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Title: SAW Sensors for Chemical Vapors and Gases

Authors:
; ;
Publication Date:
Research Org.:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1393414
Report Number(s):
A-UNIV-PUB-136
Journal ID: ISSN 1424-8220; SENSC9; PII: s17040801
DOE Contract Number:
DE-FE0004000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Sensors; Journal Volume: 17; Journal Issue: 4
Country of Publication:
United States
Language:
English

Citation Formats

Devkota, Jagannath, Ohodnicki, Paul, and Greve, David. SAW Sensors for Chemical Vapors and Gases. United States: N. p., 2017. Web. doi:10.3390/s17040801.
Devkota, Jagannath, Ohodnicki, Paul, & Greve, David. SAW Sensors for Chemical Vapors and Gases. United States. doi:10.3390/s17040801.
Devkota, Jagannath, Ohodnicki, Paul, and Greve, David. Sat . "SAW Sensors for Chemical Vapors and Gases". United States. doi:10.3390/s17040801.
@article{osti_1393414,
title = {SAW Sensors for Chemical Vapors and Gases},
author = {Devkota, Jagannath and Ohodnicki, Paul and Greve, David},
abstractNote = {},
doi = {10.3390/s17040801},
journal = {Sensors},
number = 4,
volume = 17,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
  • Here, surface acoustic wave (SAW) technology provides a sensitive platform for sensing chemicals in gaseous and fluidic states with the inherent advantages of passive and wireless operation. In this review, we provide a general overview on the fundamental aspects and some major advances of Rayleigh wave-based SAW sensors in sensing chemicals in a gaseous phase. In particular, we review the progress in general understanding of the SAW chemical sensing mechanism, optimization of the sensor characteristics, and the development of the sensors operational at different conditions. Based on previous publications, we suggest some appropriate sensing approaches for particular applications and identifymore » new opportunities and needs for additional research in this area moving into the future.« less
  • Reduction in power consumption and improvement in mass sensitivity are important considerations for surface acoustic wave (SAW) devices used in various sensing applications. Detection of minute quantities of a particular species (clinical sensing) and power requirements (wireless sensing) are two key metrics that must be optimized. In this paper, a 3-D finite element model (FEM) was employed to compare insertion loss (IL) and mass sensitivity of SAW sensors having microcavities filled with ZnO and nanocrystalline diamond to a standard two-port SAW design. Initial simulation results show that ZnO filled cavities (depth = 5 mu m) were most effective at reducingmore » power loss Delta IL = (6.03 dB) by increasing particle displacement (acousto-electric to mechanical transduction) at the output transducer. A 100-pg/cm(2) load was applied to the sensing area of each device to evaluate mass sensitivity. Our simulations suggest that ZnO filled cavities with shallow depth (2.5 mu m) have the greatest sensitivity. The FEM simulations are used to understand the acoustic wave propagation in microcavity-based SAW sensors. The observed enhancement in mass sensitivity and power transfer is attributed to waveguiding effects and constructive interference of the scattered acoustic waves from the microcavities. Devices fabricated with microcavities similar to 1 mu m deep decreased IL by 3.306 dB compared with a standard SAW device. Additional simulations were conducted for each device configuration using the same depth in order to make a direct comparison between measured and simulated results. Our findings offer encouraging prospects for designing low IL highly sensitive microcavity-based SAW biosensors.« less
  • This study developed a method for detecting organic vapors that break through charcoal tubes, using semiconductor gas sensors as a breakthrough detector of vapors. A glass column equipped with two sensors was inserted in Teflon tubing, and air containing organic vapor was introduced at a constant flow rate. After the output signal of the sensors became stable, a charcoal tube was inserted into the tubing at the upstream of the sensors. The resistance of the sensors was collected temporally in an integrated circuit (IC) card. The vapor concentration of the air near the sensors was measured with a gas chromatographmore » (GC) equipped with a flame ionization detector (FID) at intervals of 5 minutes to obtain the breakthrough curve. When the relative humidity was zero, the output signals of the sensors began to change before the breakthrough point (1% breakthrough time). This tendency was almost the same for methyl acetate, ethyl acetate, isopropyl alcohol (IPA), toluene, and chloroform. For dichloromethane and 1,1,1-trichloroethane, the time when the sensor output signals began to rise was almost the same as the breakthrough point. When the relative humidity was 80 percent, the sensors could also detect many vapors before the breakthrough point, but they could not perceive dichloromethane and chloroform vapors. A personal sampling system with a breakthrough detector was developed and its availability is discussed.« less
  • During thermally enhanced in situ remediation of soils and ground water, gas streams are generated with varying temperatures, moisture content, and organic compound concentrations. In this study, the authors evaluated the performance of tin dioxide sensors for measuring trichloroethylene (TCE) concentrations in gas streams from a thermally enhanced soil vapor extraction system. Temperature, pressure, moisture content, and vapor flow rates affected the resistivity of the sensors, and thus the signal. When fluctuations in these parameters were eliminated by condensing excess water and heating to a constant temperature prior to measurement, the sensors provided reliable in-line measurement of TCE concentrations. Gasmore » tracers such as methane were easily monitored in-line, providing quick and inexpensive data on subsurface vapor flow velocities and direction.« less
  • The synthesis, characterization, and vis-NIR-IR vapochromic/spectroscopic studies are reported for isocyanide compounds of the form [Pt(arylisocyanide){sub 4}][Pt(CN){sub 4}] (where arylisocyanide = p-CNC{sub 6}H{sub 4}C{sub n}H{sub 2n+1}; n = 1, 6, 10, 12, 14). The dark blue, solid materials change color in the NIR (near-infrared) spectral region upon exposure to the ambient room-temperature vapor pressure of volatile organic compounds (VOCs). All the spectroscopic data suggest that the VOC penetrates the solid and interacts with the linear chain chromophore to cause the spectral shifts in the vis-NIR-IR spectral regions. The vapochromic shifts are suggested to be due to diole-dipole and/or H-bonding interactionsmore » between the Pt(CN){sub 4}{sup 2-} anion and polar VOCs. For nonpolar VOCs, lypophilic interactions between the VOC and the isocyanide ligands that cause no change in the {nu}-(CN) stretching region must cause the NIR vapochromism observed. The absence of a vapochromic response for water vapor is suggested to arise from hydrophobic blocking of the water at the solid/gas interface. 21 refs., 4 figs., 3 tabs.« less