[Show abstract][Hide abstract] ABSTRACT: Reports on the microfabrication of liquid core waveguides (LCW) using Teflon<sup>®</sup> AF for integration in microfabricated micro total analysis systems. Teflon<sup>®</sup> AF has an index of refraction less than that of water. Straight micro channels (≤500 μm width, ≤100 μm depth) etched into a Pyrex wafer were coated with Teflon AF and sealed with a Teflon AF coated Pyrex capping wafer. This formed a low index of refraction channel in which a higher index, aqueous solution was flowed. Light generated in the lumen propagated by total internal reflection (TIR) to the end of the channel where the light was detected using either a photomultiplier or a miniature spectrometer. An optical microscope was used to transversely illuminate the channel at various distances from the end to measure the waveguide properties.