Conformal Dry Electrode for ECG Monitoring

This work reports the fabrication and testing of a conformal and soft dry electrode for Electrocardiogram (ECG) monitoring to address the limitations associated with traditional gel electrodes. Gel electrodes are the gold standard for bio-signal capturing, but they come with challenges like skin preparation, drying out, and skin irritation. The developed dry electrode material is anisotropic conductive rubber. The fabrication process involves screen printing Ag paste on the substrate to create a lead set, stencil-printing the dry electrode design at the top end, and finally embedding an adhesive layer to ensure firm contact with the subject surface. The dry electrode shows low electrode–toelectrode impedance (1.4Ω at 10Hz), a minimal DC offset of 10μV, and a low signal-to-noise ratio for ECG measurements compared to gel electrodes in similar conditions. Testing in contact with Ag and conductive rubber surfaces over 160-170 hours shows stable performance. In addition, dry electrode demonstrates elongation of up to 600% with a modulus less than that of human skin. Thus, they are capable of being worn with both comfort and improved electrical contact. Bending cycling, while in contact with flexible Ag, the dry electrode maintains their performance for over 1500 cycles. Future research will focus on developing a multi-lead set, and further characterization such as breathability and triboelectric noise of the lead set.