Cleaning an O2 sensor

[roccit_53 at scirocco.cs.uoguelph.ca (C Boyko)]

I've got an old O2 sensor from the one Passat that I want to make use of,
but it has a bunch of sooty, loose material on its tip, I'd like to know
what I could safely use to clean it up a bit so it can actually "see" the
exhaust stream. I'm guessing gas, but would immersing it damage it? HAve at
it, I'm sure someone has an opinion, or a suggestion. And no, I don't want
to buy a new one, I just hope to use it for some ghetto gas analysis on my
CIS car.

Cathy