When metalic wire has been cut in a organic phase saturated with cholesterol and crown ether compounds,and then put into a suitable aqueous phase,the orientable adsorption of the amphiphilic lipid molecules at the interfaces of metal/organic and organic/aqueous phases resulted in a formation of the solid supported bilayer lipid membranes (S-BLMs) modified with mesomorphic crown ethers. The membrane potentials show Nernst response to the concentration of metal cations M+ in the aqueous solution at the concentration range of 10(-4)-10(-1) mol.dm(-3). The response to K+ is more significant than that to Rb+ and Na+. The responses to Li+, Cs+ and Mg2+ have not been observed. Trace amounts of Fe2+ and Fe3+ interferes with the determination.