| 1. |
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| 2. |
- Andersson, Henrik, et al.
(författare)
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Chemically programmed ink-jet printed resistive WORM memory array and readout circuit
- 2014
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Ingår i: Materials Research Express. - : Institute of Physics (IOP). - 2053-1591. ; 1:3, s. 035021-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper an ink-jet printed write once read many (WORM) resistive memory fabricated on paper substrate is presented. The memory elements are programmed for different resistance states by printing triethylene glycol monoethyl ether on the substrate before the actual memory element is printed using silver nano particle ink. The resistance is thus able to be set to a broad range of values without changing the geometry of the elements. A memory card consisting of 16 elements is manufactured for which the elements are each programmed to one of four defined logic levels, providing a total of 4294 967 296 unique possible combinations. Using a readout circuit, originally developed for resistive sensors to avoid crosstalk between elements, a memory card reader is manufactured that is able to read the values of the memory card and transfer the data to a PC. Such printed memory cards can be used in various applications.
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| 3. |
- 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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| 4. |
- Andersson, Henrik, et al.
(författare)
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The influence of paper coating content on room temperature sintering of silver nanoparticle ink
- 2013
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 24:45, s. Art. no. 455203-
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Tidskriftsartikel (refereegranskat)abstract
- The resistance of inkjet printed lines using a silver nanoparticle based ink can be very dependent on the substrate. A very large difference in resistivity was observed for tracks printed on paper substrates with aluminum oxide based coatings compared to silica based coatings. Silica based coatings are often cationized with polymers using chloride as a counter ion. It is suggested that the precipitation of silver salts is the cause of the high resistivity, since papers pretreated with salt solutions containing ions that precipitate silver salts gave a high resistance. Silver nitrate has a high solubility and paper pretreated with nitrate ions gave a low resistivity without sintering. The results obtained show that, by choosing the correct type of paper substrate, it is possible to manufacture printed structures, such as interconnects on paper, without the need for, or at least to reduce the need for, post-print sintering. This phenomenon is, of course, ink specific. Inks without or with a low silver ion content are not expected to behave in this manner. In some sensor applications, a high resistivity is desired and, by using the correct combination of ink and paper, these types of sensors can be facilitated.
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| 5. |
- Gao, Jinlan, et al.
(författare)
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An Analytical Model for Electro-magnetically Coupled UHF RFID Sensor Tags
- 2013
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Ingår i: 2013 IEEE INTERNATIONAL CONFERENCE ON RFID (RFID). - : IEEE conference proceedings. - 9781467357500 - 9781467357487 ; , s. 66-73
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Konferensbidrag (refereegranskat)abstract
- This paper presents an analytical model for electromagnetically coupled UHF RFID sensor tags where a coupling loop with an embedded sensor is attached to an ordinary UHF RFID tag with a small gap. Electromagnetic coupling is used, in this case, to modulate the properties of the tag antenna in proportion to the values of the embedded sensor. The antenna together with the coupling loop are represented as an equivalent circuit and the analysis of the sensor tag becomes a circuit-level calculation after extracting parameters from full-wave simulations for, respectively, the separated dipole antenna and coupling loop. The results calculated from the equivalent circuit model are compared with the results from full-wave simulations and show good agreement. The presented model can thus be used for analyzing and predicting the behavior of electromagnetically coupled sensor tags. Based on the analysis with the presented model, the methods for optimizing the sensory performance of this kind of RFID sensor tags are also presented in this paper.
