Detection of volatile organic compounds using mid-infrared silicon nitride waveguide sensors.

Junchao Zhou, Diana Al Husseini, Junyan Li, Zhihai Lin, Svetlana Sukhishvili, Gerard L Coté, Ricardo Gutierrez-Osuna, Pao Tai Lin

Scientific reports 2022 Apr 02

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Mid-infrared (mid-IR) sensors consisting of silicon nitride (SiN) waveguides were designed and tested to detect volatile organic compounds (VOCs). SiN thin films, prepared by low-pressure chemical vapor deposition (LPCVD), have a broad mid-IR transparent region and a lower refractive index (nSiN = 2.0) than conventional materials such as Si (nSi = 3.4), which leads to a stronger evanescent wave and therefore higher sensitivity, as confirmed by a finite-difference eigenmode (FDE) calculation. Further, in-situ monitoring of three VOCs (acetone, ethanol, and isoprene) was experimentally demonstrated through characteristic absorption measurements at wavelengths λ = 3.0-3.6 μm. The SiN waveguide showed a five-fold sensitivity improvement over the Si waveguide due to its stronger evanescent field. To our knowledge, this is the first time SiN waveguides are used to perform on-chip mid-IR spectral measurements for VOC detection. Thus, the developed waveguide sensor has the potential to be used as a compact device module capable of monitoring multiple gaseous analytes for health, agricultural and environmental applications. © 2022. The Author(s).

Citation

Junchao Zhou, Diana Al Husseini, Junyan Li, Zhihai Lin, Svetlana Sukhishvili, Gerard L Coté, Ricardo Gutierrez-Osuna, Pao Tai Lin. Detection of volatile organic compounds using mid-infrared silicon nitride waveguide sensors. Scientific reports. 2022 Apr 02;12(1):5572