Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

Yang Jun Kang

doi:10.3390/app11167260

Abstract

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

Highlights

To obtain the correction factor of pressure (CP ) which compensates for the approximation errors that occurred for modeling coflowing lamina streams, computational fluid dynamics (CFD) simulations were conducted using commercial software (CFD-ACE+, Ver. 2019, ESI Group, Paris, France)
After constructing a discrete circuit model for the coflowing streams, the analytical formulas of pressure and shear stress were derived from the fact that both streams had the same pressure in the straight coflowing channel
Based on CFD simulations, both analytical expressions of pressure and shear stress for each stream were corrected by inserting a pressure correction factor into the expressions

Summary

Introduction

Blood behaves as a non-Newtonian fluid at lower shear rates, but as a Newtonian fluid at higher shear rates [1] It is influenced significantly by hemorheological properties (i.e., viscoelasticity [2,3], hematocrit [4,5], deformability [6,7], and aggregation [8,9]), and vessel geometries (i.e., channel size and cell-free layer). Since a microfluidic platform with the ability to fabricate blood vessels of similar sizes was introduced, it has been used widely to quantify various hemorheological properties, including viscoelasticity [14,15,16], hematocrit [17,18,19,20,21,22], RBC deformability [21,23,24,25], and RBC aggregation [26,27].

Methods

Results

Conclusion