 Lipid bilayer

A lipid bilayer is a self-assembled double layer of amphiphilic molecules. Its bending modulus controls thermal undulations and the resulting interaction between nearby membranes.

The lipid bilayer is a fundamental structure of cell membranes, composed primarily of phospholipids. In this bilayer, phospholipids arrange themselves in two layers with their hydrophilic (water-attracting) "heads" facing outward towards the water inside and outside of the cell, and their hydrophobic (water-repelling) "tails" facing inward, away from water.