A normal multimeter, equipped with 2 terminals, is a cheap and simple instrument for measuring voltage, current and resistance. However, the conventional 2-terminal method is not suitable for material evaluation.
The 4-terminal probe of the Loresta GX eliminates lead-wire connector and contact resistance. More precise measuring of resistance is achieved.
In the case of the 4-pin probe method, 4 needle-type electrodes are placed linearly on a sample. A certain current flows between 2 external pin probes (1 and 4), and a potential difference formed between 2 inner pin probes (2 and 3) is measured to determine the resistance.
Then, multiplying the measured resistance (R in the unit of Q) with the sample thickness (t) and the Resistivity Correction Factor (RCF) derives the volume resistivity. In this way, the 4-pin probe method and 4-terminal method have a common measurement system, but the electrode sections in contact with the sample is different.
Only the placement of a probe on a sample is required for measurement in this 4-pin probe method, but electrode formation over the sample is not required unlike the 4-terminal method and thus the procedure is remarkably more efficient.