He can sense when a moth is blowing a raspberry by attaching a wire to the muscle that controls the insect's tongue, and using it to transmit a signal via one of Dr Hildebrand's tiny electronic backpacks.

ECONOMIST: Robomoths

Lethal electric fences, however, use a continuous current that can make a person lock on to the wire as voltage causes involuntary muscle contractions, paralysis and death.

WSJ: Escape From a North Korean Prison

The Darpa-supported team instead moved their machine by using an "artificial muscle" made out of nickel and titanium wire designed to stretch and contract with heat.

BBC: Pentagon helps build Meshworm reconnaissance robot