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Wang, Xiaodong
Publications (8 of 8) Show all publications
Wang, X. (2013). Controlling ion transport in organic devices. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Controlling ion transport in organic devices
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Organic electronics and printed electronics have been attracting more and more research interest in the past decades. Polymers constitute an important class of materials within the field organic electronics due to their unique physical and chemical properties. One great benefit of the polymers is their solution processability, which provides us the possibility to utilize conventional printing techniques to fabricate devices on flexible substrates.

This thesis focuses on utilizing and controlling the ion transport in polyelectrolytes in electronic devices for different applications. A polyelectrolyte is a polymer in which the polymeric backbone includes ionic sites compensated by counter ions.

Firstly, we have used a specific property of the polyelectrolyte: its electric polarization is strongly dependent on the humidity level. The ions are screened by water molecules; this improves the mobility and dissociation of ions. A polyelectrolyte-based capacitor is thus ideal to sense humidity. Such a capacitor is integrated into an LC resonant circuit possessing a specific resonant frequency. The wirelessly detected resonant frequencies of the sensing circuit indicate the corresponding humidity levels. With the appropriate choice of materials, the complete sensing circuit (resistor, capacitor, capacitor-like sensor head) can be screen-printed on an antenna manufactured using a roll-to-roll dry phase patterning technique.

Secondly, we have modified the polarization characteristics of ions in a polyelectrolyte layer by trapping the ions in molecular macrocycles dispersed in a polymer overlayer. The resulting remanent polarization is read out as a hysteresis loop in the capacitance-voltage characteristic of a capacitor. The strategy is further implemented in an electrolyte-gated organic transistor to control its threshold voltage by applying defined programming voltages. Although the lifetime of the “remanent” polarization is rather short, the concept might be further improved to fit those of memory applications.

Finally, we take use of the ionic selectivity of a polyelectrolyte to stabilize the operation of a water-gated organic field-effect transistor. The polyanionic membrane is added onto the semiconductor channel to prevent small anions of the aqueous electrolyte to penetrate into the p-channel semiconductor. Moreover, the polyelectrolyte layer protects the semiconductor and thus strongly stabilizes the shelf lifetime of those transistors. This improved version of the water-gated organic transistor is a candidate for developing transistor-based sensors working in, for instance, biological media.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. p. 66
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1536
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-97353 (URN)978-91-7519-547-6 (ISBN)
Public defence
2013-09-18, Resursen, Pronova Norrköping konferens, St Persgatan 19, Norrköping, 10:15 (English)
Supervisors
Available from: 2013-09-10 Created: 2013-09-10 Last updated: 2017-02-03Bibliographically approved
Wang, X., Larsson, O., Platt, D., Nordlinder, S., Engquist, I., Berggren, M. & Crispin, X. (2012). An all-printed wireless humidity sensor label. Sensors and actuators. B, Chemical, 166-167, 556-561
Open this publication in new window or tab >>An all-printed wireless humidity sensor label
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2012 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 166-167, p. 556-561Article in journal (Refereed) Published
Abstract [en]

Printed electronics promise various kinds of sensor circuit labels, for applications in distributed sensing and monitoring, which can be manufactured using traditional printing tools at very low cost. Elevated humidity levels or water leakages cause tremendous costs in our society, such as in construction industries and in transportations. Distributed monitoring and remote sensing of the humidity level inside walls of buildings and packages is therefore desired and urgently needed. Here, we report a wireless humidity sensor label that is manufactured using screen-printing and dry-phase patterning. The sensor label includes a planar antenna, a tuning capacitor and a printed sensor-capacitor head. Through electromagnetic coupling between a reader and the printed sensor label, changes in humidity level were remotely detected and read-out as a shift of the resonant frequency. The manufacturing process of the humidity sensor label is fully compatible with inexpensive, reel-to-reel processing technologies, thus enabling low cost production.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
Printed humidity sensor label;
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-79036 (URN)10.1016/j.snb.2012.03.009 (DOI)000305356900075 ()
Available from: 2012-06-28 Created: 2012-06-28 Last updated: 2017-12-07
Wang, X., Laiho, A., Berggren, M. & Crispin, X. (2012). Remanent polarization in a cryptand-polyanion bilayer implemented in an organic field effect transistor. Applied Physics Letters, 100(2), 023305
Open this publication in new window or tab >>Remanent polarization in a cryptand-polyanion bilayer implemented in an organic field effect transistor
2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 2, p. 023305-Article in journal (Refereed) Published
Abstract [en]

