According to \cite{elamvazuthi2015development} electromyography or EMG measures the response or electrical activity which occurs when a muscle’s nerve is simulated. There are currently two types of EMG: Surface and Intramuscular EMG. Intramuscular EMG deals with the usage of hypodermic needles which are inserted directly into the muscle so surface EMG will be the main focus of this paper. EMG is relevant and useful because sometimes the traditional input method of touch screens and keys are impractical and inadequate. This is prevalent in rigorous activities such as jogging, cycling, or in special cases, simply walking. To address the impracticality of traditional keys in certain situations, alternative input techniques such as EMG, computer vision, and speech recognition.
But, why would EMG be used instead of other input techniques such as computer vision or speech recognition? As stated by \cite{Saponas_2010}, occlusion and lighting limit the capabilities of computer vision and speech recognition may be socially awkward in most situations. To further strengthen the usage of EMG, Saponas stated that the EMG approach “allows people to use their fingers for input without any sensing technology on or near their hands.”
EMG when used and applied to computer, can form muscle-computer interfaces. In an experiment conducted by \cite{saponas2008demonstrating}, 10 sensors worn in a narrow band around the upper forearm demonstrated reliable interpretations of the muscle movements. They were able to differentiate the position and the applied pressure of finger presses. And, they were able to classify tapping and lifting gestures across all of the five fingers. The problem with this however, is that lots of sensors may be cumbersome to the person.
EMG has been applied to a variety of fields. The most notable applications are in medicine. EMG has been used to rehabilitate stroke victims \cite{Viriyasaksathian_2011}, provide computer access for people who are unable to use a mouse, trackpad, touchpad, or keyboard \cite{Craig_Chin}, and control prosthetic hands more dexterously \cite{Al_Timemy_2013}. Another field is in Game Development. This will be further explained in the next section.