Simulation of microfluidic pumping in a genomic DNA blood-processing cassette

Abstract

Microfluidic cassettes that perform integrated biological sample preparation and DNA analysis require fluidic control and transport mechanisms built into the device. In this study, pneumatically actuated diaphragm pumps and valves were employed to achieve precise fluidic manipulation and enabled the execution of several sample-processing steps within a single cassette. However, the design of the microfluidic cassette to accomplish this multi-step fluidic protocol required a complex three-dimensional fluid path through valves, bends, various sized passageways and a porous filter for cell capture. In order to understand the fluidic behavior in such a device, measurements were taken of the pneumatic pressure delivered to the diaphragm pump as it pushed sample through the complicated fluidic pathway. Simultaneously monitored were the resulting volumetric flow rate, and the corresponding pre- and post-filter fluid pressures. The data enabled the construction of a model that simulated the fluidic action through the device using established fluid mechanics theory that closely matched flow rate and pressure data. The ability to simulate the behavior of diaphragm pumping and resulting fluidic movements in complex microfluidic devices provides a greater comprehension of this phenomenon and a useful tool in the application to future devices for biochemical analysis.