Knowledge of the association state of a protein, as either a monomeric or multimeric structure, is of interest when screening novel drug designs and in the quality control of recombinant binder proteins. This study reports on the development of a sensitive, convenient, and rapid binding-based method to detect the presence of quaternary protein structure in an engineered recombinant single-chain variable fragment (scFV), as the example. The method employs the Ion Channel Switch technology comprising an antigen-modified gramicidin ion channel, embedded in a tethered bilayer lipid membrane (tBLM). The conductive form of the ion channel is a dimer, with one half of the channel from each lipid leaflet. In the tethered bilayer, the outer lipid leaflet is diffusing laterally, whilst the inner leaflet is chemically fixed to a thin film gold surface. In addition, ion channels within the outer lipid leaflet are also diffusing, whilst the inner leaflet channels, like the inner leaflet lipids are chemically anchored to the gold surface. The lateral diffusion of the outer leaflet ion channel monomers leads to the dissociation and re-formation of conductive dimeric ion channels, in turn resulting in an interrupted ion flow across the lipid bilayer. For small channel numbers, this can be seen as current pulses arising from individual channel pairs. In the present study, millimetre diameter electrodes, comprising tBLMs containing millions of channels were employed. The electrode conduction, arising from the many randomly forming and dissociating channels, was measured using an a.c. impedance spectroscopy reader. Unlike the binding of an antigen-specific monomeric scFV, which can only bind to one antigen-modified ion channel, binding of an antigen-specific multimeric scFV results in forming pairs of outer leaflet channels only one of which can participate in a conducting dimer. This results in a decreased ion flow across the lipid bilayer. The method requires only microliters of nanomolar material and can respond in less than five minutes. The potential applications of this method include detecting residual levels of aggregation in recombinant binder proteins and testing potential drugs that can modulate the quaternary structure of proteins.