It works based on electric resistivity measurements between several sensors around the trunk. The basic measurement principle is that resistivity increases/decreases if there is a change in the concentration of ions between two sensors. Fungi attacks even in very early stages can be determined.
The impedance tomography is in one hand similar to other tomographic evaluations. In the other hand, in this case electricity is conducted to the wood and electric resistivity is measured. The electric field behaves different comparing to acoustic or ultrasonic signals so the measurement can highlight other conditions of the wood. The technique itself originates from geophysics. With proper modifications the measurement can be applied to living trees well. Change in the measured electric resistivity can refer to more or less water or ion concentrate, red heart (false heartwood) and damages or the presence of fungi. Discoloration of wood, water transport, the sapwood, and the heartwood can be studied by impedance tomography. Early changes in wood can be caught. The impedance tomography shows differences even when the density is still has not changed during a fungi attack, it can catch the infection before the other tomography methods
Place the resistivity meter onto the tree.
Measure the circumference and decide the proper shape (circular, elliptic or irregular). Place the electrodes onto the tree at the proper positions or measure their positions. Enter the data to the computer.
Start the measurement on the computer. During the measurement do not touch the tree. Do not measure other conditions parallel to the resistivity measurement.
Choose triangulation parameters and run the iterations. The program will calculate the resistivity map of the selected cross section.
GeoPic-32 Multielectrode Resistivity Meter
LEMO-USB connection cable (with 4 needles) to connect the Multielectrode Resistivity Meter to computer
LEMO-USB charger cable (with 3 needles) to charge the Multielectrode Resistivity Meter
4 pcs. electrode connecting cable with 8 crocodile clips on each Cable
50 pcs. stainless steel needles (as electrodes) for measurements; diameter: 1.5 mm, length: 63 mm
5 pcs. screws to fix the Multielectrode Resistivity Meter onto the tree
Electrode remover tool
Current measurement range
The length of one basic
Continuous operation time
Total measurement time of one tree
Operating temperature range
5-50V, adjustable in 5V steps
0-20mA; 0-400µA; 0-40µA
1, 5, 20, 100
Built in 5V/5000mAh Li-ion Power Bank
Approximately 2 hours
LEMO-USB cable or Bluetooth