Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

Area of Science:

• Sensor Technology
• Analytical Chemistry
• Optical Physics

Background:

• Accurate pH monitoring is crucial in various scientific and industrial applications.
• Existing pH sensing technologies face limitations in sensitivity, response time, or dynamic range.
• Optical-fiber sensors offer potential advantages for remote and multiplexed measurements.

Purpose of the Study:

• To develop and characterize a novel multichannel pH sensor utilizing optical-fiber pulse width modulation (PWM).
• To evaluate the sensor's performance metrics including sensitivity, linearity, response time, and reproducibility.
• To compare the proposed sensor's capabilities against established pH sensing methods.

Main Methods:

• Implementation of an optical-fiber sensing array based on the PWM technique.
• Calibration and testing of the sensor using standard pH buffer solutions (pH 2-12).
• Comparative analysis of performance with potentiometric, modal interferometer, and Fabry-Perot interferometer pH sensors.

Main Results:

• The optical-fiber PWM pH sensor exhibited high sensitivity (0.46 µs/pH) and excellent linearity (R² ≈ 0.997) over a broad pH range (2-12).
• Achieved a fast response time of approximately 8 seconds with good reproducibility (RSD ≈ 0.019).
• Demonstrated superior sensing abilities compared to other evaluated pH sensor types in terms of dynamic range, linearity, and response/recovery times.

Conclusions:

• The proposed optical-fiber PWM pH sensor is a highly sensitive, cost-effective, and reusable solution for multichannel pH monitoring.
• Its advantages include remote sensing capability, fast response, and excellent performance metrics.
• This technology presents a promising alternative for advanced pH sensing applications requiring high accuracy and efficiency.