| 1. |
- Suyatin, Dmitry, et al.
(författare)
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Nanowire-Based Electrode for Acute In Vivo Neural Recordings in the Brain
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- We present an electrode, based on structurally controlled nanowires, as a first step towards developing a useful nanostructured device for neurophysiological measurements in vivo. The sensing part of the electrode is made of a metal film deposited on top of an array of epitaxially grown gallium phosphide nanowires. We achieved the first functional testing of the nanowire-based electrode by performing acute in vivo recordings in the rat cerebral cortex and withstanding multiple brain implantations. Due to the controllable geometry of the nanowires, this type of electrode can be used as a model system for further analysis of the functional properties of nanostructured neuronal interfaces in vivo.
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| 2. |
- Wernersson, Lars-Erik, et al.
(författare)
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Epitaxially overgrown, stable W-GaAs Schottky contacts with sizes down to 50 nm
- 2002
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 20:2, s. 580-589
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Tidskriftsartikel (refereegranskat)abstract
- A processing scheme for the fabrication of embedded W-GaAs contacts has been established and the resulting contact characteristics have been evaluated. The main advantage of these contacts is that they are stable during high-temperature epitaxial overgrowth. The fabrication scheme is based on a liftoff process with electron beam evaporation of tungsten and subsequent epitaxial overgrowth using metalorganic vapor phase epitaxy. Various methods were used to characterize the buried contacts. First, the structural properties of GaAs surrounding embedded W features, with widths down to 50 nm, were characterized by high-resolution transmission electron microscopy. Measurements of the conductivity in individual, buried wires were performed in order to study the influence of the overgrowth process on the properties of the tungsten. We also evaluated the current-voltage characteristics for macroscopic contacts, which revealed a clear dependence on processing parameters. Optimized processing conditions could thus be established under which limited contact degradation occurred during overgrowth. Finally, we used the overgrowth technique to perform a detailed investigation of the electrical and optical properties of floating-potential embedded nano-Schottky contacts by space-charge spectroscopy.
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| 3. |
- Zhao, Qing, et al.
(författare)
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Rat sciatic nerve regeneration through a micromachined silicon chip
- 1997
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Ingår i: Biomaterials. - 1878-5905. ; 18:1, s. 75-80
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of regenerating nerve fibres to grow through a perforated silicon chip was tested using the silicone chamber model for nerve regeneration. The chips were fabricated as circular membranes, 4 mm in diameter, thickness 60 microns, with a perforated area, 2 mm in diameter, in the centre. Three types of chips were fabricated utilizing anisotropic etching. The chips were glued with silicone adhesive between two halves of silicone rubber tubing (total length 8 mm, inner diameter 1.8 mm, outer diameter 3.0 mm) which was used to bridge a 4 mm gap between the proximal and distal nerve stumps of a transected rat sciatic nerve. The capacity of regenerating nerve fibres to grow through the holes of the chip was analysed by light and scanning electron microscopy after 4 or 16 weeks of regeneration. Furthermore, the muscle contractility force of the gastrocnemius muscle was measured after 16 weeks of regeneration and compared as a percentage of the contralateral uninjured side. Nerves generated through chips with hole diameters of 10 or 50 microns were morphological and functional failures. The nerve structures distal to chips with hole diameters of 100 microns contained many myelinated nerve fibres in a minifascicular pattern after both 4 and 16 weeks of regeneration. The muscle contractility force was 56% of that of contralateral control muscles.
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| 4. |
- Bordag, Michael, et al.
(författare)
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Shear stress measurements on InAs nanowires by AFM manipulation
- 2007
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Ingår i: Small. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 3:8, s. 1398-1401
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Tidskriftsartikel (refereegranskat)abstract
- On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.
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| 5. |
- Carlberg, Patrick, et al.
(författare)
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Nanoimprint - a tool for realizing nano-bio research
- 2004
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Ingår i: 2004 4th IEEE Conference on Nanotechnology. - 0780385365 ; , s. 199-200
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a status report on how implementation of nanoimprint lithography has advanced our research. Contact guidance nerve growth experiments have so far primarily been done on micrometer-structured surfaces. We have made a stamp with 17 areas of different, submicron, line width and spacing covering a total 2.6 mm
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| 6. |
- Conache, Gabriela, et al.
(författare)
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AFM-based manipulation of InAs nanowires
- 2008
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Ingår i: Proceedings of the IVC-17 (17th International Vacuum Congress) [also] ICSS-13 (13th International Conference on Surface Science) [also] ICN+T-2007 (International Conference on Nanoscience and Technology). - Bristol : Institute of Physics (IOP). ; 100, s. 052051-052051
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Konferensbidrag (refereegranskat)abstract
- A controlled method of manipulation of nanowires was found using the tip of an Atomic Force Microscope (AFM). Manipulation is done in the ‘Retrace Lift’ mode, where feedback is turned off for the reverse scan and the tip follows a nominal path. The effective manipulation force during the reverse scan can be changed by varying an offset in the height of the tip over the surface. Using this method, we have studied InAs nanowires on different substrates. We have also investigated interactions between wires and with gold features patterned onto the substrates.
