A porous optical fiber is developed for use as a sensor for gases and liquids at low concentrations. The porous structure of the glass which remains after selective heat treatment, phase separation and chemical leaching of a borosilicate glass gives a very high surface area to the fiber. The sensitivity of the fiber is very high due to the large surface area. The porous fiber is initially tested for measuring ammonia vapors at very low concentrations. A small region (about 0.5 cm) of the porous fiber is treated with a reversible pH indicator dye. The device was demonstrated to be capable of reversibly sensing ammonia vapors. Ammonia vapor concentration as low as 0.5,4.01, was easily detected. The resulting light absorption in visible region is related to the sample ammonia concentration. The sensor device is calibrated for different ammonia vapor concentrations.

Date Published: 23 March 1988
PDF: 5 pages
Proc. SPIE 0838, Fiber Optic and Laser Sensors V, (23 March 1988); doi: 10.1117/12.942532

Published in SPIE Proceedings Vol. 0838:
Fiber Optic and Laser Sensors V
Ramon P. DePaula; Eric Udd, Editor(s)