The Airfish is an unusual blimp that moves like a trout, with no conventional motor:
The designers, led by Christa Jordi and colleagues from EMPA, the Swiss federal laboratories for materials testing and research in Dübendorf, replaced traditional motors with swaths of acrylic polymers on each side of the Airfish. The polymers connect to carbon electrodes, and when a voltage moves across them, the electrodes are attracted to each other, compressing the polymers. The Airfish is forced to flex like a contracting muscle. By alternating the voltages applied to each side of the vehicle, the team can make the ship shimmy like a fish. Membranes on the tail move it back and forth, too.
The team modeled the Airfish after rainbow trout because they’re versatile swimmers, but aren’t especially quick or agile. They programmed software to mimic the rhythm of the trout’s motion, and ran it on a computer attached to lithium-polymer batteries in the airship’s gondola, New Scientist reports.
The combined motion of the tail and the body make the Airfish move forward at roughly 1.5 feet per second, akin to a slow walking speed.