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Proceedings Paper

Submicron fiber optic sensors for calcium ions and pH with internal calibration
Author(s): Markus Plaschke; Michael Geyer; Johannes Reichert; Hans-Joachim Ache
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Paper Abstract

Submicron optical sensors can be prepared by immobilization of fluorescent indicators on tapered fiber tips. However, fluorescence intensity based sensing depends on many parameters (e.g. light source, collection geometry, quenching effects, etc.) and therefore quantification is usually complicated. Ratio measurements are established as a common method to quantify fluorescence signals using a sensing and a reference dye. The sensors described in this work are based on a new immobilization concept which consists of the encapsulation of dextran-linked fluorescence indicators in an organic hydrogel. This concept allows co-immobilization and stable encapsulation of different indicators. The calcium- and pH-sensors presented contain dextran-coupled fluorescein- derivatives as indicators (Calcium GreenTM and fluorescein) and a rhodamine-derivative (Texas RedR) as reference dye, co-immobilized in PolyHEMA. These sensors exhibit a signal stability of several weeks (when stored in buffer solution), fast response times and calibration curves which are not affected by immobilization. Due to the ratio measurement signal reproducibility was less than or equal to 5%. The working lifetime of submicron sensors was limited only by photobleaching of the indicators which can be minimized by reduction of the laser power. The dynamic range and short response times of these sensors suggest applications in physiological fluids, cell cultures or micro-bioreactors.

Paper Details

Date Published: 30 May 1997
PDF: 7 pages
Proc. SPIE 3105, Chemical, Biochemical and Environmental Fiber Sensors IX, (30 May 1997); doi: 10.1117/12.276178
Show Author Affiliations
Markus Plaschke, Forschungszentrum Karlsruhe (Germany)
Michael Geyer, Forschungszentrum Karlsruhe (Germany)
Johannes Reichert, Forschungszentrum Karlsruhe (Germany)
Hans-Joachim Ache, Forschungszentrum Karlsruhe (Germany)

Published in SPIE Proceedings Vol. 3105:
Chemical, Biochemical and Environmental Fiber Sensors IX
Robert A. Lieberman, Editor(s)

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