High-precision and fast-response Graphene-Au interdigitated electrode for long-term stability in wearable EEG and ECG monitoring

Abstract

Developing highly sensitive and stable biomedical electrodes is crucial for brain-computer interfaces, wearable devices, and implantable devices. Research on biomedical electrode materials has made certain progress; however, there is still a need for further improvement in providing sufficient spatial and temporal resolution to monitor more regions, as well as in providing reliable and stable long-term recording. Herein, Graphene-Au interdigitated electrodes have been developed for high-fidelity, simultaneous acquisition of electrocardiography (ECG) and electroencephalography (EEG) signals. In this work, the graphene material exhibits excellent electrical conductivity and good biocompatibility, and the interdigitated electrode structure can improve the collection accuracy and response time. The results show a rapid response time of 412 ns and a low electrode-electrolyte interface impedance of 20.8 $\Omega$ for lateral conduction on dry skin, alongside a contact impedance of 207 k$\Omega$ at 200 Pa, demonstrating high sensitivity and signal integrity. The electrodes exhibit stable and consistent performance in acquiring EEG and ECG signals, with accuracy comparable to traditional Ag/AgCl electrodes, as validated in emotion monitoring experiments capturing distinct physiological features. Additionally, the electrodes demonstrate exceptional durability for continuous health monitoring, maintaining a stable root mean square (RMS) peak signal of 201 $\pm$ 16 $\mu$V and a 100% P-wave detection rate in ECG recordings throughout 700 bending cycles. It overcomes traditional electrodes’ limitations in temporal resolution, biocompatibility, and long-term stability. This work provides a novel approach for designing next-generation flexible wearable medical monitoring devices.