Impedance‐based viscoelastic flow cytometry

Abstract

Elastic nature of the viscoelastic fluids induces lateral migration of particles into a single streamline and can be used by microfluidic based flow cytometry devices. In this study, we investigated focusing efficiency of polyethylene oxide based viscoelastic solutions at varying ionic concentration to demonstrate their use in impedimetric particle characterization systems. Rheological properties of the viscoelastic fluid and particle focusing performance are not affected by ionic concentration. We investigated the viscoelastic focusing dynamics using polystyrene (PS) beads and human red blood cells (RBCs) suspended in the viscoelastic fluid. Elasto‐inertial focusing of PS beads was achieved with the combination of inertial and viscoelastic effects. RBCs were aligned along the channel centerline in parachute shape which yielded consistent impedimetric signals. We compared our impedance‐based microfluidic flow cytometry results for RBCs and PS beads by analyzing particle transit time and peak amplitude at varying viscoelastic focusing conditions obtained at different flow rates. We showed that single orientation, single train focusing of nonspherical RBCs can be achieved with polyethylene oxide based viscoelastic solution that has been shown to be a good candidate as a carrier fluid for impedance cytometry.

Particle Focusing under Newtonian and Viscoelastic Flow in a Straight Rhombic Microchannel

“…To prevent particle aggregation in the particle migration experiments, the surfactant Tween 20 (Sigma-Aldrich, Saint Louis, MO, USA) was added to the suspensions at 0.1 wt%. The estimated mean viscosity of the PEO500 solution was approximately 1.85 mPa•s (DI water: 0.89 mPa•s) [22][23][24]. Its relaxation time was estimated from the previous empirical relaxation time (λ e ), which was also measured with a capillary breakup extensional rheometer (CaBER) [22][23][24].…”

High-throughput electrical position detection of single flowing particles/cells with non-spherical shape

“…As an example, the proposed approach could be used to investigate viscoelastic cell and particle focusing. 53,54 The system, providing accurate cell sizing, is also suited to applications where cell size is a biomarker of underlying cellular processes. Examples include monitoring RDW levels for early detection of cardiovascular and cerebrovascular diseases, 55 as well as monitoring apoptotic cell death, 56 formation of cell aggregates, 57 and leucocyte activation or monocyte differentiation.…”

Impedimetric Cell Detection using Microfluidic Viscoelastic Focusing

“…The final step in the solution optimization was obtaining the conductivity that yields the highest signal for the impedimetric detection. It is well-known that higher ionic conductivity of the medium leads to an improved signal for cellular detection application, since cells have a lipid containing membrane that behave as insulator (Serhatlioglu et al 2019). However, increasing the solution ionic concentration may have adverse effects on cell integrity.…”