Abstract: The present invention provides a biosensor comprising at least one lipid membrane, each membrane including at least one gated ion channel. The membranes comprise a closely packed array of self-assembly amphophilic molecules and the gated ion channel has a conductance which is dependent upon an electric field applied across the membrane. The biosensor of the present invention may comprise a plurality of discrete membranes each including at least one gated ion channel. The conductance of each of the membranes is measurable independently of the conductance of the other membranes.