A fiber-optic redox sensor for the iron(III)-iron(II) transition

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Redox-sensitive dyes are crucial for electrochemical sensing.
• Phenosafranine is a photoactive dye with distinct optical properties in oxidized and reduced states.
• Nafion films provide a stable matrix for immobilizing dyes for sensor applications.

Purpose of the Study:

• To develop a functional redox-sensitive optical sensor.
• To investigate the optical properties of phenosafranine immobilized in a Nafion film.
• To evaluate the sensor's performance in monitoring redox potential changes.

Main Methods:

• Immobilization of phenosafranine dye within a Nafion film.
• Attachment of the film to a fiber-optic probe.
• Optical absorbance measurements under varying redox conditions.
• Comparison with a commercial redox potential electrode.

Main Results:

• The phenosafranine-Nafion film exhibited changes in optical absorbance corresponding to its redox state.
• High absorbance was observed under high redox conditions (open nitrogen-purged solution).
• Low absorbance was observed under low redox conditions (iron(II) solution).
• The optical sensor accurately tracked redox potential changes during titration, mirroring a commercial electrode.

Conclusions:

• A fiber-optic redox sensor based on phenosafranine-Nafion film is feasible and effective.
• The sensor demonstrates predictable optical responses to redox potential variations.
• This technology offers a promising alternative for optical monitoring of redox environments.