Total internal reflection fluorescence spectrometry using a dual optical fiber sample cell

A novel total internal reflection fluorescence (TIRF) spectrometric technique using a dual optical fiber sample cell was developed. A conventional silica optical fiber was used for exciting fluorescence compounds in its evanescent wave field. A liquid core waveguide (LCW) was used to collect the fluorescence photons emitted from fluorescence compounds existing in an excitation fiber's evanescent wave field. The collected fluorescence photons were guided through the LCW and sent to a fluorescence spectrometer for detection. The spatial separation of excitation light and fluorescence light reduces the excitation-light-related optical noise signal, which is the major factor limiting fluorescence techniques from achieving lower detection limit. Preliminary results obtained from this work indicate that the optical fiber TIRF system of this work can detect 4.6*10(-18) mole rhodamine 6G (2.7*10(6) molecules) existing in the evanescent wave field of the excitation optical fiber.