Propagation of a thermo-mechanical signal on a lipid bilayer

A simplified model of a neuron consists of an artificial lipid membrane that possesses interesting thermodynamic properties as it changes from a gel to a liquid state. The propagation of sound waves on lipid monolayers supported on water has been previously studied during the melting transition. However, a lipid bilayer is a more approximate model of a cell membrane. A solitary wave has been thought to occur when a tiny section of a membrane in its fluid phase is brought to the gel phase. In this work, we designed and built an experimental setup to assemble long artificial lipid bilayers under water, comparable in length to a large real neuron (0.1 m). To trigger a melting transition at one end of the membrane, we applied localized heat stimulation. At the other end, we found the arrival of a thermo-mechanical perturbation. Our findings may support the existence of solitary waves, which may confirm that not only electrical signals explain the propagation of information along the nerves as it has been traditionally thought, but thermodynamics may also play an important role in the propagation of isentropic signals together with the action potential.