Table of Contents
Conference Papers in Science
Volume 2015, Article ID 513621, 8 pages
Conference Paper

Optical pH Detection with U-Shaped Fiber-Optic Probes and Absorption Transducers

1Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno 2, Czech Republic
2Institute of Photonics and Electronics AS CR, v.v.i., Chaberská 57, 182 51 Praha 8, Czech Republic

Received 12 December 2014; Accepted 18 February 2015

Academic Editor: José B. Quintana

This Conference Paper is based on a presentation given by Jakub Zajíc at “Meeting on Materials and Their Applications for Devices and Sensors 2014” held from 5 November 2014 to 7 November 2014 in Mahdia, Tunisia.

Copyright © 2015 Jakub Zajíc et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In medicine knowledge of pH values can provide us with information not only about the patients’ status but also about physiological processes in the patient’s body. Measurements of pH in small-sample volumes and online pH monitoring in vivo can be employed to obtain such information. For such measurements we have developed and investigated U-shaped fiber-optic probes with immobilized pH indicators in this paper. U-shaped probes with a diameter of about 2 mm were prepared. Three different pH indicators, methyl red, methyl orange, and bromothymol blue, were immobilized in two types of matrices, namely, porous silica (PS) and ethylcellulose (EC), and applied on the U-shaped probes. Changes in spectra of transmitted power were measured and calibration curves were determined from these spectra. It has been found that a working pH range of prepared probes was from 3.1 to 7.6. The maximum sensitivity was about 0.1 1/pH unit. Effects of structural relaxations of detection layers and indicator leaching observed in experiments are discussed.