Resistive sensors are mainly used to determine the properties of liquid media.

Resistive sensor technology leverages the effect of changing ohmic resistance. This method is mainly used at AST to measure the concentrations or purity levels of liquids and determines their conductivity via two or more stainless steel pins inserted into the liquid. To avoid galvanic effects (chemical reactions caused by direct current) at the electrodes, the pins are only AC-coupled. The purity of demineralized water in particular can be measured reliably and with little circuitry via resistive measurement.