We investigate the possibility to maintain an electric polarization in an organic bilayer via ion trapping, i.e., without any external bias. In the cryptand-polyanion bilayer, ions of specific size can be strongly coordinated with organic macrocyclic molecules. Cations move from the polyanion layer to the cryptand layer upon applying a bias and are trapped in this layer. As a result, the voltage dependence of the polarization displays a hysteresis. The bilayer is then advantageously used as an electronic insulating layer in an organic field effect transistor. The ions trapping and de-trapping can be followed by the amplitude of the threshold voltage (V(th)) shift as well as its temporal evolution.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-74848 (URN)10.1063/1.3677663 (DOI)000299126800077 ()
Note
Funding Agencies|Swedish Government||Swedish Foundation for Strategic Research||Brains and Bricks||Linkoping University||Knut and Alice Wallenberg Foundation||Onnesjo Foundation||Available from: 2012-02-10 Created: 2012-02-10 Last updated: 2017-12-07
Larsson, O., Wang, X., Berggren, M. & Crispin, X. (2010). Proton motion in a polyelectrolyte: A probe for wireless humidity sensors. Sensors and actuators. B, Chemical, 143(2), 482-486
Open this publication in new window or tab >>Proton motion in a polyelectrolyte: A probe for wireless humidity sensors
2010 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 143, no 2, p. 482-486Article in journal (Refereed) Published
Abstract [en]

Low-cost passive wireless electronic sensor labels glued onto packages are highly desirable since they enable monitoring of the status of the packages for instance along the logistic chain or while stored at a shelf. Such additional sensing feature would be of great value for many producers and vendors, active in e.g. the food or construction industries. Here, we explore a novel concept for wireless sensing and readout, in which the humidity sensitive ionic motion in a polyelectrolyte membrane is directly translated into a shift of the resonance frequency of a resonance circuit. Thanks to its simplicity, the wireless sensor device itself can be manufactured entirely using common printing techniques and can be integrated into a low-cost passive electronic sensor label.

Place, publisher, year, edition, pages
Elsevier / ScienceDirect, 2010
Keywords
Humidity sensor, Polyelectrolyte, Printed electronics, Wireless sensor, Resonance, Packaging
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-51546 (URN)10.1016/j.snb.2009.09.043 (DOI)000274774100004 ()
Note
Original Publication: Oscar Larsson, Xiaodong Wang, Magnus Berggren and Xavier Crispin, Proton motion in a polyelectrolyte: A probe for wireless humidity sensors, 2010, Sensors and actuators. B, Chemical, (143), 2, 482-486. http://dx.doi.org/10.1016/j.snb.2009.09.043 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2009-11-05 Created: 2009-11-05 Last updated: 2017-12-12Bibliographically approved
Johansson, C., Wang, X. & Robertsson, M. (2008). Printable rectifying device using Si-composite. Electronics Letters, 44(1), 53-55
Open this publication in new window or tab >>Printable rectifying device using Si-composite
2008 (English)In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 44, no 1, p. 53-55Article in journal (Refereed) Published
Abstract [en]

The R&D in finding low-cost manufacturing of electronics and electronic components is intense. One research route is aiming at roll-to-roll printing of organic electronics but the typically low mobility in organic semiconductors results in fundamental difficulties to fabricate, e.g., diodes for operation at high frequencies. A novel diode has instead been realised by screen-printing a silicon-powder composite with the intention to utilise the high mobility and the high operation frequency potential of silicon. The current against voltage (I-V) characteristics of the printed device reveal diode behaviour but so far with a too high ideality factor and resistance to be practically useful. By optimising device geometry, composite, and printing process low-cost printed, high frequency diodes (MHz-some GHz) may be viable.

