One-step method for measuring the effect of humidity on powder resistivity

We present a method for measuring powder resistivity as a function of moisture using a one-step process. The developed new resistivity cell consists of narrow horizontal electrode surrounded by a grounded guard electrode and simultaneous measurement of humidity within the powder bed. The system was modeled using computer simulations. As an example, resistivities of three different lactoses, wheat flour and quartz are presented. Resistivity was found to decrease several orders of magnitude between 10 RH% and 90 RH%. Simulated results showed that if no guard plate is used, measurement errors caused by humidity gradient are of order of magnitude.