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Proceedings Paper

Development Of Porous Glass Fiber Optic Sensors
Author(s): P. B. Macedo; Aa. Barkatt; X. Feng; S. M. Finger; H. Hojaji; N. Laberge; R. Mohr; M. Penafiel; E. Saad
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Paper Abstract

A method for producing rugged, continuous porous glass fiber optic sensors was developed. pH and temperature sensors based on this technology have been successfully produced. The sensor portion of the fiber is made porous by selective leaching of a specially formulated borosilicate glass fiber. This results in a strong, monolithic structure where the sensor portion of the fiber remains integrally attached to the rest of the fiber (which acts as a light pipe), essentially eliminating losses at the sensor-light pipe interface. Pore size in the sensor can be controllably varied by modifying heat treatment conditions, making these sensors suitable for chemical concentration measurements in liquids and gases. Appropriate dyes were chemically bonded by silanization to the large interior surface area of the porous sensors to produce the pH and temperature sensors. Cresol red and phenol red were used for pH and pinacyanol chloride was used for temperature sensing. The sensitivity of these devices can be controlled by varying the concentration of the chemically bonded dye and the length of the porous region. Optical absorbance measurements were made in the visible range. The tip of the sensors was coated with a thin, porous layer of gold to reflect the incident light, resulting in a double pass across the porous sensor. Experimental measurements were made over a pH range of 3 to 8 and a temperature range of 28-70 C. These porous glass fiber optic sensors were found to be rugged and reliable due to their monolithic structure and large interior surface area for attachment of active species. A broad range of sensors based on this technology could be developed by using different active species, such as enzymes and other biochemicals, which could be bonded to the interior surface of the porous glass sensor.

Paper Details

Date Published: 16 January 1989
PDF: 6 pages
Proc. SPIE 0986, Fiber Optic Smart Structures and Skins, (16 January 1989); doi: 10.1117/12.948905
Show Author Affiliations
P. B. Macedo, Catholic University of America (United States)
Aa. Barkatt, Catholic University of America (United States)
X. Feng, Catholic University of America (United States)
S. M. Finger, Catholic University of America (United States)
H. Hojaji, Catholic University of America (United States)
N. Laberge, Catholic University of America (United States)
R. Mohr, Catholic University of America (United States)
M. Penafiel, Catholic University of America (United States)
E. Saad, Catholic University of America (United States)


Published in SPIE Proceedings Vol. 0986:
Fiber Optic Smart Structures and Skins
Eric Udd, Editor(s)

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