sometimes I like to just look on digi-key and click the most extreme values in their parametric search stuff (yes, i'm a nerd)
apparently, you can get an op amp, the LMC662C, with a maximum input bias current of two _femtoamperes_. 0.002 pA. That's _ridiculous_. How do you even measure that‽
it's not even anything fancy and new, or even expensive. it's $1.55 in single quantity, and the datasheet was written in 1998.