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End date: 2024 × Start date: 2020 × Type: article × Publisher: London : Nature Publishing Group × WGL Institute: IOM ×

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Now showing 1 - 4 of 4
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    Programing stimuli-responsiveness of gelatin with electron beams: Basic effects and development of a hydration-controlled biocompatible demonstrator
    (London : Nature Publishing Group, 2017) Riedel, Stefanie; Heyart, Benedikt; Apel, Katharina S.; Mayr, Stefan G.
    Biomimetic materials with programmable stimuli responsiveness constitute a highly attractive material class for building bioactuators, sensors and active control elements in future biomedical applications. With this background, we demonstrate how energetic electron beams can be utilized to construct tailored stimuli responsive actuators for biomedical applications. Composed of collagen-derived gelatin, they reveal a mechanical response to hydration and changes in pH-value and ion concentration, while maintaining their excellent biocompatibility and biodegradability. While this is explicitly demonstrated by systematic characterizing an electron-beam synthesized gelatin-based actuator of cantilever geometry, the underlying materials processes are also discussed, based on the fundamental physical and chemical principles. When applied within classical electron beam lithography systems, these findings pave the way for a novel class of highly versatile integrated bioactuators from micro-to macroscales.
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    Reactive plasma cleaning and restoration of transition metal dichalcogenide monolayers
    (London : Nature Publishing Group, 2021) Marinov, Daniil; de Marneffe, Jean-François; Smets, Quentin; Arutchelvan, Goutham; Bal, Kristof M.; Voronina, Ekaterina; Rakhimova, Tatyana; Mankelevich, Yuri; El Kazzi, Salim; Nalin Mehta, Ankit; Wyndaele, Pieter-Jan; Heyne, Markus Hartmut; Zhang, Jianran; With, Patrick C.; Banerjee, Sreetama; Neyts, Erik C.; Asselberghs, Inge; Lin, Dennis; De Gendt, Stefan
    The cleaning of two-dimensional (2D) materials is an essential step in the fabrication of future devices, leveraging their unique physical, optical, and chemical properties. Part of these emerging 2D materials are transition metal dichalcogenides (TMDs). So far there is limited understanding of the cleaning of “monolayer” TMD materials. In this study, we report on the use of downstream H2 plasma to clean the surface of monolayer WS2 grown by MOCVD. We demonstrate that high-temperature processing is essential, allowing to maximize the removal rate of polymers and to mitigate damage caused to the WS2 in the form of sulfur vacancies. We show that low temperature in situ carbonyl sulfide (OCS) soak is an efficient way to resulfurize the material, besides high-temperature H2S annealing. The cleaning processes and mechanisms elucidated in this work are tested on back-gated field-effect transistors, confirming that transport properties of WS2 devices can be maintained by the combination of H2 plasma cleaning and OCS restoration. The low-damage plasma cleaning based on H2 and OCS is very reproducible, fast (completed in a few minutes) and uses a 300 mm industrial plasma etch system qualified for standard semiconductor pilot production. This process is, therefore, expected to enable the industrial scale-up of 2D-based devices, co-integrated with silicon technology.
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    Detection of small bunches of ions using image charges
    (London : Nature Publishing Group, 2018) Räcke, Paul; Spemann, Daniel; Gerlach, Jürgen W.; Rauschenbach, Bernd; Meijer, Jan
    A concept for detection of charged particles in a single fly-by, e.g. within an ion optical system for deterministic implantation, is presented. It is based on recording the image charge signal of ions moving through a detector, comprising a set of cylindrical electrodes. This work describes theoretical and practical aspects of image charge detection (ICD) and detector design and its application in the context of real time ion detection. It is shown how false positive detections are excluded reliably, although the signal-to-noise ratio is far too low for time-domain analysis. This is achieved by applying a signal threshold detection scheme in the frequency domain, which - complemented by the development of specialised low-noise preamplifier electronics - will be the key to developing single ion image charge detection for deterministic implantation.
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    Ultrafast high-resolution mass spectrometric finger pore imaging in latent finger prints
    (London : Nature Publishing Group, 2014) Elsner, C.; Abel, B.
    Latent finger prints (LFPs) are deposits of sweat components in ridge and groove patterns, left after human fingers contact with a surface. Being important targets in biometry and forensic investigations they contain more information than topological patterns. With laser desorption mass spectrometry imaging (LD-MSI) we record 'three-dimensional' finger prints with additional chemical information as the third dimension. Here we show the potential of fast finger pore imaging (FPI) in latent finger prints employing LD-MSI without a classical matrix in a high-spatial resolution mode. Thin films of gold rapidly sputtered on top of the sample are used for desorption. FPI employing an optical image for rapid spatial orientation and guiding of the desorption laser enables the rapid analysis of individual finger pores, and the chemical composition of their excretions. With this approach we rapidly detect metabolites, drugs, and characteristic excretions from the inside of the human organism by a minimally-invasive strategy, and distinguish them from chemicals in contact with fingers without any labeling. The fast finger pore imaging, analysis, and screening approach opens the door for a vast number of novel applications in such different fields as forensics, doping and medication control, therapy, as well as rapid profiling of individuals.