Biosensing electrodes

A dual modality sensor 1 comprises a tissue contact electrode 9 and a mechanical sensor 11, overlying the electrode, configured to sense a mechanical displacement, or movement, through the electrode. The sensor may be used to reduce noise in bioelectrical signals from the tissue contact electrode by using a movement signal from the mechanical sensor to attenuate or remove motion artefact. The sensor may also be used to enhance physiological sensing by combining a bioelectrical signal from the electrode with a movement signal from the mechanical sensor to determine a physical property of the user. The mechanical sensor covering the electrode may comprise a vibration sensor, a microphone or a piezoelectric transducer. The electrode may comprise an electrically conductive layer defining a diaphragm of the mechanical sensor and may be a cutaneous electrode with a conductive bio-compatible material. The mechanical sensor may be disposed on a carrier that retains the electrode.