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Scheicher, Ralph H.
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Publications (10 of 89) Show all publications
Zhang, P., Xia, M., Zhuge, F., Zhou, Y., Wang, Z., Dong, B., . . . Miao, X. S. (2019). Nanochannel-Based Transport in an Interfacial Memristor Can Emulate the Analog Weight Modulation of Synapses. Nano letters (Print), 19(7), 4279-4286
Open this publication in new window or tab >>Nanochannel-Based Transport in an Interfacial Memristor Can Emulate the Analog Weight Modulation of Synapses
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2019 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 19, no 7, p. 4279-4286Article in journal (Refereed) Published
Abstract [en]

By exploiting novel transport phenomena such as ion selectivity at the nanoscale, it has been shown that nanochannel systems can exhibit electrically controllable conductance, suggesting their potential use in neuromorphic devices. However, several critical features of biological synapses, particularly their conductance modulation, which is both memorable and gradual, have rarely been reported in these types of systems due to the fast flow property of typical inorganic electrolytes. In this work, we demonstrate that electrically manipulating the nanochannel conductance can result in nonvolatile conductance tuning capable of mimicking the analog behavior of synapses by introducing a room-temperature ionic liquid (IL) and a KCl solution into the two ends of a nanochannel system. The gradual conductance-tuning mechanism is identified through fluorescence measurements as the voltage-induced movement of the interface between the immiscible IL and KCl solution, while the successful memorization of the conductance tuning is ascribed to the large viscosity of the IL. We applied a nanochannel-based synapse to a handwritten digit-recognition task, reaching an accuracy of 94%. These promising results provide important guidance for the future design of nanochannel-based neuromorphic devices and the manipulation of nanochannel transport for computing.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
Nanochannel systems, interfacial memristor, synapse, fluorescence
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-391027 (URN)10.1021/acs.nanolett.9b00525 (DOI)000475533900009 ()31150262 (PubMedID)
Funder
Swedish Research Council, 2017-04627
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2019-08-19Bibliographically approved
Martins, E. d., Feliciano, G. T., Scheicher, R. H. & Rocha, A. R. (2019). Simulating DNA Chip Design Using All-Electronic Graphene-Based Substrates. Molecules, 24(5), Article ID 951.
Open this publication in new window or tab >>Simulating DNA Chip Design Using All-Electronic Graphene-Based Substrates
2019 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, no 5, article id 951Article in journal (Refereed) Published
Abstract [en]

In this paper, we present a theoretical investigation of an all-electronic biochip based on graphene to detect DNA including a full dynamical treatment for the environment. Our proposed device design is based on the changes in the electronic transport properties of graphene interacting with DNA strands under the effect of the solvent. To investigate these systems, we applied a hybrid methodology, combining quantum and classical mechanics (QM/MM) coupled to non-equilibrium Green's functions, allowing for the calculations of electronic transport. Our results show that the proposed device has high sensitivity towards the presence of DNA, and, combined with the presence of a specific DNA probe in the form of a single-strand, it presents good selectivity towards specific nucleotide sequences.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
DNA chip, graphene, QM/MM, non-equilibrium Green's functions
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-382470 (URN)10.3390/molecules24050951 (DOI)000462662900127 ()30857133 (PubMedID)
Funder
Swedish Research Council
Available from: 2019-05-02 Created: 2019-05-02 Last updated: 2019-05-02Bibliographically approved
Feliciano, G. T., Sanz-Navarro, C., Coutinho-Neto, M. D., Ordejon, P., Scheicher, R. H. & Rocha, A. R. (2018). Addressing the Environment Electrostatic Effect on Ballistic Electron Transport in Large Systems: A QM/MM-NEGF Approach. Journal of Physical Chemistry B, 122(2), 485-492
Open this publication in new window or tab >>Addressing the Environment Electrostatic Effect on Ballistic Electron Transport in Large Systems: A QM/MM-NEGF Approach
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2018 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 122, no 2, p. 485-492Article in journal (Refereed) Published
Abstract [en]

