Verification and application of a finite-difference model for quasi-electrostatic scanning impedance imaging

We have previously introduced liquid-contact scanning impedance imaging (SII) as a high resolution, high contrast method for imaging electrical impedance. This technique has shown its potential to measure the impedance distribution of biological tissues. In this paper, a numerical model is developed to describe the SII system based on the finite difference method. Good correspondence can be observed when comparing data simulated using the model with experimental data. The relationships between measurable resolution and system parameters such as height are shown in both simulation results and measurements. It is shown that the numerical model provides a good explanation for experimental results and can also assist in the design of the dual-conductor impedance probe used in this imaging method. Model predictions on both the conductor spacing and the resistor R used in the system have been made indicating their relationships to an empirical notion of resolution. The simulation result of the conductor spacing also gives an insight to the function of the dual-conductor probe. Based on this model, an optimum probe design can be obtained by balancing ultimate resolution with the signal-to-noise ratio by adjusting spacing and resistor values.