Liquid magnet propellers could be a safer way to power boats

A robot boat with a propeller made from liquid magnets could be a safer alternative than solid metal blades, which can damage wildlife.

Jun Shintake at the University of Electro-Communications in Chōfu, Japan, and his colleagues created a prototype aquatic craft with a propeller made from ferrofluid, which consists of magnetic iron oxide nanoparticles suspended in oil. It is controlled with electromagnets that switch on and off at high speed.…