designing a low‑noise, high‑resolution, and portable four channel acquisition system for recording surface electromyographic signal

in current years, the application of biopotential signals has received a lot of attention in literature. one of these signals is an electromyogram (emg) generated by active muscles. surface emg (semg) signal is recorded over the skin, as the representative of the muscle activity. since its amplitude can be as low as 50 µv, it is sensitive to undesirable noise signals such as power‑line interferences. this study aims at designing a battery‑powered portable four channel semg signal acquisition system. the performance of the proposed system was assessed in terms of the input voltage and current noise, noise distribution, and synchronization and input noise level among different channels. the results indicated that the designed system had several inbuilt operational merits such as low referred to input noise (lower than 0.56 µv between 8 hz and 1000 hz), considerable elimination of power‑line interference and satisfactory recorded signal quality in terms of signal‑to‑noise ratio. the muscle conduction velocity was also estimated using the proposed system on the brachial biceps muscle during isometric contraction. the estimated values were in then normal ranges. in addition, the system included a modular configuration to increase the number of recording channels up to 96.