"We successfully decreased the size of the essential parts of a heat engine, such as the working gas and piston, to only a few micrometres
and then assembled them to a machine," stated another researcher called Valentin Blickle.
They created a polymer whose external structure is 100 micrometres-high pillars, topped by a thin 40 micrometres
wide discs, upon which tiny mushroom-shapes sit.
The 'micro-bull' measures ten micrometres
long by seven deep.
Stinging cells isolated from the filaments are 60 micrometres long and 8 micrometres wide, and contain a hair-like needle 40 micrometres long.
One square centimetre of cream-coated skin can contain as many as a million tiny needles, and Daniely says that around one-third of the stinging cells in the cream end up pointing in the right direction to fire their needles into the skin - but because each is just a few micrometres thick, the process is painless.