| 1. |
- 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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| 2. |
- Junno, Tobias, et al.
(författare)
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Single-electron devices via controlled assembly of designed nanoparticles
- 1999
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Ingår i: Microelectronic Engineering. - 0167-9317. ; 47:1-4, s. 179-183
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Tidskriftsartikel (refereegranskat)abstract
- Single-electron transistors (SET) rely for their functionality on extreme control of lithography and lateral positioning as well as of properties of the building blocks from which the devices are built. By an aerosol-based nanoparticle fabrication we can prepare nanocrystals down to sub-10nm dimensions with metallic or semiconducting character, as well as having a core + shell design for definition of tunnel-gaps. We present here results for a type of device that is based on the possibility to design functionality in the internal structure of the nanoparticles which are used as building blocks. We use such pre-fabricated building blocks to construct coulomb blockade devices and show that they operate at temperatures above 150K.
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| 3. |
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| 4. |
- Malmqvist, L, et al.
(författare)
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Liquid-target laser-plasma source for X-ray lithography
- 1997
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Ingår i: Microelectronic Engineering. - 1873-5568. ; 35:1-4, s. 535-536
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Tidskriftsartikel (refereegranskat)abstract
- We describe a compact and practically debris-free laser-plasma x-ray source suitable for proximity lithography. The source is based on a microscopic fluorocarbon continuous liquid jet droplet target, generating high-brightness lambda=1.2-1.7 nm x-ray emission with similar to 5% conversion efficiency. This target type has the advantages of producing only negligible amounts of debris, and being regenerative, thereby allowing high-repetition-rate uninterrupted operation. The source is combined with an Au/SiNx x-ray mask to demonstrate lithography of sub-100 nm structures in SAL-601 chemically enhanced resist.
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| 5. |
- Malmqvist, L, et al.
(författare)
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Nanometer table-top proximity x-ray lithography with liquid-target laser-plasma source
- 1997
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 15:4, s. 814-817
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Tidskriftsartikel (refereegranskat)abstract
- A compact laser-plasma proximity x-ray lithography system suitable for laboratory-scale low-volume nanometer patterning is presented. The laser-plasma source, which is based on a fluorocarbon liquid-jet target, generates high-brightness lambda = 1.2-1.7 nm x-ray emission with only negligible debris production. The Au/SiNx x-ray mask is fabricated by employing ion milling and a high-contrast e-beam resist. With SAL-601 chemically enhanced resist we demonstrate fabrication of high-aspect-ratio, sub-100 nm structures. The exposure time is currently 20 min using a compact 10 Hz, lambda = 532 nm, 70 mJ/pulse mode-locked Nd:YAG laser. However, the regenerative liquid-jet target is designed for operation with future, e.g., 1000 Hz, lasers resulting in projected exposure times of similar to 10 s. (C) 1997 American Vacuum Society.
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| 6. |
- Montelius, Lars, et al.
(författare)
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Fabrication and characterization of a nanosensor for admittance spectroscopy of biomolecules
- 1995
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Ingår i: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 13:3, s. 1755-1760
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated nanometer-sized interdigitated electrode patterns using electron beam lithography and liftoff techniques. The aim of the investigation was to find out whether the dimensions (i.e., the electrode separations) of the pattern would affect the admittance signal of the biomolecules in between the electrodes. Since the admittance signal scales with the geometrical factor A/d, where A is the electrode area and d is the separation, we chose to keep A/d constant when changing the electrode separation in order to eliminate this trivial effect on the admittance signal. An interdigitated electrode structure having an interelectrode spacing in the nanometer regime makes it possible to reach high nonstationary as well as stationary electric field strengths while having a low applied voltage level. Hence, electrode reactions will be as small as possible, while a high signal to noise ratio is obtained. We have been able to experimentally study the response of the impedance behavior to high electric fields exhibiting either a positive or a negative shift of the permittivity as a function of the field being a high alternating-current or a direct-current field, respectively.
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| 7. |
- Stollenwerk, Maria, et al.
(författare)
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Quantitation of bacterial adhesion to polymer surfaces by bioluminescence
- 1998
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Ingår i: Zentralblatt fur Bakteriologie. - 0934-8840. ; 287:1-2, s. 7-18
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Tidskriftsartikel (refereegranskat)abstract
- Quantitation of microbes adhering to a surface is commonly used in studies of microbial adhesion to different surfaces. We have quantified different staphylococcal strains adhering to polymer surfaces by measuring bacterial ATP (adenosine triphosphate) by bioluminescence. The method is sensitive, having a detection limit of 104 bacterial cells. Viable counting of bacterial cells may yield falsely low results due to the presence of 'dormant' and adherent bacteria. By using bioluminescence, this can be avoided. Cells of different bacterial species and cells of strains of the same species were shown to differ significantly in their basal ATP content (8.7 x 10-13 - 5.2 x 10-22 MATP). The size of adherent and planktonic bacteria decreased with time (0.7 μm → 0.3 μm, 20 days). During incubation in nutrient-poor buffer ('starvation'), the ATP content of adherent bacteria decreased after 24-96 h whereas that of planktonic bacteria was stable over 20 days. The presence of human serum or plasma did not interfere significantly with the test results. Since the ATP concentration of bacterial strains of different species varies and is also influenced by the growth conditions of bacteria (solid or liquid culture medium), a species-specific standard curve has to be established for bacteria grown under the same culture conditions. We conclude that the method is a sensitive tool to quantify adherent bacteria during experiments lasting for less than 6 h and constitutes a valuable method to be used in conjunction with different microscopical techniques.
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| 8. |
- Tegenfeldt, Jonas, et al.
(författare)
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A Nanosensor for Admittance Spectroscopy
- 1995
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Ingår i: Ultimate Limits of Fabrication and Measurements. - 9789401100410 ; , s. 115-122
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Bokkapitel (refereegranskat)
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| 9. |
- Tegenfeldt, Jonas O., et al.
(författare)
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Image widening not only a question of tip sample convolution
- 1995
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Ingår i: Applied Physics Letters. - 0003-6951.
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Tidskriftsartikel (refereegranskat)abstract
- As the tip in the atomic force microscope is scanned over the sample surface an image results which contains information from the sample as well as from the tip. This mainly results in an increase of the apparent size of the sample. If the tip is reasonably sharp the contribution from the tip is small. In some cases the widening still persists in spite of a very sharp tip. In this letter, a model is presented which ascribes this to the lateral forces twisting the cantilever giving an offset between the apparent point of contact and the real point of contact. This results in a shift between forward and reverse scan of the sample position in the imaging window and, if the lateral forces due to the sample and substrate are different, a change in the apparent width of the sample.
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