Adhesives are typically either strong and permanent or reversible with limited strength. However, current strategies to create strong yet reversible adhesives needed for wearable devices, robotics and material disassembly lack independent control of strength and release, require complex fabrication or only work in specific conditions. Here we report metamaterial adhesives that simultaneously achieve strong and releasable adhesion with spatially selectable adhesion strength through programmed cut architectures. Nonlinear cuts uniquely suppress crack propagation by forcing cracks to propagate backwards for 60× enhancement in adhesion, while allowing crack growth in the opposite direction for easy release and reusability. This mechanism functions in numerous adhesives on diverse substrates in wet and dry conditions and enables highly tunable adhesion with independently programmable adhesion strength in two directions simultaneously at any location. We create these multifunctional materials in a maskless, digital fabrication framework to rapidly customize adhesive characteristics with deterministic control for next-generation adhesives.
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http://dx.doi.org/10.1038/s41563-023-01577-2 | DOI Listing |
Philos Trans A Math Phys Eng Sci
October 2024
Mechanical Engineering, Soft Materials and Structures Lab, Virginia Tech, Blacksburg VA 24061, USA.
Metamaterial design approaches, which integrate structural elements into material systems, enable the control of uncommon behaviours by decoupling local and global properties. Leveraging this conceptual framework, metamaterial adhesives incorporate nonlinear cut architectures into adhesive films to achieve unique combinations of adhesion capacity, release, and spatial tunability by controlling how cracks propagate forward and in reverse directions during separation. Here, metamaterial adhesive designs are explored with triangular cut features while integrating hierarchical and secondary cut patterns among primary nonlinear cuts.
View Article and Find Full Text PDFACS Appl Mater Interfaces
October 2024
Department of Intelligent Semiconductor Engineering, Chung-Ang University, Seoul 06974, Republic of Korea.
Metamaterials, characterized by their unique artificial periodic structures, exhibit extraordinary abilities in controlling electromagnetic waves not found in natural materials. Metamaterial absorbers, for example, have been developed by patterning solid conductive materials on dielectric surfaces. However, the foldability limitations of solid conductors make them unsuitable as foldable metamaterial absorbers since they lose those desirable properties when folded.
View Article and Find Full Text PDFACS Appl Mater Interfaces
September 2024
Laboratory for Multiphase Thermofluidics and Surface Nanoengineering, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland.
Precise micropatterning on three-dimensional (3D) surfaces is desired for a variety of applications, from microelectronics to metamaterials, which can be realized by transfer printing techniques. However, a nontrivial deficiency of this approach is that the transferred microstructures are adsorbed on the target surface with weak adhesion, limiting the applications to external force-free conditions. We propose a scalable "photolithography-transfer-plating" method to pattern stable and durable microstructures on 3D metallic surfaces with precise dimension and location control of the micropatterns.
View Article and Find Full Text PDFSoft Matter
August 2024
Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
Nat Commun
May 2024
Key Laboratory of Green Printing, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Asymmetric mechanical transducers have important applications in energy harvesting, signal transmission, and micro-mechanics. To achieve asymmetric transformation of mechanical motion or energy, active robotic metamaterials, as well as materials with asymmetric microstructures or internal orientation, are usually employed. However, these strategies usually require continuous energy supplement and laborious fabrication, and limited transformation modes are achieved.
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