Poisson Nernst Research Articles

Numerical Simulations of Electrical Double Layer and Electroosmotic Flow in a Nanopore By Openfoam

The microfluidic chip transfers the pretreatment, chemical reaction, separation, detection, and other functions of the sample to a chip of several square centimeters, which embodies the characteristics of miniaturization, integration, automation, and simplicity. The drive and control of microfluidic have become the key problems in the research of microfluidic chip. In this work, numerical simulation of the electrical double layer (EDL) formed next to a charged planar surface and an electroosmotic flow (EOF) in a nanopore is demonstrated using OpenFOAM. The electrostatics and the ionic mass transport are governed by the Poisson–Nernst –Planck (PNP) equations without considering fluid motion in the model for EDL. The numerical predictions of the electric field and ionic concentrations are in good agreement with the analytical solution. The model for EOF includes the modified Stokes equations for the flow field, the Poisson equation for the electrostatics, and the Nernst–Planck equations with the convective term for the ionic mass transport. The predicted EOF velocity quantitatively agrees with the analytical solution.

Mathematical modeling for the ionic inclusion process inside conducting polymer‐based thin‐films

AbstractIonic inclusion inside thin conducting polymer (CP) film is a major and common feature for actuator as well as membrane‐based drug release. In this study, an electro‐active polymeric thin‐film system has been conceptualized. PNP‐electro‐neutrality (Poisson–Nernst– Planck) based modeling framework with customized boundary conditions is used to depict the electrochemical phenomena. In dynamic model, kinetics of probable redox reactions is included along with electro‐migration and diffusion terms in the overall PNP framework. At steady state, interfacial voltage seems to hold the critically important role, while ionic migration and reaction kinetics play very crucial roles in determining the dynamics of such systems. The validated model predicts that lowering in the standard potential of the polymeric electrode accelerates the process of ionic ingress. Higher ionic flux is obtained using slower voltage scan. Variation of diffusivity shows the large spectrum of relatively unexplored dynamics for such electro‐active thin‐film‐based system. The significance is in designing actuator‐ or membrane‐based controlled molecular release systems. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

The cardiac ryanodine receptor: Looking for anomalies in permeation properties

Anomalies in the permeation properties of the cardiac RyR channel reconstituted into bilayer lipid membranes were investigated systematically. We tested the presence of the anomalous mole fraction effect (AMFE) for the ion conductance and the reversal potential with varying mole fractions of two permeant ions, while the total ion concentration was lower, as in previous studies, to avoid the masking effect of the channel pore saturation with ions. Mixtures of Ba 2+ with other divalents (Ca 2+, Sr 2+), of Ca 2+ with monovalents (Li +, Cs +), and of Na + with other monovalents (Cs +, Li +) were used. We revealed a clear anomaly only for the ion conductance measured in the Na +–Cs + and Ca 2+–Li + mixtures as computed by a Poisson–Nernst–Planck/density functional theory (PNP/DFT) model. Furthermore, we found a significant minimum in the concentration dependence of the reversal potential determined under Li +/Ca 2+ bi-ionic conditions. Our study led to new observations that may have important implications for understanding the mechanisms involved in ion handling in the RyR channel pore; furthermore our results could be useful for further validation of ion permeation models developed for the RyR channel.