There are also such things as "pneumonics" and "fluidics" : https://en.wikipedia.org/wiki/Fluidics https://en.wikipedia.org/wiki/Fluidics These are used, for e

There are also such things as "pneumonics" and "fluidics" : https://en.wikipedia.org/wiki/Fluidics https://en.wikipedia.org/wiki/Fluidics These are used, for example, in avia and rocket engines - in first or independent contours of their control systems. Such logic devices are very reliable, relatively simple and can work at extreme temperatures.