Adhesive Leaf Created by a Corona Discharge

Abstract

Here, we report a new concept of both the adhesive manner and material, named "adhesive leaf (AL)," based on the leaf of the plant Heteropanax fragrans. The treatment of the corona discharge on the leaf surface can cause the nano-/microdestruction of the leaf epidermis, resulting in an outward release of sap. The glucose-containing sap provided the AL with a unique ability to stick to various substrates such as steel, polypropylene, and glass. Moreover, we reveal that the AL adhesion strength depends on the AL size, as well as the corona-discharge intensity. Conventional adhesives, such as glue and bond, lose their adhesive property and leave dirty residues upon the removal of the attached material. Unlike the conventional methods, the AL is advantageous as it can be repeatedly attached and detached thoroughly until the sap liquid is exhausted; its adhesive ability is maintained for at least three weeks at room temperature. Our findings shed light on a new concept of a biodegradable adhesive material that is created by a simple surface treatment.Evolutionary processes have created the diverse adhesive methods of the organisms in nature [1][2][3][4][5][6] . For instance, on each footpad of the gecko animal, hundreds of thousands of setae with a density of 5300/m 2 exist 7 . Each seta consists of hundreds of spatulas, and each microspatula applies approximately 20 μN using a number of forces including the van der Waals, dipole, and capillary forces 1,2 . All of the forces are congregated and contribute to the adhesion of the gecko onto walls. In contrast to the manner of the gecko foot, chemical adhesive methods are also used in nature; for example, mussels can attach to all surfaces 4,6 . Mussels produce hair-like fibers that are composed of amino acids including 3,4-dihydrxy-L-phenylalanine and lysine, and the fibers allow the mussels to adhere to sea-rock surfaces. Another interesting organism, the Onychophora, squeezes out a slime known as a food web that overcomes its slow migration speed to obtain feed (prey); an adhesive property of the slime is enough to entangle the organism's prey 8 . Taking advantage of nature-developed techniques, the ancient Egyptians made paper from papyrus, which possesses an adhesive property without any additives 9 ; since then, it appears that researchers have continuously studied the adhesive method of organisms for many centuries [1][2][3][5][6][7] . Today, this research area is called biomimetics 10 . By using the morphological benefit of the gecko footpad, for example, gecko tape has been developed to ensure a collective adhesion; a method of the microfabrication of dense arrays of flexible plastic pillars is used to make the gecko tape 7 . A mimicking of the high-strength adhesive material that is produced by mussels has shown that it is nontoxic to living cells, thereby suggesting its potential suitability for surgical and other biomedical applications 11 . Besides, many studies are currently underway to mimic the techniques in nature effectively in terms of biocompatible a...

Bioinspired Micro Glue Threads Fabricated by Liquid Bridge-to-Solidification as an Effective Sensing Platform

“…For several decades, various natural micro–nano structures and their fabrication methods have inspired the development of new micro–nano technologies. − Recently, the development of advanced materials using these micro–nano structures was attempted to developed devices applicable in various technologies, such as flexible microsensors, solar cells, and camouflage systems. − Biomimetic micro–nano adhesives, for example, were developed by mimicking the natural mechanisms of mussels, − velvet worms, and snails that cling to surfaces or synthesize microfibers to capture food. As such, the manufacture of micro–nano structures, such as nanoparticles, nanotubes, nanowires, and nanofibers, has attracted significant research interest because these materials can sensitively detect molecular analytes. − Among various biomimicked technologies, the spider web and its production method have been extensively applied in the fabrication of micro–nano fibers because of its outstanding mechanical properties.…”

“…1−4 Recently, the development of advanced materials using these micro−nano structures was attempted to developed devices applicable in various technologies, such as flexible microsensors, solar cells, and camouflage systems. 5−7 Biomimetic micro−nano adhesives, for example, were developed by mimicking the natural mechanisms of mussels, 8−10 velvet worms, 11 and snails 12 that cling to surfaces or synthesize microfibers to capture food. As such, the manufacture of micro−nano structures, such as nanoparticles, nanotubes, nanowires, and nanofibers, has attracted significant research interest because these materials can sensitively detect molecular analytes.…”