Optimization of dry laser-induced graphene (LIG) electrodes for electrocardiography (ECG) signals monitoring

Abstract

This work presents the optimization of the fabrication procedure for laser-induced graphene (LIG) electrodes intended for biopotentials acquisition. The results presented in this study demonstrate a significant improvement with respect to the performance obtained for other LIG-based electrodes previously reported in the literature. In particular, we propose the use of a galvanometric laser instead of a CNC laser to improve the engraving resolution and the LIG synthesis process, thus enhancing the surface area of the interface skin–electrode. For that, we have studied the resistance of the resulting LIG patterns as a function of the laser parameters (engraving power and scan speed) seeking their optimization. After tunning the laser fabrication process, we have fabricated and characterized electrocardiogram (ECG) electrodes with different surface areas using a commercial silver-based electrode as a reference. Thus, circular electrodes with a diameter of 15 mm, 10 mm and 6.5 mm were used to acquire the ECG on different volunteers using a commercial equipment. The signals acquired were processed afterwards with cutting edge processing techniques to perform a statistical analysis in terms of sensitivity, specificity, positive prediction and accuracy for the detection of QRS complexes. The results demonstrate that the proposed electrodes improve the signal acquisition with respect to the previously reported LIG-based electrodes in terms of noise and do present comparable or even better results than commercial electrodes (even with a smaller surface area) with the additional advantage of not requiring the use of an electrolyte gel.

Graphene-Enabled Wearable for Remote ECG and Body Temperature Monitoring

“…On the one hand, LIG has been identified as a promising active material in conventional electrochemical double-layer capacitors (EDLCs), whose charge storage is realized by electrostatic adsorption, owing to its high specific surface area [29]. On the other side, the foam-like structure of the LIG is also of special interest to be used in electrodes for biosignals acquisition due to its high available surface area, which allows for a conformal contact when the electrode is pressed onto the skin, thus contributing to improving the acquisition performance by minimizing motion artifacts and noise [30], [31]. In these two cases, the laser parameters must be adjusted to maximize the electrical conductivity of the resulting material, thus reducing electrical losses and maximizing the power density in supercapacitors applications, and improving the contact resistance and Signal-to-noise ratio (SNR) in biosignals acquisition.…”