Blood plasma separation and transfer on a centrifugal microfluidic disk: Numerical analysis and experimental study

Lab-On-a-Disk, as a subfield of microfluidic systems, recently has drawn attention to being utilized in blood biomarker diagnosis, blood typing, and immunoassays because of being high-throughput, highly precise, and easy to use. Blood plasma separation is a most vital unit for pre-processing in these systems, since the blood plasma contains a lot of proteins and enzymes that should be separated, and precisely examined. Therefore, in this paper, for the first time, a numerical model was proposed to evaluate the plasma separation in various time scales and geometries, and an appropriate design was proposed. Furthermore, because the blood plasma volume is different between patients, and the designed geometry should precisely control the transferred volume between chambers to prevent migration of RBCs along with plasma, the transfer process by a siphon valve was numerically modeled, simulated, and experimentally evaluated. For the separation process, three geometries differing in bottleneck width were evaluated. The purpose of applying a bottleneck in the design was to build a barrier-like between plasma and blood cells after the completion of separation; therefore, we can make sure that no cells will transfer to the plasma section. Subsequently, we interconnected the separation unit with a siphon valve to a secondary chamber to evaluate the process of transferring plasma for post-processing. The results suggested that more than 95% of separated plasma can be transferred without any remixing with cells.