界达电位（zeta potential）在胶体化学中，是指胶体粒子上累积的离子所引发的静电压；胶体粒子由电双层构成，包含固定层和扩散层。一个粒子可以借由亨利公式（Henry's function）导出电泳的移动率，进而求出其界达电位的值。

Zeta potential is a scientific term for electrokinetic potential in colloidal dispersions. In the colloidal chemistry literature, it is usually denoted using the Greek letter zeta (ζ), hence ζ-potential. From a theoretical viewpoint, the zeta potential is the electric potential in the interfacial double layer (DL) at the location of the slipping plane relative to a point in the bulk fluid away from the interface. In other words, zeta potential is the potential difference between the dispersion medium and the stationary layer of fluid attached to the dispersed particle.