Calibration Free and Fluorescein Based Fiber Optic pH Sensor for Clinical Applications

Abstract

This communication describes how fluorescein grafted at the end of an optical fiber can be used for calibration free pH sensing in the range of physiological values. The method is based on a complete mathematical description of the fluorescence mechanisms of this pH indicator. The analysis of the shape of the fluorescence spectra allows computing values of both the pH and the pKa3. Doing this, it becomes possible to access calibration pH sensing using conventional optical fibers. This is, to the best of our knowledge, the first fiber optic calibration free pH sensor reported to date. Keywords-pH sensing; calibration free; fluorescein; optical fiberI.

Fluorescence Spectra of Prototropic Forms of Fluorescein and Some Derivatives and Their Potential Use for Calibration-Free pH Sensing

“…Double silanization is an option [30]. The indicator layer must then be as reproducible as possible, which can be achieved using the method described in [31]. In this way, First, the migration of cations into the Nafion is clearly visible in Figure 8a.…”

“…Double silanization is an option [30]. The indicator layer must then be as reproducible as possible, which can be achieved using the method described in [31]. In this way, it is likely that a fluorescein-based calibration-free pH sensor can be fabricated using the spectroscopic data processing described in this paper.…”