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Author: Arzt, Eduard × End date: 2024 × DDC: 570 × Has files: Yes × WGL Institute: INM ×

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Now showing 1 - 6 of 6
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    Self-Adhesive Silicone Microstructures for the Treatment of Tympanic Membrane Perforations
    (Weinheim : Wiley-VCH, 2021) Lana, Gabriela Moreira; Sorg, Katharina; Wenzel, Gentiana Ioana; Hecker, Dietmar; Hensel, René; Schick, Bernhard; Kruttwig, Klaus; Arzt, Eduard
    Inspired by the gecko foot, polymeric microstructures have demonstrated reliable dry adhesion to both stiff objects and sensitive surfaces such as skin. Microstructured silicone patches are proposed, herein, for the treatment of tympanic membrane perforations with the aim of serving as an alternative for current surgical procedures that require anesthesia and ear canal packing. Sylgard 184 PDMS micropillars of 20 μm in diameter and 60 μm in length are topped by a Soft Skin Adhesive (SSA) MG7-1010 terminal layer, of about 25 μm thickness. The adhesion is evaluated by specially designed tack tests against explanted murine eardrums and, for comparison, against a rigid substrate. Functional effects are evaluated using auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAE). The adhesion strength of the microstructure and unstructured controls to explanted murine tympanic membranes is comparable (typically 12 kPa), but the microstructured patches are easier to handle by the surgeon. For the first time, partial recovery of hearing performance is measured immediately after patch application. The novel patches adhere without the need for further fixation, removing the need for ear canal packing. The proposed material design holds great promise for improving clinical treatments of tympanic membrane perforations.
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    Surface structure influences contact killing of bacteria by copper
    (Hoboken, NJ : Wiley, 2014) Zeiger, Marco; Solioz, Marc; Edongué, Hervais; Arzt, Eduard; Schneider, Andreas S.
    Copper kills bacteria rapidly by a mechanism that is not yet fully resolved. The antibacterial property of copper has raised interest in its use in hospitals, in place of plastic or stainless steel. On the latter surfaces, bacteria can survive for days or even weeks. Copper surfaces could thus provide a powerful accessory measure to curb nosocomial infections. We here investigated the effect of the copper surface structure on the efficiency of contact killing of Escherichia coli, an aspect which so far has received very little attention. It was shown that electroplated copper surfaces killed bacteria more rapidly than either polished copper or native rolled copper. The release of ionic copper was also more rapid from electroplated copper compared to the other materials. Scanning electron microscopy revealed that the bacteria nudged into the grooves between the copper grains of deposited copper. The findings suggest that, in terms of contact killing, more efficient copper surfaces can be engineered.
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    Bioinspired pressure actuated adhesive system
    (Saarbrücken : Leibniz-Institut für Neue Materialien, 2011) Paretkar, Dadhichi R.; Kamperman, Marleen; Schneider, Andreas S.; Arzt, Eduard
    We developed a dry snythetic adhesive system inspired by gecko feet that can switch reversibly from adhesion to non-adhesion with applied pressure as external stimulus. Micropatterned polydimethylsiloxane (PDMS) surfaces with pillars of 30 µm length and 10 µm diameter were fabricated using photolithography and moulding. Adhesion properties were determined with a flat probe as a function of preload. For low and moderate applied compressive preloads, measured adhesion was 7.5 times higher on the patterned surfaces than on flat controls whereas for high preloads adhesion dropped to very low values. In situ imaging showed that the increased preload caused the pillars to deform by bending and/or buckling and to lose their adhesive contact. The elasticity of PDMS aids the pillar recovery to the upright position upon removal of preload enabling repeatability of the switch. Such systems have promising properties e.g. for industrial pick-and-carry operations.
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    "Gecko-Workshop 2010" - INM initiates new worldwide conference series
    (Saarbrücken : Leibniz-Institut für Neue Materialien, 2011) Kamperman, Marleen; Arzt, Eduard
    In July 2010, scientists from all over the world gathered at INM to discuss gecko inspired adhesion at a workshop entitled "Bioinspired adhesion: from geckos to new products". The talks covered a range of current issues, including natural attachment systems, developments in artificial gecko-mimics, advances in mechanical models and possible products. This was the first dedicated workshop on this topic. The attendees unanimously agreed to create an international workshop series based on the INM example.
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    Adhesion characteristics of PDMS surfaces during repeated pull-off force measurements
    (Hoboken, NJ : Wiley, 2010) Kroner, Elmar; Arzt, Eduard; Maboudian, Roya
    To mimic the adhesive effects of gecko toes, artificial surfaces have been manufactured recently using polydimethylsiloxanes (PDMS). However, the effects of repeated contacts on the adhesive properties remain largely unexplored. In this paper we report on the effect of repeated pull-off force measurements on the adhesion behavior of PDMS (polymer kit Sylgard 184, Dow Corning) tested with a borosilicate glass probe. A decrease in pull-off force with increase in number of test cycles is found until a plateau is reached. The initial value and the rate of change in pull-off force strongly depend on the sample preparation procedure, including curing time and cross-linking. It is proposed that the behavior is due to steady coverage of the probe with free oligomers. The results are crucial for developing reusable, durable, and residue-free bioinspired adhesives.
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    Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: implications for the limits of biological control over the growth mode of abalone sea shells
    (London : BioMed Central, 2012) Schneider, Andreas S.; Heiland, Birgit; Peter, Nicolas J.; Guth, Christina; Arzt, Eduard; Weiss, Ingrid M.
    Background: Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results: Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions: In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM) [Gilbert et al., Journal of the American Chemical Society 2008, 130:17519–17527]. Polarized optical microscopy revealed unprecedented super-structures in the calcitic shell part. This bears, in principle, the potential for in vivo studies, which might be useful for investigating the growth modes of nacre and other shell types.