Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, HI, 96822, USA.
Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA.
Adv Mater. 2017 Aug;29(30). doi: 10.1002/adma.201701516. Epub 2017 Jun 9.
The zeta potential is an electric potential in the Debye screening layer of an electrolyte, which represents a key physicochemical surface property in various fields ranging from electrochemistry to pharmaceuticals. Thus, characterizing the zeta potential is essential for many applications, but available measurement techniques are limited. Electrophoretic light scattering is typically used to measure the zeta potential of particles in suspension, whereas zeta potential measurements of a solid wall in solution rely on either streaming potential or electroosmotic mobility measurement techniques, both of which are expensive and sophisticated. Here, a simple, robust method to simultaneously measure the zeta potential of particles in suspension and solid walls is presented. The method uses solute gradients to induce particle and fluid motions via diffusiophoresis and diffusioosmosis, respectively, which are both sensitive to the zeta potential of the particle and the wall. By visualizing the particle dynamics, both zeta potentials can be determined independently. Finally, a compact microscope is used to demonstrate low-cost zeta potentiometry that allows measurement of both particle and wall zeta potentials, which suggests a cost-effective tool for pharmaceuticals as well as for educational purposes.
Zeta 电位是电解质的德拜屏蔽层中的电势，它代表了从电化学到制药等各个领域的关键物理化学表面特性。因此，表征 Zeta 电位对于许多应用至关重要，但可用的测量技术却受到限制。电泳光散射通常用于测量悬浮颗粒的 Zeta 电位，而溶液中固体壁的 Zeta 电位测量则依赖于流动电势或电渗透迁移率测量技术，这两种技术都既昂贵又复杂。本文提出了一种简单、稳健的同时测量悬浮颗粒和固体壁 Zeta 电位的方法。该方法使用溶质梯度通过扩散泳和扩散渗透分别诱导颗粒和流体运动，这两者都对颗粒和壁的 Zeta 电位敏感。通过可视化颗粒动力学，可以独立地确定两个 Zeta 电位。最后，使用紧凑型显微镜演示了低成本的 Zeta 电位测量法，该方法可以同时测量颗粒和壁 Zeta 电位，这为制药以及教育目的提供了一种具有成本效益的工具。
