Possibility of Obtaining Two Orders of Magnitude Larger Electrokinetic Streaming Potential through Liquid Infiltrated Surfaces

Electrokinetic flow emerges as a promising method for liquid energy harvesting. However, the generated streaming potential on a smooth surface is still too low for practical applications. To solve this problem, we employed slippery liquid-filled surface to introduce charged slipping interfaces for enhanced electrokinetic effects. It is shown that the magnitude of the streaming potential can be significantly enhanced from ∼0.02 V to as much as ∼1.6 V, in electrokinetic flows through microchannels. This was done through flows on liquid-filled surfaces, where the grooves were filled with oils of viscosity in the range 30–3000 mPa·s. The presence of immiscible oils and the improved slip are both factors that could significantly increase the streaming potential. The analytical relationship between streaming potential and filled lubricant viscosity was derived and verified through corresponding experimental results. The work yields novel insights into complex electrolyte flows and indicates avenues for more efficient energy harvesting.