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Dual mode NOx sensor: measuring both the accumulated amount and instantaneous level at low concentrations.

Groß A, Beulertz G, Marr I, Kubinski DJ, Visser JH, Moos R - Sensors (Basel) (2012)

Bottom Line: Experimental results are presented demonstrating the sensor's integrating properties for the total amount detection and its sensitivity to both NO and to NO(2).The long-term detection of NO(x) in the sub-ppm range (e.g., for air quality measurements) is discussed.Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed.

View Article: PubMed Central - PubMed

Affiliation: Department of Functional Materials, Bayreuth Engine Research Center (BERC), University of Bayreuth, 95440 Bayreuth, Germany.

ABSTRACT
The accumulating-type (or integrating-type) NO(x) sensor principle offers two operation modes to measure low levels of NO(x): The direct signal gives the total amount dosed over a time interval and its derivative the instantaneous concentration. With a linear sensor response, no baseline drift, and both response times and recovery times in the range of the gas exchange time of the test bench (5 to 7 s), the integrating sensor is well suited to reliably detect low levels of NO(x). Experimental results are presented demonstrating the sensor's integrating properties for the total amount detection and its sensitivity to both NO and to NO(2). We also show the correlation between the derivative of the sensor signal and the known gas concentration. The long-term detection of NO(x) in the sub-ppm range (e.g., for air quality measurements) is discussed. Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed.

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Setup of the accumulating-type NOx sensor.
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f3-sensors-12-02831: Setup of the accumulating-type NOx sensor.

Mentions: The setup of the presented resistive type integrating NOx sensor is shown in Figure 3. The sensor devices consist of a 96% pure alumina substrate (630 μm thick) with screen-printed interdigital electrodes (IDE) made from gold (DuPont) or platinum (Heraeus)—the electrode material was found to have no influence on the sensor performance—with an electrode width and spacing of 100 or 50 μm each. The electrode areas (5 × 6 mm) are covered with layers of a potassium-based LNT-material in various thicknesses ranging from about 30–100 μm. The raw material was provided by Johnson Matthey and the composition is described in [38]. The sensors were operated in a quartz tube (25 mm in diameter) located in a heated furnace at 380 °C (furnace temperature) and supplied with various synthetic gas mixtures of 2 L/min. The gas exchange time of the test bench upstream of the sensor (dosing unit, quartz tube) was estimated to be in the range of 6 s.


Dual mode NOx sensor: measuring both the accumulated amount and instantaneous level at low concentrations.

Groß A, Beulertz G, Marr I, Kubinski DJ, Visser JH, Moos R - Sensors (Basel) (2012)

Setup of the accumulating-type NOx sensor.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376581&req=5

f3-sensors-12-02831: Setup of the accumulating-type NOx sensor.
Mentions: The setup of the presented resistive type integrating NOx sensor is shown in Figure 3. The sensor devices consist of a 96% pure alumina substrate (630 μm thick) with screen-printed interdigital electrodes (IDE) made from gold (DuPont) or platinum (Heraeus)—the electrode material was found to have no influence on the sensor performance—with an electrode width and spacing of 100 or 50 μm each. The electrode areas (5 × 6 mm) are covered with layers of a potassium-based LNT-material in various thicknesses ranging from about 30–100 μm. The raw material was provided by Johnson Matthey and the composition is described in [38]. The sensors were operated in a quartz tube (25 mm in diameter) located in a heated furnace at 380 °C (furnace temperature) and supplied with various synthetic gas mixtures of 2 L/min. The gas exchange time of the test bench upstream of the sensor (dosing unit, quartz tube) was estimated to be in the range of 6 s.

Bottom Line: Experimental results are presented demonstrating the sensor's integrating properties for the total amount detection and its sensitivity to both NO and to NO(2).The long-term detection of NO(x) in the sub-ppm range (e.g., for air quality measurements) is discussed.Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed.

View Article: PubMed Central - PubMed

Affiliation: Department of Functional Materials, Bayreuth Engine Research Center (BERC), University of Bayreuth, 95440 Bayreuth, Germany.

ABSTRACT
The accumulating-type (or integrating-type) NO(x) sensor principle offers two operation modes to measure low levels of NO(x): The direct signal gives the total amount dosed over a time interval and its derivative the instantaneous concentration. With a linear sensor response, no baseline drift, and both response times and recovery times in the range of the gas exchange time of the test bench (5 to 7 s), the integrating sensor is well suited to reliably detect low levels of NO(x). Experimental results are presented demonstrating the sensor's integrating properties for the total amount detection and its sensitivity to both NO and to NO(2). We also show the correlation between the derivative of the sensor signal and the known gas concentration. The long-term detection of NO(x) in the sub-ppm range (e.g., for air quality measurements) is discussed. Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed.

Show MeSH