Keywords
rectifying circuits, semiconductor device manufacture, current against voltage characteristics, high frequency diodes, organic electronics, organic semiconductors, printable rectifying device, printed device, roll-to-roll printing, silicon-powder composite
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-13137 (URN)10.1049/el:20082824 (DOI)
Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2017-12-13
Silins, I., Wang, X., Tadesse, A., Jansen, K. U., Schiller, J. T., Åvall-Lundqvist, E., . . . Dillner, J. (2004). A population-based study of cervical carcinoma and HPV infection in Latvia.. Gynecologic Oncology, 93(2), 484-492
Open this publication in new window or tab >>A population-based study of cervical carcinoma and HPV infection in Latvia.
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2004 (English)In: Gynecologic Oncology, ISSN 0090-8258, E-ISSN 1095-6859, Vol. 93, no 2, p. 484-492Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: We wished to quantify the population-based importance of cervical carcinoma risk factors in Latvia.

METHODS: Totally, 223 of 224 eligible cases of incident invasive cervical carcinoma were enrolled during July 1998-February 2001 in Latvia. An age-matched sample of 300 healthy control women was selected from the Latvian population registry and 239 of these women (79%) were enrolled. A demographic and life-style questionnaire was completed, cervical brush samples were analyzed for human papillomavirus (HPV) DNA by PCR and serum samples for HPV antibodies.

RESULTS: Risk factors for cervical cancer in multivariate analysis were HPV type 16 or 18 DNA positivity (OR = 32.4; CI 95% 16.5-63.6) and living in the capital (OR = 2.4; CI 95% 1.2-4.7). Oral contraceptive use was not a risk factor (OR = 0.4; CI 95% 0.2-1.1). A strong protective effect was found for having had more than three Pap smears in the last 5 years (OR = 0.07 CI 95% 0.03-0.19).

CONCLUSIONS: Inadequate population coverage of Pap smears, in spite of excessive smear usage, caused 28.4% of cervical cancers in age groups eligible for screening. HPV type 16 infection was the most important risk factor for cervical cancer in Latvia, with a population-attributable risk percent for all ages of 58.5%.

Place, publisher, year, edition, pages
Academic Press, 2004
Keywords
Cervical cancer, Epidemiology, HPV infection, Screening
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-113935 (URN)10.1016/j.ygyno.2004.01.044 (DOI)000221120500035 ()15099967 (PubMedID)2-s2.0-1942508837 (Scopus ID)
Available from: 2015-02-03 Created: 2015-02-03 Last updated: 2017-04-20Bibliographically approved
Wang, X., Crispin, X. & Berggren, M. Improving the stability of water-gated organic transistors for sensing applications.
Open this publication in new window or tab >>Improving the stability of water-gated organic transistors for sensing applications
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The instability of water-gated organic transistors is a major obstacle for their sensing applications in aqueous media. In the present work, we demonstrate that adding a fluorinated ion exchange membrane, Nafion, on a water-gated organic transistor can increase significantly the stability of the device to air exposure. In addition, choosing a suitable operating voltage range, e.g. Vg=0 ↔ -0.7 V, is shown to be crucial for achieving stable (repeatable) measurements in aqueous media. It is also feasible to exploit this kind of transistor as a chemical sensor to discriminate different chemicals which are dissolved in water.

Keywords
Printed humidity sensor label;
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-97351 (URN)
Available from: 2013-09-10 Created: 2013-09-10 Last updated: 2017-02-03Bibliographically approved
Wang, X., Platt, D., Crispin, X., Engquist, I. & Berggren, M. Printed low loss capacitors for use in a wireless humidity sensor label.
Open this publication in new window or tab >>Printed low loss capacitors for use in a wireless humidity sensor label
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

A low loss printed capacitor is achieved by using a screen printable benzocyclobutene-based solution. The dissipation factor is measured to be 0.001 at frequencies around 3 MHz, which is low compared to commercially available dielectric inks with dissipation factors of ~0.05 in the same frequency region. By incorporating low loss printed capacitors with a planar antenna and a printed humidity sensor capacitor, a humidity sensor label which resonates at 3 MHz is demonstrated. The label is fully printed on a flexible substrate pre-patterned with the antenna and the manufacturing process is compatible with low-cost reelto-reel processing technology. The quality factor (Q factor) of the sensor label is enhanced up to about 15 in ambient environment. This allows readout of the sensor response at a distance and through damping materials such as walls in a building.

Keywords
Printed humidity sensor label;
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-97350 (URN)
Available from: 2013-09-10 Created: 2013-09-10 Last updated: 2017-02-03Bibliographically approved
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