Recording EMG Signals on a Computer Sound Card.

For a few dollars and in a few minutes, a simple circuit can be built to permit a cheap external sound card and a laptop computer to be used as a portable data acquisition system for recording EMG. The circuit uses a common audio amplifier integrated circuit to increase the gain of the EMG signals recorded from EMG surface electrodes and to match the impedance of the electrode-skin interface with the input impedance of the sound card. Data can be recorded using open source sound editing software and analyzed offline using simple Python code. It is hoped that such activities provide opportunities to undergraduates to gain confidence as experimentalists and as innovators.