Rheology of Soft and Rigid Micro Particles in Curved Microfluidic Channels
We investigated the rheological behavior of micro particles in inertial flow in a curved microfluidic channel. Different from the typical microfluidic regime operating at low Reynolds number, inertial flow provides hydrodynamic manipulation, namely inerti
- PDF / 353,316 Bytes
- 5 Pages / 595.276 x 790.866 pts Page_size
- 80 Downloads / 150 Views
Rheology of Soft and Rigid Micro Particles in Curved Microfluidic Channels Jia Liu, Yuhao Qiang, Michael Mian, Weihe Xu, and E. Du Abstract We investigated the rheological behavior of micro particles in inertial flow in a curved microfluidic channel. Different from the typical microfluidic regime operating at low Reynolds number, inertial flow provides hydrodynamic manipulation, namely inertial focusing of particles at high flow speeds. Primary influences of inertial flow on particle motions are several: repulsive force from the wall due to a pressure buildup in the constriction between the wall and the particle, shear gradient lift force due to the parabolic flow profile at microscale, and secondary drag force in the crosssectional direction due to channel curvature. These forces result in particle moving across the streamlines to certain predictable equilibrium positions in the flow. With regard to soft particles, their flow behavior and equilibrium positions may deviate from the theoretical predictions based on rigid particles. This study provides a proof-of-concept of inertial focusing-based separation of particles with different deformability. We demonstrated its capability by separating yeast cells and polystyrene particles of similar sizes in a double spiral channel. Keywords Biological cell • Inertial focusing • Hydrodynamics • Deoxygenation • Particle separation
12.1
Introduction
Sickle cell disease (SCD) is caused by an inherited abnormal sickle hemoglobin (HbS), where the glutamic acid (E/Glu) in the normal β-chain is substituted by valine [1, 2]. This leads to intracellular HbS polymerization at low partial oxygen pressure (pO2), and consequent morphological deformation, e.g. into its characteristic “sickle” shape. Diagnosis of SCD relies on detection of the presence of significant quantities of HbS by isoelectric focusing, cellulose acetate electrophoresis, high-performance liquid chromatography, or DNA analysis [3, 4]. A potential alternative method is label-free detectoin and counting fraction of red blood cells (RBCs) that can sickle under low pO2 levels. This is supported by a comprehensive microfluidics study of sickle RBCs using a hypoxic microfluidic chip and a microvascular occlusion model [5]. It was found that the fraction of in vitro hypoxia-induced cell sickling is strongly correlated with the mean HbS concentrations. Cellular rheological behavior evaluated by mean cell velocity and capillary obstruction ratio, is closely associated with oxygen concentration and patients’ hematological measures. In this case, a simple, effective yet relatively low-cost sample preparation, i.e. sorting rigid sickled cells from deformable unsickled cells, could benefit SCD diganosis and treatment. Microfluidics has been broadly used in cell level operations. Separation of different cell types has been a subject of intense study. Among various microfluidic approaches, a promising method is inertial focusing, which was first implemented experimentally by Di Carlo et al. [6]. The physics behind inertial focus
Data Loading...