The effects of the environment in nanoscopic materials can play a crucial role in device design. Particularly in biosensors, where the system is usually embedded in a solution, water and ions have to be taken into consideration in atomistic simulations of electronic transport for a realistic description of the system. In this work, we present a methodology that combines quantum mechanics/molecular mechanics methods (QM/MM) with the nonequilibrium Green’s function framework to simulate the electronic transport properties of nanoscopic devices in the presence of solvents. As a case in point, we present further results for DNA translocation through a graphene nanopore. In particular, we take a closer look into general assumptions in a previous work. For this sake, we consider larger QM regions that include the first two solvation shells and investigate the effects of adding extra k-points to the NEGF calculations. The transverse conductance is then calculated in a prototype sequencing device in order to highlight the effects of the solvent.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-343858 (URN)10.1021/acs.jpcb.7b03475 (DOI)000423140600010 ()28721724 (PubMedID)
Funder
Swedish Research CouncilEU, Horizon 2020, 676598
Available from: 2018-03-02 Created: 2018-03-02 Last updated: 2018-03-02Bibliographically approved
Vovusha, H., Amorim, R. G., Scheicher, R. H. & Sanyal, B. (2018). Controlling the orientation of nucleobases by dipole moment interaction with graphene/h-BN interfaces. RSC Advances, 8(12), 6527-6531
Open this publication in new window or tab >>Controlling the orientation of nucleobases by dipole moment interaction with graphene/h-BN interfaces
2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 12, p. 6527-6531Article in journal (Refereed) Published
Abstract [en]

The interfaces in 2D hybrids of graphene and h-BN provide interesting possibilities of adsorbing and manipulating atomic and molecular entities. In this paper, with the aid of density functional theory, we demonstrate the adsorption characteristics of DNA nucleobases at different interfaces of 2D hybrid nanoflakes of graphene and h-BN. The interfaces provide stronger binding to the nucleobases in comparison to pure graphene and h-BN nanoflakes. It is also revealed that the individual dipole moments of the nucleobases and nanoflakes dictate the orientation of the nucleobases at the interfaces of the hybrid structures. The results of our study point towards a possible route to selectively control the orientation of individual molecules in biosensors.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-347655 (URN)10.1039/c7ra11664k (DOI)000425034000041 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Research CouncilCarl Tryggers foundation
Available from: 2018-04-06 Created: 2018-04-06 Last updated: 2018-04-06Bibliographically approved
Prasongkit, J., Martins, E. d., de Souza, F. A. L., Scopel, W. L., Amorim, R. G., Amornkitbamrung, V., . . . Scheicher, R. H. (2018). Topological Line Defects Around Graphene Nanopores for DNA Sequencing. The Journal of Physical Chemistry C, 122(13), 7094-7099
Open this publication in new window or tab >>Topological Line Defects Around Graphene Nanopores for DNA Sequencing
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 13, p. 7094-7099Article in journal (Refereed) Published
Abstract [en]

Topological line defects in graphene represent an ideal way to produce highly controlled structures with reduced dimensionality that can be used in electronic devices. In this work, we propose using extended line defects in graphene to improve nucleobase selectivity in nanopore-based DNA sequencing devices. We use a combination of quantum mechanics/molecular mechanics and nonequilibrium Green's function methods to investigate the conductance modulation, fully accounting for solvent effects. By sampling over a large number of different orientations generated from molecular dynamics simulations, we theoretically demonstrate that distinguishing between the four nucleobases using line defects in a graphene-based electronic device appears possible. The changes in conductance are associated with transport across specific molecular states near the Fermi level and their coupling to the pore. Through the application of a specifically tuned gate voltage, such a device would be able to discriminate the four types of nucleobases more reliably than that of graphene sensors without topological line defects.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-352690 (URN)10.1021/acs.jpcc.8b00241 (DOI)000429625600009 ()
Funder
Swedish Research Council
Available from: 2018-06-08 Created: 2018-06-08 Last updated: 2018-06-08Bibliographically approved
de Souza, F. A. L., Amorim, R. G., Prasongkit, J., Scopel, W. L., Scheicher, R. H. & Rocha, A. R. (2018). Topological line defects in graphene for applications in gas sensing. Carbon, 129, 803-808
Open this publication in new window or tab >>Topological line defects in graphene for applications in gas sensing
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2018 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 129, p. 803-808Article in journal (Refereed) Published
Abstract [en]

