Physiological bending sensor based on tilt angle loss measurement using dual optical fibre

This paper presents the development of an extrinsic optical fibre sensor for continuous measurement of the human spine bending movement based on intensity modulation technique. Using the investigated sensor configuration, the bending angle was measurable in both flexion and extension direction with a maximum range of motion of 18o and -10o, respectively. From the output drift assessment of the sensor, bending accuracy of up to 0.5o was achievable, thus making it suitable for clinical environment application. A divided-beam referencing technique was also implemented in the sensor configuration to compensate for the input power fluctuation and temperature variation.