Hydrogel based Fabry-Pérot cavity for a pH sensor.

Area of Science:

• Optical Fiber Sensors
• Chemical Sensing
• Materials Science

Background:

• Accurate pH monitoring is crucial in various scientific and industrial applications.
• Existing pH sensing technologies often face limitations in response time, reliability, or complexity.
• Fabry-Pérot interferometry offers a promising platform for developing robust optical sensors.

Purpose of the Study:

• To develop a simple, reliable, and rapid fiber optic pH sensor.
• To investigate the performance characteristics of a Fabry-Pérot (FP) structure-based pH sensor.
• To evaluate the sensor's sensitivity and response time in acidic environments.

Main Methods:

• Fabrication of a Fabry-Pérot (FP) cavity using a pH-sensitive hydrogel and single-mode fiber (SMF) within a fused silica capillary.
• Characterization of hydrogel thickness using the spin coating method at varying spin speeds.
• Testing the sensor's response to different pH solvents in the acidic range.

Main Results:

• The proposed sensor achieved a pH sensitivity of 0.30 nm/pH.
• A fast response time of 15 s to 20 s was observed for acidic pH solvents.
• The temperature sensitivity of the fiber-based interferometer (FPI) sensor was determined to be -0.56 nm/°C.

Conclusions:

• A simple and effective fiber optic pH sensor based on a reactive Fabry-Pérot (FP) structure has been successfully demonstrated.
• The sensor exhibits excellent sensitivity and rapid response, making it suitable for real-time pH monitoring in acidic conditions.
• The developed sensor provides a reliable and quick method for optical pH sensing.