Papers by Juergen Brugger
Micro and Nanosystemse, 2009
This paper presents drop-on-demand inkjet printing of SU-8 on functionalized surfaces for direct ... more This paper presents drop-on-demand inkjet printing of SU-8 on functionalized surfaces for direct printing of computer controlled polymer patterns. The high viscosity of SU-8 required an in-depth investigation of the print parameters such as pulse amplitude, pulse length and temperature in the piezo-actuated nozzle. The results show that the optimal drop velocity to obtain a stable printing is ~2 ms-1 which corresponds to pulse amplitude and length of 220 V and 70-80 μs, respectively. The diameter of the SU-8 drop was reduced from 117 μm on non-treated silicon to 58 μm on a surface terminated by a silane-based self-assembled monolayer.
TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference, 2007
We report the fabrication and characterization of nickel Hall sensors integrated on SU-8 cantilev... more We report the fabrication and characterization of nickel Hall sensors integrated on SU-8 cantilevers. Sensors having active area down to 1 x 1 mum 2 show a magnetic field resolution better than 1 /n muT / Hz 1/2 in the thermal noise frequency range. The fabricated devices have been tested for magnetic imaging using the scanning Hall probe microscopy technique.
2012 38th IEEE Photovoltaic Specialists Conference, 2012
ABSTRACT We fabricated amorphous silicon n-i-p solar cells with two types of nanopatterned back r... more ABSTRACT We fabricated amorphous silicon n-i-p solar cells with two types of nanopatterned back reflectors using stencil lithography. One reflector type has a plasmonic grating that is embedded in the ZnO layer; the other one has a metallic grating patterned on top of the Ag layer. From comparing the short-circuit current densities of the two device types, we conclude that light trapping through grating coupling is more efficient than coupling of light through the excitation of localized surface plasmons. The back reflectors were patterned with dot arrays by evaporation of Ag through millimeter-size stencil membranes. The stencils themselves were patterned by wafer-scale nanosphere lithography. The dot arrays have a periodicity of 428 nm and efficiently scatter light in the near-infrared wavelength range. Both back reflectors types lead to the same morphology for the silicon films. This allows us a fair comparison of the two light coupling mechanisms. We found a 14% and 19% short-circuit current density enhancement for the plasmonic and for the metallic grating, respectively. The external quantum efficiency gains between 550 and 650 nm show similar guided modes resonances for both device types, but the excitation is stronger for the device with the metallic grating.
Molecular and Cellular Biology, 2008
53BP1, the vertebrate ortholog of the budding yeast Rad9 and fission yeast Crb2/Rhp9 checkpoint p... more 53BP1, the vertebrate ortholog of the budding yeast Rad9 and fission yeast Crb2/Rhp9 checkpoint proteins, is recruited rapidly to sites of DNA double-strand breaks (DSBs). A tandem tudor domain in human 53BP1 that recognizes methylated residues in the histone core is necessary, but not sufficient, for efficient recruitment. By analysis of deletion mutants, we identify here additional elements in 53BP1 that facilitate recognition of DNA DSBs. The first element corresponds to an independently folding oligomerization domain. Replacement of this domain with heterologous tetramerization domains preserves the ability of 53BP1 to recognize DNA DSBs. A second element is only about 15 amino acids long and appears to be a C-terminal extension of the tudor domain, rather than an independently functioning domain. Recruitment of 53BP1 to sites of DNA DSBs is facilitated by histone H2AX phosphorylation and ubiquitination. However, none of the 53BP1 domains/elements important for recruitment are k...
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2009
In this contribution we describe the application of Ink-Jet printing and Stencil Lithography in b... more In this contribution we describe the application of Ink-Jet printing and Stencil Lithography in bionanotechnology. Both techniques are alternative patterning methods that can be used for the fabrication of biocompatible microand nanostructures out of the costly and restricted clean room environment. The applications presented in this contribution are 1) the cell patterning using Au dot arrays deposited on PDMS,by stencil lithography, 2) the fabrication of biosensors based on localized surface plasmon resonance in Au nanodots deposited by stencil lithography and 3) the printing of cells and biomolecules by InkJet printing.
A nanoelectromechanical mass sensor based on a submicron size resonating metallic beam is used to... more A nanoelectromechanical mass sensor based on a submicron size resonating metallic beam is used to characterize material deposition rates in stencil lithography. The material flux through micron size apertures is mapped with high spatial (below 1 m) and deposition rate (below ...
The Journal of Physical Chemistry C, 2014
ABSTRACT Ionic liquids incorporating a polymerizable anion were prepared in a facile manner and u... more ABSTRACT Ionic liquids incorporating a polymerizable anion were prepared in a facile manner and used to fabricate stable titania nano-particle films. The nanotitania was directly patterned by UV imprinting using micrometer size test structures in a polydimethylsiloxane mold. The resulting resist microstructures are resistant to cracking with only slight shrinkage observed for the system made using a hydrophobic ionic liquid. Because ionic liquids with a plethora of different physical and chemical properties can be made (designed) in a facile manner their application in this facile process instead of organic solvents could lead to many new types of functional materials.
