There was a post about a hydraulic computer here the other day, this looks like further reading. Interestingly, there seems to be a slow increase in intrest for

There was a post about a hydraulic computer here the other day, this looks like further reading. Interestingly, there seems to be a slow increase in intrest for ionotronics where logic is implemented using nanopores in salt water, where current is carried by ions instead of electrons. Generally the propogation delay is orders of magnitude longer than in electronic circuits, but the parallel between fluidic computation and biological processing (as in brains) is compelling. I was able to put together a few gates and oscillating electrofluidic circuits using electrically addressable nanopores in my PhD work, but others have more recently made complete circuits.