| 1. |
- 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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| 2. |
- Feng, Yi, et al.
(författare)
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Flexible UHF resistive humidity sensors based on carbon nanotubes
- 2012
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 12:9, s. 2844-2850
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the investigation of the resistive humidity-sensing properties of multi-walled carbon nanotubes (MWCNTs). MWCNTs functionalized by acid treatment (f-MWCNTs) exhibit rather high sensitivity in resistance toward humidity, owing to the presence of carboxylic groups on the nanotube surface. By integrating the f-MWCNTs resistor into a wireless sensor platform, flexible humidity sensors for ultra-high frequency applications are investigated. The operating frequency range of the sensor is dramatically increased from 600 MHz to 2 GHz by adjusting the resistor-electrodes' configuration. This enhancement is predominately attributed to the variation in parasitic capacitance between the resistor-electrodes.
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| 3. |
- Sieber, Arne, et al.
(författare)
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Smart electrochemical oxygen sensor for personal protective equipment
- 2012
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Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 12:6, s. 1846-1852
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Tidskriftsartikel (refereegranskat)abstract
- Self contained closed circuit rebreathers are life supporting breathing systems, where the exhaled gas is recycled by filtering CO2 and replacing metabolized O-2. For the O-2 injection control galvanic O-2 sensors are used to measure the partial pressure of O-2. A malfunction of the sensors can lead to a gas mixture beyond life supporting limits which is life threatening. Galvanic O-2 sensors are often used in anaesthetic machines in hospitals. Also in this case, a malfunction of the sensors can cause severe injury to a person. It is obvious that such sensors are key elements in life supporting equipment and as such must be designed in order to achieve high functional safety. However these sensors are consuming sensors, and with that, will fail at a certain time. Failure modes include current limitation, non linearity, electrolyte evaporation or leakage, etc. Within this paper a novel low cost read out electronic circuit for galvanic O-2 sensors is presented, which allows not only digital readout, digital temperature compensation, on board storage of calibration and manufacturing data, but also can be used for performing voltammetry cycles to test the Pb anode for exhaustion. First measurements are presented and compared to data from a Solartron SI 1287 impedance analyzer, which is state-of-the-art in electrochemical sensor characterization.
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| 4. |
- 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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| 5. |
- Huang, Chuan, et al.
(författare)
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MAINS : A Magnetic-Field-Aided Inertial Navigation System for Indoor Positioning
- 2024
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Ingår i: IEEE Sensors Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1530-437X .- 1558-1748. ; 24:9, s. 15156-15166
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Tidskriftsartikel (refereegranskat)abstract
- A magnetic-field-aided inertial navigation system (MAINS) for indoor navigation is proposed in this article. MAINS leverages an array of magnetometers to measure spatial variations in the magnetic field, which are then used to estimate the displacement and orientation changes of the system, thereby aiding the inertial navigation system (INS). Experiments show that MAINS significantly outperforms the stand-alone INS, demonstrating the remarkable two orders of magnitude reduction in position error. Furthermore, when compared with the state-of-the-art magnetic-field-aided navigation approach, the proposed method exhibits slightly improved horizontal position accuracy. On the other hand, it has noticeably larger vertical error on datasets with large magnetic-field variations. However, one of the main advantages of MAINS compared with the state of the art is that it enables flexible sensor configurations. The experimental results show that the position error after 2 min of navigation in most cases is less than 3 m when using an array of 30 magnetometers. Thus, the proposed navigation solution has the potential to solve one of the key challenges faced with current magnetic-field simultaneous localization and mapping (SLAM) solutions-the very limited allowable length of the exploration phase during which unvisited areas are mapped.
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| 6. |
- Lai, Yangming, et al.
(författare)
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Joint Detection and Localization of Multiple Moving Targets in a Distributed Radar System
- 2024
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Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 24:17, s. 27914-27925
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates the joint detection and localization (JDL) problem of unknown number multiple moving targets in a distributed radar system. Upon formulating this problem as a composite multiple hypothesis testing problem, we derive a generalized information criterion (GIC)-based detector to simultaneously extract targets and estimate their unknown parameters, including their number, amplitudes, locations, and velocities. Although this solution theoretically achieves impressive performance by using raw echoes data to jointly detect and estimate multiple targets at the fusion center (FC), it also requires an unbearable computational load in practice. It is because multiple targets are expected to be simultaneously extracted by realizing a joint maximization task and making an enormous search. To reduce the computational burden, we propose a low-complexity solution to decompose the high-dimensional problem into several low-dimensional optimization problems. For local radars to undertake a portion of the calculations, the log-likelihood ratio (LLR) data are generated at each local station and then completely transmitted to the FC. Different from extracting multiple targets simultaneously using a GIC-based detector, we devise an extended successive-interference-cancellation (SIC) algorithm to detect targets one by one at the FC, and meanwhile, the parameters of targets can be simultaneously estimated at each iteration. Finally, the effectiveness of the proposed algorithm is demonstrated by the provided simulations.