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| 7. |
- Conache, Gabriela, et al.
(författare)
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Bias-controlled friction of InAs nanowires on a silicon nitride layer studied by atomic force microscopy
- 2010
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Ingår i: Physical Review B Condensed Matter. - College Park, Md. : American Physical Society. - 0163-1829 .- 1095-3795. ; 82:3
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Tidskriftsartikel (refereegranskat)abstract
- By studying how nanowires lying on a surface bend when pushed by an atomic force microscopy tip we are able to measure the friction between them and the substrate. Here, we show how the friction between InAs nanowires and an insulating silicon nitride layer varies when a dc voltage is applied to the tip during manipulation. The bias charges the capacitor formed by the wire and the grounded silicon back contact. Electrostatic forces increase the contact pressure and allow us to tune the friction between the wire and the silicon nitride surface. Using nanowires of about 40-70 nm diameter and a few microns in length we have applied biases in the range +12 to -12 V. A monotonic increase of the sliding friction with voltage was observed. This increase in friction with the normal force implies that the mesoscopic nanowire-surface system behaves like a macroscopic contact, despite the nanometer size of the contact in the direction of motion. The demonstrated bias-controlled friction has potential applications in MEMS/NEMS devices.
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| 8. |
- Conache, Gabriela, et al.
(författare)
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Comparative friction measurements of InAs nanowires on three substrates
- 2010
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Ingår i: Journal of Applied Physics. - College Park, MD : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 108:9
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated friction between InAs nanowires and three different substrates: SiO2, fluorosilanized SiO2, and Si3N4. The nanowires were pushed laterally with the tip of an atomic force microscope and the friction force per unit length for both static and sliding friction was deduced from the equilibrium shape of the bent wires. On all three substrates, thick wires showed a difference between sliding and static friction of up to three orders of magnitude. Furthermore, all substrates display a transition to stick-slip motion for nanowires with a diameter of less than about 40 nm. Hydrophobic and hydrophilic substrates display similar friction behavior suggesting that a condensed water layer does not strongly influence our results. The patterns and trends in the friction data are similar for all three substrates, which indicates that they are more fundamental in character and not specific to a single substrate. ©2010 American Institute of Physics.
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| 9. |
- Conache, Gabriela, et al.
(författare)
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Friction measurements of InAs nanowires on Silicon nitride by AFM manipulation
- 2009
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Ingår i: Small. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 5:2, s. 203-207
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Tidskriftsartikel (refereegranskat)abstract
- A study was conducted to perform friction measurements of InAs nanowires (NW) on silicon nitride (Si 3N 4) through atomic force microscopy (AFM) manipulation. The investigations revealed the friction force per unit length for sliding and static friction over a range of nanowire diameters. It was found that there is a significant difference between the coefficients of the two sliding modes for large wires. It was also found that the difference between the two sliding modes disappears at smaller diameters and the sliding friction becomes equal with the static friction. The AFM investigations were performed on a Nanoscope IIIa Dimension 3100, using rectangular cantilevers, with a nominal spring constant of 30 N m -1. The nanowires were manipulated, using the 'Retrace Lift' mode of the AFM controller. The friction force per unit length was gathered from the local curvature of the NWs, using standard elasticity theory.
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| 10. |
- Conache, Gabriela, 1977-, et al.
(författare)
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Nanowire friction with an applied bias
- 2009
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Konferensbidrag (refereegranskat)abstract
- Recently, we have shown how the friction acting on nanowires pushed across a surface by an AFM tip can be determined by measuring the radius of curvature of the bent wire aŸer manipulation. This technique allows us to study the friction properties of an extended mesoscale contact. Our main focus has been to determine whether such contacts behave like macroscopic objects, in which dišerences between the 'true' and 'apparent' contact areas play a key role and friction varies linearly with the applied normal force, or whether they are more like atomic-scale point contacts, wheremore fundamental processes dominate and friction oŸen is independent of the normal force. In this work we show how the friction between InAs nanowires and an insulating silicon nitride layer on a conductive silicon substrate varies when a DC voltage is applied to the AFM tip during manipulation. e tip charges the capacitor formed by the wire and the grounded silicon back contact, giving rise to attractive Coulomb forces and thus increasing the contact pressure between the wire and the silicon nitride. In this way we can vary the normal force on the sliding surfaces using a single wire, with a constant structure and contact geometry. Using nanowires of about 40-50 nm diameter and a few microns in length we have applied tip voltages in the range +12 to -12 V. Simplemodeling indicates that these voltages su›ce to give similar levels of band-lling and depletion to when the same wires are used in working wrap-gate or back-gate devices. A monotonic increase of the sliding friction with the voltage applied on the tip was observed. is implies that the friction increases with the normal force and that this mesoscopic system behaves more like a macroscopic contact, despite the nanometer size of the contact in the direction of motion.
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