Measurement of finger joint angle using a flexible polymer sensor

This paper aims to develop a measurement system for the finger joint angle by using a flexible polymer sensor. In rehabilitation, it is important to evaluate human motions quantitatively for effective treatment. In this study, we focus on hand's grasping motion, which is important motion for eating and drinking. About the flexible polymer sensor, in the previous studies, it has been elucidated that the outputs from the flexible polymer sensor are proportional to the average curvature of measuring surface. Therefore, using the sensor, finger bending motion can be measured by attaching the sensor on finger surface. Firstly, the relationship between the average curvature of finger surface and finger joint angle is theoretically investigated. Then, in order to obtain the relationship between sensor outputs and finger joint angles, sensor outputs and finger joint angles during grasping acrylic cylinders are measured. From the results, it was found that the developed system is useful to measure the finger joint angles.