Soft Matter
Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287 Darmstadt, Germany.
Published: February 2022
Gecko adhesion is investigated by molecular dynamics simulations. It is known, that the gecko adhesion system shows increased pull-off forces in humid environments. A coarse-grained model of gecko beta keratin, previously developed in our group, is extended and used to elucidate the molecular mechanisms involved in this humidity effect on adhesion. We show that neither the change of the elastic properties of gecko keratin, nor capillary forces, can solely explain the increased pull-off forces of wet gecko keratin. Instead, we establish a molecular picture of gecko adhesion where the interplay between capillary bridges and a mediator effect of water, enhances pull-off forces, consistent with observations in AFM experiments at high humidities. We find that water density is raised locally, in molecular scale asperities of the gecko keratin and that this increase in local water density smoothes the surface-spatula interface. Water, which is absorbed into the keratin, acts as a mediator, and leads during pull-off to the dominant contribution in the van der Waals energy, because the dispersion interactions between water and surface are primarily opposing the pull-off.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1039/d1sm01232k | DOI Listing |
Small Methods
January 2025
State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
Bionic adhesive materials with 3D complex micro/nanostructures have several advantages of low preload, strong adhesion, switchable adhesion, etc. As the primary high-precision fabrication method for such materials, lithography is inherently limited by its 2D processing capabilities. Achieving complex 3D morphologies typically requires auxiliary processes, such as dipping and double-sided separate UV exposures, which increase both the complexity and limitations of the fabrication process.
View Article and Find Full Text PDFJ Exp Biol
January 2025
Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA.
Despite the myriad studies examining the diversity and mechanisms of gecko adhesion in the lab, we have a poor understanding of how this translates to locomotion in nature. It has long been assumed that greater adhesive strength should translate to superior performance in nature. Using 13 individuals of Bradfield's Namib day gecko (Rhoptropus bradfieldi) in Namibia, I tested the hypothesis that maximum running performance in nature (speed and acceleration) is driven by maximum frictional adhesive strength.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Centre for MicroElectroMechanical Systems (CMEMS), University of Minho, Azurem Campus, 4800-058 Guimaraes, Portugal.
The World Health Organization (WHO) reports 684,000 deaths/year due to slips and falls (SFs), with ∼38 million people requiring medical attention per annum. In particular, SFs on ice surfaces account for 45% of all SF incidents, costing over $100 billion globally in healthcare, intensive care, and insurance expenses. Current antislip solutions focus on hydrophobicity to repel interfacial fluids, aiming to maintain solid-to-solid contact.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Department of Chemical & Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA.
The ability to "switch on" adhesion between a thin hydrogel and a biological tissue can be useful in biomedical applications such as surgery. One way to accomplish this is with an electric field, a phenomenon termed electroadhesion (EA). Here, it is shown that cationic gels can be adhered by EA to tissues across all of biology.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Micro-and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China.
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!
© LitMetric 2025. All rights reserved.