Performance enhancement of graphene-based biopotential electrodes through electrical contact geometry optimization

Electrocardiography (ECG) is crucial for diagnosing and monitoring heart conditions, providing real-time insights into the heart's electrical activity. It enables early detection of cardiovascular issues, guiding effective treatment and improving patient outcomes. Therefore, ECG signal quality is vital for accurate diagnosis and monitoring of heart conditions, as poor signal quality can lead to misinterpretation and incorrect treatment. In this regard terminal contact resistance is crucial for the performance of biopotential electrodes for ECG measurements. Maintaining low contact resistance is important for high-quality signal acquisition, reducing noise, and preserving signal intensity. In this paper, we developed PVDF (polyvinylidene fluoride)/GNP (graphene nanoplatelets) dry flexible electrodes for ECG application and conducted a comprehensive study on the impact of contact geometry and the number of contact points on output signals. Our investigation revealed that electrical resistance decreases progressively with an increase in the number of contact points around the electrode. Specifically, the highest resistance was recorded at 141.43 ± 67.6 Ω for a single point contact, while the lowest resistance was 59.63 ± 10.8 Ω for circumferential contact. Additionally, we observed that the signal-to-noise ratio (SNR) significantly improved with increased contact points, that is, for single contact point measurement was lower at 24.6 dB, whereas the SNR for circumferential contact measurement was higher at 26.4 dB. This enhancement in SNR resulted in improved ECG signal quality by minimizing noise and enhancing signal clarity. Consequently, these findings suggest that optimizing the contact geometry of PVDF/GNP dry flexible electrodes can lead to more accurate and reliable ECG recordings, providing valuable insights for the development of better-performing biomedical sensors.