Enhancing Screen-Printed Electrode Performance Through Simulation-Driven Design Optimization for Wearable Applications

Wearable biosensors are transforming remote health monitoring with non-invasive sweat biomarker detection. Nevertheless, achieving reliable sensing requires miniaturized, flexible platforms capable of detecting, with ultra-high sensitivity, biomarker levels down to pg/mL. Electrochemical platforms, especially those using three-electrode platforms, hold significant promise but require careful geometric optimization to meet these needs. To address this, we evaluated four geometric layouts of screen-printed carbon three-electrode platforms on flexible polyethylene terephthalate (PET) substrates. Our investigation comprises experimental evaluations by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), supported by simulations through a novel 3D COMSOL Multiphysics<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> model. The results reveal that a fourfold increase in the active area leads to a twofold increase in the CV peak currents, while reduced electrode spacing enhances current density and minimizes diffusion effects. Comparisons of experimental and simulated CV currents show that larger areas may be more prone to surface disuniformities, making performance more dependent on material properties than on area optimization. The EIS analysis reveals that a fourfold increase in the active area reduces charge transfer resistance (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_CT</i>) by 45%, while doubling the electrode distance results in a 29% increase in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_CT</i>, indicating inefficient charge transfer due to weakened electric fields and reduced charge carrier concentration. Our findings highlight the need for compact designs and simulation-guided geometric optimization for enhanced performance.