Four-probe method:

Two common techniques used in four-probe method are (i) Four-point collinear probe method and (ii) van der Pauw method.

Four-point collinear probe method:

This is the most common way of measuring the resistivity of a material, which involves four equally spaced probes as shown in Figure 25.01 in contact with a materials of unknown resistance.

Figure 25.01: Schematic of four-point collinear probe method.

This method can be used either in bulk or thin film specimen.