Fluorescence-based optical sensor and method for detection of lipid-soluble analytes

A sensor, probe, system and method for detecting the presence of or concentration of lipid-soluble analytes such as anesthetics, which involve the use of fluorophore-containing lipid layers or similar amphiphilic structures as the sensor. The lipid layer is constituted such that it has a phase transition temperature equal to or close to the temperature at which the measurement of the analyte is conducted. Partitioning of a suitable analyte into the lipid layer results in a phase change which is then reflected in a change in a fluorescence characteristic, such as a shift in the wavelength of maximum intensity of fluorescence, of the fluorophore, in proportion to the amount of analyte.