Integration of a Metal–Organic Framework Film with a Tubular Whispering-Gallery-Mode Microcavity for Effective CO₂ Sensing

Abstract

Carbon dioxide (CO2) sensing using an optical technique is of great importance in the environment and industrial emission monitoring. However, limited by the poor specific adsorption of gas molecules as well as insufficient coupling efficiency, there is still a long way to go toward realizing a highly sensitive optical CO2 gas sensor. Herein, by combining the advantages of a whispering-gallery-mode microcavity and a metal–organic framework (MOF) film, a porous functional microcavity (PF-MC) was fabricated with the assistance of the atomic layer deposition technique and was applied to CO2 sensing. In this functional composite, the rolled-up microcavity provides the ability to tune the propagation of light waves and the electromagnetic coupling with the surroundings via an evanescent field, while the nanoporous MOF film contributes to the specific adsorption of CO2. The composite demonstrates a high sensitivity of 188 nm RIU–1 (7.4 pm/% with respect to the CO2 concentration) and a low detection limit of ∼5.85 × 10–5 RIU. Furthermore, the PF-MC exhibits great selectivity to CO2 and outstanding reproducibility, which is promising for the next-generation optical gas sensing devices.

From Whispering Gallery Mode Resonators to Biochemical Sensors

“…The functionalized rolled-up microcavities were made of Y 2 O 3 /ZrO 2 which were subsequently sandwiched between two films of ZIF-8 by ALD. Recent works showed the highest optical sensitivity to CO 2 achieved so far, reaching 188 nm per refractive index unit (RIU) with a limit of detection (LOD) of 5.85 × 10 –5 RIU …”

“…Zeolitic Recent works showed the highest optical sensitivity to CO 2 achieved so far, reaching 188 nm per refractive index unit (RIU) with a limit of detection (LOD) of 5.85 × 10 −5 RIU. 73 Surface Wetting. The coating/film formation methods mentioned above rely on the substrate (material to be coated) being homogeneous to ensure high-quality coating.…”

Nanomembrane-assembled nanophotonics and optoelectronics: from materials to applications

“…The modified optical microcavity can therefore be applied in highly sensitive hydrogen detection (figure 4(e)-(ii)). Kong et al [146]reported that metal-organic framework (MOF) layer also can be deposited onto both inner and out surfaces of tube wall to enhance selective gas absorption due to the nanoporosity of MOF layer (figure 4(f)-(i)). Figure 4(f)-(ii) shows that the rolled-up microcavity modified by MOF layer is effective in CO 2 sensing, and the WGM wavelength shifts linearly with CO 2 concentration [146].…”

Design and Synthesis of Transferrable Macro‐Sized Continuous Free‐Standing Metal‐Organic Framework Films for Biosensor Device

“…[ 6 , 7 , 8 ] In our group, we also adopted an effective technique to prepare MOF films on substrates by engaging an induction effect of oxide nanomembranes deposited by atomic layer deposition (ALD), which leads to growth of MOF films with good adhesion, uniformity, and conformality. [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ] However, the high temperature of ALD and severe corrosion of solvents in the wet chemistry process may harm the fragile substrate, and the conformal growth of MOF films of this ALD‐based induction approach hinders the single‐surface growth on substrate with complex geometry. Especially in the post‐Moore law period, MOF can hardly act as active materials in on‐chip device, because the strict preparation conditions could damage the integrated circuit and even the whole device.…”