A neural prosthesis to improve gait in people with muscle weakness

Functional Electrical Stimulation (FES) can be used to induce contractions in muscles that do not receive adequate signals from the nervous system. People who have lost function in their foot and/or ankle following a stroke may benefit from a neural prosthesis. In this project, we designed, built and tested a neural prosthesis to assist people with muscle weakness who are at risk of falling. The neural prosthesis was designed to stimulate the gastrocnemius (GN) muscle during the push off phase using a manual switch. The neural prosthesis included a FES unit for muscle stimulation, electronic circuitry, and sensors including inertial measurement units (IMUs) and foot pressure sensors to detect movement characteristics. The neural prosthesis was tested on a healthy individual who walked in a straight line while the neural prosthesis collected data. Tests were performed with and without the neural prosthesis activated. The neural prosthesis was able to successfully collect gait data and cause contraction in the GN muscle. The test results showed that the GN muscle stimulation changed the gait by inducing a plantarflexion movement on the foot and expediting the toe off event. The performance of the neural prosthesis was evaluated using a commercial camera motion capture system. The IMUs and the motion capture system had and an average correlation coefficient around 95% which was close to some literature. This research showed that a neural prosthesis utilizing low cost IMUs was able to estimate the joint angle while walking. In addition, the device had an observable effect on the gait when tested on a healthy individual