensor cannot determine which kind of liquid is altering the rum, it can easily detect when the original rum has been adulterated, even with small amounts of liquid. The sensor also provides high repeatability and reversibility while using a fast and simple fabrication process.