Properties validation of an anisotropic dry adhesion designed for legged climbing robots

Journal of Adhesion Science and Technology

Sharif

Menon

2012

The effectiveness of biomimetic dry adhesives at different ambient pressures was investigated. Biomimetic dry adhesives have great potential for space applications but there have been few studies on how these adhesives perform in low-pressure environments. The best performing geometry for dry adhesives with respect to normal adhesion has previously been determined to be mushroom shaped fibers, but the pressure sensitivity of these designs has been unclear -with some groups reporting pressure dependent adhesion, and others claiming no effect. We have compared the microscale adhesion of mushroom shaped polymer fibers at different ambient pressures and have determined that suction cup effects are negligible for fibers with caps less than 16.4 μm in diameter. Further investigation in this work showed that a simple suction cup model provided estimates for the geometry requirements for a non-negligible suction cup effect and determined that the minimum cap radius for the 10 μm pillar diameter used in this study should be over 26 μm -past the dimension that can be successfully fabricated using this technology.

Section: Introductionmentioning

confidence: 99%

Investigation of low-pressure adhesion performance of mushroom shaped biomimetic dry adhesives

Journal of Adhesion Science and Technology

Sharif

Menon

2012

“…There is however a convergence on what appropriate designs for dry adhesives include-specifically, for non-directional adhesives requiring high normal strength, a flaw tolerant overhanging cap on each fiber is critical for polymer-based dry adhesives [6,12]. Certain applications like climbing robots [20][21][22][23][24][25][26][27][28][29], require other properties of real gecko adhesion, including self-cleaning [16,[30][31][32] or nonfouling behavior and direction sensitive (anisotropic) adhesion strength [13,25,26,[33][34][35][36][37]. Both these properties have been successfully demonstrated in recent dry adhesive designs, although there is no one synthetic dry adhesive system that has successfully matched all desirable properties of the gecko adhesive system.…”

Section: Introductionmentioning

confidence: 99%

Deep UV patterning of acrylic masters for molding biomimetic dry adhesives

J. Micromech. Microeng.

Menon

2010

We present a novel fabrication method for the production of biomimetic dry adhesives that allows enormous variation in fiber shapes and sizes. The technology is based on deep-UV patterning of commercial acrylic with semi-collimated light available from germicidal lamps, and combined careful processing conditions, material selection and novel developer choices to produce relatively high-aspect-ratio fibers with overhanging caps on large areas. These acrylic fibers are used as a master mold for subsequent silicone rubber negative mold casting. Because the bulk acrylic demonstrates little inherent adhesion to silicone rubbers, the master molds created in this process do not require any surface treatments to achieve high-yield demolding of interlocked structures. Multiple polymers can be cast from silicone rubber negative molds and this process could be used to structure smart materials on areas over multiple square feet. Using direct photopatterning of acrylic allows many of the desired structures for biomimetic dry adhesives to be produced with relative ease compared to silicon-based molding processes, including angled fibers and hierarchical structures. Optimized fiber shapes for a variety of polymers can be produced using this process, and adhesion measurements on a well-characterized polyurethane, ST-1060, are used to determine the effect of fiber geometry on adhesion performance.

“…3 Dry adhesion has been investigated in depth in the last decade 4-6 and engineers and physicists studied different micro/nano designs [7][8][9] and developed different fabrication methodologies [10][11][12][13][14][15] for obtaining synthetic versions of dry adhesives. 3 Dry adhesion has been investigated in depth in the last decade 4-6 and engineers and physicists studied different micro/nano designs [7][8][9] and developed different fabrication methodologies [10][11][12][13][14][15] for obtaining synthetic versions of dry adhesives.…”

Section: Introductionmentioning

confidence: 99%

“…There is evidence that geckos 1 and some species of spiders 2 are able to climb almost any surface by taking advantage of their dry adhesives, which rely primarily on Van der Waals forces. 3 Dry adhesion has been investigated in depth in the last decade [4][5][6] and engineers and physicists studied different micro/nano designs [7][8][9] and developed different fabrication methodologies [10][11][12][13][14][15] for obtaining synthetic versions of dry adhesives. These adhesives could potentially enable the development of climbing robots for surveillance, security, rescue, and maintenance operations in hazardous environments.…”

Section: Introductionmentioning

confidence: 99%

Abigaille II: toward the development of a spider-inspired climbing robot

Ahmed

et al. 2011

Robotica

This paper presents a novel robotic platform, Abigaille II, designed to climb vertical surfaces using dry adhesion. Abigaille II is a lightweight hexapod prototype actuated by 18 miniaturized motors. The robot's feet consist of adhesive patches, which have microhairs with mushroomshaped caps fixed on the top of millimeter-scale flexible posts. A pentapedal gait is used to climb flat vertical surfaces as this gait maximizes the number of legs in contact to the surface. Abigaille can however also walk by using other gaits, including the tripod gait.