Our interests have focused on the investigation and development of biosensors that use chemically selective membranes to measure the concentration of specific species in complex media. One fundamental idea is that protein, which can bind selectively to a specific organic or biochemical species, can be incorporated into an ordered lipid or surfactant membrane assembly such that selective binding events lead to changes in the structure of the membrane (transduction) that can be measured quantitatively. The primary advantage of this method of detection is that it is applicable to interactions of enzymes, antibodies, receptors, and lectins, and it may be extended to investigations of DNA/RNA hybridization. This detection method therefore provides a sensitive generic strategy for sensor applications. The central problem to be solved is how the alteration of the structure of a membrane that is caused by binding events of protein or genetic material can give rise to an analytical signal. We have been focusing our efforts in the areas of fluorescence spectroscopy and electrochemical methods. The electrochemical methods rely on detection in changes of the permeability of membranes to ions and provide systems with very low background signal, leading to the possibility of detection of single molecular-binding events. Fluorescent systems operate on the basis that a chemically selective membrane containing a fluorescent indicator can provide an analytical signal caused by the change of the structure of the membrane due to the binding events. Keywords: fluorescence, lipid membrane, electrochemistry, receptor, biosensor.