Optical Fiber Tip Sensor for the Measurement of Glucose Aqueous Solutions

A reflective fiber optic sensor based on multimode interference for the measurement of refractive index variations in glucose aqueous solutions is proposed. The sensor is fabricated by splicing a short section of coreless silica fiber to standard single mode fiber. The influence of the coreless fiber dimensions on the sensor performance is analyzed. By changing the sensor length, no significant impact is observed. However, the reduction of the sensing head diameter leads to a large improvement of the sensitivity. The smaller sensor, with a length of 5 mm and a diameter of 24 μm, presents a maximum sensitivity of 1467.59 nm/RIU, for the refractive index range between 1.364 and 1.397 RIU. Taking into account the acquisition system, a maximum theoretical resolution of 6.8 × 10 -5 RIU is achieved.