A new streaming potential chamber for zeta potential measurements of particulates

A novel streaming potential measurement device has been validated by determining the average electrokinetic (zeta) potential of densely packed particulate such as human erythrocytes and ground bovine cortical bone. The new streaming potential device used in this study is easy to construct in the laboratory, designed to allow dense packing of particles, and determines zeta potentials for a broad range of particle sizes. The streaming potential device consists of four Plexiglas parts: (i) an upper and (ii) a lower chamber, which act as reservoirs for fluid; (iii) a midchamber which connects the upper and lower chambers and holds the sample holder, and (iv) a sample holder. Pressurization of fluid in the top chamber generates a pressure gradient that induces movement of fluid through the stationary sample and into the bottom chamber. Pressure induced flow through the interconnected pores of the densely packed particulate generates a potential difference across the sample that is measured using electrodes housed in the top and bottom chambers. The measured potential difference is then converted to zeta potentials. The advantage of this chamber is its ability to handle densely packed particulates exhibiting a broad distribution of sizes. Dense packing of particulate is achieved by compacting samples at the bottom of the sample holder under centrifugal forces before the device is assembled. This approach allowed us to determine average zeta potentials of densely packed particulate made of soft and hard materials.