Setup for Sensing change in concentration of NaCl
This will work with the correct set up. You're constructing a galvanic cell, which will result in a cell voltage. The cell voltage will change when you alter the concentration of NaCl on either side. Important though that your two half cells (each side) are connected both electronically and ionically. Do you have a salt bridge or a membrane between them? https://en.wikipedia.org/wiki/Salt_bridge