A System for Simultaneous Finger Joints Goniometric Measurements Based on Inertial Sensors

In this work, a system to record continuously and simultaneously the flexion and extension of finger joints and to compute a range of motion of the hand joints is presented. The system is based on micro-inertial sensors and a graphical interface in LabVIEW with a mathematical algorithm for signal conditioning. Ten sensors were attached to fingers with adjustable velcro belts, eight on proximal and distal phalanges from index to little fingers, one on the proximal phalanx of the thumb and another on the hand dorsum. The evaluation protocol consisted of 3 sessions of 10 repetitions each, on both hands of 6 healthy volunteers where the angular trajectory was recorded during grasping a 7.8 cm diameter sphere. A statistical analysis was performed in order to determine the variation among the measurements. The purpose of this study was to demonstrate the suitability of this system for simultaneous measurements of range of motion during flexion and extension, considering that it can be used interchangeably in the two hands, regardless the size. The results showed that the developed system is suitable for registering objectively the range of motion of the hand.