Powerline Noise Mechanisms in Biopotential Measurements

Interactive simulation of how the 50/60Hz power grid corrupts ECG signals.

Interference Scenarios

Parameters

Electrode 1 Skin Impedance (Z1) 50 kΩ
Electrode 2 Skin Impedance (Z2) 50 kΩ
Impedance Mismatch (ΔZ): 0 kΩ

Adjust the sliders to simulate poor skin preparation. Notice how a difference between Z1 and Z2 drastically increases the noise.

220V / 50Hz Power Grid PATIENT Z1 Z2 Ground INA High Input Impedance Mechanism: The body acts as an antenna, picking up 50Hz AC voltage. Coupling Type: Capacitive (Electric Field from Grid) Damage: Increases Common-Mode Voltage (Vcm) on the entire body. High Vcm can saturate INA inputs or exceed its CMRR limits. Solution: Use a Right Leg Drive (RLD) circuit to actively cancel Vcm, and utilize amplifiers with extremely high CMRR.

INA Output Signal (Oscilloscope)