Capillary Pumping Independent of Liquid Sample Viscosity

Area of Science:

• Microfluidics and Nanofluidics
• Fluid Dynamics
• Physical Chemistry

Background:

• Capillary flow is crucial for micro- and nanoscale liquid transport.
• Traditional capillary imbibition follows the Washburn equation, resulting in time- and viscosity-dependent flow rates.
• This variability presents challenges for precise liquid delivery in microfluidic applications.

Purpose of the Study:

• To introduce and experimentally validate a novel capillary pump design.
• To achieve a constant, time- and viscosity-independent flow rate for capillary-driven systems.
• To develop a theoretical model for gravitation-independent capillary filling.

Main Methods:

• Experimental verification of a new compact capillary pump design.
• Development of a detailed theoretical model for capillary filling.
• Identification and analysis of distinct flow regimes in capillary pumping.

Main Results:

• The novel capillary pump demonstrates a constant flow rate, independent of liquid viscosity.
• The theoretical model accurately predicts pump performance within experimental error.
• A fourth flow regime, gas inertia dominated flow, is identified in capillary pumping.

Conclusions:

• The developed capillary pump offers predictable and reliable liquid transport.
• This technology has significant potential for lab-on-a-chip systems and diagnostic devices.
• The findings advance the understanding of capillary flow dynamics on the micro- and nanoscale.