Topological line defects in graphene synthesized in a highly controlled manner open up new research directions for nanodevice applications. Here, we investigate two types of extended line defects in graphene, namely octagonal/pentagonal and heptagonal/pentagonal reconstructions. A combination of density functional theory and non-equilibrium Green's function methods was utilized in order to explore the application potential of this system as an electronic gas sensor. Our findings show that the electric current is confined to the line defect through gate voltage control, which combined with the enhanced chemical reactivity at the grain boundary, makes this system a highly promising candidate for gas sensor applications. As a proof of principle, we evaluated the sensitivity of a prototypical device toward NO2 molecule, demonstrating that it is indeed possible to reliably detect the target molecule.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Nanosensor, Graphene, Electronic transport
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-347530 (URN)10.1016/j.carbon.2017.11.029 (DOI)000424885800094 ()
Funder
Carl Tryggers foundation Swedish Research Council
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-04Bibliographically approved
Arjmandi-Tash, H., Bellunato, A., Wen, C., Olsthoorn, R. C., Scheicher, R. H., Zhang, S.-L. & Schneider, G. F. (2018). Zero-Depth Interfacial Nanopore Capillaries. Advanced Materials, 30(9), Article ID 1703602.
Open this publication in new window or tab >>Zero-Depth Interfacial Nanopore Capillaries
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2018 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 9, article id 1703602Article in journal (Refereed) Published
Abstract [en]

High-fidelity analysis of translocating biomolecules through nanopores demands shortening the nanocapillary length to a minimal value. Existing nanopores and capillaries, however, inherit a finite length from the parent membranes. Here, nanocapillaries of zero depth are formed by dissolving two superimposed and crossing metallic nanorods, molded in polymeric slabs. In an electrolyte, the interface shared by the crossing fluidic channels is mathematically of zero thickness and defines the narrowest constriction in the stream of ions through the nanopore device. This novel architecture provides the possibility to design nanopore fluidic channels, particularly with a robust 3D architecture maintaining the ultimate zero thickness geometry independently of the thickness of the fluidic channels. With orders of magnitude reduced biomolecule translocation speed, and lowered electronic and ionic noise compared to nanopores in 2D materials, the findings establish interfacial nanopores as a scalable platform for realizing nanofluidic systems, capable of single-molecule detection.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
2D nanopores, biomolecules, 1, f noise, mechanical stability, translocation speed
National Category
Condensed Matter Physics Atom and Molecular Physics and Optics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-350489 (URN)10.1002/adma.201703602 (DOI)000426491600035 ()
Funder
Swedish Research Council, 621-2014-6300]EU, European Research Council, 335879
Available from: 2018-05-09 Created: 2018-05-09 Last updated: 2019-06-19Bibliographically approved
de Souza, F. A. L., Amorim, R. G., Scopel, W. L. & Scheicher, R. H. (2017). Electrical detection of nucleotides via nanopores in a hybrid graphene/h-BN sheet. Nanoscale, 9(6), 2207-2212
Open this publication in new window or tab >>Electrical detection of nucleotides via nanopores in a hybrid graphene/h-BN sheet
2017 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 6, p. 2207-2212Article in journal (Refereed) Published
Abstract [en]

