Excitable Artificial Membrane Mimicking Nervous Membrane

Abstract

Sustained rhythmic oscillations of electrochemical potential occur spontaneously across a fine-pore membrane doped with glycerol-α-monooleate (monoolein), sorbitan monooleate (Span 80) or glycerol trioleate (triolein), separating equimolar solutions of KCl and NaCl : these oscillations occur in the absence of any external stimulus such as voltage, an electrical current, a hydrostatic pressure, or osmotic pressure. As an extention of these phenomena, spontaneous firing was found in a Langmuir-Blodgett film (L-B film) of dioleoyllecithin (DOPC) deposited onto a porous membrane. By comparing temperature dependences of liquid film of triolein and LB film of DOPC, a plan was suggested a construction of molecular assemblies to obtain desired oscillation patterns and pattern stabilities. Furthermore, electrical properties of these membranes (triolein, monoolein and L-B film of DOPC) were discussed by measuring current controlled voltage characteristics. The membrane was found to exhibit the properties of switching and differential negative resistance. In this presentation, the speaker insisted that electrical oscillation should be explained by phase transition and that phases should be defined by electrical resistances.