The Electrical Sensing Zone
The electrical sensing zone (ESZ) technique, also known as the Coulter principle, analyzes samples particle by particle. Requiring only a small volume of sample for analysis, it provides the highest particle size measurement resolution of the techniques presented here. A homogeneously dispersed suspension of sample material is prepared in an electrolytic solution. A tube with a small orifice of short path length is submerged in the suspension, an electrode being positioned on both sides of the orifice. A pump establishes a flow of electrolyte through the orifice, providing a conductive path between the two electrodes and a small electrical current is established between them. Both electrolyte and particles pass through the orifice. The particles, being non-conductive, impede the electrical current flow as they enter the orifice. This creates an electrical signal proportional to the volume of the particle. Each individual particle is counted and classified according to volume, thus producing a volume frequency distribution. The particles are considered to be spherical and a particle diameter can be determined from volume.
Unlike other measurement techniques, the electrical sensing zone method can size samples that have assorted optical properties, densities, colors, and shapes. The Elzone II can determine the size, number, concentration, and mass of innumerable organic and inorganic materials.
- Sizes and counts both organic and inorganic materials from 0.4 to 266 μm
- Different conductive liquids can be used without needing to enter an extensive set of liquid properties
- Does not require previous knowledge of material properties (density, refractive index)
- Automated features include: start-up, run, and shut-down routines; blockage detection and clearing; flushing/rinsing; and calibration
- A CCD camera provides real-time video display of the aperture to assure a clear path through the detection zone
Click Here to Learn More >>