The development of conventional BLMs (planar lipid bilayers) and later s-BLMs and sb-BLMs, have made it possible for the first time to study, directly, electrical properties and transport phenomena across a 5 nm ultrathin film separating two phases, in particular as models of biomembranes. As a result of extensive studies over the past 4 decades, biomembranes have now been recognized as the basic structure of Nature's sensors and molecular devices. To impart relevant functions in BLMs, a variety of compounds such as ionophores, enzymes, receptors, pigments, tissues, etc. have been embedded. Some of these incorporated compounds cause the BLMs to exhibit non-linear phenomena and photoelectric effects. The self-assembled lipid bilayer, the most crucial component of all biomembranes, is in a liquid-crystalline and dynamic state. Such a system, as we know intuitively, must act as some sort of a transducer capable of gathering information, processing it, and then delivering a response based on this information. Today, planar lipid bilayer research is a matured field of endeavor, as a result of applications of many disciplines and techniques including interfacial chemistry, electrochemistry, patch-clamp techniques, spectroscopy, microelectronics, and others. In membrane reconstitution experiments, for example, the evidence is that intracellular signal transduction begins at membrane receptors. The research area covered in this paper is highly interdisciplinary. Emphasis has been placed on basic research. The past work has been benefited by a cross-fertilization of ideas among various branches of sciences. The biomimetic approach to practical applications is unique and full of exciting possibilities. We can glean the design principles from Nature's successful products and apply them to our research and development from which molecular medicine and advanced biosensors may ultimately depend.