A Clogging-free Microfluidic Device for Platelet Enrichment
Ninad Mehendale,
Research Scholar,
Indian Institute of Technology Bombay
Platelets are required for many diagnostic applications, such as, the study of clotting factor, wound healing, and tissue growth factors (e.g. FGF -2 and TGF-ß). The platelet count after separation can be indicative of certain diseases including dengue, vitamin B-12 deficiency and cirrhosis. Microfluidic chips have been developed for fractionating different components of blood, using techniques like deterministic lateral displacement [1], size exclusion filtration [2], crossflow [3], etc. These pillar-based microfluidic devices suffer from clogging issues, which limit their use. Most passive cell separation devices use a linear arrangement of micropillars, leading to clogging in a very short time.
We report a new microfluidic device design (fig. A) to solve the problem of clogging by self-generating cross-flows. Fig. B shows the schematic diagram of the experimental set up. As shown in fig. A, the device has a central sample inlet and several concentric rows of pillars. The gap between the pillars is varied throughout the device to exploit the difference in size and deformability of different blood cells, and thereby trap them in specific zones. The radial arrangement of the pillars leads to a secondary cross-flow between two successive rows when a part of the device gets clogged. The cross flow allows the device operation to continue. There are two outlets to collect the RBCs and the platelets after separation. We have verified that our device works with whole blood and can be used for more than 8 hours without clogging. Our device works best at low flow rates without activating the platelets. We were able to obtain a 50X enrichment of platelets in our device, which is suitable for most clinical applications.
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