Illustration of a high-viscosity adhesive patch inspired by an octopus suction cup that has a microscopic spherical structure inside [Source by Ministry of Science, ICT and Future Planning]
South Korean researchers have developed a high-viscosity adhesive patch inspired by octopus suction cups, which can stick repeatedly to wet and dry surfaces of variable geometries, including the human skin.
Prof. Bang Chang-hyun and his colleagues at Sungkyunkwan University fabricated a 3x3 cm polymer patch covered with miniature replicas of the octopus suction cups and demonstrated this artificial patch works in damp conditions or when fully submerged in water, the Ministry of Science, ICT and Future Planning announced on Wednesday.
In the new research, the researchers focused on a central bump in the suction cup and suction pressure resulting from a liquid cohesive force on the surface inside the suction cup.
When a suction cup is pressed into a surface in the presence of liquid, it contracts, pushing some of the fluid out, while the remaining liquid in the cup is drawn into a space around the bump by capillary forces. When the outer force is released, the collected liquid is maintained by a cohesive force, while the space between the suction cup and the surface turns into a vacuum that creates a high suction pressure.
The researchers demonstrated that the adhesive patch can maintain viscosity with no loss of suction after more than 10,000 cycles of attachment and detachment on the surface of various geometries in both dry and wet conditions.
The researchers also tested the patch’s adhesiveness to an 8-inch silicon wafer in water, concluding that the suction cup patch could be widely used in the manufacture of silicon chips and wound healing.
The research provides a better understanding of why the suction cups of the octopus are good at grabbing hold of surfaces, shedding light on the role of the spherical bump in the suction cups for the first time. The research findings were published in Nature.
By Seo Jin-woo
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