Micro-Viscometer for Measuring Shear-Varying Blood Viscosity over a Wide-Ranging Shear Rate

Abstract

In this study, a micro-viscometer is developed for measuring shear-varying blood viscosity over a wide-ranging shear rate. The micro-viscometer consists of 10 microfluidic channel arrays, each of which has a different micro-channel width. The proposed design enables the retrieval of 10 different shear rates from a single flow rate, thereby enabling the measurement of shear-varying blood viscosity with a fixed flow rate condition. For this purpose, an optimal design that guarantees accurate viscosity measurement is selected from a parametric study. The functionality of the micro-viscometer is verified by both numerical and experimental studies. The proposed micro-viscometer shows 6.8% (numerical) and 5.3% (experimental) in relative error when compared to the result from a standard rotational viscometer. Moreover, a reliability test is performed by repeated measurement (N = 7), and the result shows 2.69 ± 2.19% for the mean relative error. Accurate viscosity measurements are performed on blood samples with variations in the hematocrit (35%, 45%, and 55%), which significantly influences blood viscosity. Since the blood viscosity correlated with various physical parameters of the blood, the micro-viscometer is anticipated to be a significant advancement for realization of blood on a chip.

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

“…Conventionally, blood viscosity has been measured at sufficiently high shear rates (i.e., . γ > 10 s −1 [11,12] or . γ > 50-100 s −1 [13,14]), especially in microfluidic environments.…”

“…Second, various devices such as a microelectromechanical system (MEMS)-based microfluidic device, a 3D-printed microfluidic device [13,24], and a paper-based device [25] have been suggested for inducing blood flow in a specifically constrained direction. Third, quantification techniques such as advancing meniscus (i.e., variations of a blood column over time) [15,22,26,27], the falling time of a metal sphere in a tube [28], electric impedances (i.e., resistance, capacitance) [29,30], droplet length [31], digital flow compartment with a microfluidic channel array [11,12], interface detection in co-flowing streams [32,33], and reversal flow switching in a Wheatstone bridge analog of a fluidic circuit [14] have been suggested to measure blood viscosity.…”

Microfluidic-Based Technique for Measuring RBC Aggregation and Blood Viscosity in a Continuous and Simultaneous Fashion

“…To measure blood viscosity in a microfluidic device, blood is made to flow at a specific flow rate or velocity using several driving sources, such as syringe pumps, pressure sources [ 28 ], surface tension [ 29 , 30 , 31 , 32 ], and pipettes [ 33 ]. After that, as shown in Table 1 , several measurement techniques, including co-flowing streams [ 34 ], modified parallel flows [ 9 , 24 ], microflow compartments [ 35 , 36 ], reversal flow-switching [ 10 , 37 , 38 , 39 ], advancing meniscus [ 28 , 29 , 30 , 31 , 32 , 33 ], and electric impedance measurements [ 40 , 41 ], can be used to measure blood viscosity. Considering some critical issues, such as RBC clogging and precise flow-rate control and calibration, the modified parallel flows method (MPFM) [ 9 , 24 ] shows high potential for continuous measurement of blood viscosity.…”

Design and Fabrication of a BiCMOS Dielectric Sensor for Viscosity Measurements: A Possible Solution for Early Detection of COPD

“…For example, Microvisk (Microvisk Ltd., Oxfordshire, UK), a commercially available viscometer, analyzes glucose concentration in blood for Point-of-Care (POC) applications using Micro Electro Mechanical Systems (MEMS). Similarly, various research-oriented viscometers have been developed for blood analysis or coagulation monitoring using the MEMS technology [ 5 , 6 , 7 ]. The key principle of these piezoelectric-based viscosity sensors is based on the deflation of their piezo material-based cantilevers or beams when they are exposed to the viscous fluid.…”