Biomolecules such as transmembrane proteins and enzymes are often used as the selective medium in biosensors because of their inherent selectivity. For any sensing device, there is a chemically selective component that is connected to a transducer so that chemical signals can be converted to usable information. For such sensors, the biomolecule used for sensing must be maintained in its active form while in close proximity to the transducer surface. For this reason, we have embarked on a body of work aimed at producing a biomimetic transducer interface that will maintain biomolecule activity, and we have chosen lipid bilayers as the medium. The organization and structure of proteins and lipids in biological membranes is a fluid mosaic, and any interface we design must have similar fluid properties. To understand the fluid properties of bilayer structures and how to control them, we have examined molecular interactions and molecular-scale organization in lipid bilayer structures. With this understanding in place, we will be in a position to introduce biomolecules into the mimic membranes on the transducer surface for sensing applications. We focus on a system where a hydrophilic spacer is placed between the transducer surface and the polar head groups of the bilayer bottom leaflet. The lipid bilayer is composed of phospholipids or fatty acids, with the addition of small amounts of tethered pyrene as a chromophore. Fluorescence spectroscopic data indicate both the polarity of the pyrene immediate environment and the extent to which the chromophore is aggregating within the bilayer structure. Electrochemical data point to the lower leaflet exhibiting limited organization, with a distribution of environments available to pyrene which depend on the identity of the bilayer constituents.