Abstract
We proposed an innovative method to achieve dynamic control of particle separation by employing viscoelastic fluids in deterministic lateral displacement (DLD) arrays. The effects of shear-thinning and elasticity of working fluids on the critical separation size in DLD arrays are investigated. It is observed that each effect can lead to the variation of the critical separation size by approximately 40%. Since the elasticity strength of the fluid is related to the shear rate, the dynamic control can for the first time be easily realized through tuning the flow rate in microchannels.
Highlights
A deterministic lateral displacement (DLD) array is a microfluidic particle-separation device that takes advantage of the asymmetric bifurcation of laminar flow around obstacles, which was firstly introduced by Huang et al.[1]
The principle of the critical particle size implies that the particle motion in a fixed DLD array is bimodal either with diameter lower than Dc in “zigzag mode” or with diameter larger than Dc in “displacement mode”
Various advanced DLD devices were designed for multiple critical thresholds, and the corresponding methods can be regarded as passive ones and active ones
Summary
A deterministic lateral displacement (DLD) array is a microfluidic particle-separation device that takes advantage of the asymmetric bifurcation of laminar flow around obstacles, which was firstly introduced by Huang et al.[1]. When a small particle enters the array and negotiates the posts, it will follow streams continuously, and after encountering N posts i.e. N rows, it will restore to the original direction, moving in an average flow direction matching the fluid. This particle motion is termed as “zigzag mode” (see Fig. 1(c) and Supplementary Video S1). In DLD devices, the introduction of shear-rate-dependent viscosity and nonlinear elastic forces is expected to modify the critical particle size Dc. Comparing with other active DLD devices, an obvious advantage of employing non-Newtonian fluids in DLD devices is that other auxiliary equipment is no longer required. We further realize a dynamic variation of Dc by altering the flow rate utilizing the elasticity
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