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On the Road to Graphene Biosensors
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.ORCID iD: 0000-0003-1831-3980
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Biosensors are devices that detect biological elements and then transmit a readable signal. Biosensors can automatize diagnostics that would otherwise have to be performed by a physician or perhaps not be possible to perform at all. Current biosensors are however either limited to particular diseases or prohibitively expensive. In order to further the field, sensors capable of many parallel measurements at a lower cost need to be developed. Field effect transistor (FET) based sensors are possible candidates for delivering this, mainly by allowing miniaturization. Smaller sensors could be cheaper, and enable parallel measurements.

Graphene is an interesting material to use as the channel of FET-sensors. The low electrochemical reactivity of its plane makes it possible to have graphene in direct contact with the sample liquid, which enhances the signal from impedance changes. Graphene-FET based impedance sensors should be able to sense almost all possible analytes and allow for scaling without losing sensitivity.

In this work the steps needed to make graphene based biosensors are presented. An improved graphene transfer is described which by using low pressure to dry the graphene removes most contamination. A method to measure the contamination of graphene by surface enhanced Raman scattering is presented. Methods to produce double gated and electrolyte gated graphene transistors on a large scale in an entirely photolithographic process are detailed. The deposition of 1-pyrenebutyric acid (PBA) on graphene is studied. It is shown that at high surface concentrations the PBA stands up on graphene and forms a dense self-assembled monolayer. A new process of using Raman spectroscopy data to quantify adsorbents was developed in order to quantify the molecule adsorption. Biosensing has been performed in two different ways. Graphene FETs have been used to read the signal generated by a streaming potential setup. Using FETs in this context enables a more sensitive readout than what would be possible without them. Graphene FETs have been used to directly sense antibodies in high ionic strength. This sensing was done by measuring the impedance of the interface between the FET and the electrolyte.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. , 68 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1488
Keyword [en]
Graphene, Biosensors, Microprocessing, Photolithography, Surface Physics, Raman Spectroscopy, Transistors
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
URN: urn:nbn:se:uu:diva-317092ISBN: 978-91-554-9845-0 (print)OAI: oai:DiVA.org:uu-317092DiVA: diva2:1080420
Public defence
2017-04-28, Polhemssalen/10134, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation, 2011.0113Swedish Research Council, VR, No.621-2014-5591
Available from: 2017-04-07 Created: 2017-03-10 Last updated: 2017-04-21
List of papers
1. Scalable residue-free graphene for surface-enhanced Raman scattering
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2016 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 98, 567-571 p.Article in journal (Refereed) Published
Abstract [en]

A room-temperature polymer-assisted transfer process is developed for large-area, single-layer graphene grown by means of chemical vapor deposition (CVD). This process leads to transferred graphene layers free of polymer contamination. The absence of polymer residues boosts the surface-enhanced Raman scattering (SERS) of the CVD graphene with gold nanoparticles (Au NPs) deposited atop by evaporation. The SERS enhancement of the CVD graphene reaches similar to 120 for the characteristic 2D peak of graphene, the highest enhancement factor achieved to date, when the Au NPs are at the threshold of percolation. Our simulation supported by experiment suggests that the polymer residues persistently present on the graphene transferred by the conventional polymer-assisted method are equivalent to an ultrathin film of less than 1 nm thickness. The presence of polymer residues drastically reduces SERS due to the separation of the Au NPs from the underlying graphene. The scalability of CVD graphene opens up for the possibility of graphene-based SERS sensors.

National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-269192 (URN)10.1016/j.carbon.2015.11.043 (DOI)000367233000070 ()
Funder
Knut and Alice Wallenberg Foundation, 2011.0113Knut and Alice Wallenberg Foundation, 2011.0082Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, 621-2014-5591
Available from: 2015-12-14 Created: 2015-12-14 Last updated: 2017-03-10Bibliographically approved
2. A two-in-one process for reliable graphene transistors processed with photolithography
Open this publication in new window or tab >>A two-in-one process for reliable graphene transistors processed with photolithography
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2015 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, no 20, 203104Article in journal (Refereed) Published
Abstract [en]

Research on graphene field-effect transistors (GFETs) has mainly relied on devices fabricated using electron-beam lithography for pattern generation, a method that has known problems with polymer contaminants. GFETs fabricated via photo-lithography suffer even worse from other chemical contaminations, which may lead to strong unintentional doping of the graphene. In this letter, we report on a scalable fabrication process for reliable GFETs based on ordinary photo-lithography by eliminating the aforementioned issues. The key to making this GFET processing compatible with silicon technology lies in a two-in-one process where a gate dielectric is deposited by means of atomic layer deposition. During this deposition step, contaminants, likely unintentionally introduced during the graphene transfer and patterning, are effectively removed. The resulting GFETs exhibit current-voltage characteristics representative to that of intrinsic non-doped graphene. Fundamental aspects pertaining to the surface engineering employed in this work are investigated in the light of chemical analysis in combination with electrical characterization.

National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-269191 (URN)10.1063/1.4935985 (DOI)000365688700049 ()
Funder
Knut and Alice Wallenberg Foundation, 2011.0113, 2011.0082Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, 621-2014-5591
Available from: 2015-12-14 Created: 2015-12-14 Last updated: 2017-03-10Bibliographically approved
3. On Monolayer Formation of Pyrenebutyric Acid on Graphene
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(English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827Article in journal (Refereed) Submitted
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-317087 (URN)
Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2017-03-10
4. Highly sensitive detection of allergic proteins by nano-scale field effect transistor-integrated electrokinetic sensor
Open this publication in new window or tab >>Highly sensitive detection of allergic proteins by nano-scale field effect transistor-integrated electrokinetic sensor
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(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-317089 (URN)
Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2017-04-07
5. Protein sensing beyond the Debye Length Using Graphene Field-effect Transistors
Open this publication in new window or tab >>Protein sensing beyond the Debye Length Using Graphene Field-effect Transistors
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(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-317088 (URN)
Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2017-03-10

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