Elastic membrane enabled inward pumping for liquid manipulation on a centrifugal microfluidic platform

Area of Science:

• Microfluidics
• Biomedical Engineering
• Lab-on-a-chip technology

Background:

• Centrifugal microfluidic (CM) platforms are widely used for point-of-care assays due to their simplicity and self-contained nature.
• A key limitation of CM platforms is the radial arrangement of fluidic components, restricting fluid flow from the disk's center outward.
• Enabling fluid return from the periphery to the center of the disk would enhance CM platform utility and space efficiency.

Purpose of the Study:

• To develop and demonstrate a novel inward pumping mechanism for centrifugal microfluidic platforms.
• To utilize elastic membranes for controlled fluid return from the disk's periphery to its center.
• To validate the efficiency and applicability of this inward pumping for enhanced fluid mixing and multi-step assays.

Main Methods:

• A novel centrifugal microfluidic disk design incorporating elastic membranes covering fluidic chambers was developed.
• Inward pumping was achieved by manipulating disk rotation speed: high speed for filling chambers, low speed for elastic membrane-driven fluid return.
• Fluidic resistance in two distinct channels determined the inward flow path, with a lower resistance channel facilitating recirculation.

Main Results:

• The elastic membrane-driven inward pumping mechanism demonstrated efficiencies ranging from 78% to 89%.
• The mechanism was successfully applied to enhance fluid mixing on the centrifugal microfluidic disk.
• A combined plasma separation and inward pumping disk design was implemented, showcasing its utility for multi-step assays.

Conclusions:

• Elastic membrane-based inward pumping offers a viable solution to overcome the radial flow limitation in centrifugal microfluidic platforms.
• This technology significantly enhances the utility and real estate utilization of centrifugal microfluidic disks.
• The demonstrated applications in fluid mixing and integrated plasma separation highlight the potential for complex, multi-step point-of-care assays.