Electrokinetic Transport Phenomena in Microfluidic Systems

Electrokinetic transport in microfluidic systems arises from the coupling of electric fields and ionic fluids at submillimetre scales. When a solid surface bearing net charge contacts an electrolyte, mobile counter-ions accumulate in a nanometre-thick region known as the electric double layer. Application of an external electric field induces bulk fluid motion (electroosmotic flow) and drives charged species (electrophoresis), enabling precise manipulation of fluids and particles without moving parts. Complementary effects such as streaming potential and induced-charge electro-osmosis further extend control over pressure-driven flow and vortical structures. Fundamental parameters—including the Debye length, zeta potential and fluid rheology—govern velocity profiles, pumping efficiency and mixing performance. Advances in surface engineering, channel geometry and field modulation now underpin applications from rapid biochemical assays to on-chip energy harvesting, with global significance in diagnostics, environmental sensing and sustainable power generation.

Research from Nature Portfolio

Recent studies have demonstrated innovative approaches to enhance electrokinetic energy conversion and fluid throughput at the microscale. One investigation achieved record streaming potentials by flowing saline solution over liquid-filled surfaces infiltrated with low-dielectric liquids, harnessing slip at the interface to boost voltage generation per unit pressure. Another exploration of non-Newtonian bio-fluids in nanofluidic channels grafted with permeable polyelectrolyte layers revealed that the interplay between softness-induced electrical body forces and fluid rheology can substantially increase net throughput, offering design rules for channels handling shear-thinning and shear-thickening fluids.

Electrokinetic Transport Phenomena in Microfluidic Systems publication trend

The graph below shows the total number of articles in electrokinetic transport phenomena in microfluidic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Electric double layer (EDL): A structure of oppositely charged ions that forms at a solid-liquid interface, governing electrokinetic phenomena.

Electroosmotic flow (EOF): Bulk fluid motion induced by an external electric field acting on the EDL’s mobile ions.

Streaming potential: Electrical potential generated when pressure-driven flow displaces ions in the EDL along a charged surface.

Zeta potential: The electric potential at the shear plane within the EDL, reflecting surface charge and influencing flow velocity.

Induced-charge electro-osmosis (ICEO): Nonlinear flow arising when an external field polarises a conductive surface, creating local EDLs that drive fluid motion.

Debye length: Characteristic thickness of the EDL, determining how far the electric potential extends into the bulk fluid.

References

1. Enhanced voltage generation through electrolyte flow on liquid-filled surfaces. Nature Communications (2018).
2. Softness Induced Enhancement in Net Throughput of Non-Linear Bio-Fluids in Nanofluidic Channel under EDL Phenomenon. Scientific Reports (2018).
3. Experimental investigation of inflow-outflow asymmetry in induced-charge electro-osmosis. Energy Storage and Saving (2024).
4. Dynamic control of high-voltage actuator arrays by light-pattern projection on photoconductive switches. Microsystems & Nanoengineering (2023).