Abstract:
This study presents an adaptive analogue calibration method to compensate electrode–skin impedance mismatch
during biopotential signal (electrocardiogram, electroencephalogram and electromyogram) acquisition with enhanced immunity
to electromagnetic interference (EMI). The method continuously measures the variation of the impedance mismatch between
the electrode–skin interfaces arising primarily due to motion artefacts, and thereafter compensate for the resulting distortions at
the output. The compensation is done with the help a proportional–integral–derivative controller in the feedback loop, together
with the acquisition of the biopotential signals. A common mode shunt feedback at the output attenuates the common mode EMI
and reduces the common mode deviation. As compared to previously reported techniques, the proposed technique refutes any
need for offline manual calibration and shows a significant improvement in EMI attenuation without interrupting the main
system's operation. This study explains the proposed technique with the comprising blocks, illustrates the theoretical models
and analyses, and evaluates the superior performances of the proposed method by comparing the responses with those
obtained from the other EMI-Immune electrode mismatch compensating front-ends existing in the literature.
