Measurement of wearable electrode and skin mechanical interaction using displacement and pressure sensors

This paper presents the methods of measuring electrode-skin mechanical interaction which is closely related to the motion artifacts of bio-potential body surface electrode. The interaction was defined as inplane electrode-skin relative movement parallel with skin and their contact pressure perpendicular to skin. The wearable electrode was fabricated using sliver coated fabrics. Thin film pressure sensor and optical displacement sensor were integrated into the electrode for electrode-skin relative movement and their contact pressure measurement. The sensor-embedded electrode were placed at specific position: RA, LR and RL for electrocardiogram (ECG) recording with a default pressure of 2KPa. Electrode-skin relative movement and their contact pressure was measured during designate body movement and exercise. The results demonstrated that electrode-skin relative movement speed was in the range of 0-50mm/sec. Spectrum analysis revealed that the movement frequency laid within 0-2.5Hz which overlapped with normal ECG signal but attenuated quickly. Electrode-skin contact pressure was within the range of 0.4-1.7KPa and showed influential effect on ECG signal which can be adopted in adaptive filtering for reducing motion artifacts.