Hollow waveguide-enhanced mid-infrared sensor for fast and sensitive ethylene detection

Abstract

Purpose

This paper aims to provide a sensor for fast, sensitive and selective ethylene (C₂H₄) concentration measurements.

Design/methodology/approach

The paper developed a sensor platform based on tunable laser absorption spectroscopy with a 3,266-nm interband cascade laser (ICL) as an optical source and a hollow waveguide (HWG) as a gas cell. The ICL wavelength was scanned across a C₂H₄ strong fundamental absorption band, and an interference-free C₂H₄ absorption line located at 3,060.76 cm⁻¹ was selected. Wavelength modulation spectroscopy with the second harmonic detection (WMS-2f) technique was used to improve the sensitivity. Furthermore, the HWG gas cell can achieve a long optical path in a very small volume to improve the time response.

Findings

The results show excellent linearity of the measured 2f signal and the C₂H₄ concentration with a correlation coefficient of 0.9997. Also, the response time is as short as about 10 s. The Allan variance analysis indicates that the detection limit can achieve 53 ppb with an integration time of 24 s.

Practical implications

The ethylene sensor has many meaningful applications in environmental monitoring, industrial production, national security and the biomedicine field.

Originality/value

The paper provides a novel sensor architecture which can be a versatile sensor platform for fast and sensitive trace-gas detection in the mid-infrared region.

Citation

Li, J., Du, Z., Zhang, Z., Song, L. and Guo, Q. (2017), "Hollow waveguide-enhanced mid-infrared sensor for fast and sensitive ethylene detection", Sensor Review, Vol. 37 No. 1, pp. 82-87. https://doi.org/10.1108/SR-05-2016-0087