A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection

Area of Science:

• Optoelectronics
• Chemical Sensing
• Fiber Optics

Background:

• Simultaneous gas detection is crucial for environmental monitoring and industrial safety.
• Existing sensors often lack portability or the ability to measure multiple gases concurrently.
• Optical fiber sensors offer advantages in remote sensing and harsh environments.

Purpose of the Study:

• To develop a novel, portable optical fiber array-type sensing instrument for simultaneous real-time detection of oxygen, carbon dioxide, and ammonia.
• To enhance sensor sensitivity through fiber etching, polishing, and optimized dye coatings.
• To integrate a multi-sensing array with a real-time measurement module and human-machine interface.

Main Methods:

• Fabrication of an optical fiber array with etched and polished fibers for enhanced sensitivity.
• Coating single-mode fibers with dye for ammonia and temperature sensing, incorporating fiber Bragg and long-period filter gratings.
• Utilizing multimode fibers coated with specific compounds for carbon dioxide and oxygen sensing.
• Employing gas-induced fluorescent light intensity variation for gas concentration detection.
• Integrating photo-electronic modules and a human-machine interface for real-time data acquisition and processing using the piecewise-linear method.

Main Results:

• The developed instrument successfully measures oxygen, carbon dioxide, and ammonia simultaneously with temperature compensation.
• Oxygen sensor sensitivities were 1.54%/V (<1.5% concentration) and 9.62%/V (1.5%-6% concentration).
• Carbon dioxide sensor sensitivities were 8.33%/V (<2% concentration) and 9.62%/V (2%-5% concentration).
• Ammonia sensor achieved a sensitivity of 27.78%/V for concentrations below 2%.

Conclusions:

• The novel optical fiber array sensor enables simultaneous, real-time, and portable detection of key gases.
• The sensor design demonstrates high sensitivity and potential for various environmental and industrial applications.
• The integrated system with a human-machine interface facilitates practical gas monitoring.