On the development of a low-cost EMG switch for communication using minimal muscle contractions

In the final stages of muscle-wasting diseases like Amyotrophic Lateral Sclerosis and in extreme cases of disability the control of muscles is almost completely lost. However, in some cases there can be almost imperceptible residual control of some muscles. This paper presents the results of a study using an affordable, lightweight, portable EMG switch that has been designed in-house for communication in severely disabled or locked-in patients. It is possible to affect communication with the outside world by using these small residual muscle movements; in this case, more specifically muscles around the eyebrow. The subject makes the device "switch", obtaining a binary "yes/no" answer, through imperceptible muscle contractions. In these preliminary proof-of-principle tests we show an accuracy of around 87% when tested on 19 healthy volunteers over a number of measurement protocols.