In this work, we exploit the general-purpose solver COMSOL, equipped with electrolyte and semiconductor physics modules, to implement a versatile model of potentiometric chemical sensors including arbitrarily complex surface reactions at the oxide/electrolyte interface with examples on 2D devicelevel simulations of an ISFET. Firstly, Multiphysics simulations of V TH sensitivity to pH sensing are compared with analyses based on semiconductor TCAD. Then, more complex Na + sensing experiments are examined and numerical simulations are compared against 1D electrochemical models.