Individual nanoparticle zeta potential measurements using tunable resistive pulse sensing

Tunable resistive pulse sensing has been used to measure the zeta potential of two sets of 200 nm diameter polystyrene nanoparticles in 0.1 M KCl electrolyte. Data were analysed using two methods, both of which yield particle-by-particle zeta potential values based on electrophoretic mobility. Five pore specimens were used, and in most cases data clearly indicate that one particle set had a higher (less negative) zeta potential than the calibrated zeta potential of the other particle set (-35 mV). Three tungsten needles were used to fabricate the pores, and comparable results were obtained for pores made by the same needle. Measurements were carried out with varying potential applied, and a reliable working range of 0.3 to 0.6 V was observed. Measurement of zeta potentials on individual nanoparticles is important for colloidal applications such as foods, cosmetics, mineral extraction and biomedical technologies.