Enhanced voltage generation through electrolyte flow on liquid-filled surfaces

Abstract

The generation of electrical voltage through the flow of an electrolyte over a charged surface may be used for energy transduction. Here, we show that enhanced electrical potential differences (i.e., streaming potential) may be obtained through the flow of salt water on liquid-filled surfaces that are infiltrated with a lower dielectric constant liquid, such as oil, to harness electrolyte slip and associated surface charge. A record-high figure of merit, in terms of the voltage generated per unit applied pressure, of 0.043 mV Pa−1 is obtained through the use of the liquid-filled surfaces. In comparison with air-filled surfaces, the figure of merit associated with the liquid-filled surface increases by a factor of 1.4. These results lay the basis for innovative surface charge engineering methodology for the study of electrokinetic phenomena at the microscale, with possible application in new electrical power sources.

Self-operating transpiration-driven electrokinetic power generator with an artificial hydrological cycle

“…In recent years, energy harvesting devices that utilize water as an energy source have gained great attention since water is the most abundant and ubiquitous liquid on earth. [1][2][3] A variety of devices have been reported, where each device requires their own methods for water supplementation. [1][2][3][4][5][6] For example, Liang, et al demonstrated a graphene oxide (GO) paper-based moisture-driven electric power generator, 5 and Xu et al presented a pristine GO film-based water diffusion-driven power generator.…”

Inner Surface Design of Functional Microchannels for Microscale Flow Control

“…Liquid‐lined porous structures of lungs provide mechanical compliance for breathing and facilitate selective transportation of gas. Inspired from these natural liquid‐lined structures, various liquid‐infused channels and materials have been fabricated for applications in medical, environmental, and energy‐related fields . Liquids are mobile and have random shapes in bulk systems, while they can be fixed in micro‐/nanoscale channels due to the capillary force, and the van der Waals force between the solid surface and fluids.…”

“…Above experimental results indicated the importance of the chemistry matching between the microchannel surfaces and functional liquid, and the surface roughness for building of liquid‐infused microchannels. Bandaru and co‐workers reported the electrolyte flow in the liquid‐filled microchannels for the study of electrokinetic phenomena at the microscale (Figure B) . The liquid‐filled microchannels were prepared through bonding straight‐line patterned PDMS microchannels with liquid‐filled grooves patterned silicon surfaces.…”

“…B) Schematic of pressure‐driven electrolyte solution flow in liquid‐infused microchannel built from covering a PDMS microchannel on the groove structured surface and subsequent liquid filling (i), and image of the liquid infused grooves structures (ii). Reproduced with permission . Copyright 2018, Springer Nature.…”

“…Their results show that the output voltage increased from ≈0.85 to ≈3 V after modification of PEI, but the current decreased due to the increase of internal resistance in the microchannel. Bandaru and co‐workers reported the enhanced voltage generation in a liquid‐filled microchannels . They demonstrated that the streaming potential of electrolyte solution in the liquid‐filled microchannels were increased by a factor of 1.4 compared to air‐filled microchannels.…”