Wireless Functional Electrical Stimulator for Foot Drop: design and preliminary results

Population of people with sequels on gait who require rehabilitation or assistance due to stroke is very large. The most common sequel in these patients is the foot drop. Functional electrical stimulators (FES) correct this foot drop by stimulating the peripheral nerves during the swinging phase of gait; but they usually present failures due to rupture of the wires that connect the stimulator with the electrodes and with the sensor for the command. This article presents the development of a FES system that minimizes the wiring length. It consists of a stimulator that is placed under the knee of the affected leg with a housing for the electrodes, and an application for Smartphone that, through wireless communication with the stimulator, allows the user to configure the stimulation parameters and to start and end the stimulation. An inertial measurement unit was used as a command sensor. A preliminary evaluation of the implemented design was carried out. It was observed the effectiveness in the control and configuration of the stimulator by a user through the Android application was checked and the electrical stimulation pulses generated through an oscilloscope. A test of plantar flexion and dorsiflexion movements was performed in a controlled manner with the stimulator placed on the leg, where it was found that the values ​​obtained by the sensor were consistent with the movement. Based on these results, the design requirements could be checked and the objectives aimed.