Thus, for pH ≪ pK a,base the microgel has a charge of q b,max = +N b e, while it becomes neutral in the limit pH ≫ pK a,base . As explained above, we describe the suspension of microgels using the cell model approximation, where a single microgel is located at the center of an electroneutral spherical cell, whose radius is determined by the microgel concentration. A schematic representation of the cell model is shown in Fig. . Although the cell model is considerably simpler than the full suspension, it cannot be solved analytically. As a further simplification, we introduce a mean-field approximation wherein the microions are represented as ideal point particles interacting with an electrostatic mean-field, disregarding correlations between them.