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Current Instability for Silicon Nanowire Field-Effect Sensors Operating in Electrolyte with Platinum Gate Electrodes
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
School of Biotechnology, KTH, Stockholm.
School of Biotechnology, KTH, Stockholm.
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2011 (English)In: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 14, no 7, J34-J37 p.Article in journal (Refereed) Published
Abstract [en]

Current instability is observed for silicon nanowire field-effect transistors operating in electrolytes with Pt gate electrodes. A comparative study involving an Ag/AgCl-reference gate electrode reveals that the effect results from a drift in the potential at the Pt-electrode/electrolyte interface. In a phosphate buffer saline of pH 7.4, the stabilization of the potential of the Pt electrode was found to require approximately 1000 s. A concurrent potential drift, with a comparable time constant, occurring at the electrolyte/oxidized-nanowire interface rendered a complex device current response which complicated the interpretation of the results.

Place, publisher, year, edition, pages
2011. Vol. 14, no 7, J34-J37 p.
National Category
Engineering and Technology Inorganic Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry; Engineering Science with specialization in Electronics
URN: urn:nbn:se:uu:diva-154111DOI: 10.1149/1.3584082ISI: 000290276400027OAI: oai:DiVA.org:uu-154111DiVA: diva2:419378
Available from: 2011-05-26 Created: 2011-05-26 Last updated: 2016-04-20Bibliographically approved
In thesis
1. Electronic Sensors Based on Nanostructured Field-Effect Devices
Open this publication in new window or tab >>Electronic Sensors Based on Nanostructured Field-Effect Devices
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Point-of-care (POC) diagnostics presents a giant market opportunity with profound societal impact. In particular, specific detection of DNA and protein markers can be essential for early diagnosis of e.g. cancer, cardiovascular disease, infections or allergies. Today, identification of these markers often requires extensive laboratory work and hence is expensive and time consuming. Current methods for recognition and detection of specific biomolecules are mostly optics based and thus impose severe limitations as to convenience, specificity, sensitivity, parallel processing and cost reduction.

Electronic sensors based on silicon nanowire field-effect transistors have been reported to be able to detect biomolecules with concentrations down to femtomolar (fM) level with high specificity. Although the reported capability needs further confirmation, the CMOS-compatible fabrication process of such sensors allows for low cost production and high density integration, which are favorable for POC applications. This thesis mainly focuses on the development of a multiplex detection platform based on silicon nanowire field-effect sensors integrated with a microfluidic system for liquid sample delivery. Extensive work was dedicated to developing a top-down fabrication process of the sensors as well as an effective passivation scheme. The operation mechanism and coupling efficiencies of different gate configurations were studied experimentally with the assistance of numerical simulation and equivalent circuits. Using pH sensing as a model system, large effort was devoted to identifying sources for false responses resulting from the instability of the inert-metal gate electrode. In addition, the drift mechanism of the sensor operating in electrolyte was addressed and a calibration model was proposed. Furthermore, protein detection experiments were performed using small-sized Affibody molecules as receptors on the gate insulator to tackle the Debye screening issue. Preliminary results showed that the directionality of the current changes in the sensors was in good agreement with the charge polarities of the proteins. Finally, a graphene-based capacitor was examined as an alternative to the nanowire device for field-effect ion sensing. Our initial attempts showed some attractive features of the capacitor sensor.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 71 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1018
biosensor, field-effect transistor, nanowire, ISFET
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Nano Technology
Research subject
urn:nbn:se:uu:diva-194015 (URN)978-91-554-8596-2 (ISBN)
Public defence
2013-03-27, Häggsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Available from: 2013-03-05 Created: 2013-02-07 Last updated: 2013-04-02Bibliographically approved

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