Improvement in detection limit of a non-dispersive infrared multi-channel gas sensor using metal-organic framework-coated preconcentrator

This paper reports on a new sensing platform with potential to improve the limit of detection (LoD) of a compact non-dispersive infrared (NDIR) multi-channel gas sensor (K96) using a sampling device (preconcentrator). A commercial metal-organic framework (HKUST-1) powder was first coated on the internal surfaces of the preconcentrator to enrich methane. HKUST-1 coating provides both excellent methane adsorption performance and selectivity but suffers from high water vapor adsorption and poor adhesion to the metal surface. Afterwards, we mixed HKUST-1 with Polydimethylsiloxane (PDMS) to create a composite coating to enhance stability, reduce interference from water vapor and enrich methane. Our preliminary test results showed that we can successfully enrich low concentration (10 ppm) methane in calibrated air sample by using the newly developed preconcentrator and increase methane concentration by ~5 times when using standalone HKUST-1 coating. The HKUST-1+PDMS composite coating further improved the methane enrichment ~9 times uses ~40% less HKUST-1 coating mass and reduced the impact of water vapor. The preliminary results demonstrate the potential of coupling sampling devices like preconcentrators to improve the detection capability of low-cost commercial detectors.