Flexible screen-printed graphene oxide-based biosensor for sweat sodium detection

Abstract

Sweat contains valuable biomarkers indicative of physiological health conditions such as electrolyte imbalance, stress, and disease, enabling continuous, non-invasive monitoring through miniaturized wearable electrochemical biosensors. Here, a flexible, cost-effective electrochemical sweat Na⁺ ion sensor is fabricated using a screen-printing method on a flexible polyethylene terephthalate (PET) substrate. The sensor incorporates a low-cost Ion-Selective Layer (ISL) and graphene oxide (GO) enhancing sensitivity and electrochemical performance across a broad range of Na⁺ ions. The sensor exhibits a high sensitivity of 1.213 mA/mM.cm², low limit detection of 14.49 mM, and good stability. Real-time sweat analysis demonstrated Na⁺ ion levels of 19 mM in the morning and 23 mM in the evening aligning with the analytical range of Na⁺ ion concentration in sweat. This work addresses challenges in precision and individual variability in Na⁺ ion concentration highlighting the potential of scalable, affordable sensors in wearables technology for personalized health monitoring.