Abstract
The electromyography (EMG) signal provides insight into neuromuscular
activity which is used in medical and technological fields. Traditional
needle electrodes and surface electrodes have several drawbacks making
them less suitable for portable and long-term use. In contrast, emerging
capacitive electrodes offer promising features over the existing
electrodes. Yet, the full potential of capacitive electrodes remains
untapped due to the lack of comprehensive design optimization for
consistently reliable signal quality. This study highlights the complex
interplay of factors influencing correlation in capacitive EMG (CEMG)
and surface EMG (SEMG) signals. The study emphasizes the importance of
the surface area of capacitive electrodes, muscle force, preprocessing,
and sampling frequency in understanding and improving the correlation
between CEMG and SEMG signals, providing valuable insights for future
research and applications in the field. The study reveals that the
electrode area has no significant effect on the correlation. However,
the correlation significantly depends on the muscle force. In addition,
removing artifacts from the CEMG increases the correlation, especially
for lower force where artifacts are significant. Again, oversampling the
EMG signal above 800 Hz does not have any impact on increasing the
correlation but the correlation decreases with higher inter-electrode
distance (IED). In this research, the highest correlation of 92.94%
between CEMG and SEMG has been achieved for high muscle force with a
plate area of 4 cm2. Therefore, the capacitive electrode can be an
alternative for EMG signal acquisition.