Effect of nanochannel geometry on electrokinetic ion transport in a micro-nanofluidic system

In this paper, the electrokinetic ion transportation in a micro-nanofluidic system is demonstrated through employing Poisson-Nernst-Planck equations coupled with Navier-Stokes equations. The effects of nanochannel geometry, volumic surface charge density, nanochannel length and nanochannel radius on the electric field, ion transport field, and fluid field are investigated. Theoretical research shows that the potential drop relies mainly on the nanochannel’s volume instead of nanochannel geometry. Two acute-angle structures in a trapezoid nanochannel relative to a right-angle structure in a semicircular or rectangular nanochannel can intensify the electric double layer field. For a cross sectional shape of the trapezoid, a higher ion concentration is obtained through enhancing the volumic surface electric charge, increasing the nanochannel length, and decreasing the radius. The results enabled the provision of a beneficial method for better understanding the design principle of the nanochannel structure.