Effect of Electrode Size on Amplitude Estimation of HDsEMG Maps

The purpose of this work is to evaluate the effect of the electrode size on recorded High Density surface electromyography (HDsEMG) maps. We recorded the sEMG signals using a grid of electrodes (16 x 8) placed on biceps brachii (5 mm inter electrode distance, IED). Each instantaneous map was interpolated using the 2D Sinc function to obtain a "continuous" map (CM, with 10,000 samp/m). To simulate acquisition with different electrode sizes, each CM was filtered with a circular averaging filter (2-10 mm diameter) and re-sampled with 10 mm IED. Inverse transfer function to compensate the effect of electrode size was applied on each map. The results suggest that greater electrode size implies higher error of power (RMS2) of each map values with respect to the CM. The error of power estimation introduced by electrode size is smaller than the error due to IED.