The Electrical Impedance Tomograph (EIT) uses electrical current/voltage to investigate the tree. The results are a 2D map of the electrical impedance of the tree. The EIT measures the chemical properties of the wood such as water content, ion concentration etc., which will change if decay is present in the tree.
Examples of Treetronic EIT :
Red = HIGH impedance (dry or/and little amount of ions)
Blue = LOW impedance (wet or/and high amount of ions)
The operation of the EIT is very similar to that of the Sonic Tomograph; instead of tapping on the nails, very low voltages are used to conduct electrical currents through the wood.
Used in combination, the Sonic Tomograph and Electrical Impedance Tomograph can provide good indications of sound wood, early stages decay, active/dead fungus, sap wood, cracks, included bark etc.