Highly Sensitive CH₄/C₂H₂ Dual-Component TDLAS Sensor Based on a Dual-Channel Hexagram Multi-Pass Cell

Area of Science:

• Spectroscopy
• Gas Sensing
• Analytical Chemistry

Background:

• Accurate detection of methane (CH4) and acetylene (C2H2) is crucial for environmental monitoring and industrial safety.
• Existing methods may lack the sensitivity or real-time capabilities for simultaneous detection of both gases.

Purpose of the Study:

• To develop and demonstrate a novel tunable diode laser absorption spectroscopy (TDLAS) sensor for highly sensitive, simultaneous detection of CH4 and C2H2.
• To design and optimize a dual-channel multi-pass cell (MPC) for enhanced gas absorption and real-time synchronous monitoring.

Main Methods:

• Development of a vector-based ray-tracing model for multi-pass cell (MPC) design.
• Implementation of a dual-channel MPC with an interlaced dual hexagonal star pattern.
• Simultaneous continuous monitoring of CH4 and C2H2 concentrations using TDLAS.

Main Results:

• The sensor demonstrated an excellent linear response to varying concentrations of both CH4 and C2H2.
• Achieved a minimum detection limit (MDL) of 132.08 ppb for CH4, improving to 77.32 ppb with a 300s averaging time.
• Measured an MDL of 20.19 ppb for C2H2, which was further reduced to 3.50 ppb with a 300s averaging time.

Conclusions:

• The developed TDLAS sensor offers a highly sensitive and effective solution for simultaneous real-time detection of CH4 and C2H2.
• The novel dual-channel MPC design significantly enhances gas absorption and synchronous monitoring capabilities.
• This technology holds promise for applications requiring precise and rapid gas analysis.