A gecko can stick to almost any surface, so it can even run upside down on a ceiling of polished glass. This is due to the way tiny chemical forces are exploited by tiny hairs called setae, about 1/10 of a millimetre long and packed 5,000 per square millimetre (three million per square inch). The end of each seta has about 400–1,000 branches ending in a spatula-like structure about 0.2–0.5 microns—less than 1/50,000 of an inch—long (a micron is 1/1,000 of a millimetre). This is an amazingly fine structure that the researchers said was ‘beyond the limits of human technology’…