Supplementary Material

The supplementary material includes (I) details on the numerical solving of the mPB model, (II) the inverse di- electric permittivity profile for a DPPC bilayer, (III) in- verse dielectric permittivity profiles for the DPPS bilay- ers, and their variation when the fitting function includes 0, 1 or 2 Gaussians, (IV) details on the calibration of the mPB model and the independent permittivity mea- surements on bulk water, (V) a comparison of Born and electrostatic energy profiles, (VI) the area compressibil- ity modulus as a function of hydration level at different temperatures, (VII) the dependence of the area per lipid, and relevant permittivities as a function of dw, and (VII) the list of simulated systems and their compositions.