Design and Development of A Low-Cost Electromyogram Amplifier for General-Purpose Biosignal Amplification

Abstract

The electromyogram (EMG) is a biological signal which manifests during muscle contraction. It is widely used for health, biomechanics and machine control. However, high-performance EMG amplifiers are costly while self-developed solutions face reliability issues. In this paper, a low-cost solution to EMG amplification is introduced. The proposed design incorporates a front-end filter, a differential stage, and a bandpass filter. The resulting prototype consists of six differential inputs and is constructed into a compact housing. Being battery-powered, it is portable and safer as it is not powered by the mains. The developed device was rated to achieve a common-mode rejection ratio (CMRR) of over 90 DB with a high input impedance of 20 GΩ which is comparable to the commercial device. In addition, test results also showed that the baseline noise amplitude was similar with or without the right-leg drive.