A plastic optical fiber (POF) sensor with in-fiber microholes for level measurement is investigated. The sensor has eight 0.9-mm-diameter holes spaced 5 cm apart and fabricated by micro-drilling. When water is poured into a measuring cylinder equipped with a POF sensor for level measurement, the sensor transmittance increases with the number of holes immersed in water. The experimental data are in good agreement with the theoretical data. The research results show that a POF sensor with in-fiber micro-holes can be used to measure liquid level.

This paper presents a novel respiration sensor based on multiple in‐fiber microholes drilled along a plastic optical fiber (POF) that is stitched to a waist‐band wrapped around the patient's abdomen. The bending loss of a POF with a single microhole is analyzed in order to enhance the sensor sensitivity. Several sensors were fabricated using a 1.5 mm‐diameter POF with different numbers and spacing of 0.7 mm‐diameter microholes. The sensitivity of the respiration sensor increased when increasing the number and spacing of the microholes, where the POF respiration sensor with seven 0.7 mm‐diameter in‐fiber microholes spaced at 15 mm showed the highest sensitivity and sufficient strength for respiratory monitoring. Thus, the experimental results confirmed that a POF sensor based on in‐fiber microholes can be effectively used to monitor the respiration of patients.

AbstractsPlastic optical fiber level measurement sensor based on in-line side holes is investigated theoretically and experimentally. The sensor consists of a plastic optical fiber with in-line side holes spaced about 5 cm apart. The 0.9 diameter in-line side holes were fabricated by micro-drilling. An analytical expression of the sensor transmittance was obtained using a simple ray optics approach. The measurements of the sensor transmittance were performed with a 55 cm height Mass cylinder. Both results show that the sensor transmittance increases as the number of side holes filled with water increases. The research results indicate that the plastic optical fiber based on in-line side holes can be used for water level measurement.