Gait monitoring with a wearable plastic optical sensor

A wearable low-cost system designed to evaluate quantitatively the human gait is presented in this report. The system is based on transmittance changes when a plastic optical fiber is bent. To enhance sensibility, a portion of the fiber was side-polished improving attenuation due to macro bending. By calibration, the intensity of light received by a photo detector was related to the flexion angle. The fiber was bonded to the location of a commercial knee-support where it is desired to measure the joint angles. The prototype was calibrated with a video-based system and a gait cycle was obtained. The preliminary results show that the technique can be an important tool to aid physicians in diagnosis and rehabilitation of knee injuries or to monitor the performance of high competition athletes.