Cyclic compression and decompression of a lipid bilayer

In this study, we measure transient thicknesses of a lipid bilayer during electrostatic compression and decompression and deduce non-equilibrium molecular interactions of the surfactants' tails within the layer. The bilayer under investigation (sorbitan monooleate) is single-tailed and self-assembles between a water drop and hafnium oxide in dodecane. We detect minute changes in bilayer thickness (∼0.01 Å/s) resulting from step changes in electrostatic pressure. The dynamic response of the bilayer consists of an elastic response followed by an inelastic dissipative behavior. We observe a distinct asymmetry between the inelastic responses: compression triggers a linear reduction in thickness over time, whereas decompression induces a logarithmic increase in thickness.