| 1. |
- Alam, Mohammad Anzar, et al.
(författare)
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Limitation of a line-of-light online paper surface measurement system
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:8, s. 2715-2724
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Tidskriftsartikel (refereegranskat)abstract
- A new prototype device has been developed based on a laser triangulation principle to measure online surface topography in the paper and paperboard industries. It characterizes the surface in a wide spatial scale of topography from 0.09-10 mm. The prototype's technique projects a narrow line-of-light perpendicularly onto the moving paper-Web surface and scattered reflected light is collected at a low angle, low specular, and reduced coherent length onto the CCD sensors synchronized with the laser sources. The scattering phenomenon determines surface deviations in the z-direction. The full-width, at half-maximum of a laser line in cross section is sensitive in computation of the surface topography. The signal processing aspect of the image processing, for example, threshold and filtering algorithms are also sensitive in estimating the accurate surface features. Moreover, improper light illumination, intensity, reflection, occlusion, surface motion, and noise in the imaging sensor, and so forth, all contribute to deteriorate the measurements. Optical techniques measure the surface indirectly and, in general, an evaluation of the performance and the limitations of the technique are both essential and challenging. The paper describes the accuracy, uncertainty, and limitations of the developed technique in the raw profiles and in terms of the rms roughness. The achieved image subpixel resolution is 0.01 times a pixel. Statistically estimated uncertainty (2σ) in the laboratory environment was found 0.05 μm for a smooth sample, which provides a 95% confidence level in the rms roughness results. The depth of field of the prototype is ~2.4 mm.
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| 2. |
- Alam, Mohammad Anzar, et al.
(författare)
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Real time surface measurement technique in a wide range of wavelengths spectrum
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:1, s. 285-294
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Tidskriftsartikel (refereegranskat)abstract
- Real time surface topography measurement in the paper and paperboard industries is a challenging research field. The existing online techniques measure only a small area of paper surface and estimate topographical irregularities in a narrow scale as a single predictor. Considering the limitations and complications in measuring the surface at high speed, a laser line triangulation technique is explored to measure surface topography in a wide scale. The developed technique is new for the paper and paperboard application that scans a line onto the paper-web surface up to 210 mm in length in the cross machine direction. The combination of a narrow laser linewidth imaging, a subpixel resolution, and the selection of a unique measurement location has made it possible to measure roughness and simultaneously characterize paper surface topography from 0.1 to 30 mm spatial wavelength. This spatial range covers wide scale surface properties such as roughness, cockling, and waviness. The technique clearly distinguishes and characterizes the surface of newspaper, and lightweight coated, coated, and uncoated paperboard in real time during the paper manufacturing process. The system temporal noise for the average roughness is estimated as 37 dB. The signal to noise ratio found is from 5.4 to 8.1 in the short spatial wavelength up to 1 mm, whereas it is more than 75 in the long spatial wavelength from 5 to 10 mm.
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| 3. |
- Andersson, Henrik, et al.
(författare)
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Inkjet printed silver nanoparticle humidity sensor with memory effect on paper
- 2012
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 12:6, s. 1901-1905
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the design and the manufacture of an inkjet printed resistive type humidity sensor on paper are reported. After having been exposed to humidity above a given threshold level, the resistance of the sensor decreases substantially and remains at that level even when thehumidity is reduced. It is possible to deduce the humidity level by monitoring the resistance. The main benefit of the printed sensor presented in this case is in relation to its very low production costs. It has also been shown that both the ink type and this paper combination used prove to be crucial in order to obtain the desired sensor effect. More research is required in order to fully understand the humidity sintering effect on the nano particle ink and the role of the substrate. However, the observed effect can be put to use in printed humidity sensors which possess a memoryfunction. The sensor can be used in various applications for environmental monitoring, for example, in situations where a large number of inexpensive and disposable humidity sensors are required which are able to detect whether they have been subjected to high humidity. This could be the checking of transportation conditions of goods or monitoring humidity within buildings. © 2001-2012 IEEE.
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| 4. |
- Andersson, Henrik, et al.
(författare)
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Investigation of Humidity Sensor Effect in Silver Nanoparticle Ink Sensors Printed on Paper
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:3, s. Art. no. 6615915-
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Tidskriftsartikel (refereegranskat)abstract
- Thin inkjet-printed tracks of silver nanoparticles have previously been observed to show a non-reversible decrease in resistance when exposed to a high degree of relative humidity and thus providing sensor functionality with a memory effect. This paper provides a more in-depth explanation of the observed humidity sensor effect that originates from inkjet-printed silver nanoparticle sensors on a paper substrate. It is shown that the geometry of the sensor has a large effect on the sensor's initial resistance, and therefore also on the sensor's resistive dynamic range. The importance of the sensor geometry is believed to be due to the amount of solvent from the ink interacting with the coating of the paper substrate, which in turn enables the diffusion of salts from the paper coating into the ink and thus affecting the silver ink.
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| 5. |
- Anderås, Emil, 1982-, et al.
(författare)
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Tilted c-Axis Thin-Film Bulk Wave Resonant Pressure Sensors With Improved Sensitivity
- 2012
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 12:8, s. 2653-2654
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum nitride thin film bulk wave resonant pressure sensors employing c- and tilted c-axis texture, have been fabricated and tested for their pressure sensitivities. The c-axis tilted FBAR pressure sensors demonstrate substantially higher pressure sensitivity compared to its c-axis oriented counterpart. More specifically the thickness plate quasi-shear resonance has demonstrated the highest pressure sensitivity while further being able to preserve its performance in liquid environment.