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| 6. |
- Gao, Jinlan
(författare)
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Antenna-based passive UHF RFID sensor tags : Design and application
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- RFID, as a low cost technology with a long life time, provides great potential for transmitting sensor data in combination with the ordinary ID number. The sensor can, for example, be integrated either in the chip or in the antenna of an RFID tag.This thesis focuses on the design of antenna-based UHF RFID sensor tags as wireless sensors at the lowest possible cost level compatible with standard communication systems in logistics. The applications of the sensor tags, in this work, mainly target remote humidity sensing. Antenna-based sensory UHF RFID tags utilize the influence that the physical or chemical parameters to be sensed have on the electrical properties of a tag antenna. The variations of the electrical properties of the tag antenna can be measured in many ways. In the thesis, a description is provided as to how these variations are normally measured by an RFID reader without any other assistant equipment. Three structures of antenna-based RFID sensor tags are presented with detailed characterizations. The first one utilizes the sensitivity of the antenna to the surrounding environment to construct RFID sensor tags, where a moisture absorbing layer providing wetness/humidity sensor functionality is placed on the RFID tag antenna to increase the humidity concentration surrounding the tag antenna and the thesis describes how to overcome certain limitations due to disturbances associated with background materials. The second structure directly integrates a small resistive sensor element into an RFID tag antenna and the sensor information can thus modulate the antenna performance by means of galvanic contact. The third structure embeds a small resistive sensor element into a loop which is positioned on top of the tag antenna and the sensor information can thus modulate the performance of the tag antenna by means of electromagnetic coupling. Both theoretical analysis and fullwave simulations are presented for the latter two sensor tag structures in order to characterize the performance of the sensor tags. An ultra-low cost printed humidity sensor with memory functionality is also designed and thoroughly characterized for integration into RFID tag antennas by means of galvanic contact or electromagnetic coupling. The sensor is a 1-bit write-once-read-many (WORM) memory printed using conductive ink. The WORM works as a pure resistive humidity sensor and can provide information about an historical event. The WORM sensor is presented by introducing its geometry, characterizingits behavior in humidity and explaining the principle of the humidity effect. The WORM sensors are also integrated into the RFID tags by means of both galvanic contact and electromagnetic coupling in order to experimentally verify the two concepts. To lower the cost of the RFID tags, the antennas are normally printed, milledor etched on flexible substrates using low-cost high-speed manufacturing methods which in some cases cause a high degree of edge roughness. The edge roughness will affect the behavior of the antenna, however, the characteristics of edge roughness on RFID antennas have previously not received any significant attention. Unforeseen antenna behavior can affect the antenna-based sensor tags, thus the influence of edge roughness is also investigated in the thesis.
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| 7. |
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| 8. |
- Gao, Jinlan, et al.
(författare)
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On the Influence of Edge Roughness in High-Speed RFID Antenna Manufacturing Processes
- 2013
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Ingår i: Proceeding of the 34th Progress in Electromagnetics Research Symposium (PIERS 2013). ; , s. 571-576
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Konferensbidrag (refereegranskat)abstract
- High speed manufacturing processes are commonly associated with high mechanical tolerances. For RFID antennas, mechanical manufacturing tolerances imply uncertainties in the antennas outer dimensions as well as in the surface- and line-roughness of the antennas geometry. Rough edges can for example be caused by high speed dry patterning processes. This work investigates the impact that rough patterns along the edges of an antenna structure have on UHF RFID tags' communication capabilities. The work characterizes the negative influence that edge roughness of different levels has on standard RFID dipoles. Results show that, as expected, the performance degradation for an RFID tag antenna increases with increased edge roughness amplitude. The results also show that the performance degradation due to edge roughness is almost identical for the investigated antennas' different line widths when the roughness level is normalized to its specific antenna line width, i.e., an antenna with a wider line width is more robust and can withstand a higher degree of edge roughness.
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| 9. |
- Gao, Jinlan, et al.
(författare)
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Printed electromagnetic coupler with an embedded moisture sensor for ordinary passive RFID tags
- 2011
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 32:12, s. 1767-1769
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents a printed UHF RFID sensor solution that indicates if a passive RFID tag has been exposed to a certain degree of moisture. The printed sensor operates as a write-once-read-many (WORM) resistive memory device as it permanently changes its resistance from about 10 to 10 after exposure to moisture or water. A printed coupling loop with an embedded WORM sensor is horizontally placed just above the surface of an ordinary UHF RFID tag. Electromagnetic coupling is used to modulate the properties of the tag antenna by changing its input impedance and introducing ohmic losses in proportion to the embedded sensor values. The passive RFID tag can change state from readable to unreadable when the WORM bit is set, i.e., is put in a low-resistance state. The proposed concept verifies that commercial RFID tags can be used as sensor tags by simply adding an electromagnetically coupled sensor as a sticker or by similar means, without the need for ohmic contacts between the sensor and the original RFID tag. © 2006 IEEE.
