It’s been slow going today working on my project. I was able to assemble a quick prototype sensor however.
The basic construction involves the plastic barrel of an ink pen, onto which I tape two equal length segments of steel wire that have been soldered to insulated wire leads. Electrical tape is used to expose only a small segment of the steel wire to the solution where the probe will be immersed.
Constructing the probe involved the use of a soldering iron, some solder and clamps to hold the wires in place. Next will offer a chance to mix some salt solutions of known concentration and directly observe the ability of the probe to differentiate between them through resistance measurements.
In the mean time, I was able to connect the prototype probe to my Arduino UNO and demonstrate crude functionality. Check out the video below for a proof of concept: