Detect Breaks in Mesh Circuits PS: I will mess up a lot of terminology throughout the question.
Anyways,
I want to build a circuit which is in the shape of a mesh, something like a table and subsequently detect whenever there is a break at one of the nodes (i.e. the intersection of vertical and horizontal wires). It will carry very little current (from a AA battery).
Can anyone help me how to execute this idea?
 A: Since lurscher thinks he is so smart but obviously doesn't care to help you with the physics of this problem, I will. Get a square tub and fill in a couple of inches of saltwater. This will simulate a dense conducting mesh. Now make yourself two flat electrodes from copper or steel that are approx. 5-10% of the width/length of the tub. Connect them to an Ohm-meter and hang them into the water on two sides of the tub. Measure the conductivity of the saltwater. Now insert a non-conducting object (e.g. a glass jar) into the water. That object has to go all the way from the bottom of the tub to the surface of the water (it should stick out). This way you have interrupted the flow of electricity in the volume of that object. Compare the conductivity between the two electrodes to the conductivity without the object. Make a number of plots of these measurements for different locations of that object. Leave the object in the middle of the tub and make a plot of the conductivity depending on the position of the electrodes. Change the non-conducting object against a bigger/smaller one. What do you see? How big is the effect as function of the size of the object? 
Have fun!
This, by the way, is a perfectly valid engineering method for a number of physical problems that was in use until computers were fast enough to do numerical calculations on these kinds of problem. 
