The principle of EIT

In a typical EIT measurement we feed electric currents into an object using electrodes. In this experiment, arranged by Professor Jon Newell at the Rensselaer Polytechnic Institute, there are 32 electrodes. The lung-shaped agar targets are less conductive than the saline solution in the background, while the round "heart" has higher conductivity than background.

In a typical EIT measurement we feed electric currents into an object using electrodes. In this experiment, arranged by Professor Jon Newell at the Rensselaer Polytechnic Institute, there are 32 electrodes. The lung-shaped agar targets are less conductive than the saline solution in the background, while the round "heart" has higher conductivity than background.

In a typical EIT measurement we feed electric currents into an object using electrodes. In this experiment, arranged by Professor Jon Newell at the Rensselaer Polytechnic Institute, there are 32 electrodes. The lung-shaped agar targets are less conductive than the saline solution in the background, while the round "heart" has higher conductivity than background.

In a typical EIT measurement we feed electric currents into an object using electrodes. In this experiment, arranged by Professor Jon Newell at the Rensselaer Polytechnic Institute, there are 32 electrodes. The lung-shaped agar targets are less conductive than the saline solution in the background, while the round "heart" has higher conductivity than background.

In a typical EIT measurement we feed electric currents into an object using electrodes. In this experiment, arranged by Professor Jon Newell at the Rensselaer Polytechnic Institute, there are 32 electrodes. The lung-shaped agar targets are less conductive than the saline solution in the background, while the round "heart" has higher conductivity than background.

In a typical EIT measurement we feed electric currents into an object using electrodes. In this experiment, arranged by Professor Jon Newell at the Rensselaer Polytechnic Institute, there are 32 electrodes. The lung-shaped agar targets are less conductive than the saline solution in the background, while the round "heart" has higher conductivity than background.

Applying the nonlinear D-bar method to the data produces this image.

For more information, see this article:

Isaacson D, Mueller J L, Newell J and Siltanen S 2004,
Reconstructions of chest phantoms by the d-bar method for electrical impedance tomography,
IEEE Transactions on Medical Imaging 23(7), pp. 821- 828. PDF (664 KB)

This is the classical mathematical model for infinite-precision EIT measurements.

While the Dirichlet-to-Neumann (DN) operator is linear, the relationship between conductivity and the DN map is nonlinear. This fact adds to the difficulty of the image formation task of EIT.