Sensors, Vol. 19, Pages 820: Dual-Gas Sensor of CH4/C2H6 Based on Wavelength Modulation Spectroscopy Coupled to a Home-Made Compact Dense-Pattern Multipass Cell (Sensors)

A sensitive dual-gas sensor for the detection of CH4 and C2H6 is demonstrated. Two tunable semiconductor lasers operating at 1.653 μm (for CH4 monitoring) and 1.684 μm (for C2H6) were used as the light source for spectroscopic measurements of CH4 and C2H6. Long-path absorption in a home-made compact dense-pattern multipass cell (Leff = 29.37 m) was employed, combined with wavelength modulation and second harmonic detection. Simultaneous detection of CH4 and C2H6 was achieved by separated wavelength modulations of the two lasers. Modulation frequencies and amplitudes were optimized for sensitivity detection of CH4 and C2H6 simultaneously. The dual-gas sensor exhibits 1σ detection limits of 1.5 ppbv for CH4 in 140 s averaging time and 100 ppbv for C2H6 in 200 s.