Bio-inspired climbing technology could increase troop safety and freedom of maneuver
Historically, gaining the high ground has always been an operational advantage for warfighters, but the climbing instruments on which they're frequently forced to rely-tools such as ropes and ladders-have not advanced significantly for millennia. Not only can the use of such tools be overt and labor intensive, they also only allow for sequential climbing whereby the first climber often takes on the highest risk.
"The gecko is one of the champion climbers in the Animal Kingdom, so it was natural for
Geckos can climb on a wide variety of surfaces, including smooth surfaces like glass, with adhesive pressures of 15-30 pounds per square inch for each limb, meaning that a gecko can hang its entire body by one toe. The anatomy of a gecko toe consists of a microscopic hierarchical structure composed of stalk-like setae (100 microns in length, 2 microns in radius). From individual setae, a bundle of hundreds of terminal tips called spatulae (approximately 200 nanometers in diameter at their widest) branch out and contact the climbing surface.
A gecko is able to climb on glass by using physical bond interactions-specifically van der Waals intermolecular forces-between the spatulae and a surface to adhere reversibly, resulting in easy attachment and removal of the gecko's toes from the surface. The van der Waals mechanism implied that it is the size and shape of the spatulae tips that affect adhesive performance, not specific surface chemistry. This suggested that there were design principles and physical models derived from nature that might enable scientists to fabricate an adhesive inspired by gecko toes.
Humans, of course, have much more weight to carry than a gecko. One of the initial challenges in developing a device to support human climbing was the issue of scaling: a typical Tokay gecko weighs 200 grams, while an average human male weighs 75 kilograms. To enable dynamic climbing like a gecko at this larger scale required that the engineers create climbing paddles capable of balancing sufficient adhesive forces in both the shear (parallel to the vertical surface) and normal (perpendicular to the vertical surface) directions. That feature is necessary for a climber to remain adhered on a surface without falling off while in the act of attaching and detaching the paddles with each movement.
The first human climbing demonstration occurred in
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