This instructor was a representative for NGK/NTK. He was a (sic) evangelical Pentecost preacher. I never met a man more enthused about oxygen sensors in my entire life. He started with Walther Nernst's philosophy and worked his way to the current ( I think) 4 different styles or types of sensors.
I want to get my training material/notes together rather than trust my memory. If I can't help you decide what to do I think I still have his business card. You can reach him to help with what you want to know.
I found his card, but i can't find my training material. Ralph D.Harris, NGK Spark Plugs Inc. email address is rharris@ngksparkplugs.com . I hope he is still available, he is very a very exciting person to communicate with.
In the meantime here is something to get you started thinking. http://en.wikipedia.org/wiki/Oxygen_sensor