Computational and Theoretical Methods for Mass-Transport Analysis in 3D-Printed Milli Fluidic Electrochemical Devices with Channel Band Electrodes

Available models for mass transport in microfluidic electrochemical sensors fall short in capturing critical features of millimeter-scale devices 3D-printed using fused deposition modeling, including inherent porosity and non-flat electrode geometries, thereby reducing their predictive power and transferability. Meanwhile, growing interest in low-cost and accessible fabrication methodologies has driven the quantitative use of these devices without first understanding the effects of such structural features on current responses. Here, the quantitative electrochemical performance of millimeter-scale 3D-printed devices with channel band electrodes is studied through computational and theoretical methods aimed at understanding their fundamental behavior. Simulations and dimensionless analysis reveal the influence of electrode shape and porosity on current responses under laminar flow. An adjusted Levich model is proposed to incorporate non-flat electrode geometries, while two new analytical models—general and transition-specific—predict currents through all mass transport regimes (convection, diffusion, and transition) that can simultaneously emerge due to porosity effects. Moreover, we introduce a low-cost “print–pause–print” fabrication strategy for such systems, employing a desktop 3D printer and 3D pen, which allows electrode integration and activation through polishing and “in-channel” electrochemical treatment. These advances facilitate developing next-generation 3D-printed milli fluidic electrochemical platforms with improved performance and scalability.