A tiny biodegradable bubble can move away from lactic acid on its own, without a motor.
The bubble is a hollow sphere made of biodegradable polymer, about 200 times smaller than a human hair.
Its flexible skin binds lactic acid, creating an imbalance that generates a microscopic flow, propelling the particle away.
This autonomous movement could one day be used for targeted drug delivery, as tumors and inflamed tissues produce lactic acid.