Dry Laser-Induced Graphene Fractal-like ECG Electrodes

Abstract

Fractal-like geometries applied to biosignal-electrodes design show great potential for enhancing the signal acquisition of sensing systems. This study reports a novel approach for flexible, silver-free, and dry fractal-like electrodes based on Laser-Induced Graphene (LIG) obtained through laser photothermal processing of a commercial polyimide film. This one-step mask-less manufacturing process enables the simple fabrication of natural and optimized fractal-like shapes inspired by actual snowflake patterns. To ensure a reliable and standardized connection to the measurement unit, the electrodes are equipped with a snap terminal. The electrodes are structurally characterized using various techniques including Scanning Electron Microscopy (SEM), Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). By benchmarking the performance of these electrodes against Ag/AgCl wet commercial electrodes and LIG electrodes shaped as commercial ones, a heart rate-monitoring accuracy of over 96.8% is achieved, with high specificity, positive prediction, and sensitivity, surpassing the 95.8% achieved by conventional commercial electrodes. These results demonstrate the efficacy of fractal-based designs in combination with LIG-based transduction, offering flexible and cost-effective electrocardiogram (ECG) electrodes with improved performance compared to traditional wet electrodes.