Might be good to run the measured voltage through an op amp to get a better range to at analog in, if you are going to be holding it to less than 0.4 V. Stainless steel or graphite electrodes would also be better than a washer.
Might be good to run the measured voltage through an op amp to get a better range to at analog in, if you are going to be holding it to less than 0.4 V. Stainless steel or graphite electrodes would also be better than a washer.