Snail‐Inspired Dry Adhesive with Embedded Microstructures for Enhancement of Energy Dissipation

Abstract

reversible, and smart adhesives have been implemented in clean transfer systems on large-area glass (or wafers), [5,6] reversible attachments and fixations on various nonflat surfaces (e.g., skin and organs) for medical applications, [5,[7][8][9] and effective locomotion of medical robotics. [10,11] To improve performance and functionality, i.e., the adaptability or directionality of dry adhesion, various nanoscale geometrical and material features have been investigated for amplification of van der Waals forces or mechanical interlocking. Such examples can be found in the hierarchical and slanted microhairs of geckos, [12][13][14] interlocking nanohairs inspired by wing-locking devices of beetles, [15,16] and endoparasite-like microneedles. [17] Recently, additional rules of the 3D architectures of octopi suction cups have been unveiled to explain their enhanced wet adhesion via capillary interaction and suction effects. [5,7] While striking advances have been made in adhesive architectures created on engaged surfaces, another strategy has been investigated to improve adhesion strengths by employing an energy-dissipation layer. [18,19] According to well-established models, [18,20] the energy-dissipation layer plays a key role in improving adhesion strengths during both peel-off and pulloff detachment. In addition, employing heterogenous energydissipation layers inside the adhesives has been highlighted to improve durability and resistance against fatigue, [21] an approach different from previous studies like zip-like microstructured fasteners assisted by mechanical interlocking. [22][23][24] Very recently, versatile tough adhesives have been developed by introducing viscoelastic energy dissipation based on the hysteresis of polymer chains, wherein a tough hydrogel matrix effectively dissipates energy when the interface is stressed during detachment. [18,19] Despite their striking performance on diverse surfaces (e.g., wet and rough), hydrogel-based adhesives with chemical moieties remain challenging to apply in reversible clean-transfer/fixing devices or contamination-free skin patches because of their viscoelastic chemical residues after detachment. [18,19,25] To generate the arresting effect via an energydissipation layer without glue or chemistries, many efforts have focused on subsurface microstructures by controlling various geometries, arrangements (e.g., stripes or plaids), and viscous liquid chambers, resulting in remarkable enhancement In various organisms in nature, the energy-dissipation layers within their adhesive systems are known to play a significant role in enhancement of adhesion performance in pulling and peeling directions. Reported here is that the pedal-muscle structures of snails can be exploited to form a repeatable, microstructure-embedded adhesive, enabling enhanced adhesion in both pulling (13 N cm −2 ) and peeling (20 J m −2 ) directions with excellent repeatability (<1000 cycles). The measured adhesion strengths and energies depend on the geometrical and material parameters of the mi...

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A Tough Reversible Biomimetic Transparent Adhesive Tape with Pressure-Sensitive and Wet-Cleaning Properties

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