Multiscale investigation of polyelectrolyte gel-based electronic devices*

Gel-based electronic devices (sensors and diodes) are attracting attention due to their low cost, favorable mechanical properties, and biocompatibility. We have performed coarse-grained molecular dynamics and continuum simulations of model polyelectrolyte gels used in such devices to study the relationship between voltage and ion distribution on the nanoscale. For sensors, we consider a system consisting of a negatively charged backbone and positive floating counterions. By interfacing two regions with different degree of ionizations, we compute the electrostatic potential difference and show that it obeys a modified Nernst-Donnan equation when accounted for counterion condensation [1]. The pressure is found to be proportional to the Donnan-Potential, which provides a molecular basis for the piezoionic effect observed in experiments. For gel-based diodes, we interface two gels with oppositely charged ions, study its rectifying behavior with molecular simulations and challenge the results obtained through a description based on the Poisson-Boltzmann approximation.
[1] Triandafilidi, V., Hatzikiriakos, S. G., & Rottler, J. (2018). Molecular simulations of the piezoionic effect. Soft matter, 14(30), 6222-6229.