Continuous particle sorting is one of the most important fundamental applications of microfluidics. Fast and accurate sorting procedures can be performed using unique hydrodynamic characteristics of microfluidics. One of the most practical microfluidic applications is the sampling, trapping, sorting, treatment, and analysis of bioparticles. Hydrodynamic and inertial microfluidics, e.g. fluid-based or structural features to separate bioparticles, are based on the forced or passive migration of particles where randomly dispersed bioparticles (cells, viruses, protein aggregates etc.) migrate laterally to several equilibrium positions. While these techniques are suitable for small bioparticles &lt;10 μm, there have been few examples of sorting and assessing larger bioparticles. Herein, we present a microfluidic system for the sorting of bioparticles ranging up to 750 μm, as demonstrated with the capture, imaging, and sorting of the calcium carbonate shells of mixed foraminifera species. We aimed to achieve a size-separation resolution of 50-100 microns, i.e. binning of forams with differences of 100 μm in diameter. We aimed to achieve a lateral and vertical positioning resolution of less than 50 μm, which is less than 20% of average foram diameter. By controlling flow rates and sample position, we can reduce variability and the necessary precision required from the imaging components to photograph and classify the bioparticles; moreover, the classification and pre-sorting of samples provides a refined pipeline for subsequent isotopic and trace metal analyses.

Toward automated identification and sorting of foraminifera via microfluidics

ACS Fall 2021

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