Modeling and Simulation of Thermo-Fluid-Electrochemical Ion Flow in Biological Channels

TL;DR

This paper extends the classical electrodiffusion model for ion transport in biological channels by incorporating thermal effects through new thermo-fluid-electrochemical models, validated via simulations of realistic channels.

Contribution

It introduces two novel velocity-extended models, vTHD and vET, that include thermal forces and energy conservation, advancing the modeling of ion transport in biological channels.

Findings

Successful simulation of Gramicidin-A channel

Simulation of bipolar nanofluidic diode

Models incorporate thermal effects into ion transport

Abstract

In this article we address the study of ion charge transport in the biological channels separating the intra and extracellular regions of a cell. The focus of the investigation is devoted to including thermal driving forces in the well-known velocity-extended Poisson-Nernst-Planck (vPNP) electrodiffusion model. Two extensions of the vPNP system are proposed: the velocity-extended Thermo-Hydrodynamic model (vTHD) and the velocity-extended Electro-Thermal model (vET). Both formulations are based on the principles of conservation of mass, momentum and energy, and collapse into the vPNP model under thermodynamical equilibrium conditions. Upon introducing a suitable one-dimensional geometrical representation of the channel, we discuss appropriate boundary conditions that depend only on effectively accessible measurable quantities. Then, we describe the novel models, the solution map used to iteratively solve them, and the mixed-hybrid flux-conservative stabilized finite element scheme used to discretize the linearized equations. Finally, we successfully apply our computational algorithms to the simulation of two different realistic biological channels: 1) the Gramicidin-A channel considered in~\cite{JeromeBPJ}; and 2) the bipolar nanofluidic diode considered in~\cite{Siwy7}.