Refractive index sensor based on a gradually hot-pressed flatted plastic optical fiber

This paper proposes a gradually hot-pressure plastic optical fiber (POF) refractive index (RI) sensor with a flatted structure to detect the glucose concentration, and experimentally investigates the performance of RI sensor with straight and micro-bending POFs. The sensor is fabricated by a temperature-controllable metal rod to form the hot-pressed end face of POF which can increase signal-to-noise ratio (SNR) of the sensor. The experimental results show that the proposed sensor, utilizing a flatted structure POF with thickness of 0.5 mm and diameter of 0.4 cm, achieves maximum intensity sensitivity of up to 1748.91 %/RIU and resolution of up to 5.97 x 10-4 RIU in the RI range of 1.33 to 1.382. Furthermore, its simple design and manufacturing process shows potential for application, especially in biochemistry and environmental safety.