FLEXOELECTRICITY AND PHOTOFLEXOELECTRICITY IN MODEL AND BIOMEMBRANES

Flexoelectricity provides an exact relationship between electric and m echanical degree of freedom of a bilayer membrane, i.e. between transm embrane voltage and membrane curvature. Detailed studies by means of l aser stroboscopic interferometry technique of direct flexoelectric eff ect in dipolar, zwitterionic and charged black lipid membranes (BLMs) and first observation of converse flexoelectric effect in an uranyl ac etate-stabilized BLM are reviewed and theoretically interpreted. A new effect also involving another, optical degree of freedom of BLM, i.e. photo-flexoelectricity, was discovered very recently. It is observed in a composite BLM containing in-situ generated photo-semiconductor Cd S nanosized particles (mimicking integral proteins of biomembranes) up on bandgap illumination. Light-dependent flexoelectric response is rat ionalized in terms of curvature-modulated BLM photo-potential. Possibl e applications of these new effects in membrane sensors (for sound, li ght, chemical species), in membrane actuators and their biological rel evance are discussed.