Download full-text (Open Access)Abstract
-
In this paper, 3D particle focusing in a straight channel with asymmetrical
expansion–contraction cavity arrays (ECCA channel) is achieved by exploiting the
dean-flow-coupled elasto-inertial effects. First, the mechanism of particle focusing
in both Newtonian and non-Newtonian fluids was introduced. Then particle focusing
was demonstrated experimentally in this channel with Newtonian and non-
Newtonian fluids using three different sized particles (3.2 lm, 4.8 lm, and 13 lm),
respectively. Also, the effects of dean flow (or secondary flow) induced by expansion–
contraction cavity arrays were highlighted by comparing the particle distributions
in a single straight rectangular channel with that in the ECCA channel.
Finally, the influences of flow rates and distances from the inlet on focusing performance
in the ECCA channel were studied. The results show that in the ECCA
channel particles are focused on the cavity side in Newtonian fluid due to the synthesis
effects of inertial and dean-drag force, whereas the particles are focused on
the opposite cavity side in non-Newtonian fluid due to the addition of viscoelastic
force. Compared with the focusing performance in Newtonian fluid, the particles
are more easily and better focused in non-Newtonian fluid. Besides, the Dean flow
in visco-elastic fluid in the ECCA channel improves the particle focusing performance
compared with that in a straight channel. A further advantage is threedimensional
(3D) particle focusing that in non-Newtonian fluid is realized according
to the lateral side view of the channel while only two-dimensional (2D) particle
focusing can be achieved in Newtonian fluid. Conclusively, this novel Dean-flowcoupled
elasto-inertial microfluidic device could offer a continuous, sheathless, and
high throughput (>10 000 s-1) 3D focusing performance, which may be valuable
in various applications from high speed flow cytometry to cell counting, sorting,
and analysis.