The efficient analysis of the function of ion channels is an important task in many different fields ranging from (bio)analytics and drug-screening to nanoelectronics. Here, the modulation of the channel activity of a synthetic ligand gated ion channel by a specific antibody is measured in tethered lipid bilayers by impedance spectroscopy. Tethered single lipid bilayers with exceptionally high electrical resistances suitable for the detection of a few channels are presented. [DOI: 10.1380/ejssnt.2005.203]