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March 2017
DocID030195 Rev 1
1/15
www.st.com
AN4995
Application note
Using an electromyogram technique to detect muscle activity
Sylvain Colliard-Piraud
Introduction
Electromyography (EMG) is a medical technique to evaluate and record the electrical activity of nerves
and muscles. It allows the quality of muscular contractions to be studied using electrodes. During an
electromyography, the aim is to detect the electrical potential generated by muscles to detect medical
abnormalities or activation levels. Two complementary EMG techniques exist:
Detection EMG: the goal is to measure the electrical activity of a muscle at rest and during a
voluntary contraction.
Stimulation EMG: the aim is to measure the nerve conduction speed after stimulation of the nerve
with a short and small electrical current.
In this application note, we use the first technique to detect muscle activity using skin electrodes. Then,
using signal conditioning based on operational amplifiers (op amps), we show how to amplify the muscle
activity. The user can use this information to trigger a specific action e.g. light a lamp, change the TV
channel, stop his alarm, etc.
