In the electric sensing zone method a well diluted and dispersed suspension in an electrolyte is caused to flow through a small aperture [Kubitschek, Research, 13, 129 (1960)], the changes in the resistivity between two electrodes on either side of the aperture, as the particles pass through, are related to the volumes of the particles. The pulses are fed to a pulse-height analyzer were they are counted and scaled. The method is limited by the resolution of the pulse-height analyzer of about 16,000:1 (corresponding to a volume diameter range of about 25:1) and the need to suspend the particles in an electrolyte [ISO 13319:2000 Determination of particle size distributions - Electrical sensing zone method].
