Assessing the apparent effective thickness of the supported hybrid bilayermembranes consisting of octadecanethiol and phospholipid by ac impedance spectroscopy

The electrochemical behavior of the gold electrode modified by hybrid bilay er membranes in different concentrations of Fe(CN)(6)(3-)/Fe(CN)(6)(4-) was investigated by electrochemical impedance spectroscopy and cyclic voltamme try technology. The electron transfer between gold and the redox species se parated by the hybrid bilayers assembly was completed by an electron tunnel ing process. A detailed equivalent circuit for electron transport across th e HBMs is proposed. It was found that the apparent effective thickness of t he hybrid bilayer membranes was lower than that of the sum of the chain len gth of octadecanethiol and phospholipid so some possible collapsed sites mi ght exist at the hybrid bilayer membranes.