Evanescent fiber optic sensors are being developed for remote in situ immunoassay. The evanescently excited fluorescence can be collected from either the proximal or distal end of the sensing fiber. The tradeoffs between the two directions of collection are investigated to determine the efficiency of fluorescence detection. Tetramethylrhodamine was used as the fluorescent standard with excitation by the 514.5nm line of an argon laser. A comparison of the two collection geometries demonstrated that although the distal end collection had a higher background, similar fluorescence concentrations were detected. The immunoassay technique was demonstrated with the specific binding of tetramethylrhodamine-conjugated goat anti-human immunoglobulin G (aH-IgG) to preadsorbed H-IgG on the sensor surface. A detection limit of 14nmole/L was measured. Future improvements and disadvantages of the current optical system are discussed, as well as the importance of quantifying the protein concentration in terms of the fluorescence.

Date Published: 8 April 1988
PDF: 6 pages
Proc. SPIE 0904, Microsensors and Catheter-Based Imaging Technology, (8 April 1988); doi: 10.1117/12.945232

Published in SPIE Proceedings Vol. 0904:
Microsensors and Catheter-Based Imaging Technology
Alan I. West, Editor(s)