Imagine a world where we can manipulate the movement of ions in a liquid with incredible precision. This seemingly abstract idea holds the key to revolutionary advancements in diagnostics, energy storage, and beyond. At Universiti Teknologi Malaysia (UTM), researchers are delving into the intricate behavior of electrolyte-saturated polymer gels containing charged inclusions to unlock this potential.

These gels, studded with tiny charged spheres, act as a model system for understanding electrokinetic transport processes at the microscale. The researchers are studying how a weak gradient of electrolyte concentration affects the behavior of ions within the gel. Previous work established an electrokinetic model and examined the effects of a weak electric field on homogenous composites. This new research builds upon that foundation by exploring how the charged inclusions influence the movement of ions and the electric field generated by the concentration gradient.

The findings reveal that these inclusions dramatically alter the effective diffusion coefficients of ions. The charge on the surface of the inclusions, known as the ζ-potential, plays a crucial role. Astonishingly, depending on this surface charge, asymmetric electrolytes (those with unequal positive and negative ion mobility) can behave like symmetrical ones, and vice versa. This discovery opens up exciting possibilities for tailoring electrolyte behavior for specific applications.

Furthermore, the research quantifies the flow induced by concentration-gradient-induced disturbances to the equilibrium diffuse double layers. This flow, similar to diffusiophoresis, can move either in the direction of the concentration gradient or against it, offering another avenue for control.

The significance of this research lies in its potential to revolutionize various fields. Imagine more accurate and sensitive diagnostic tools, powered by precisely controlled ion transport within these gels. Consider advanced energy storage devices with enhanced performance, thanks to tailored electrolyte behavior. These are just some of the possibilities that this research unlocks.

The next steps involve further exploration of these phenomena and the development of practical applications. By understanding and manipulating the interplay between charged inclusions and electrolytes, researchers at UTM are paving the way for a new era of microscale electrokinetic technologies. https://doi.org/10.1016/j.aca.2025.344262