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| 7. |
- Li, Jianguo, 1993, et al.
(författare)
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OFDM Radar Range Accuracy Enhancement Using Fractional Fourier Transformation and Phase Analysis Techniques
- 2020
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Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 20:2, s. 1011-1018
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Tidskriftsartikel (refereegranskat)abstract
- Orthogonal Frequency Division Multiplexing (OFDM) technique is obtained significant attention in radar applications for its interference resilience property. In this paper, Fractional Fourier Transformation (FRFT) and phase analysis techniques are proposed to enhance ranging accuracy of an OFDM Radar. A proof-of-concept radar is built and tested at 79 GHz and a range accuracy of 20 m at 5 MHz measurement rate was measured. The range accuracy is 500 times higher than using fast Fourier transformation (FFT) method.
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| 8. |
- Vasiljevic, D.Z., et al.
(författare)
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Performance analysis of flexible ink-jet printed humidity sensors based on graphene oxide
- 2018
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Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 18:11, s. 4378-4383
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents design, fabrication, and characterization of flexible capacitive graphene oxide (GO) based humidity sensors, which can be used in many applications, such as environmental protection, civil engineering, and agriculture. They consist of interdigitated electrodes ink-jet printed on a polyimide flexible substrate and GO based sensing layer. Measurement setup for testing and characterization was developed in laboratory conditions. The dependence of the capacitance and resistance of the GO based humidity sensors on the percentage of the applied humidity is presented. The main advantage of developed GO based capacitive humidity sensors is very large variation of capacitance, almost five orders of magnitude, compared with the previously demonstrated sensors. The other advantages of the sensors are fast response-recovery time, excellent reproducibility of the measurement results, and use of cost-effective additive ink-jet technology.
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| 9. |
- Alhashimi, Anas, 1978-, et al.
(författare)
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Calibrating distance sensors for terrestrial applications without groundtruth information
- 2017
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Ingår i: IEEE Sensors Journal. - : IEEE. - 1530-437X .- 1558-1748. ; 17:12, s. 3698-3709
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a new calibration procedure for distance sensors that does not require independent sources of groundtruth information, i.e., that is not based on comparing the measurements from the uncalibrated sensor against measurements from a precise device assumed as the groundtruth. Alternatively, the procedure assumes that the uncalibrated distance sensor moves in space on a straight line in an environment with fixed targets, so that the intrinsic parameters of the statistical model of the sensor readings are calibrated without requiring tests in controlled environments, but rather in environments where the sensor follows linear movement and objects do not move. The proposed calibration procedure exploits an approximated expectation maximization scheme on top of two ingredients: an heteroscedastic statistical model describing the measurement process, and a simplified dynamical model describing the linear sensor movement. The procedure is designed to be capable of not just estimating the parameters of one generic distance sensor, but rather integrating the most common sensors in robotic applications, such as Lidars, odometers, and sonar rangers and learn the intrinsic parameters of all these sensors simultaneously. Tests in a controlled environment led to a reduction of the mean squared error of the measurements returned by a commercial triangulation Lidar by a factor between 3 and 6, comparable to the efficiency of other state-of-the art groundtruth-based calibration procedures. Adding odometric and ultrasonic information further improved the performance index of the overall distance estimation strategy by a factor of up to 1.2. Tests also show high robustness against violating the linear movements assumption.
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| 10. |
- Jonsson, Patrik, 1968-, et al.
(författare)
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Road surface status classification using spectral analysis of NIR camera images
- 2015
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 15:3, s. 1641-1656
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for an automated road status classification system considering the vast number of weather-related accidents that occur every winter. Previous research has shown that it is possible to detect hazardous road conditions, including, for example, icy pavements, using single point infrared illumination and infrared detectors. In this paper, we extend this research into camera surveillance of a road section allowing for classification of area segments of weather-related road surface conditions such as wet, snow covered, or icy. Infrared images have been obtained using an infrared camera equipped with a set of optical wavelength filters. The images have primarily been used to develop multivariate data models and also for the classification of road conditions in each pixel. This system is a vast improvement on existing single spot road status classification systems. The resulting imaging system can reliably distinguish between dry, wet, icy, or snow covered sections on road surfaces.
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