Design of Bimodal PCFs for Interferometric Gas Sensors With High Sensitivity

Iron/iron oxide-based nanocomposites were prepared by IR laser sensitized pyrolysis ofFe(CO)5and methyl methacrylate (MMA) mixtures. The morphology of nanopowder analyzed by TEM indicated that mainly core-shell structures were obtained. X-ray diffraction techniques evidence the cores as formed mainly by iron/iron oxide crystalline phases. A partially degraded (carbonized) polymeric matrix is suggested for the coverage of the metallic particles. The nanocomposite structure at the variation of the laser density and of the MMA flow was studied. The new materials prepared as thick films were tested for their potential for acting as gas sensors. The temporal variation of the electrical resistance in presence ofNO2, CO, andCO2, in dry and humid air was recorded. Preliminary results show that the samples obtained at higher laser power density exhibit rather high sensitivity towardsNO2detection andNO2selectivity relatively to CO andCO2. An optimum working temperature of200°Cwas found.

Download Full-text

Comparison of Online Sensors for Liquid Phase Hydrogen Sulphide Monitoring in Sewer Systems

Water ◽

10.3390/w13131876 ◽

2021 ◽

Vol 13 (13) ◽

pp. 1876

Author(s):

Daneish Despot ◽

Micaela Pacheco Fernández ◽

Matthias Barjenbruch

Keyword(s):

Liquid Phase ◽

Gas Sensors ◽

High Sensitivity ◽

Laboratory Method ◽

Control Measures ◽

Monitoring And Control ◽

Sewer Systems ◽

H2s Emission ◽

H2s Detection ◽

Online Sensors

Hydrogen sulfide (H2S) related to wastewater in sewer systems is known for causing significant problems of corrosion and odor nuisance. Sewer systems severely affected by H2S typically rely on online H2S gas sensors for monitoring and control. However, these H2S gas sensors only provide information about the H2S emission potential at the point being monitored, which is sometimes inadequate to design control measures. In this study, a comparison of three market-ready online sensors capable of liquid-phase H2S detection in sewer systems was assessed and compared. Two of the three sensors are based on UV/Vis spectrophotometry, while the other adapted the design and principles of a Clark-type electrochemical microsensor. The H2S measurements of the sensors were statistically compared to a standard laboratory method at first. Following that, the performance of the online sensors was evaluated under realistic sewer conditions using the Berlin Water Company (BWB) research sewer pilot plant. Test applications representing scenarios of typical H2S concentrations found in sulfide-affected sewers and during control measures were simulated. The UV/Vis spectrometers showed that the performance of the sensors was highly dependent on the calibration type and measurements used for deriving the calibration function. The electrochemical sensor showed high sensitivity by responding to alternating anaerobic/anoxic conditions simulated during nitrate dosing. All sensors were prone to measurement disturbances due to high amounts of sanitary solids in wastewater at the study site and required continuous maintenance for reliable measurements. Finally, a summary of the key attributes and limitations of the sensors compared for liquid phase H2S detection is outlined.

Download Full-text

Design Guidelines for High Sensitivity ZnO Nanowire Gas Sensors With Schottky Contact

IEEE Sensors Journal ◽

10.1109/jsen.2018.2878783 ◽

2019 ◽

Vol 19 (3) ◽

pp. 976-981

Author(s):

Kihyun Kim ◽

Hyeon-Tak Kwak ◽

Hyeonsu Cho ◽

M. Meyyappan ◽

Chang-Ki Baek

Keyword(s):

Gas Sensors ◽

Schottky Contact ◽

High Sensitivity ◽

Design Guidelines ◽

Zno Nanowire

Download Full-text

Doubly resonant sub-ppt photoacoustic gas detection with eight decades dynamic range

10.21203/rs.3.rs-431688/v1 ◽

2021 ◽

Author(s):

Zhen Wang ◽

Hui Zhang ◽

Qiang Wang ◽

Simone Borri ◽

Iacopo Galli ◽

...

Keyword(s):

Gas Sensors ◽

Near Infrared ◽

Dynamic Range ◽

High Sensitivity ◽

Fast Response ◽

Wide Dynamic Range ◽

Acoustic Resonators ◽

Light Waves ◽

Energy Environment ◽

Small Footprint

Abstract Gas sensors with high sensitivity, wide dynamic range, high selectivity, fast response, and small footprint are desirable across a broad range of applications in energy, environment, safety, and public health. However, designing a compact gas sensor with ultra-high sensitivity and ultra-wide dynamic range remains a challenge. Laser-based photoacoustic spectroscopy (PAS) is a promising candidate to fill this gap. Herein, we report a novel method to simultaneously enhance the acoustic and light waves for PAS using integrated optical and acoustic resonators. This increases sensitivity by more than two orders of magnitude and extends the dynamic range by more than three orders of magnitude, compared with the state-of-the-art photoacoustic gas sensors. We demonstrate the concept by exploiting a near-infrared absorption line of acetylene (C2H2) at 1531.59 nm, achieving a detection limit of 0.5 parts-per-trillion (ppt), a noise equivalent absorption (NEA) of 5.7×10-13 cm-1 and a linear dynamic range of eight orders of magnitude. This study enables the realization of compact ultra-sensitive and ultra-wide-dynamic-range gas sensors in a number of different fields.

