My project simulates a hydration sensor, to check if you are sufficiently hydrated, as it is a very essential thing in our body, as dehydration can cause fatigue and nauseas.

I have adapted it to be a conductivity sensor. For example, if you put a metal or banana or fabric with water and salt, on it, the green LED turns on. On the other hand, if you put your finger on it, it will not turn on because it isn't conductive. I made it with a 4.5V battery connected to a resistor where it goes directly to the LED, and then connects a brad on another part of the battery and the other brad to the resistor. I use plastic, a green LED, an inner tube, wires, a resistor, 2 brads, tape and blue foam.

If you have high conductivity indicates high hydration. Also with low conductivity you are dehydrated. The green light indicates conductivity and hydration. This device can be used by everyone no matter their age.