picoOhm variation sensor

[raphchev]

Hello;

I am investigating a technique to detect breakage of a copper wire in parallel with a stainless wire.
The idea was to measure resistance change; but the sensitivity required is around 2-10pΩ; that seems practically impossible, even with a four wire & a total resistance around 0.1Ω.

But I was thinking, since the wire breakage is likely to be quick (hypothesis; switching from ON to OFF takes about 1ns),  have you ever encountered a circuit that could sense that quick change in resistance? Maybe a four wire coupled with a capacitor to get rid of DC and let the change through?

Best,

R