When a faucet stops dripping, the last drop sometimes pulls a thin thread behind it. The thread doesn't break all at once but in two places, leaving a small extra droplet in between. These parasitic droplets interfere with printing microchips, clog printers, and spoil medicines.

Scientists at Peking University have found a way to get rid of these droplets. They added a bit of protein to water: bovine serum albumin. The protein self-assembles at the water surface, forming an ultrathin film. This film doesn't just sit on top; it's elastic like a rubber band and viscous like honey. When the thread starts to break, the film contracts and prevents it from breaking in two places.

To confirm that the film is indeed the key, the scientists compared water with different amounts of protein. With just a tiny bit, droplets still form. But adding as little as one ten-thousandth of a percent of protein makes the droplets disappear completely. For comparison, they used ordinary soap, which also changes the water surface but doesn't form an elastic film. With soap, the droplets remained. So the secret lies in the elastic protein film.

Now, adding a bit of protein to printer ink or microchip fluids could stop them from spitting out extra droplets. It's a simple and cheap method that nature has long used in our cells.