A FES device developed for treating drop foot

Abstract

Multiple sclerosis, stroke and peripheral neural disorders affect the centralnervous system and cause various nervous and muscular disabilities. One of thesedisabilities is called drop foot, which prevents the patient from raising the foot at the ankle and effectively swinging the leg when walking. This situation can be corrected by using muscle stimulators and synchronizing functional electrical stimulation of thecommon peroneal nerve to the swing phase of the gait cycle.This thesis presents a portable, two channels, functional electrical stimulator that was designed and developed to assist drop foot patients during walking. The device has two independently programmable constant current outputs, which can produce biphasicpulses having pulse with up to 350 us and amplitude up to 100 mA. A microcontroller core controls all of the parameters. A new program code has been written for controlling stimulation parameters and storing them for a future application. The system can be programmed using push buttons and an LCD display. A foot switch worn by the patient, under the heel, is used for getting feedback control for stimulation timing during the gaitcycle. This foot switch triggers the output channels to stimulate the related musclesthrough electrodes that are placed over the nerves. Various tests have shown that our system is reliable and the performance of the design is satisfactory enough.|Keywords: Functional electrical stimulation, drop foot, muscle stimulation.