Showing papers by "Irina V. Grigorieva published in 2003"
TL;DR: A prototype of such 'gecko tape' is reported on, made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion.
Abstract: The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries1,2,3 However, only in the past few years2,3 has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos Each hair produces a miniscule force ≈10−7 N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of ≈10 N cm−2: sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling It is very tempting3 to create a new type of adhesive by mimicking the gecko mechanism Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved
1,234 citations
TL;DR: It is revealed that domain walls can become trapped between crystalline planes, and that they propagate by distinct jumps that match the lattice periodicity, which offers a means for probing experimentally the physics of topological defects in discrete lattices.
Abstract: The discrete nature of crystal lattices plays a role in virtually every material property. But it is only when the size of entities hosted by a crystal becomes comparable to the lattice period--as occurs for dislocations, vortices in superconductors and domain walls--that this discreteness is manifest explicitly. The associated phenomena are usually described in terms of a background Peierls 'atomic washboard' energy potential, which was first introduced for the case of dislocation motion in the 1940s. This concept has subsequently been invoked in many situations to describe certain features in the bulk behaviour of materials, but has to date eluded direct detection and experimental scrutiny at a microscopic level. Here we report observations of the motion of a single magnetic domain wall at the scale of the individual peaks and troughs of the atomic energy landscape. Our experiments reveal that domain walls can become trapped between crystalline planes, and that they propagate by distinct jumps that match the lattice periodicity. The jumps between valleys are found to involve unusual dynamics that shed light on the microscopic processes underlying domain-wall propagation. Such observations offer a means for probing experimentally the physics of topological defects in discrete lattices--a field rich in phenomena that have been subject to extensive theoretical study.
92 citations