Bioimpedance spectroscopy tensor probe for anisotropic measurements

The tetrapolar electrode configuration used in bioimpedance suffers from negative sensitivity and is confounded by anisotropic tissue such as blood vessels or muscle and nerve fibres. Proposed is a circular array of electrodes to focus current directly underneath the probe and provide anisotropy information. It is shown that an implementation using 16 miniature electrodes is able to outperform the tetrapolar method in sensitivity and impedance estimation. The proposed method can also recover anisotropic conductivity tensors from experiments for the first time.