It's called a superhydrophobic knife and it slices water droplets easier than a butter-knife cuts through butter. As its name suggests, anything that is 'superhydrophobic' is highly hydrophobic, i.e., extremely difficult to wet. This special knife uses polyethylene - a common plastic - zinc, and copper. Its surfaces was dipped into a solution of silver nitrate and a superhydrophobic solution called HDFT for 20 seconds, and once it was washed and air-dried, it was super-great at repelling water.