Long-term stable electroosmotic pump with ion exchange membranes

Area of Science:

• Microfluidics
• Electrokinetics
• Materials Science

Background:

• Electroosmotic (EO) pumps are crucial for microfluidic systems.
• Previous EO pump designs faced challenges with stability and controlled flow.
• Ion exchange membranes are key components in advanced EO pump architectures.

Purpose of the Study:

• To design, fabricate, and test a novel inline frit-based electroosmotic (EO) pump.
• To enhance pump stability through a new flow component controlling the diffusion layer width.
• To characterize the performance of the EO pump with ion exchange membranes.

Main Methods:

• Fabrication of the pump casing using polymers and the EO active frit using nanoporous silica.
• Integration of ion exchange membranes into an inline frit-based design.
• Performance testing including pressure (Deltapm/DeltaV) and flow rate (Qm/I) measurements across various buffer concentrations and extended operation.

Main Results:

• The novel pump design demonstrated improved stability compared to previous types.
• Achieved a pressure capability of 0.15 bar V⁻¹ and a flow rate to current ratio of 6 µL min⁻¹ mA⁻¹.
• Attained a maximum pressure of 4.5 bar and a flow rate of 6 µL min⁻¹ at 30 V, with reproducible results over hour-long tests.

Conclusions:

• The developed inline frit-based EO pump with ion exchange membranes offers a stable and controllable fluidic manipulation platform.
• The new flow component effectively manages the diffusion layer, leading to enhanced pump performance.
• The pump's characteristics are well-defined and reproducible, making it suitable for various microfluidic applications.