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Contacting versus Insulated Gate Electrode for Si Nanoribbon Field-Effect Sensors Operating in Electrolyte
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. (emerging electronics)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. (emerging electronics)
2011 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 83, no 24, p. 9546-9551Article in journal (Refereed) Published
Abstract [en]

Electric response to pH variations is employed to investigate Si nanoribbon field-effect transistors (SiNRFETs) operating in electrolyte with different gate configurations. For devices with a concluding gate electrode for direct metal electrolyte contact, a well-defined electrode reaction leading to a stable electrode potential is essential for retaining a stable electrical potential of the electrolyte. However, noble metals such as Pt do not meet the stability requirement and consequently bring severe distortions to the electronic response. For devices with an insulated gate electrode relying on the principle of capacitive gate coupling, the capacitance between the gate electrode and the electrolyte should be made much larger than the gate capacitance established between the SiNR and the electrolyte. In this case, an efficient gate control as well as a high stability against external disturbances can be ensured. Further studies show that surface charging of the gate insulator is the main cause responsible for the pH response of the SiNRFETs. Hence, devices with different gate configurations give rise to a comparable pH sensitivity.

Place, publisher, year, edition, pages
2011. Vol. 83, no 24, p. 9546-9551
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
URN: urn:nbn:se:uu:diva-164117DOI: 10.1021/ac2023316ISI: 000297946900053OAI: oai:DiVA.org:uu-164117DiVA, id: diva2:466537
Available from: 2011-12-16 Created: 2011-12-16 Last updated: 2017-12-08Bibliographically 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. p. 71
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1018
Keywords
biosensor, field-effect transistor, nanowire, ISFET
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Nano Technology
Research subject
Electronics
Identifiers
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)
Opponent
Supervisors
Available from: 2013-03-05 Created: 2013-02-07 Last updated: 2013-04-02Bibliographically approved

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Publisher's full texthttp://pubs.acs.org/doi/abs/10.1021/ac2023316

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Chen, SiZhang, Shi-Li

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