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Publications (4 of 4) Show all publications
Afrasiabi, R., Söderberg, L., Jönsson, H., Björk, P., Svahn Andersson, H. & Linnros, J. (2016). Integration of a Droplet-Based Microfluidic System and Silicon Nanoribbon FET Sensor. Micromachines, 7(8), Article ID 134.
Open this publication in new window or tab >>Integration of a Droplet-Based Microfluidic System and Silicon Nanoribbon FET Sensor
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2016 (English)In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Micromachines, Vol. 7, no 8, article id 134Article in journal (Refereed) Published
Abstract [en]

We present a novel microfluidic system that integrates droplet microfluidics with a silicon nanoribbon field-effect transistor (SiNR FET), and utilize this integrated system to sense differences in pH. The device allows for selective droplet transfer to a continuous water phase, actuated by dielectrophoresis, and subsequent detection of the pH level in the retrieved droplets by SiNR FETs on an electrical sensor chip. The integrated microfluidic system demonstrates a label-free detection method for droplet microfluidics, presenting an alternative to optical fluorescence detection. In this work, we were able to differentiate between droplet trains of one pH-unit difference. The pH-based detection method in our integrated system has the potential to be utilized in the detection of biochemical reactions that induce a pH-shift in the droplets.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute, 2016
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Medical Laboratory and Measurements Technologies Medical Biotechnology
Identifiers
urn:nbn:se:kth:diva-250368 (URN)10.3390/mi7080134 (DOI)000382467700006 ()2-s2.0-84984791952 (Scopus ID)
Note

QC 20190520

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-08-19Bibliographically approved
Afrasiabi, R., Jokilaakso, N., Schmidt, T., Björk, P., Eriksson Karlström, A. & Linnros, J. (2015). Effect of microwave-assisted silanization on sensing properties of silicon nanoribbon FETs. Sensors and actuators. B, Chemical, 209, 586-595
Open this publication in new window or tab >>Effect of microwave-assisted silanization on sensing properties of silicon nanoribbon FETs
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2015 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 209, p. 586-595Article in journal (Refereed) Published
Abstract [en]

An important concern with using silicon nanoribbon field-effect transistors (SiNR FET) for ion-sensing is the pH-response of the gate oxide surface. Depending on the application of the FET sensor, this response has to be chemically manipulated. Thus in silicon oxide-gated pH-sensors with integrated sensor and reference FETS, a surface with high pH-sensitivity, compared to the bare gate oxide, is required in the sensor FETs (SEFET), whereas in the reference FETs (REFET) the surface has to be relatively pH-insensitive. In order to control the sensitivity and chemistry of the oxide surface of the nanoribbons, a silanization reagent with a functional group is often self-assembled on the SiNR surface. Choice of a silanization reaction that results in a self-assembled layer on a silicon oxide surface has been studied extensively over the past decades. However, the effect of various self-assembled layers such as monolayers or mixed layers on the electrical response of SiNR FETs in aqueous solution needs to be exploited further, especially for future integrated SEFET/REFET systems. In this work, we have performed a comprehensive study on 3-aminopropyltriethoxysilane (APTES) silanization of silicon oxide surfaces using microwave (MW) heating as a new biocompatible route to conventional methods. A set of complementary surface characterization techniques (ellipsometry, AFM and ATR-FTIR) was used to analyze the properties of the APTES layer deposited on the silicon surface. We have found that a uniform monolayer can be achieved within 10 min by heating the silanization solution to 75 degrees C using MW heating. Furthermore, electrical measurements suggest that little change in device performance is observed after exposure to MW irradiation. Real-time pH measurements indicate that a uniform APTES monolayer not only reduces the pH sensitivity of SiNR FET by passivating the surface silanol groups, but also makes the device less sensitive to cation concentration in the background electrolyte. Our silanization route proves promising for future chemical surface modification of on-chip REFETs.

Keywords
Silicon nanoribbon field-effect transistors, Microwave heating, Silanization, Surface characterization, Electrical measurements, pH sensitivity
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-161089 (URN)10.1016/j.snb.2014.12.030 (DOI)000349082200077 ()2-s2.0-84919754424 (Scopus ID)
Funder
VINNOVAKnut and Alice Wallenberg Foundation
Note

QC 20150318

Available from: 2015-03-18 Created: 2015-03-09 Last updated: 2017-12-04Bibliographically approved
Afrasiabi, R., Sugunan, A., Shahid, R., Toprak, M. S. & Muhammed, M. (2012). Microwave mediated synthesis of semiconductor quantum dots. Paper presented at 16th International Semiconducting and Insulating Materials Conference (SIMC-XVI) Location: Royal Inst Technol (KTH), Stockholm, Sweden Date: JUN 19-23, 2011. Physica Status Solidi. C, Current topics in solid state physics, 9(7), 1551-1556
Open this publication in new window or tab >>Microwave mediated synthesis of semiconductor quantum dots
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2012 (English)In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 7, p. 1551-1556Article in journal (Refereed) Published
Abstract [en]

Colloidal quantum dots (QD) have tuneable optoelectronic properties and can be easily handled by simple solution processing techniques, making them very attractive for a wide range of applications. Over the past decade synthesis of morphology controlled high quality (crystalline, monodisperse) colloidal QDs by thermal decomposition of organometallic precursors has matured and is well studied. Recently, synthesis of colloidal QDs by microwave irradiation as heating source is being studied due to the inherently different mechanisms of heat transfer, when compared to solvent convection based heating. Under microwave irradiation, polar precursor molecules directly absorb the microwave energy and heat up more efficiently. Here we report synthesis of colloidal II-VI semiconductor QDs (CdS, CdSe, CdTe) by microwave irradiation and compare it with conventional synthesis based on convection heating. Our findings show that QD synthesis by microwave heating is more efficient and the chalcogenide precursor strongly absorbs the microwave radiation shortening the reaction time and giving a high reaction yield.

Keywords
CdSe, Microwave, Quantum dots, Reaction rate
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-95406 (URN)10.1002/pssc.201100545 (DOI)000306479300007 ()2-s2.0-84864000771 (Scopus ID)
Conference
16th International Semiconducting and Insulating Materials Conference (SIMC-XVI) Location: Royal Inst Technol (KTH), Stockholm, Sweden Date: JUN 19-23, 2011
Note
QC 20120810Available from: 2012-05-24 Created: 2012-05-24 Last updated: 2017-12-07Bibliographically approved
Afrasiabi, R., Jokilaakso, N., Schmidt, T., Eriksson Karlström, A. & Linnros, J.Microwave-assisted silanization of SiNW-FET: characterization and effect on sensing properties.
Open this publication in new window or tab >>Microwave-assisted silanization of SiNW-FET: characterization and effect on sensing properties
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(English)Manuscript (preprint) (Other academic)
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-133695 (URN)
Note

QS 2013

Available from: 2013-11-08 Created: 2013-11-08 Last updated: 2013-11-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1002-6699

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