Designing the next generation of solid-state biosensors requires developing detectors which can operate with high precision at the single-molecule level. Nano-scaled architectures created in two-dimensional hybrid materials offer unprecedented advantages in this regard. Here, we propose and explore a novel system comprising a nanopore formed within a hybrid sheet composed of a graphene nanoroad embedded in a sheet of hexagonal boron nitride (h-BN). The sensitive element of this setup is comprised of an electrically conducting carbon chain forming one edge of the nanopore. This design allows detection of DNA nucleotides translocating through the nanopore based on the current modulation signatures induced in the carbon chain. In order to assess whether this approach is feasible to distinguish the four different nucleotides electrically, we have employed density functional theory combined with the nonequilibrium Green's function method. Our findings show that the current localized in the carbon chain running between the nanopore and h-BN is characteristically modulated by the unique dipole moment of each molecule upon insertion into the pore. Through the analysis of a simple model based on the dipole properties of the hydrogen fluoride molecule we are able to explain the obtained findings.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-319864 (URN)10.1039/c6nr07154f (DOI)000395626600014 ()28120993 (PubMedID)
Funder
Carl Tryggers foundation Swedish Research Council
Available from: 2017-04-13 Created: 2017-04-13 Last updated: 2017-11-29Bibliographically approved
Sivaraman, G., Amorim, R. G., Scheicher, R. H. & Fyta, M. (2017). Insights into the detection of mutations and epigenetic markers using diamondoid-functionalized sensors. RSC Advances, 7(68), 43064-43072
Open this publication in new window or tab >>Insights into the detection of mutations and epigenetic markers using diamondoid-functionalized sensors
2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 68, p. 43064-43072Article in journal (Refereed) Published
Abstract [en]

Nanogaps functionalized with small diamond-like particles, diamondoids, have been shown to effectively distinguish between different DNA nucleotides. Here, we focus on the detection of mutations and epigenetic markers using such devices. Based on quantum mechanical simulations within the density functional theory approach coupled with the non-equilibrium Green's function scheme, we provide deeper insight into the inherent differences in detecting modified nucleotides. Our results strongly underline the influence of the type of functionalization molecule of the nanogap, as well its conformational details within the nanogap, on the sensing efficiency of the device. The electronic features for the mutations and epigenetic markers are compared to those for the respective canonical nucleotides that are detected by different devices. The calculations directly correlate the structural and electronic properties of the different nucleotides with the electronic transmission across the diamondoid-based device. The latter was found to be controlled by the functionalizing molecule and its binding to the nucleotides. We report on the direct connection of these characteristics to the sensitivity of the diamondoid-functionalized nanogaps, which could eventually be embedded in a nanopore device, and discuss the implications for DNA sensing.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-335533 (URN)10.1039/c7ra06889a (DOI)000409548200047 ()
Funder
Swedish Research CouncilCarl Tryggers foundation
Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2017-12-07Bibliographically approved
Hinnemo, M., Zhao, J., Ahlberg, P., Hägglund, C., Djurberg, V., Scheicher, R. H., . . . Zhang, Z.-B. (2017). On Monolayer Formation of Pyrenebutyric Acid on Graphene. Langmuir, 33(15), 3588-3593
Open this publication in new window or tab >>On Monolayer Formation of Pyrenebutyric Acid on Graphene
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2017 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 15, p. 3588-3593Article in journal (Refereed) Published
Abstract [en]

As a two-dimensional material with high charge carrier mobility, graphene may offer ultrahigh sensitivity in biosensing. To realize this, the first step is to functionalize the graphene. This is commonly done by using 1-pyrenebutyric acid (PBA) as a linker for biornolecules. However, the adsorption of PBA on graphene remains poorly understood despite reports of successful biosensors functionalized via this route. Here, the PBA adsorption on graphene is characterized through a combination of Raman spectroscopy, ab initio calculations, and spectroscopic ellipsometry. The PBA molecules are found to form a self-assembled monolayer on graphene, the formation of which is self-limiting and Langmuirian. Intriguingly, in concentrated solutions, the PBA molecules are found to stand up and stack horizontally with their edges contacting the graphene surface. This morphology could facilitate a surface densely populated with carboxylic functional groups. Spectroscopic analyses show that the monolayer saturates at 5.3 PBA molecules per nm(2) and measures similar to 0.7 nm in thickness. The morphology study of this PBA monolayer sheds light on the pi-pi stacking of small-molecule systems on graphene and provides an excellent base for optimizing functionalization procedures.

National Category
Physical Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-322804 (URN)10.1021/acs.langmuir.6b04237 (DOI)000399860000003 ()28350965 (PubMedID)
Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2017-06-09Bibliographically approved
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