Tissue electrodes in electrocardiograms (E-C-G) establish a conductive pathway for electrical currents between the tissues and the measuring electrodes, enabling the observation of heart activity.

The electrode-tissue interface dynamics has a circuit model encompassing electrode resistance, the capacitance at the electrode-tissue interface, and tissue resistance. The potential difference represents the voltage difference between the electrode and the tissue.

Here, the input impedance equals the tissue resistance. The output impedance is the addition of the tissue resistance to the parallel combination of resistance and capacitance at the electrode-tissue interface.

The ratio of the output phasor to the input phasor, calculated using the known resistance and capacitance values is the transfer function.

This can be approximated across three distinct frequency ranges.

The Bode magnitude plot on a semilog graph depicts the calculated logarithmic gain in decibels against frequency in radians per second.

The low and high-frequency asymptotes are horizontal lines with a constant gain. In the intermediate frequency range, the asymptotic magnitude plot is linear with a 20-decibel-per-decade slope.