Weight Measurement and Vibration Detection Sensor Based on a Thermoplastic Polyurethane Optical Fiber

An elastomeric optical fiber core was fabricated by drawing a 1160-D thermoplastic polyurethane preform. The cut-back technique was used to measure fiber attenuation for a light spectrum ranging from 550 nm to 875 nm, resulting in an average value of less than 0.25 dB/cm, which is suitable for use in short-distance applications. The potential of the fiber was evaluated in two applications where the advantages of this type of optical fiber, its elasticity and flexibility, are important. In the first application, for weight measurement, the sensor response showed asymptotic behavior at high weights that can be divided into two linear sections of 2.9 dB/N for weights ranging from 0 N up to 1 N, and 2.1 dB/N for 1 N to 1.7 N. In the second application, as a vibration sensor, signals were detected between 1 kHz and 20 kHz with an amplitude of approximately 35 dB above the background noise.