| 1. |
- Ahmad, Jawad, 1985-, et al.
(författare)
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Screen Printed Piezoresistive Sensors for Monitoring Pressure Distribution in Wheelchair
- 2019
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Ingår i: IEEE Sensors Journal. - : IEEE. - 1530-437X .- 1558-1748. ; 19:6, s. 2055-2063
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged sitting inadequacies cause pressure ulcer to many individuals, especially to disadvantaged with reduced mobility. The measurement of distributed pressure and detection of irregular sitting postures is essential for preventing the risk of developing pressure ulcer. In this paper, a pressure sensing system capable of recognizing sitting postures by means of measuring interface pressure through printed pressure sensors is presented. A thin and flexible large area sensor is screen-printed using silver flake and carbon particle inks and comprises 16 sensing elements. For the evaluation of practical usability, the sensor characterization is carried out by conducting stability, repeatability, drift and bending tests. The performance of the sensor is checked under varying environmental conditions. Sitting posture detection accuracy above 80 % is achieved using a classification algorithm for four different sitting postures. Pressure distribution is monitored at a scanning rate of 10 Hz. A low power and small form factor of read-out electronics enables a compact packaging inside the seat cushion. The presented sensor design targets smart wheelchairs, but it is extendable to much larger areas, for example to be used in beds. The proposed sensing system would be of a great assistance for caregivers and health professionals.
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| 2. |
- 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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| 3. |
- Gao, Jinlan, et al.
(författare)
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Printed Humidity Sensor with Memory Functionality for Passive RFID tags
- 2013
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 13:5, s. 1824-1834
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a printed UHF RFID sensor solution that indicates whether a passive RFID tag has been exposed to a certain degree of humidity. The printed sensor operates as a Write Once Read Many (WORM) resistive memory as it permanently changes its resistance from about 2 kÙ to less than 50 Ù after exposure to humidity or water. The change of the sensor resistance is used to modulate the properties of a UHF RFID tag antenna by changing antenna input impedance and also introducing or removing ohmic losses in the antenna structure. The final result is reflected in the change of the minimum transmit power required to power-up the RFID tag. Both the sensor and the tag antenna are printed horizontally on a paper substrate. Different geometric combinations of sensor and antenna structures are investigated. Typical applications include non-invasive methods for detecting wetness or humidity levels in hidden locations such as within construction structures. The sensor setup can also serve to provide information as to whether a package sent over a supply chain has exceeded a certain level of humidity during its route.
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| 4. |
- Nilsson, Hans-Erik, et al.
(författare)
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Printed write once and read many sensor memories in smart packaging applications
- 2011
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 11:9, s. 1759-1767
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Tidskriftsartikel (refereegranskat)abstract
- A horizontal printed Write Once Read Many (WORM) resistive memory has been developed for use in wireless sensortags targeting single event detection in smart packaging applications. The WORM memory can be programmed using a 1.5 V printedbattery. An alternative programming method is to use chemical sintering which allows the development of exposure-time triggeredsingle event tags that can be accessed wirelessly. The new WORM memory has very low losses in the ON-state which allows directintegration into antenna structures.A sensor tag that utilizes the WORM memory functionality and the well established Electronic Article Surveillance (EAS)communication standard has been outlined. Both active and fully passive sensor tag solutions have been proposed.The role of printed electronics in smart packaging applications has been reviewed and discussed. Important enabling factors forthe future development have been highlighted, such as the need for hierarchical design and test tools, better printed interconnecttechnologies as well as better components that allow communication with existing information and communication technology (ICT)standards. This is illustrated and underlined by the presented smart packaging concept demonstrators.
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| 5. |
- Unander, Tomas, et al.
(författare)
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Designing of RFID based Sensor Solution for Packaging Surveillance Applications
- 2011
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 11:11, s. 3009-3018
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a two-chip battery assisted Radio Frequency Identification (RFID) based sensor platform is presented. The radio frequency communication interface is based on the EPC Gen 2 standard. A laboratory setup of the platform has been shown and characterized for a moisture content sensor application. The laboratory setup of the sensor platform has a reading range of 3.4 meters which is in comparison to commercial available Gen 2 tags. The laboratory platform has an average power consumption of 2.1 μW operating at 3 V, which together with a printed battery gives an estimated lifetime for data logging of several years. The proposed RFID platform provides a tradeoff between, communication performance, compatibility with international standards, and flexibility in on-package customization including type and number of sensors. The proposed architecture separates the high-performance communication circuit and the low-frequency sensor interface logic. In the future, the sensor interface maybe integrated using printed logics to further enhance the flexibility and low-ost customization features of the architecture
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