Abstract
Non-invasive glucose monitoring using physiological sweat offers a compelling alternative to traditional invasive blood sampling for diabetes management and personal metabolic tracking. However, low glucose concentrations in sweat, variations in physiological pH, and sensor mechanical instability under skin deformation remain major challenges. Here, we present a flexible, skin-conformal electrochemical biosensor utilizing electrodeposited hierarchical copper-cobalt oxide (Cu-Co oxide) nanostructures for continuous, non-enzymatic sweat glucose monitoring. The Cu-Co oxide nanostructured film was electrochemically deposited onto gold-patterned polyimide substrates, yielding high electrocatalytic activity toward glucose oxidation in near-neutral and slightly acidic physiological regimes. Integrated with a soft microfluidic routing channel, the platform continuous captures and refreshes sweat over active electrode areas. In benchtop evaluations, the sensor demonstrated a broad linear range from 10 µM to 1.5 mM, a high sensitivity of 1,420 µA mM⁻¹ cm⁻², a low detection limit of 2.1 µM (S/N = 3), and exceptional selectivity against common sweat interferences such as ascorbic acid, uric acid, and lactate. Mechanical testing demonstrated robust electrochemical performance after 1,000 bending cycles at a 3 mm curvature radius. On-body human trials during physical exercise revealed a strong correlation (R² = 0.93) between real-time sweat glucose dynamics and blood glucose values measured via standard finger-prick glucometers, accounting for a physiological lag time of approximately 9–11 minutes. This wearable microfluidic platform represents a promising advance toward fully continuous, non-invasive metabolic diagnostic systems.
