Wednesday, January 05, 2005


On this bright morning, I am very pleased to draw your attention to the remarkable adhesive qualities of gecko feet:

In 2002, biologist Kellar Autumn at Lewis & Clark University in Oregon discovered that the adhesion came from van der Waals Forces, minute molecular-scale attraction (spider feet work in a similar, albeit simpler, manner). Each gecko foot is covered with millions of tiny hairs, or setae, which branch in to nanoscale tips, or spatulae; each seta is strong enough to lift 20mg. The combined adhesive power of a gecko's four feet is over 90 lbs.
Duly impressed, Autumn set out to create a biomimetic structure with similar adhesive capabilities:
In 2003, they managed to create artificial setae with adhesion on the order of 0.5 Newton per square centimeter; their eventual goal is adhesion force equivalent to gecko setae, 10 Newton per square centimeter.

One feature of systems of millions of tiny attraction points is that they can be both incredibly strong and readily detached. A gecko is able to peel its feet up and run at a good clip, or stand still and be nearly impossible to pull from a window or wall. As Autumn suggests, geckomimetic adhesive could be of enormous value in object construction, as the adhesion force could be quite strong. At the same time, being able to simply peel apart components -- with no chemical residue -- would enhance our ability to design for disassembly, an important part of cradle-to-cradle thinking.


Pastabagel said...

Interesting post.

Though you should consider that as a general rule disassembly of an article requires more energy than any of recycling, reusing, or discarding (that one is obvious) the article. If we are going to think "cradle-to-cradle" we need to consider that energy loss.

Could be an interesting alternative to Velcro though.


Phila said...

Nice of you to drop in, PB!

Though I welcome your comment, it probably won't surprise you to learn that I find it utterly bizarre. First off, the "general rule" you refer to is meaningless unless we define what type of manufactured item we're talking about. Of all the vague pseudoscientific pronouncements I've ever seen, yours may be the vaguest.

Beyond that, the idea that disassembly of a given item is "generally" more energy-intensive than discarding it is...well, I'll be polite and say it's dubious. Uunless you're talking about, say, individual energy rather than energy distributed throughout a system. Which I hope you're not, 'cause that'd be dumb.

Your argument also assumes that the sole concern of C2C is energy savings, which is not the case at all. C2C, while not some magic bullet for the world's ills, does look at a broad spectrum of effects, which have to be variably balanced to achieve minimum environmental impact. Even outside that paradigm, though, there have always been situations where expending a little more energy would be a more efficient use of resources (including money) than discarding a little more mercury (for instance).

And last, talking about reuse and recycling as though they're in opposition to disassembly is silly, since one of the potential goals of disassembly is reuse and recycling.