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| 6. |
- Arapan, Lilia, et al.
(författare)
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Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
- 2011
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Ingår i: IEEE Sensors Journal. - : IEEE Sensors Council. - 1530-437X .- 1558-1748. ; 11:12, s. 3330-3331
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Tidskriftsartikel (refereegranskat)abstract
- Thin film plate acoustic resonators devices operating in the lowest order symmetric Lamb wave mode (S0) in coriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressure and mass as well as for their ability to work in liquid environment.
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| 7. |
- Athalye, Akshay, et al.
(författare)
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Novel Semi-Passive RFID System for Indoor Localization
- 2013
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 13:2, s. 528-537
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a novel semi-passive radio-frequency identification (RFID) system for accurate indoor localization. The system is composed of a standard ultra high frequency (UHF) ISO-18000-6C compliant RFID reader, a set of standard passive RFID tags whose locations are known, and a newly developed tag-like RFID component, which is attached to the items that need to be localized. The new semi-passive component, referred to as sensatag (sense-a-tag), has a dual functionality: it can sense and decode communication between the reader and standard tags in its proximity, and can communicate with the reader like standard tags using backscatter modulation. Based on the information conveyed by the sensatags to the reader, localization algorithms based on binary sensor principles can be developed. We conduct a number of experiments in a laboratory to quantify the performance of our system, including two real applications, one finding the exact placement of items on shelves, and the other estimating the direction of item movement.
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| 8. |
- Barac, Filip, 1983-, et al.
(författare)
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Channel Diagnostics for Wireless Sensor Networks in Harsh Industrial Environments
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:11, s. 3983-3995
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Tidskriftsartikel (refereegranskat)abstract
- Wireless sensor network communication in industrial environments is compromised by interference, multipath fading, and signal attenuation. In that respect, accurate channel diagnostics is imperative to selecting the adequate countermeasures. This paper presents the lightweight packet error discriminator (LPED) that infers the wireless link condition by distinguishing between errors caused by multipath fading and attenuation, and those inflicted by interfering wideband single-channel communication systems (e.g., IEEE 802.11b/g), based on the differences in their error footprints. The LPED uses forward error correction in a novel context, namely, to determine the symbol error density, which is then fed to a discriminator for error source classification. The classification criteria are derived from an extensive set of error traces collected in three different types of industrial environments, and verified on a newly collected set of error traces. The proposed solution is evaluated both offline and online, in terms of classification accuracy, speed of channel diagnostics, and execution time. The results show that in ≥91% of cases, a single packet is sufficient for a correct channel diagnosis, accelerating link state inference by at least 270%, compared with the relevant state-of-the-art approaches. The execution time of LPED, for the worst case of packet corruption and maximum packet size, is below 30 ms with ≤3% of device memory consumption. Finally, live tests in an industrial environment show that LPED quickly recovers from link outage, by losing up to two packets on average, which is only one packet above the theoretical minimum.
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| 9. |
- Becker, Elin, 1981, et al.
(författare)
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Study of the Sensing Mechanism Towards Carbon Monoxide of Platinum-Based Field Effect Sensors
- 2011
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Ingår i: IEEE Sensors Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-1748 .- 1530-437X. ; 11:7, s. 1527-1534
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the temperature dependence and the effect of hydrogen on the CO response of MISiC field effect device sensors. The evolution of adsorbates on a model sensor was studied by in situ DRIFT spectroscopy and correlated to sensor response measurements at similar conditions. A strong correlation between the CO coverage of the sensor surface and the sensor response was found. The temperature dependence and hydrogen sensitivity are partly in agreement with these observations, however at low temperatures it is difficult to explain the observed increase in sensor response with increasing temperature. This may be explained by the reduction of a surface oxide or removal of oxygen from the Pt/SiO2 interface at increasing temperatures. The sensing mechanism of MISiC field effect sensors is likely complex, involving several of the factors discussed in this paper.
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| 10. |
- Bur, Christian, et al.
(författare)
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Detecting Volatile Organic Compounds in the ppb Range with Gas Sensitive Platinum gate SiC-Field Effect Transistors
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:9, s. 3221-3228
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the use of a platinum gate gas-sensitive SiC field-effect transistor (SiC-FET) was studied for the detection of low concentrations of hazardous volatile organic compounds (VOCs). For this purpose, a new gas mixing system was realized providing VOCs down to sub-parts per billion levels with permeation ovens and gas predilution. Benzene, naphthalene, and formaldehyde were chosen as major indoor air pollutants and their characteristics are briefly reviewed. Measurements have shown that the selected VOCs can be detected by the SiC-FET in the parts per billion range and indicate a detection limit of ~1 ppb for benzene and naphthalene and ~10 ppb for formaldehyde in humid atmospheres. For 10-ppb naphthalene at 20% r.h., the sensor response is high with 12 mV, respectively, a relative response of 1.4%. Even in a background of 2-ppm ethanol, the relative response is still 0.3%. Quantification independent of the humidity level can be achieved using temperature cycled operation combined with pattern recognition, here linear discriminant analysis. Discrimination of benzene, naphthalene, and formaldehyde is also possible.
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