PHOTOFLEXOELECTRIC EFFECTS IN BILAYER-LIPID MEMBRANES

Cadmium sulfide (CdS) nanocrystalline particulate Films were generated, in situ, on one side of glycerol monooleate (GMO) bilayer lipid membranes (BLMs). The CdS growth on the GMO BLMs was followed by optical microscopy. Curvature-induced polarization (flexoelectricity) of GMO BLMs, in the absence and in the presence of CdS nanocrystalline particulate films, was investigated in the dark and under bandgap illumination. Flexoelectric responses were elicited by oscillating acoustic pressure, in the 100-1000 Hz frequency range, applied onto the side of the GMO BLM which did not contain CdS. Electric currents, generated under a voltage clamp, and membrane potentials, generated under a current clamp, were measured. GMO BLMs, in the absence of CdS, gave photoindependent flexoelectric responses. On the other hand, flexoelectric responses of GMO BLMs, decorated by CdS, changed upon illumination. Photoflexoelectric responses were observed to vary as a function of the amount of CdS deposited onto the GMO BLM. The obtained results were rationalized in terms of modulation of the illumination-generated photovoltage by the oscillating BLM.