Dynamic Modeling of a Stream-Current-Based Microfluidic Nanogenerator

A microfluidic nanogenerator (MF-NG) that utilizes stream current is developed to convert fluidic hydropower into a continuous direct current (DC) output, demonstrating superior performance and distinct advantages in ion transport manipulation and energy harvesting. Despite its promise, the operational mechanisms of this technology remain insufficiently understood. In this study, we establish a theoretical model for the MF-NG, simulating and analyzing the ion transport system within micro/nanoscale channels by coupling the Poisson equation, Nernst-Planck equation, and Navier-Stokes equation. We present a comprehensive theoretical framework that elucidates the dynamic interaction and equilibrium between displacement current and ionic transport current. Our findings offer a detailed understanding of electrokinetic energy conversion in MF-NGs. Key factors such as pressure, solution concentration, and surface charge, along with the effects of barrier electric fields, play crucial roles in determining charge distribution polarization and facilitating the establishment of the induced streaming electric field, leading to the formation of streaming potential. This work outlines an interdependent chain of constraints governing electrokinetic phenomena in pressure-driven flows, providing a solid theoretical foundation for the design and optimization of streaming-potential-based MF-NGs.