Tied up in knots: the tiny knotted robot could find applications in agriculture and reforestation. (Courtesy: Bella Ciervo/Penn Engineering)

Researchers at the University of Pennsylvania and the University of California, Los Angeles, have created a tiny, soft knot-like fibre that can jump metres into the air .

The fibre is less than a millimetre thick, and a few millimetres long and contains a Kevlar core surrounded by a shell of liquid crystal elastomer (LCE).

The Kevlar provides strength and stiffness while the LCE adds some flexibility and responsiveness.

“People think of a knotted fibre as something passive,” says Shu Yang from the University of Pennsylvania.…