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Issue 24, 2012
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Blood plasma separation in a long two-phase plug flowing through disposable tubing

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Abstract

We report a simple technique to separate plasma from blood in a flowing immiscible plug. We investigate the effect of various control parameters such as blood dilution, injection flow rate, observation time and fluid properties on plasma separation. We find that the technique works best for diluted blood samples at low plug velocities and long observation times. We postulate that the main mechanism responsible for efficient separation is the sedimentation of blood cells in the plug and their subsequent collection by the moving plug causing a significant accumulation of cells at the rear of the plug. We discuss the time scales determining the sedimentation, advection and collection of a blood cell in the immiscible plug and propose a phase diagram that is able to predict the operating space for effective plasma separation. We demonstrate that the technique allows for the extraction of more than 60% of the plasma by volume from 1 μL of diluted blood. We show the practical significance of this method by compartmentalizing the separated plasma into discrete microfluidic droplets and detecting cholesterol. This technique features low consumption of blood (nL-scale) and low shear rate (∼1 s−1). It is inexpensive, easy to use, and has the potential to be developed as an efficient point-of-care device for blood diagnostics in resource-poor environments. More advanced applications could also be envisioned by integrating our plasma separation method into existing microfluidic drop manipulation techniques.

Graphical abstract: Blood plasma separation in a long two-phase plug flowing through disposable tubing

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Publication details

The article was received on 11 May 2012, accepted on 07 Oct 2012 and first published on 10 Oct 2012


Article type: Paper
DOI: 10.1039/C2LC40544J
Lab Chip, 2012,12, 5225-5230

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    Blood plasma separation in a long two-phase plug flowing through disposable tubing

    M. Sun, Z. S. Khan and S. A. Vanapalli, Lab Chip, 2012, 12, 5225
    DOI: 10.1039/C2LC40544J

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