In-Silico EIS Characterization of Supported Lipid Bilayers on PEDOT:PSS Electrodes

Lipid bilayers are essential structures in life sciences and bioelectronics. One of their key features is their ability to compartmentalize electrolyte domains, allowing cells to selectively exchange ions, create concentration gradients, and establish electric potential differences. In the field of organic electronics, supported lipid bilayers (SLBs) on conductive polymer electrodes enable the study of specific ion-channel proteins or the detection of pore-forming toxins. For this purpose, scientists often employ electrochemical impedance spectroscopy (EIS) measurements. However, this technique is very sensitive to membrane leakage and defects, leading to challenges in data reproducibility and quantitative analysis. In successful experiments, the impedance data is numerically fitted with circuit models, and the relative changes in membrane resistance are used as transduction mechanisms.
In this work, we performed extensive finite-element method (FEM) simulations on SLB-coated PEDOT:PSS electrodes to analyze the impact of defects in SLBs on EIS. In particular, we investigate SLB ionic leakage based on the size and spatial distribution of single and multiple pores and compare that to experimental data. Furthermore, we propose and validate circuit analytical models using FEM simulations to shed light on ionic conductive paths and provide understanding of the main contributors to the membrane resistance.