Indeed the implementation of the equations isn’t such a big deal (although, it can get more elaborate when you start adding cell geometry, and networks).
I’m curious whether anyone has attempted using Hodgkin-Huxley or related models as an input layer to DiffEqFlux, and subsequently training on real data to learn the coefficients. If someone has tried it or has some experience, it would be great to hear how it went for them. If not, I may just give it a go by my lonesome 
Also, thanks for the link @jpsamaroo interesting indeed!