Search Results

Now showing 1 - 2 of 2
  • Item
    In Situ Observation Reveals Local Detachment Mechanisms and Suction Effects in Micropatterned Adhesives
    (Weinheim : Wiley-VCH, 2019) Tinnemann, Verena; Hernández, Luissé; Fischer, Sarah C.L.; Arzt, Eduard; Bennewitz, Roland; Hensel, René
    Fibrillar adhesion pads of insects and geckoes have inspired the design of high-performance adhesives enabling a new generation of handling devices. Despite much progress over the last decade, the current understanding of these adhesives is limited to single contact pillars and the behavior of whole arrays is largely unexplored. In the study reported here, a novel approach is taken to gain insight into the detachment mechanisms of whole micropatterned arrays. Individual contacts are imaged by frustrated total internal reflection, allowing in situ observation of contact formation and separation during adhesion tests. The detachment of arrays is found to be governed by the distributed adhesion strength of individual pillars, but no collaborative effect mediated by elastic interactions can be detected. At the maximal force, about 30% of the mushroom structures are already detached. The adhesive forces decrease with reduced air pressure by 20% for the smooth and by 6% for the rough specimen. These contributions are attributed to a suction effect, whose strength depends critically on interfacial defects controlling the sealing quality of the contact. This dominates the detachment process and the resulting adhesion strength. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  • Item
    A self-adhesive elastomericwound scaffold for sensitive adhesion to tissue
    (Basel : MDPI, 2019) Boyadzhieva, Silviya; Sorg, Katharina; Danner, Martin; Hensel, René; Fischer, Sarah C.L.; Schick, Bernhard; Wenzel, Gentiana; Arzt, Eduard; Kruttwig, Klaus
    Pressure sensitive adhesives based on silicone materials are used particularly for skin adhesion, e.g., the fixation of electrocardiogram (ECG) electrodes or wound dressings. However, adhesion to sensitive tissue structures is not sufficiently addressed due to the risk of damage or rupture. We propose an approach in which a poly-(dimethylsiloxane) (PDMS)-based soft skin adhesive (SSA) acts as cellular scaffold for wound healing. Due to the intrinsically low surface free energy of silicone elastomers, functionalization strategies are needed to promote the attachment and spreading of eukaryotic cells. In the present work, the effect of physical adsorption of three different proteins on the adhesive properties of the soft skin adhesive was investigated. Fibronectin adsorption slightly affects adhesion but significantly improves the cellular interaction of L929 murine fibroblasts with the polymeric surface. Composite films were successfully attached to explanted tympanic membranes. This demonstrates the potential of protein functionalized SSA to act as an adhesive scaffold in delicate biomedical applications.