Metal-organic framework functionalized polymer coating for fiber optical methane sensors

Metal–organic framework thin films as versatile chemical sensing materials

“…MOF-based optical sensors are intriguing because they typically exhibit rapid response times (often on the order of seconds), [101][102][103][104] high sensitivity (ppb or lower LOD), 103,105,106 recyclability (via removal of analyte from the MOF after each sensing cycle), 103,104,[107][108][109] and usually can be integrated with inexpensive, portable equipment, 90 such as fiber optic-based platforms. 104,110,111 Indeed, many optical sensors allow for naked-eye detection of analytes and require only simple laser pointers, lightemitting diodes, UV lamps, or other portable excitation sources for operation. 103,112,113 Thus, provided MOF films can be tailored to be sufficiently selective for analytes of interest for "real-world" deployment, 114 optical sensors represent a powerful platform for detecting a wide range of analytes.…”

“…108 The readout mechanisms shown in Figure 6 are also applicable here: peaks may gain or lose intensity as a function of analyte interaction, or may shift in energy. The underlying mechanism for these changes in the optical spectrum are often driven by RI changes 77,78,104,108,111,145 and/or changes in the coordination environment of MOF metal centers. 109,138 As with luminescentbased sensors, absorbance sensors exhibit desirable characteristics such as the need for relatively low-cost, portable equipment, 104 recyclability, 78,104,110 and rapid response times.…”

Application of Metal-Organic Framework-Based Composites for Gas Sensing and Effects of Synthesis Strategies on Gas-Sensitive Performance

“…As MOF material can increase the adsorption sites, with the increase of MOF loading, the response of H2S (expressed as fluorescence intensity) increases significantly, as shown in Figure 30b. Additionally, in 2020 Cao et al [263] applied a ZIF-8/PDMS polymer coating on an optical fiber to prepare an optical fiber gas sensor to detect CH4 in N2 at concentrations as low as 1%. Here, PDMS polymer provides hydrophobicity, good mechanical properties with good permeability to CH4 gas, and MOF to increase the free volume of the polymer and the diffusion of CH4 rate.…”

“…Regarding the higher selectivity of CH4 relative to N2, the authors summarized three points: (1) CH4 has a higher adsorption potential than N2 in PDMS and ZIF-8. (2) The molecular size of CH4 is smaller, so it diffuses more quickly Additionally, in 2020 Cao et al [263] applied a ZIF-8/PDMS polymer coating on an optical fiber to prepare an optical fiber gas sensor to detect CH 4 in N 2 at concentrations as low as 1%. Here, PDMS polymer provides hydrophobicity, good mechanical properties with good permeability to CH 4 gas, and MOF to increase the free volume of the polymer and the diffusion of CH 4 rate.…”

Alcohols detection by a polymeric sensing film deposited on a long-period fiber grating

“…This interaction can be measured as changes in the transmission spectrum of the LPFG. The sensor selectivity can be changed by deposition around the LPFG of a sensing film that can be made of different materials, such as polydimethylsiloxane (PDMS), due to its interaction with VOC [11], some of the PDMS interesting points are its affinity to alcohols, reversible sensor response besides some characteristics as low cost, simple deposition on the fiber surface and its refractive index is lower than that of the fiber, which allows observing the interaction as spectrum shifts [12]. Currently, there are organic vapor sensors that use the principle mentioned above and special quartz optical fiber with low OH concentration [13].…”