Time dependent variation of human blood conductivity as a method for an estimation of RBC aggregation

Abstract

Time variation of whole human blood conductivity and shear stresses were investigated at rectangular and trapeziumshaped Couette viscometric flow under electric field of 2 kHz. The kinetics of conductivity signals were recorded both under transient flow and after the complete stoppage of shearing at shear rates from 0.94 to 94.5 s −1 and temperatures T = 25 • C and 37 • C. Contraves Low Shear 30 rotational viscometer as a base unit and a concurrent measuring system, including a device, developed by the conductometric method with a software for measurement of conductivity of biological fluids (data acquisition system), previously described (were used for the experiments.The obtained experimental relationships show that the human blood conductivity is time, shear rate, hematocrit and temperature dependent under transient flow. It is also dependent on the regime of the applied shear rates. Non-linear curve approximation of the growth and relaxation curves is done. The results show that valuable information could be received about the kinetics of "rouleaux formation" and the time dependences of the blood conductivity follow the structural transformations of RBC aggregates during the aggregation-disaggregation processes. The results suggest that this technique may be used to clarify the mechanism of dynamics of RBC aggregates.

Microfluidic-Based Biosensor for Blood Viscosity and Erythrocyte Sedimentation Rate Using Disposable Fluid Delivery System

“…By applying shear stress to the blood sample with external driving systems (i.e., an SP [34], pinch valve [16], or stirring motor [35]), the RBCs in the blood sample are aggregated or disaggregated, depending on the shear rate. Several quantification methods, such as light intensity (i.e., transmission, and back-scattering) [16], electrical conductivity [36,37], microscopic RBC images [38][39][40], ultrasonic images [41], and optical tweezers [42] have been suggested for obtaining temporal variations of RBCs aggregation. As another approach, RBC aggregation can be quantified by measuring the sedimentation distances of RBCs in a blood sample during a specific duration (i.e., ESR).…”

Measurement of Impedance Values of Different Erythrocyte Suspensions

“…Aggregation denotes the formation of reversible clumps of RBC under sufficiently low shear stresses (21,22). It has been reported that electrical properties of red cell suspensions also change during aggregation (11,13,14,(23)(24)(25)(26)(27). The electrical properties of blood plasma and blood cells differ from each other.…”

Assessment of the “cross-bridge”-induced interaction of red blood cells by optical trapping combined with microfluidics

“…Intensive studies were performed during the last few decades for characterizing the RBC aggregation and using it as a parameter for diagnostics and monitoring of the pathological states. Different methods, such as laser beam scattering on blood suspension, 5,6 microscopic image analyses, 7 measurement of electrical conductivity, 8 electrophoresis, 9 and others, 10 were developed to quantify the RBC aggregation. On the other hand, for assessing RBCs interaction mechanism, methods such as micropipette aspiration technique, 11 scanning electron microscopy, 12 atomic force microscopy, 13 and optical tweezers 14 were implemented.…”