Yes, this is an active area of research. Neural networks are a very good application for analog computing (imo). You have a ton of floating point operations th

Yes, this is an active area of research. Neural networks are a very good application for analog computing (imo). You have a ton of floating point operations that all need to happen more or less simultaneously. And what are floating point numbers if not digital approximations of analog values? :) This can be implemented as a network of transistors on a chip, but driven in the linear region instead of trying to switch them on as hard as possible as fast as possible. Which is, I believe, what researchers are trying to do. There are also some interesting ideas about photonic computing, but I'm not sure if that's going anywhere. A few months back, someone on YouTube attempted to design a mechanical neural network as a single 3D printed mechanism. It ended up not working, but the concept was pretty solid.