Fluidics is a branch of science and engineering that is actually developed to a large extent. Fluidics uses fluid flow- gas, liquid or water to create logic circuits like adder, sub-tractor, multiplier etc. That is , engineers like Murray O. Meetze, Jr. have developed fluidic diode, fluidic triode and such logic elements that can easily be transferred to a semiconductor circuit.
Fluids have the capacity to generate a signal and even respond to signals. This branch is being employed for use in better aircrafts and other mechanical devices which earlier ran on purely mechanical components.