If there's one animal that's inspired endless scientific research — it's the gecko. The lizard's ability to seemingly defy gravity and walk on walls has resulted in robots that can repair spaceships in flight, and now maybe even self-cleaning reusable sticky tape.
It turns out that in addition to being naturally sticky thanks to microscopic hairs called setae that adhere to things on the molecular level, Gecko's also have a special walking technique where the friction of their foot against a surface helps to clear microscopic dirt particles. Larger particles simply roll away, while smaller particles fall into folds in the lizard's skin leaving their feet sticky again for the next step.
So researchers at the Karlsruhe Institute of Technology in Germany and Carnegie Mellon University wondered if the same techniques could be used to make self-cleaning tape. They emulated a gecko's setae with mushroom-shaped elastic microscopic protrusions, and instead of dirt they used tiny glass beads for their experiments.
When the glass beads were larger than the micro-mushrooms, pulling the tape off of a surface after the strip was slid laterally resulted in it regaining almost all of its stickiness. But the results were less successful when the glass beads were smaller than the micro-mushrooms, and the simulated dirt actually got stuck in-between them.
But hope is not lost. It just means that those elastic mushrooms will have to be very small — somewhere in the nanometer size range — for this reusable tape to actually be effective in the real world. Of course, the researchers will have to test it with real world dirt, like dust and grease from fingerprints, but they seem confident that one day self-cleaning tape could revolutionise medical adhesives and gift wrapping as we know it. (Much to the dismay of Big Tape.) [Karlsruhe Institute of Technology via Gizmag]