Automatic adaptation of a self-adhesive multi-electrode array for active wrist joint stabilization in tetraplegic SCI individuals

The novel ¿OrthoJacket¿ device aims at restoring restricted or completely lost hand and arm functions in highly tetraplegic spinal cord-injured (SCI) individuals. This system is based on the combination of a hybrid orthosis with integrated fluidic actuators and functional electrical stimulation (FES). Its primary goal is the improvement of paralyzed upper extremity functions and, thus, to enhance a patient´s independence in activities of daily living (ADL). A crucial issue of the FES of paralyzed muscles in the orthosis is the precise and stable control of the artificially generated movements under varying conditions. The reproducibility of the movements necessary for restoring hand and wrist joint functions can be improved by the use of a self-adhesive multi-electrode array. Since motor deficits vary considerably among tetraplegic individuals, the new orthosis has to be adapted to each handicapped subject prior to the its application in everyday life. This paper will present a system that allows for an automatic adaptation of the multi-electrode array to the paralyzed limbs of upper extremities such that a given joint movement is executed optimally. A new assessment scheme is introduced for the precise measurement of graduated joint movements generated by stimulation via the electrode array. Additionally, criteria have been developed for evaluating the quality and the deviation of the artificially generated movement from a given reference movement.