To keep droplets of liquid floating in midair, the device in the video above relies on a hum of sound just above the range of human hearing. This technology, called an acoustic levitator, suspends these tiny balls of liquid using two speakers that project sound waves in opposite directions, counteracting the force of gravity. Originally, NASA developed the device to simulate microgravity. Now researchers at Argonne National Lab are using it as a way to evaporate drug compounds in midair so they take on a more potent chemical form than they would in a container.
