Abstract: The invention relates to synthetic proteins that can be used in in vitro sensing devices to detect the presence of physiologically active substances. The synthetic proteins are mimetic to native ion channels in mammalian systems. The invention also relates to a biosensor comprising a support assembly, a synthetic lipid bilayer containing the active channel protein. Lastly, the invention relates to the use of the biosensor disclosed in the application for the in vitro detection of physiologically active substances including antiseptics, antibiotics, neurotransmittors, and others.