Correction factor for four-probe resistivity measurements on resistive sheets with parallel electrodes

This article discusses the use of the four-probe method for direct measurem ents of the resistance per square of a resistive sheet with parallel electr odes. These measurements must be adjusted by a correction factor, which is calculated in this work by modeling the resistive sheet as a two-dimensiona l square with opposing: cylindrical electrodes and setting the resistance o f the electrodes equal to zero. The correction factor is then computed by p ostulating the boundary condition that the potentials on the two sides are constant. Although it is the resistive sheet with parallel electrodes that controls the performance of the resistive-sheet pressure response type of d igitizer; this performance has been evaluated only by indirect methods. Nev ertheless, the simulations and experiments described in this paper confirm that the resistance per square of a resistive sheet with parallel electrode s can be measured by the four-probe method when the correction factor deriv ed here is used. (C) 2001 Scripta Technica.