Tuesday, August 23, 2005

Using water tension as a controlled adhesive

File this one under "invention of velcro." I just spent this morning peeling my rain-drenched bike pants off, so it seems especially appropriate!

A materials engineer is taking a page from a palm beetle-s book to make a reversible adhesive device composed of thousands of microscopic water droplets. The beetle has footpads loaded with oil droplet-laden hairs, and when attacked it simply grabs hold of a leaf, with a tensile strength corresponding to 60 times its body mass, and waits for the predator to go away. The adhesion is reversible, so the beetle can just walk off. During regular walking the miniature bristles are kept away from the leaf surface.

The engineered variant uses water and electricity. The water is doped with ions, so a tiny field can cause the droplet to migrate between the underside and the top of a small porous (glass) disk. The working model uses micron-size pores, and requires 5 volts or so; but the hope is that scaling down will improve the speed of performance and reduce energy requirements.

I want to walk like a gecko!

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