Characterization of Streaming Potential in Electrical Double Layers*

Non-equilibrium thermodynamics is a very active research field due to significant progresses in theoretical understanding, new research tools, and important applications. Electrokinetic phenomena are those originate from tangential fluid motion adjacent to a charge surface such as electric double layers. Such EDL has been studied extensively due to its importance ranging from technology such as supercapacitors, to geology, and to biology. In nature, the liquid could undergo flow as in ground water and rock, micro- and nano-fluidic devices, cells and membranes. One of the interesting phenomena is called the streaming potential where fluid flow generates electrical potential, called streaming potential.

The goal of this ongoing project is to characterize experimentally the streaming potential of several important materials. We carried out electrical measurements, including impedance spectroscopy, under various flow conditions, pH values, salinity, and different types of ions of the electrolytes. The streaming potential relaxation characteristics are important signatures for recognizing and detecting the contrast agents. This project investigates systematically the dependences of streaming potential characteristics on materials properties and the electrolytes properties. From these relationships I will propose mechanisms and processes responsible for such characteristics such as relaxation times and try to provide theoretical and numerical validations of the proposed mechanisms.