High-speed and high-sensitivity multi-gas detection based on parallel heterodyne LITES sensor

Area of Science:

• Spectroscopy
• Sensor Technology
• Chemical Analysis

Background:

• Traditional gas detection methods often struggle with simultaneous multi-gas analysis, speed, and sensitivity.
• Existing sensors may require complex calibration and processing for accurate concentration retrieval.
• There is a need for integrated systems capable of high-speed, high-sensitivity, and multi-gas detection.

Purpose of the Study:

• To introduce and validate a novel parallel heterodyne light-induced thermoelastic spectroscopy (PH-LITES) sensor.
• To achieve high-speed and high-sensitivity multi-gas detection using a synergistic signal enhancement and intelligent processing approach.
• To demonstrate the system's capability for accurate concentration retrieval of multiple gases simultaneously.

Main Methods:

• Development of a PH-LITES sensor integrating a cylindrical multi-pass cell (MPC) and a quartz tuning fork (QTF).
• Implementation of a collaborative signal enhancement architecture (CSEA) for improved detection responsivity.
• Application of a collaborative intelligent processing architecture (CIPA) with CNN-HAM-BiLSTM for spectral analysis and concentration retrieval.
• Utilized parallel heterodyne modulation for simultaneous spectral acquisition from multiple gases.

Main Results:

• Achieved high optical path length to volume ratio (37.4 cm⁻²) and utilized a low resonant frequency QTF (~7.9 kHz) for enhanced responsivity.
• Demonstrated high-speed, simultaneous acquisition of spectral information from multiple gases using parallel heterodyne modulation.
• Experimental validation with methane (CH₄) and acetylene (C₂H₂) yielded minimum detection limits (MDLs) of 378 ppb and 285 ppb, respectively, within 4s.
• The CNN-HAM-BiLSTM model accurately retrieved gas concentrations from parallel spectra.

Conclusions:

• The proposed PH-LITES sensor offers a significant advancement in high-speed and high-sensitivity multi-gas detection.
• The synergistic integration of physical layer signal enhancement and intelligent information processing is effective.
• This technology provides an efficient solution for applications demanding rapid and sensitive analysis of gas mixtures.