Remora-Inspired Reversible Adhesive for Underwater Applications

adhesive, causing plasticization, swelling, erosion, degradation, or hydrolysis of adhesives, which eventually leads to cohesive failure. [8,9] Therefore, the development of underwater adhesives remains a significant challenge.An efficient way of developing underwater adhesives is by taking inspiration from nature. For instance, sessile marine organisms such as mussels and sandcastle worms use L-3,4-dihydroxyphenylalanine (DOPA) to achieve permanent underwater adhesion, whereas aquatic creatures such as remora and clingfish use unique microstructures for temporary underwater attachment. [10][11][12][13] Inspired by these unique underwater adhesion strategies, significant progress has been made in the design and fabrication of novel underwater adhesives in the past decade.Previous reviews on underwater adhesion have mainly focused on the micromechanics and bonding mechanisms. Adhesives for soft and wet tissues and hydrogels have been discussed in other recent reviews. [1,[14][15][16] However, only a few have been devoted to bulk underwater adhesives. [10,12,13,[16][17][18][19][20] In this review, we summarize the currently reported adhesives that show macroscopic adhesion to mainly, but not limited to, solid surfaces under wet and underwater conditions. We provide an overview of the development and performance of underwater adhesives based on different bonding methods and mechanisms. In addition, we discuss the possible research directions and perspectives for underwater adhesives. Current Design Strategies for Underwater AdhesionThe keys to achieving wet adhesion are the breaking down of the hydration layer and interaction with the substrate surface, which can be designed at different length scales (Figure 1). [21][22][23] To achieve dehydration at the molecular level (∼nm), hydrophobic organic solvents, monomers, and polymers have been used to remove the hydration layer and facilitate surface wetting, especially for hydrophobic substrates. [24,25] The use of water-absorbing fillers, including inorganic substances and hydrophilic polymers, is an alternative strategy that is widely used for wet surfaces. [26][27][28] At a larger length scale (μm to mm), surface microstructures can promote water drainage to prevent permanent water trapping. [29] Accompanied by the dehydration process, the interfacial bonding of adhesives is achieved by the formation of covalent/ non-covalent bonds (∼nm), which highly depends on the interfacial chemistry between the adherend and the adhesive. [10] For Underwater adhesives are in high demand in both commercial and industrial sectors. Compared with adhesives used in dry (air) environments, adhesives used for wet or submerged surfaces in aqueous environments have specific challenges in development and performance. In this review, focus is on adhesives demonstrating macroscopic adhesion to wet/underwater substrates. The current strategies are first introduced for different types of underwater adhesives, and then an overview is provided of the development and performance of underwater ad...

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Section: Tape‐type Underwater Adhesivesmentioning

confidence: 99%

Bioinspired Underwater Adhesives

2021

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“…Zhou et al also presented a pneumatic sucker exhibiting excellent adaptable adhesion up to 3.75 N on a rough surface (with surface roughness R a = 200 µm) under a sucker's modulus of 1.29 MPa (Figure 3F) (Zhuo et al, 2020). Recently, a 3D Printing based bottom-up approach was applied to a micro-suction disk, which exerts high friction of up to 266.8 kPa (Figure 3G) (Lee et al, 2019). Furthermore, hexagonal-shaped micropatterns were presented as strong wet adhesives, where the synergistic effects of the low bending stiffness of the pillars and a high number density of the pattern in the sliding direction exhibit a robust friction force, even underwater (Chen et al, 2015;Iturri et al, 2015;Ko et al, 2017a).…”

Section: Bioinspired Wet Adhesive Structuresmentioning

confidence: 99%

“…The self-cleaning capability enables easy removal of the contaminants from the adhesive surfaces, i.e., the dry adhesive can quickly and fully recover a clean adhesion that does not transfer contaminants to the substrate (Bhushan and Sayer, 2007;Sethi et al, 2008). Moreover, underwater organisms, such as octopuses, remoras, and clingfishes, use a unique sucker structure to stably adhere to various wet surfaces (Lee et al, 2016(Lee et al, , 2019. Strong wet adhesion allows them to grasp objects or to firmly adhere to slippery surfaces with ease.…”

Section: Introductionmentioning

confidence: 99%

Applications of Bioinspired Reversible Dry and Wet Adhesives: A Review

et al. 2021

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Bioinspired adhesives that emulate the unique dry and wet adhesion mechanisms of living systems have been actively explored over the past two decades. Synthetic bioinspired adhesives that have recently been developed exhibit versatile smart adhesion capabilities, including controllable adhesion strength, active adhesion control, no residue remaining on the surface, and robust and reversible adhesion to diverse dry and wet surfaces. Owing to these advantages, bioinspired adhesives have been applied to various engineering domains. This review summarizes recent efforts that have been undertaken in the application of synthetic dry and wet adhesives, mainly focusing on grippers, robots, and wearable sensors. Moreover, future directions and challenges toward the next generation of bioinspired adhesives for advanced industrial applications are described.

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“…Many living creatures in nature have a special own surviving method, and many studies of bio‐mimicking have been widely conducted to apply their novel living methods in our life. [ 1–6 ] One of the most famous studies in the biomimetics is a dry adhesive inspired by gecko foot. The gecko foot consists of numerous micro/nano hierarchical hair, which is composed of 30–130 µm long setae and 0.2–0.5 µm spatula‐shaped terminating structures and can be strongly attached to the surface by the “van der Waals forces.” [ 7–11 ] Notably, although the gecko lizards can stick with an adhesion strength of more than 100 kPa, they can move in speeds as high as 0.8 m s −1 through their extraordinary adhesion switching capability.…”

Section: Introductionmentioning

confidence: 99%

Surface Adaptable and Adhesion Controllable Dry Adhesive with Shape Memory Polymer

Lee

Song

Park

et al. 2022

Macromol. Rapid Commun.

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Gecko feet consist of numerous micro/nano hierarchical hairs and exhibit a high adhesion onto various surfaces by van der Waals forces. The gecko, despite its mighty adhesion, can travel efficiently with a rapid adhesion switching due to the end of the hairs on the gecko feet are slanted in one direction. Herein, a shape memory polymer (SMP)‐based switchable dry adhesive (SSA), inspired by gecko feet, having tremendous surface adaptability and adhesion switching capability, is reported. The SSA shows not only high adhesion to the various surfaces (≈332.8 kPa) but also easy detachment (nearly 3.73 kPa) due to the characteristic of SMP, which can reversibly recover from a deformed shape to its initial shape. On the basis of the novel adhesion switching property, it is suggested the SSA‐applied advanced glass transfer system can lead to feasible application. This experiment confirms that an ultrathin and light glass film is transferred easily and sustainably, and it is believed that the SSA may be a breakthrough and a powerful alternative for not only conventional dry adhesives but also the next‐level transfer systems.

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Remora-Inspired Reversible Adhesive for Underwater Applications

Cited by 35 publications

References 53 publications

Bioinspired Underwater Adhesives

Bioinspired Underwater Adhesives

Applications of Bioinspired Reversible Dry and Wet Adhesives: A Review

Surface Adaptable and Adhesion Controllable Dry Adhesive with Shape Memory Polymer

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