Dynamic modeling of steric effects on polarizable electrodes

We present a new dynamic ionic transport model to describe the interface of a polarizable electrode with an explicit expression of the steric effect. This is essential for describing the capacitive and transient responses of any field-effect chemical sensors in electrolytes. Based on the revised diffusivity and Einstein relation to account for steric repulsion, the model is named Steric Poly-Electrolyte Ebbed Drift Diffusion (SPEEDD). We then present experimental validation and extraction of the steric ionic size by the potential step responses. Correction to the hard-shell model is briefly discussed.