I menat the device they used to rebuild that guys fingers. It seems to me they put a silver mesh into the wound (a steril one I guess) as cathode and the anode higher up on the arm. Here, Fig. 2 and onward:
[link to www.rexresearch.com]
To me as layman it looks like if they produce the silver ions directly in the wound.

Thanks for all the other tips, should be easy to build a generator for producing colloidal silver solution.