Fiber-optic ammonia sensor using Ag/SnO_2 thin films: optimization of thickness of SnO_2 film using electric field distribution and reaction factor

Pathak, Anisha; Gupta, Banshi D.

doi:10.1364/ao.54.008712

Cited by 41 publications

(17 citation statements)

References 32 publications

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“… Optical technique Range (ppm) Response/recovery times (sec) Detection Limit (ppb) Ref. Bromocresol purple coated U-shaped plastic fiber 145–3518 10 10,000 7 Silica gel coated micro fiber coupler 0.25–10.4 50/35 5 23 Surface plasmon resonance, Ag/Sn O 2 10–100 n/a 154 24 Nanostructured dye-doped 12–216 50 5,000 25 Mach-Zehnder interferometer using graphene 0–360 0.5 300 26 Graphene-coated microfiber Bragg grating 0–100 n/a 200 27 Silica gel coated microsphere (this work) 0.0025–0.0123 1.5/3.6 0.16 …”

Section: Discussionmentioning

confidence: 99%

Silica Gel Coated Spherical Micro resonator for Ultra-High Sensitivity Detection of Ammonia Gas Concentration in Air

Mallik¹,

Farrell²,

Liu³

et al. 2018

Sci Rep

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A silica gel coated microsphere resonator is proposed and experimentally demonstrated for measurements of ammonia (NH3) concentration in air with ultra-high sensitivity. The optical properties of the porous silica gel layer change when it is exposed to low (parts per million (ppm)) and even ultra-low (parts per billion (ppb)) concentrations of ammonia vapor, leading to a spectral shift of the WGM resonances in the transmission spectrum of the fiber taper. The experimentally demonstrated sensitivity of the proposed sensor to ammonia is estimated as 34.46 pm/ppm in the low ammonia concentrations range from 4 ppm to 30 ppm using an optical spectrum analyser (OSA), and as 800 pm/ppm in the ultra-low range of ammonia concentrations from 2.5 ppb to 12 ppb using the frequency detuning method, resulting in the lowest detection limit (by two orders of magnitude) reported to date equal to 0.16 ppb of ammonia in air. In addition, the sensor exhibits excellent selectivity to ammonia and very fast response and recovery times measured at 1.5 and 3.6 seconds, respectively. Other attractive features of the proposed sensor are its compact nature, simplicity of fabrication.

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Section: Discussionmentioning

confidence: 99%

Silica Gel Coated Spherical Micro resonator for Ultra-High Sensitivity Detection of Ammonia Gas Concentration in Air

Mallik¹,

Farrell²,

Liu³

et al. 2018

Sci Rep

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“…Examples of fiber optical sensors showing good ammonia detection capabilities include Gd 2 O 3 nanorods (with thickness ranging from 80 to 120 nm), thin films based on Ag/SnO 2 and nanocrystalline SnO 2 . [56][57][58] All these MOXs contain hard acid species. For fiber optic ammonia sensor, the sensing mechanism is completely different than the one specific to chemiresistive sensors.…”

Section: Mox-based Sensing Layers For Ammonia Optical Detectionmentioning

confidence: 99%

Nanostructured Semiconducting Metal Oxides for Ammonia Sensors. A Novel HSAB Sensing Paradigm

Serban

Buiu²,

Cobianu³

et al. 2018

ACSi

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The paper demonstrates how the Hard-Soft Acid Base (HSAB) theory can be used as a valuable criterion in the selection process of semiconducting metal oxides (MOX) suitable as sensing layers for ammonia detection. Six different cases of ammonia detection performed by chemiresistive sensors employing MOX and related nanocomposites as sensing layers are identified and discussed. The role of HSAB as an efficient selection tool for appropriate sensing layer (any type of gas), is further reinforced by analyzing and discussing literature results on MOX-based trimethylamine sensing layers. By analyzing the operation of a fiber-optic ammonia sensor, we demonstrate that the HSAB principle can be also successfully applied to the selection of sensing layers for detectors employing other sensing principles, different than the chemiresistive one. Changing the sensing paradigm (i.e., the amino groups-based compounds are part of the sensing layer, rather than part of the analyte), the paper shows that these types of molecules (polymers, carbon nanotubes, ionic liquids) are appropriate constituents of a CO 2 sensing layer, in full accordance to the HSAB criteria.

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“…It is also the focus of gas sensors to improve the adsorption and selectivity of the detection gas based on different sensitizing substances. Some of the sensitive materials used for ammonia gas detection are silver nanoparticles/PVP/PVA hybrid [ 14 ], Ag/SnO 2 thin films [ 15 ], silver nanoparticles doped silica nanocomposites [ 16 ], silica-gel [ 17 ], graphene/polyaniline [ 13 ], three-dimensional zinc oxide nanoflowers [ 18 ] and PANI@SnO 2 nanocomposite [ 19 ]. In recent years, in view of the high sensitivity and response speed of evanescent field caused by microfiber to environmental changes, more and more researchers are paying attention to the microfiber sensor for ammonia gas sensing [ 20 , 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Ammonia Gas Sensor Based on Graphene Oxide-Coated Mach-Zehnder Interferometer with Hybrid Fiber Structure

Fan

Deng

Wei

et al. 2021

Sensors

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A graphene oxide-coated in-fiber Mach-Zehnder interferometer (MZI) formed with a multimode fiber-thin core fiber-multimode fiber (MMF-TCF-MMF) is proposed and experimentally demonstrated for ammonia gas (NH3) sensing. The MZI structure is composed of two segments of MMF of length 2 mm, with a flame-tapered TCF between them as the sensing arm. The MMFs act as mode couplers to split and recombine light owing to the core diameter mismatch with the other fibers. A tapered TCF is formed by the flame melting taper method, resulting in evanescent wave leakage. A layer of graphene oxide (GO) is applied to the tapered region of the TCF to achieve gas adsorption. The sensor operates on the principle of changing the effective refractive index of the cladding mode of a fiber through changing the conductivity of the GO coating by adsorbed NH3 molecules, which gives rise to a phase shift and shows as the resonant dip shifts in the transmission spectrum. So the concentration of the ammonia gas can be obtained by measuring the dip shift. A wavelength-shift sensitivity of 4.97 pm/ppm with a linear fit coefficient of 98.9% is achieved for ammonia gas concentrations in the range of 0 to 151 ppm. In addition, we performed a repetitive dynamic response test on the sensor by charging/releasing NH3 at concentration of 200 ppm and a relative humidity test in a relative humidity range of 35% to 70%, which demonstrates the reusability and stability of the sensor.

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Fiber-optic ammonia sensor using Ag/SnO_2 thin films: optimization of thickness of SnO_2 film using electric field distribution and reaction factor

Cited by 41 publications

References 32 publications

Silica Gel Coated Spherical Micro resonator for Ultra-High Sensitivity Detection of Ammonia Gas Concentration in Air

Silica Gel Coated Spherical Micro resonator for Ultra-High Sensitivity Detection of Ammonia Gas Concentration in Air

Nanostructured Semiconducting Metal Oxides for Ammonia Sensors. A Novel HSAB Sensing Paradigm

Ammonia Gas Sensor Based on Graphene Oxide-Coated Mach-Zehnder Interferometer with Hybrid Fiber Structure

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