This document presents an apparatus comprising: a first signal line (201) configured to couple signals from a first electrode (200) to a signal detection circuitry for measurement of biometric signals sensed by the first electrode a second signal line (203) configured to couple signals from a second electrode (202), different from the first electrode, to the signal detection circuitry for measurement of biometric signals sensed by the second electrode and a coupling circuitry (218) configured to selectively couple the first signal line and the second signal line to a common electrical potential so as to equalize electrical potential difference between the first electrode and the second electrode. The selective coupling enables the suppression of interference caused by different charges in the electrodes due to a triboelectric effect.The apparatus may be configured to measure a heart activity (ECG), or muscle activity using electromyography (EMG).
