Eavesdripping, by Sascha Pohflepp, uses water as medium and display to render invisible communication visible and experienceable.

A matrix of magnetic nozzles opens a valve when current is applied. To add some controllability to the setup, a computer running MAX-MSP/Jitter processes information and connects to two relay-boards which are controlling the individual nozzles.
To increase the visibility of the splashes on the ground, the water surface sits in a container made of clear acrylic. From one side, light is being pumped in by an array of super-bright LEDs. Since the acrylic and also the surface of the water is subject to the effect of total reflection, the water stays perfectly black. However, when a drop of water breaks the surface, the light brightly lights up the spot.
Because the way of displaying is physically so present, it would be best to initially use it to visualize something and make it sensually experienceable which is equally present, but not perceptible. The metaphor of the installation would be to wash something from the air and make it visible on the ground in front of you. The idea of visualizing internet wireless conversations emerged. For achieving this, the packages were successfully “sniffed” from the air, parsed to readable text, processed for being output in the form of drops and then displayed on the ground for everyone to read.
Video.
Via Plugimi.
See also Erez Kikin-Gil’s Water Play.