http://www.freymartin.de/en/projects/snoil

[Ferrofluid]

Ferrofluid is a liquid that reacts to magnetism. It is attracted by magnets, pretty similar to iron. This can lead to areas where the liquid partly resists to gravitation when a magnet approaches. Thereby a small bump is formed close to the loadstone. This behavior is enabled by magnetic nano-particles that are suspended in a carrier fluid. Normally the particles are coated with a surfactant to prevent their agglomeration. This results in stable ferrofluid dispersions.

[Directed deformation]

SnOil makes use of the ferrofluids magnetic sensitivity to selectively position and shape the fluid. This is done by electromagnets, which enable the appearing and disappearing of a magnetic field by switching the flow of an electric current. Therefore SnOil consists of two main parts: An approx. 25 by 25 cm sized basin that is filled with ferrofluid up to a height of a few millimeters. Directly underneath there is a grid of 144 (12 by 12) electromagnets that are arranged closely to each other. The magnets are arranged in four structurally identical blocks with 36 pieces each. The electronics for triggering the separate magnets are located on several layers of printed circuit boards directly underneath the layer of magnets. This makes the system highly scaleable in size and its footprint.

[Display]

This array enables the creation of 144 individually selectable "fluid-bumps". By pulsing the magnetic field intermediate states between maximum and no height can be realized. The maximum elevation of the fluid-accumulation can measure several millimeters in height. The base material of ferrofluid consists of oil. This results in a deep black, strong glossy surface. In addition to the spatial mutation the bumps stand out from the remaining surface due to the changing reflections of the surrounding light sources. The occurrence and the disappearance of the fluid-bumps, as well as the appearance of the surface has a slight mystical and extreme aesthetic impression. Images and animations can be produced in a pixel-graphic style as well as plain pixel-typography.

[Snake]

Snake is the name of a classic arcade game. A creature, resembling a snake has to be steered over the screen and has to be fed. Each time the snake eats a piece of food, its tail grows. The snake is continuously moving on. Hitting the own tail or touching the "walls" that surround the playing area, the snake looses one life. The simplicity of the game is what made the game very widespread on early entertainment computers and classic video game consoles. This very day the game is popular on e.g. mobile phones.

[Snake + Oil = SnOil]

There are different reasons, why an interesting application for the ferrofluid-display is based on the game Snake: the food pieces are shaped out of the surrounding fluid and are instantly converted to the snakes body after consumption. So the growth in length of the snakes tail comes along with a real swelling volume of the collected fluid. The snake on the screen is steered by a joystick or a keyboard whereas the input interface of SnOil relies on a straighter action: The player holds the whole ferrofluid-basin in his hands and controls the flow direction of the snake by slightly tilting in the according direction. The controller measures this by tilt-sensors.Having lost three lifes, the game ends with the classical lettering "Game Over" across the display, before a new game can be started.