While electronics and water don’t generally mix, researchers at Ochanomizu University in Japan have come up with an ephemeral display method that uses floating clusters of bubbles to show messages on a liquid surface.
The device, known as UTAKATA, utilizes a line of seven electrodes under Arduino Uno control that activate to form hydrogen bubbles via electrolysis. When arranged properly, these bubbles can be made to produce letters and words, which as shown in the video below, dissipate as they flow downstream in the container.