Separation and enrichment of platelets in blood plasma play a major role in monitoring the human health condition and transfusion purposes. Although centrifugation is frequently employed to achieve platelet separation, recent advancements in the field of cell separation place microfluidic platforms in advantageous positions over the conventional ones. In this work, we report the development of a PDMS-based passive microfluidics device to separate and enrich platelets in blood plasma. The devices were tested with whole blood in a practically relevant flow rate range of 0.2–0.6 mL/min. One of our proposed devices, comprising gradual constriction–expansion, is able to separate and enrich platelets with 8.7-fold enrichment factor, 25.5% purity, and with minimum activation at a flow rate of 0.4 mL/min using whole human blood. The amount of enrichment and purity is found to be sensitive to the ratio of RBCs and WBCs to platelets in the incoming sample. The ability of the microdevice to handle whole blood at a high flow rate, and enrich platelets in plasma with minimal activation, makes the microdevice unique. These results also demonstrate the strong effect of the RBCs and WBCs to platelet ratio on the amount of enrichment and purity that can be obtained from passive microdevices.

No abstract

Separation and enrichment of platelets from whole blood find numerous applications for biomedical research, dermatology, and transfusion purposes. Therefore, there is a great value in selectively isolating and enriching platelets in plasma from whole blood. The conventional method of centrifugation involves several manual steps and cannot be integrated with point-of-care devices.Here, we present an evolved passive microdevice for the enhanced fold enrichment and separation efficiency of platelets in a platelet-enriched plasma sample. The design steps for arriving at the final design are also presented, as learnings from these early designs helped in evolution of the final microdevice; these early designs can also be used as a reference for further studies. The final proposed microdevice is easy to fabricate, requires less hardware and pumping power than available microdevices, and separates high-quality platelets from a whole blood sample. Our microdevice is able to achieve ∼15-fold platelet enrichment. Several biological tests attest to the high quality of platelets obtained from the microdevice. The performance of the developed microdevice is superior to those of few available microdevices. Our work suggests that passive microdevices can attain or even surpass the performance of active microdevices.

No abstract

Selective isolation of human blood cells has numerous applications in the field of disease diagnostic, prognostics, drug discovery, and drug delivery. In particular, isolation of white blood cells (WBCs) is required for the detection of various diseases such as leukemia, Human immunodeficiency virus (HIV) infection, Epstein–Barr virus (EBV), cancers etc. Although, the conventional methods of centrifugation and flow cytometry are broadly employed for the isolation of WBCs in clinical practice, they experience several limitations such as the requirement of large volume of samples and reagents, trained personnel, large setup, and have adverse effect on the quality of cells. In contrast, microfluidics based methods have appeared as a superior approach of cells isolation with advantages such as low cost, easy to operate, compact in size, and requiring a lower sample volume. In this review, we focus on the various microfluidics techniques for the isolation of WBCs from blood. Here, we have discussed the working mechanism of various microfluidics techniques, microdevice designs, and their performance parameters to isolate WBCs. A detailed discussion on the various forces acting on cells while flowing through microchannels is also provided. In addition, a brief description of the numerous advantages and limitations of the existing microdevices, and their future prospects aiming to develop an affordable, user friendly point-of-care solution is provided.