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| 10. |
- 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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| 11. |
- Gao, Jinlan, 1984-, et al.
(författare)
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Printed Temperature Sensors for Passive RFID Tags
- 2010
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Ingår i: Proceeding of 27th conference in Progress In Electromagnetics Research Symposium (PIERS2010 Xian). ; , s. 835-838
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Konferensbidrag (refereegranskat)
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| 12. |
- Sidén, Johan, et al.
(författare)
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Electric and Electromagnetic Coupled Sensor Components for Passive RFID
- 2011
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Ingår i: 2011 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems, COMCAS 2011. - : IEEE conference proceedings. - 9781457716928 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- This work discuss the possibilities of integrating passive sensor components to passive UHF RFID tags. The sensor system works by degrading a tag's communication performance in proportion to a sensed quantity. Two approaches are studied, sensors directly integrated to tag antenna structures and sensors electromagnetically coupled to tag antennas. The em coupled sensors provide the possibility to produce small sensor components as easily applied add-ons to ordinary commercial RFID tags.
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| 13. |
- Sidén, Johan, et al.
(författare)
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Home Care with NFC Sensors and a Smart Phone
- 2011
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Ingår i: ACM International Conference Proceeding Series. - New York, NY, USA : ACM Press. - 9781450309134
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Konferensbidrag (refereegranskat)abstract
- The world's aging population and limited hospital resources together with advancements in information technology provides a thorough basis for further development of tele-healthcare and assisted living. For ordinary people, and especially elderly people, to be diagnosed and treated in their homes there is a definite need for technical equipment that is extremely easy to handle. One way to facilitate tele-healthcare is to take advantage of modern cell phone technology and the infrastructure surrounding these units. Many elderly people are today comfortable with using cell phones and even advanced smart phones can be purchased to a cost that is low compared to corresponding specialized medical equipment. The concept presented in this work is based upon Near Field Communication (NFC), a wireless feature that is currently being widely launched in cell phones. Amongst other capabilities, NFC technology allows a phone to act as a 13.56 MHz RFID reader. This work shows how NFC-equipped phones can be used to read passive NFC tags that in turn are equipped with general resistive sensors and how sensor data are read and communicated to a web server without the need to push a single button. © 2011 ACM.
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| 14. |
- Sidén, Johan, 1975-, et al.
(författare)
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Microstrip Antennas for Remote Moisture Sensing using Passive RFID
- 2009
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Ingår i: APMC: 2009 ASIA PACIFIC MICROWAVE CONFERENCE, VOLS 1-5. - : IEEE conference proceedings. - 9781424428021 ; , s. 2375-2378
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Konferensbidrag (refereegranskat)abstract
- The paper presents how materials with a highability of absorbing moisture can be used with microstripantennas and passive RFID chips for constructing remotely readmoisture sensors. The concept is based on pairs of microstripantennas, applied on the same piece of PCB and each equippedwith one RFID chip, where one antenna is covered by themoisture absorbent material and the other is left open. In ahumid or wet environment the moisture concentration is higherin the absorbent material than in the surrounding environmentwhich causes degradation to the embedded antenna both interms of dielectric losses and change of input impedance. Thelevel of relative humidity or the amount of water in theabsorbent material is determined for a passive RFID system bycomparing the difference in RFID reader output power requiredto power up respectively the open and embedded tag. While ithas previously been shown how this can be accomplished withsimple one-layer antennas we here look into using microstripantennas to get around the problem with high influence frombackground material. Typical applications include moisturedetection in buildings, especially from leaking water pipeconnections hidden beyond walls or simply to measure the levelof relative humidity at hidden locations.
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| 15. |
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