Sensors and Actuators A: Physical, 1998
Practical Metallography, 2009
Optics Express, 2011
Rhodamine B and Alexa Fluor 430 fluorophores have been used as doping agents for xerogel waveguid... more Rhodamine B and Alexa Fluor 430 fluorophores have been used as doping agents for xerogel waveguides defined over an antiresonant (ARROW) filter. This configuration has a significant level of integration, since it merges the waveguide, the light emitter and the filter in a single photonic element. Different technologies have been combined for their implementation, namely soft lithography, standard silicon-based technology and silicon bulk micromachining. The spectral response of 15-mm long waveguides without fluorophore is first analyzed as a function of the waveguide width. Here, it has been observed how the xerogel used has a high transparency in the visible spectra, having only significant absorption at the wavelength where the ARROW filter is in resonance. In a second step, identical waveguides but doped with two different concentrations of Rhodamine B and Alexa Fluor 430 are studied. In addition to the effect of the filter, fluorophore-doped xerogel waveguides show losses close to 2 dB (equivalent to 2 dB of light emission). In addition, it has been observed how an increase of the fluorophore concentration within the xerogel matrix does not provide with a emission increase, but saturation or even a decrease of this magnitude due to self-absorption. Finally, the total losses of the proposed waveguides are analyzed as a function of their width, obtaining losses close to 5 dB for waveguide widths higher than 50 µm.
Nanotechnology, 2010
In this paper, a fast and inexpensive wafer-scale process for the fabrication of arrays of nanosc... more In this paper, a fast and inexpensive wafer-scale process for the fabrication of arrays of nanoscale holes in thin gold films for plasmonics is shown. The process combines nanosphere lithography using spin-coated polystyrene beads with a sputter-etching process. This allows the batch fabrication of several 1000 microm(2) large hole arrays in 200 nm thick gold films without the use of an adhesion layer for the gold film. The hole size and lattice period can be tuned independently with this method. This allows tuning of the optical properties of the hole arrays for the desired application. An example application, refractive index sensing, is demonstrated.
Nanotechnology, 2008
Wafer-scale nanostencil lithography (nSL) is used to define several types of silicon mechanical r... more Wafer-scale nanostencil lithography (nSL) is used to define several types of silicon mechanical resonators, whose dimensions range from 20 µm down to 200 nm, monolithically integrated with CMOS circuits. We demonstrate the simultaneous patterning by nSL of ∼2000 nanodevices per wafer by post-processing standard CMOS substrates using one single metal evaporation, pattern transfer to silicon and subsequent etch of the sacrificial layer. Resonance frequencies in the MHz range were measured in air and vacuum. As proof-of-concept towards an application as high performance sensors, CMOS integrated nano/micromechanical resonators are successfully implemented as ultra-sensitive areal mass sensors. These devices demonstrate the ability to monitor the deposition of gold layers whose average thickness is smaller than a monolayer. Their areal mass sensitivity is in the range of 10(-11) g cm(-2) Hz(-1), and their thickness resolution corresponds to approximately a thousandth of a monolayer.
Nanotechnology, 2006
We have developed a new hybrid AFM probe combining an SU-8 polymer body with a full tungsten cant... more We have developed a new hybrid AFM probe combining an SU-8 polymer body with a full tungsten cantilever having a nanometric tip. The fabrication is based on surface micromachining a silicon wafer, where tungsten is sputter deposited in oxidation sharpened moulds to yield sharp tips with radius below 20 nm. The material properties of tungsten were measured, yielding a hardness of 14 GPa, a specific resistivity of 14.8 µ cm and Young's modulus of 380 GPa. Analyses of the probes show a mechanical quality factor of 90 in air, and a low contact resistance of 25 on a gold sample is measured. AFM imaging is demonstrated. As a step in the development of a robust electrically conducting AFM probe, the results are very promising.
Nanoscale, 2011
Dynamic stencil lithography uses a moving shadow-mask to draw patterns by having directionally ev... more Dynamic stencil lithography uses a moving shadow-mask to draw patterns by having directionally evaporated material deposited through the stencil apertures onto the substrate. Sub-micrometre, two-dimensional patterning is demonstrated at full 100 mm wafer scale, with two examples emphasizing this technique's unique features. Structures having a width-modulated height below a certain aperture size are fabricated by moving the stencil according to a two-dimensional trajectory. Variable-period gratings are obtained by translating a row of apertures at different orientations with respect to the row's axis. Despite the long deposition sequences one could envision for a stencil in dynamic mode, the apertures' active life-time in the sub-micrometre domain remains limited by the material's accretion on the membrane, resulting in the eventual clogging of the openings. A novel solution to this problem containing a micro-heater embedded in the membrane is described and its effectiveness in preventing material from clogging the apertures is demonstrated.
Nanoscale, 2011
We report on the synthesis, characterization and application of a novel nanocomposite made of a n... more We report on the synthesis, characterization and application of a novel nanocomposite made of a negative tone epoxy based photoresist modified with organic-capped Fe(2)O(3) nanocrystals (NCs). The mechanical properties of the nanocomposite drastically improve upon incorporation of a suitable concentration of NCs in the polymer, without deteriorating its photolithography performance. High aspect ratio 3D microstructures made of the nanocomposite have been fabricated with a uniform surface morphology and with a resolution down to few micrometres. The embedded organic-capped Fe(2)O(3) NCs drastically increase the stiffness and hardness of the epoxy based photoresist matrix, making the final material extremely interesting for manufacturing miniaturized polymer based mechanical devices and systems. In particular, the nanocomposite has been used as structural material for fabricating photoplastic Atomic Force Microscopy (AFM) probes with integrated tips showing outstanding mechanical response and high resolution imaging performance. The fabricated probes consist of straight cantilevers with low stress-gradient and high quality factors, incorporating sharp polymeric tips. They present considerably improved performance compared to pure epoxy based photoresist AFM probes, and to commercial silicon AFM probes.
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Papers by Juergen Brugger