The ZPA 20 can be used to measure the zeta potential of solid macroscopic samples by measuring the streaming potential or streaming current produced when shearing counter-ions along a charged sample's surface. This instrument features a bi-directional oscillating piston to control and tune the flow of electrolyte in either direction over/through the sample.

The instrument comes with two types of flow cells:

- The gap cell - Can measure two opposing identical planar samples of dimensions 20x10 mm (these dimensions are critical!). Maximum 2+2 mm sample thickness. Sample/substrate needs to strongly adhere to the provided double sided tape or directly to the PEEK component by other means that doesn't damage the PEEK, or bonded to a substrate that can be taped... Recommended gap height during measurement is 100-130 µm.

- The permeable (fiber) cell - Can measure fiber bundles, textiles and other types of samples where the electrolyte can be flowed through the sample. The sample must be able to fill the cylindrical compartment in X-Y direction fully and not pass through or around the filter membranes. The amount of sample and an adjustable compression torquewrench is used to dial in the required pressure range for a measruement. If you wish to measure powders, you MUST contact the tool responsible first, as the instrument can easily be damaged if the powder is unsuitable or mounted incorrectly!!!