Download Full-text

High sensitivity and selectivity chlorine gas sensors based on 3D open porous SnO2 synthesized by solid-state method

Ceramics International ◽

10.1016/j.ceramint.2019.07.036 ◽

2019 ◽

Vol 45 (16) ◽

pp. 20566-20574 ◽

Cited By ~ 6

Author(s):

Weiming Zhang ◽

Qiang Li ◽

Chao Wang ◽

Jiangwei Ma ◽

Chao Wang ◽

...

Keyword(s):

Solid State ◽

Gas Sensors ◽

High Sensitivity ◽

Solid State Method ◽

Chlorine Gas ◽

Sensitivity And Selectivity ◽

State Method

Download Full-text

Selective C2H2 detection with high sensitivity using SnO2 nanorod based gas sensors integrated with a gas chromatography

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2019.127598 ◽

2020 ◽

Vol 307 ◽

pp. 127598

Author(s):

Jun Ho Lee ◽

Min Sun Park ◽

Hwaebong Jung ◽

Yong-Sahm Choe ◽

Wonkyung Kim ◽

...

Keyword(s):

Gas Chromatography ◽

Gas Sensors ◽

High Sensitivity ◽

Sno2 Nanorod

Download Full-text

High Sensitivity of NO Gas Sensors Based on Novel Ag-Doped ZnO Nanoflowers Enhanced with a UV Light-Emitting Diode

ACS Omega ◽

10.1021/acsomega.8b01882 ◽

2018 ◽

Vol 3 (10) ◽

pp. 13798-13807 ◽

Cited By ~ 17

Author(s):

You-Ting Tsai ◽

Shoou-Jinn Chang ◽

Liang-Wen Ji ◽

Yu-Jen Hsiao ◽

I-Tseng Tang ◽

...

Keyword(s):

Gas Sensors ◽

Uv Light ◽

Light Emitting Diode ◽

High Sensitivity ◽

Light Emitting ◽

Doped Zno

Download Full-text

Discriminable Sensing Response Behavior to Homogeneous Gases Based on n-ZnO/p-NiO Composites

Nanomaterials ◽

10.3390/nano10040785 ◽

2020 ◽

Vol 10 (4) ◽

pp. 785 ◽

Cited By ~ 24

Author(s):

Wen-Dong Zhou ◽

Davoud Dastan ◽

Jing Li ◽

Xi-Tao Yin ◽

Qi Wang

Keyword(s):

Gas Sensors ◽

Gas Sensing ◽

Sol Gel ◽

High Sensitivity ◽

Oxide Semiconductor ◽

Sensing Properties ◽

Gas Sensing Properties ◽

P Type ◽

Type Response ◽

Properties Of Composites

Metal oxide semiconductor (MOS) gas sensors have the advantages of high sensitivity, short response-recovery time and long-term stability. However, the shortcoming of poor discriminability of homogeneous gases limits their applications in gas sensors. It is well-known that the MOS materials have similar gas sensing responses to homogeneous gases such as CO and H2, so it is difficult for these gas sensors to distinguish the two gases. In this paper, simple sol–gel method was employed to obtain the ZnO–xNiO composites. Gas sensing performance results illustrated that the gas sensing properties of composites with x > 0.425 showed a p-type response to both CO and H2, while the gas sensing properties of composites with x < 0.425 showed an n-type response to both CO and H2. However, it was interesting that ZnO–0.425NiO showed a p-type response to CO but an discriminable response (n-type) to H2, which indicated that modulating the p-type or n-type semiconductor concentration in p-n composites could be an effective method with which to improve the discriminability of this type of gas sensor regarding CO and H2. The phenomenon of the special gas sensing behavior of ZnO–0.425NiO was explained based on the experimental observations and a range of characterization techniques, including XRD, HRTEM and XPS, in detail.

Download Full-text

NO2 and NH3 Sensing Characteristics of Inkjet Printing Graphene Gas Sensors

Sensors ◽

10.3390/s19153379 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3379 ◽

Cited By ~ 3

Author(s):

Caterina Travan ◽

Alexander Bergmann

Keyword(s):

Gas Sensors ◽

Inkjet Printing ◽

High Mobility ◽

High Sensitivity ◽

Low Noise ◽

Manufacturing Method ◽

Long Term Stability ◽

Wide Range ◽

Ideal Technique

Graphene is a good candidate for filling the market requirements for cheap, high sensitivity, robust towards contamination, low noise, and low power consumption gas sensors, thanks to its unique properties, i.e., large surface, high mobility, and long-term stability. Inkjet printing is a cheap additive manufacturing method allowing fast, relatively precise and contactless deposition of a wide range of materials; it can be considered therefore the ideal technique for fast deposition of graphene films on thin substrates. In this paper, the sensitivity of graphene-based chemiresistor gas sensors, fabricated through inkjet printing, is investigated using different concentrations of graphene in the inks. Samples have been produced and characterized in terms of response towards humidity, nitrogen dioxide, and ammonia. The presented results highlight the importance of tuning the layer thickness and achieving good film homogeneity in order to maximize the sensitivity of the sensor.

Download Full-text