Microfluidic Separation and Enrichment of Escherichia coli by Size Using Viscoelastic Flows

Abstract

Here, we achieve the separation and enrichment of Escherichia coli clusters from its singlets in a viscoelastic microfluidic device. E. coli, an important prokaryotic model organism and a widely used microbial factory, can aggregate in clusters, leading to biofilm development that can be detrimental to human health and industrial processes. The ability to obtain high-purity populations of E. coli clusters is of significance for biological, biomedical, and industrial applications. In this study, polystyrene particles of two different sizes, 1 and 4.8 μm, are used to mimic E. coli singlets and clusters, respectively. Experimental results show that particles migrate toward the channel center in a size-dependent manner, due to the combined effects of inertial and elastic forces; 4.8 and 1 μm particles are found to have lateral equilibrium positions closer to the channel centerline and sidewalls, respectively. The size-dependent separation performance of the microdevice is demonstrated to be affected by three main factors: channel length, the ratio of sheath to sample flow rate, and poly(ethylene oxide) (PEO) concentration. Further, the separation of E. coli singlets and clusters is achieved at the outlets, and the separation efficiency is evaluated in terms of purity and enrichment factor.

High-throughput and high-purity separation of malignant tumor cells in pleural and peritoneal effusions using interfacial elasto-inertial microfluidics

“…Therefore, a sample throughput as high as 120 μL min −1 was reported in our device, which was much higher than that of previous work using PEO as the elastic enhancer. 29–32 The good biocompatibility of HA solution was well validated in many previous studies. 36…”

“…As compared with single-phase viscoelastic microfluidics, the interfacial viscoelastic microfluidics offers an improved performance for cell separation by using a co-flowing system. 29 Currently, the interfacial viscoelastic microfluidics is successfully applied to separate Escherichia coli clusters from their singlets, 30 circulating tumor cells from background blood cells, 31,32 and large extracellular vesicles from small exosomes. 33,34 As can be seen from the above progress, great successes have been achieved in the field of viscoelastic microfluidics.…”

Recent progress of microfluidic sample preparation techniques

“…μFAE is a type of passive force‐assisted extraction/separation method, by driving analyte passing through specific channel structures with the inherent fluid effect in microscale, including laminar co‐flow [33], Dean flow [52], viscoelastic flow [53, 54], and inertial migration [34, 36, 37]. For example, Wang et al.…”

“…μFAE is a type of passive force-assisted extraction/separation method, by driving analyte passing through specific channel structures with the inherent fluid effect in microscale, including laminar co-flow [33], Dean flow [52], viscoelastic flow [53,54], and inertial migration [34,36,37]. For example, Wang et al [33] reported the μFAE of Mg(OH) 2 from seawater by laminar co-flow-induced nonequilibrium, which avoids the interference of coexisted Ca 2+ easily happens in conventional seawater Mg extractions.…”

Inertial Separation of Particles Assisted by Symmetrical Sheath Flows in a Straight Microchannel

“…Moreover, the introduced external forces like the mechanical kicking force generated from the cavitation bubbles can seriously damage biological samples, e.g., mammalian cells . The passive approaches such as hydrophoresis, deterministic lateral displacement (DLD), viscoelastic microfluidics, and inertial microfluidics are available for particle separation . However, hydrophoresis requires additional functional microstructures within the microchannel, − DLD suffers from lifetime fouling and clogging and viscoelastic microfluidics asks for the specific non-Newtoninan solutions like polyethylene oxide medium. , Inertial microfluidics, which works at intermediate Reynolds numbers (∼1 < Re < ∼100), is prominent in precise particle control and high throughput, thus being widely used for particle separation …”