| 1. |
- Arteaga, Natalia, et al.
(författare)
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A SU-8 dish for cell irradiation
- 2007
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 263:2, s. 523-528
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the CELLION project is radiation research at low doses. The main cell responses to low dose irradiation are bystander effects, genomic instability and adaptive responses. In order to study these effects it is convenient to make the cells addressable in space and time through locking the cell position. A new alternative dish has been developed for irradiation procedures at the Lund Nuclear Probe. The versatile dish can be used both to cultivate and to hold the cells during the irradiation procedure. The irradiation dish is made of an epoxy-based photopolymer named SU-8 chosen by its flexibility, non-toxicity and biological compatibility to cell attachment. It has been fabricated using a UV lithographic technique. The irradiation dish forms a 2 × 2 mm2 grid which contains 400 squares. Each square has 80 μm side and is separated from neighbouring ones by 20 μm wide walls. The location of each square is marked by a row letter and column number patterned outside the grid. The Cell Irradiation Facility at the Lund Nuclear Probe utilizes protons to irradiate living cells. A post-cell detection set up is used to control the applied dose, detecting the number of protons after passing through the targeted cell. The transmission requirement is fulfilled by our new irradiation dish. So far, the dish has been used to perform non-targeted irradiation of Hepatoma cells. The cells attach and grow easily on the SU-8 surface. In addition, the irradiation procedure can be performed routinely and faster since the cells are incubated and irradiated in the same surface.
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| 2. |
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| 3. |
- Arteaga, Natalia, et al.
(författare)
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The new cell irradiation facility at the Lund nuclear probe
- 2007
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 260:1, s. 91-96
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Tidskriftsartikel (refereegranskat)abstract
- The CELLION project is directed towards the studies on cellular response to targeted single ions. This paper gives an account of the modifications made at the Lund sub-micron beam line in order to create a Single Ion Hit Facility for biological applications within the CELLION project. The most relevant new feature is the specially developed software used to locate the cells. A program for cell recognition and localization that gives the coordinates of the centre of the cells has been designed. The recognition is made online. A picture taken by a microscope is used as input parameter for the recognition program. Using V79 Chinese hamster cells, the recognition procedure can be done in less than 0.5 s for a picture size of 800 x 600 pixels with approximately 96% efficiency. This paper also reports target accuracy test results and the first non-targeted irradiation procedure performed at the Lund sub-micron beam line. (c) 2007 Elsevier B.V. All rights reserved.
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| 4. |
- Auzelyte, Vaida
(författare)
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Direct writing with an MeV proton beam: Development and Applications
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents work aimed at the development and application of a new lithography system for direct material patterning with the MeV proton beam at the Lund Nuclear Microprobe (NMP) facility. MeV proton beams are advantageous for use as a patterning tool due to their deep and well defined penetration through matter and their highly local energy deposition. This allows the fabrication of three dimensional microstructures with high aspect-ratio and density in various materials. This new and exciting application of nuclear microbeams is called Proton Beam Writing (PBW). In the work presented here, an MeV proton beam focused to micrometer size was used for high lateral resolution patterning. To achieve this, the existing beam and sample control and data-acquisition setups were complemented by use of nuclear electronics and a new beam blanker, resulting in a lithography system. The beam irradiation time and the position control were improved after the installation of a fast electrostatic beam blanker at the micro beamline. High-accuracy beam current measurement became possible when a new on-line pA-range measurement setup was added to the sub-micro beamline. Proton beam writing, using the new lithography system, was successfully performed and various complex microstructures in SU-8 negative resist and porous silicon were produced. The exposure process was optimised to achieve the minimum structure size and structures with the highest aspect and density ratios for a given beam size and resist thickness. The smallest microstructures 1.5 ?m in diameter, the highest density and aspect ratio of 4:1 and 20:1, respectively, in 4-95 ?m thick SU-8 resist were fabricated. An inversed anodisation at low fluence in porous silicon was demonstrated. It was shown that, with large exposure latitude PBW is a simple and easily controlled fabrication method. Two new applications of the PBW technique were realised. Structures with high aspect ratio and high density were used for the fabrication of thin opaque phosphor micro-grids in metal. The micro-grids represented an order of magnitude improvement for single ion detection resolution in Ion Photon Emission Microscopy (IPEM). The other application utilises MeV proton beam patterned porous p-type silicon that serves as an anchor plate for sample deposition intended for Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI MS). The new sample anchor plate confines an increased volume of analyte and enhances the sensitivity of the detection method.
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| 5. |
- Auzelyte, Vaida, et al.
