Method of fluorescence analysis comprising evanescent wave excitation

Abstract

Fluorescence measuring methods and apparatus use planar optical waveguides to excite fluorescence in the evanescent field of the waveguides and photodetectors to sense the fluorescence produced. Chemically sensitive fluorophores are bound to the evanescent regions of the planar optical waveguides. Substrates support the waveguides. Photodetectors, positioned in the substrates with fields of view normal to the waveguides, detect the fluorescence. Wavelength-selective material coating surfaces of the photodetectors allow fluorescence to be detected while restricting entry of light at the excitation wavelengths. The photodetectors have high aspect ratios for detection of fluorescence generated by the optical waveguides. Preferably, the photodetectors are closely coupled to the fluorescence generated in the evanescent field of the waveguide. In alternative embodiments, lightguides near the waveguides direct fluorescence from the plane of the waveguides for transmission by integrated optical fibers to remote sensors. For chemical detection and analysis, energy is introduced to an edge of the waveguide. The edges are coated to reflect the energizing energy throughout the waveguide. The energy excites the chemically sensitive fluorophore film positioned on the waveguide. Inexpensive photodetectors without expensive photo-multipliers are mounted in substrates beneath the waveguides or at ends of lightguides extending from the substrates for detecting fluorescence.