Thermo-pneumatic pumping in centrifugal microfluidic platforms

Abstract

The pumping of fluids in microfluidic discs by centrifugal forces has several advantages, however, centrifugal pumping only permits unidirectional fluid flow, restricting the number of processing steps that can be integrated before fluids reach the edge of the disc. As a solution to this critical limitation, we present a novel pumping technique for the centrifugal microfluidic disc platform, termed the thermo-pneumatic pump (TPP), that enables fluids to be transferred the center of a rotating disc by the thermal expansion of air. The TPP is easy to fabricate as it is a structural feature with no moving components and thermal energy is delivered to the pump via peripheral infrared (IR) equipment, enabling pumping while the disc is in rotation. In this report, an analytical model for the operation of the TPP is presented and experimentally validated. We demonstrate that the experimental behavior of the pump agrees well with theory and that flow rates can be controlled by changing how well the pump absorbs IR energy. Overall, the TPP enables for fluids to be stored near the edge of the disc and transferred to the center on demand, offering significant advantages to the microfluidic disc platform in terms of the handling and storage of liquids.

Displacement Pumping of Liquids Radially Inward on Centrifugal Microfluidic Platforms in Motion

“…A non-contact pneumatic pumping method was described by Kong [10,11], but the arrangement requires an external air pressure source. A thermo-pneumatic pumping method was also recently described by Abi-Samra [12] but requires an external heat source.…”

Membrane-based valves and inward-pumping system for centrifugal microfluidic platforms

“…Most of the prior researchers focused on the pneumatic expansion method to achieve inward pumping [17][18][19]. Its drawback lies in the inconvenient actuation method and relative low pumping efficiency.…”

Baking-powder driven centripetal pumping controlled by event-triggering of functional liquids

“…These can include the addition of energy from external sources, transfer of energy to the liquid through the spindle motor and the storage of energy on the disc. External energy sources include connection to air bottles [4], the use of a thermal heat source to expand trapped gas (and thus displace liquid radially inwards) [5] and the use of external electrical energy to electrolytically displace liquid [6].…”