The topographic data contained within the AFM images give a peak-to-peak distance across the square lattice of 181 and 233 Å for MO:DOPS 98:2 and MO:DOPS:CHOL 67:3:30 mol% respectively. For a surface where the bilayer is continuous, one of the two water channel networks within the QII phase is 'capped' while the other is open to the external water. The peak-to-peak spacing therefore represents the spacing of water channels within one network. For the 𝑄 𝐼𝐼 𝑃 phase, the spacing would therefore represent the size of the cubic unit cell (see simulations in Figure ).