The sponge is a piece of foam equipped with sensors (accelerometers and force sensing resistors) which can detect when it is squeezed, twisted or shaken. Sensor data is then sent wirelessly (XBee protocol) to a computer. It could probably be used to control any kind of digital process (like video or lighting), but I designed it as a musical interface. I use it in live performances to control sound synthesis and processing.
M. Marier, “The sponge a flexible interface,” in Proceedings of the international conference on new interfaces for musical expression, Sydney, Australia, 2010, p. 356–359. [pdf]
M. Marier, “Designing mappings for the sponge: towards spongistic music,” in Proceedings of the international conference on new interfaces for musical expression, London, United Kingdom, 2014, p. 525–528. [pdf]