(författare)
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Exposure parameters for MeV proton beam writing on SU-8
- 2006
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 1873-5568 .- 0167-9317. ; 83:10, s. 2015-2020
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Tidskriftsartikel (refereegranskat)abstract
- Proton beam writing was performed on a lithographic resist to determine the main parameters required to achieve the minimum feature size, maximum pattern lateral density and maximum aspect ratio. A 2.5 MeV proton beam focused to sizes between 1.5 and 2.5 mu m was used to expose SU-8 negative resist. The number of protons per pixel was varied in the exposure of SU-8 with thicknesses between 5 and 95 pm. Patterns consisting of single pixels, single-pixel lines and multi-pixel areas with different densities were fabricated. The smallest structures achieved were posts 1.5 pin in diameter with 4:1 structure-space ratio in 15 pm thick resist and the highest aspect ratio structures of 20:1 in 40 pm resist were produced. It was found that the minimum feature size depended only on the beam size, and +/- 10% post size accuracy could be achieved within 40-70% variation of the number of protons. MeV proton beam allows a direct fabrication of complex shapes without a mask in single-step irradiation and. in addition, no proximity correction is needed. We present examples of MeV proton beam written single and multi-pixel microstructures with easily reproducible high aspect ratios and densities. (c) 2006 Elsevier B.V. All rights reserved.
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| 6. |
- Auzelyte, Vaida, et al.
(författare)
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Fabrication of phosphor micro-grids using proton beam lithography
- 2006
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 242:1-2, s. 253-256
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Tidskriftsartikel (refereegranskat)abstract
- A new nuclear microscopy technique called ion photon emission microscopy or IPEM was recently invented. IPEM allows analysis involving single ions, such as ion beam induced charge (IBIC) or single event upset (SEU) imaging using a slightly modified optical microscope. The spatial resolution of IPEM is currently limited to more than 10 mu m by the scattering and reflection of ion-induced photons, i.e. light blooming or spreading, in the ionoluminescent phosphor layer. We are developing a '' Microscopic Gridded Phosphor '' (also called Black Matrix) where the phosphor nanocrystals are confined within the gaps of a micrometer scale opaque grid, which limits the amount of detrimental light blooming. MeV-energy proton beam lithography is ideally suited to lithographically form masks for the grid because of high aspect ratio, pattern density and sub-micron resolution of this technique. In brief, the fabrication of the grids was made in the following manner: (1) a MeV proton beam focused to 1.5-2 mu m directly fabricated a matrix of pillars in a 15 mu m thick SU-8 lithographic resist; (2) 7:1 aspect ratio pillars were then formed by developing the proton exposed area; (3) Ni (Au) was electrochemically deposited onto Cu-coated Si from a sulfamate bath (or buffered CN bath); (4) the SU-8 pillars were removed by chemical etching; finally (5) the metal micro-grid was freed from its substrate by etching the underlying Cu layer. Our proposed metal micro-grids promise an order-of-magnitude improvement in the resolution of IPEM.
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| 7. |
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| 8. |
- Auzelyte, Vaida, et al.
(författare)
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On-line measurement of proton beam current in pA range
- 2006
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 249, s. 760-763
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Tidskriftsartikel (refereegranskat)abstract
- A MeV proton beam with a current in the range of fA-nA is usually measured using a secondary beam signal that is dependent on a sample or requires noise-free accurate charge integration in a Faraday cup. We propose a simple on-line beam current measurement setup that can be used to directly measure beam current during ion beam analysis. A fast beam blanker is used to modulate the beam position after the last set of collimator slits in and out of a mini Faraday cup connected to fA-sensitive electrometer. Less than 100 fA current can be measured during an undisturbed irradiation with kHz sampling frequency. The fast, simple and easily controlled current measurement set-up is going to be routinely used for ion beam analysis and modification at the new Lund sub-micron beam line. (c) 2006 Elsevier B.V. All rights reserved.
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| 9. |
- Auzelyte, Vaida, et al.
(författare)
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The beam blanking system for microlithography at Lund Nuclear microprobe
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 219-20, s. 485-489
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Tidskriftsartikel (refereegranskat)abstract
- A new beam blanking system was installed at the Lund Nuclear Microprobe and employed in proton beam lithography (PBL) for polymer microstructures fabrication. The blanker consists of two parallel plates connected to a high voltage generator. Measurement of the beam blanking time on a sample was performed by means of the standard PIXE system. The beam is blanked and returns to a sample within 200 ns. The blanking system is designed for the new sub-micrometer beamline under installation in the accelerator laboratory. A number of pilot MeV ion beam lithography experiments were performed to illustrate the possibility to use the blanking system in combination with the existing data acquisition and scanning system. A 2.5 MeV proton beam was used to irradiate 50 mum SU-8 negative resist. The blanker was shown to be a necessary part of the lithography system. It enables blanking between each pixel and hence fabrication of various patterns down to a single pixel. The blanker has significantly simplified beam control and enhanced process time and spatial resolution. Three-dimensional microstructures with 20:1 aspect ratio were fabricated.
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| 10. |
- Elfman, Mikael, et al.
(författare)
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The Lund Nuclear Microprobe sub-micron set-up. Part III: Sample stage, optical imaging and detector configuration in the experimental chamber
- 2005
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 231:1-4, s. 14-20
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Tidskriftsartikel (refereegranskat)abstract
- A new sub-micron beamline for high-resolution nuclear microprobe applications has been constructed at the Lund nuclear microprobe facility. The design and construction of the main experimental chamber.. sample viewing system and computer controlled precision sample stage movement is presented in this paper. The chamber is especially designed for using a large area annular HPGe detector. The advantages with such a large area detector are discussed and illustrated. In addition the quality of the optical viewing and the precision sample stage is discussed.
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