Liquid Jets as Logic-Computing Fluid-User-Interfaces

We present a fluid user interface that functions as a logic-computing input/output device, based on touching small jets of water. Tactile interaction occurs in two directions: (1) from the human to the device, where minute motions of the finger through fluid flow are sensed by a computer; (2) from the device to the human, where water pressure (or flow) is controlled by computer and sensed by the finger. Tactile feedback occurs due to a fluid pressure-to-proximity relationship. This human-in-the-loop system was used as a multisensory teaching tool, to demonstrate logic gates and flip flops, demonstrating the elementary logic operations of digital electronics via liquid flow rather than via the flow of electricity. Fuzzy logic could be demonstrated by smooth variations in fluid flow control. Applications also included game development and tactile communication-at-a-distance, where we implemented a first-mover-advantage game, based on pushing virtual packets of water over virtual pipes faster than the speed of sound, through electronic packets that encoded the exact finger expressions created in the fluid flow in each jet.