Hi all,
I'm trying to design a product that is able to sense the presence of warm water to a pad - the solution right now is pretty open ended, but I'm gathering components for a shopping cart to prove out concepts.
Current ideas right now are using Velostat, using a moisture sensor (we're going to break open a bed-wetting alert blanket to see how they're doing it), and using a IR Thermopile sensor. A coworker of mine suggested using capactive sensing as well since water will have a different capacitance, but I can't seem to find one that's a) flexible and b) will spread out over a large surface area. Any help here for how we'd create that solution using some off-the-shelf parts would be greatly appreciated! Thanks in advance!
It sounds like the warm water is urea based solution. I am assuming this is battery operated non throw away product. If you are making this you could use conductive thread to monitor the moisture. The resistance could be measured between adjacent wires and will decrease when wet. For temperature you could measure the resistance of a single wire, it will increase with temperature. This solution will allow it to dry out and be reused. Any type of foil will retain moisture. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Moisture sensing on two plates requires the moisture to be applied in between the two plates, not very practical.
Two wires spaced close together over a long distance and wound back and forth close together over the surface would suffice. Use insulated wire naturally such as motor winding wire. (often known as magnetic wire by some)
You could possibly buy one of the Arduino capacitive sensor modules and use the "guts" of it for your main sensor and adjust the output to suit the new input wire length/capacitance.
