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

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.

Sequential quantification of blood and diluent using red cell sedimentation-based separation and pressure-induced work in a microfluidic channel

“…This study was primarily aimed at minimizing the blood volume suctioned in the driving syringe. In previous studies, RBC sedimentation has been tested under different conditions, including suction blood volume (40–200 μL, 41 0.2 mL, 17,33 0.3 mL, 45 0.6 mL, 35 1 mL, 16,32,36 and 4–10 mL 56,62 ), and test reservoir (straight tube, 21,28 disposable syringe, 36 polycarbonate cartridge, 41 conical tube 17,33 ). A considerable blood volume (∼1 mL) was injected into the blood syringe to monitor RBC sedimentation in a driving syringe pump.…”

“…P j increased substantially at higher blood ow rates. According to the Hagen-Poiseuille law, 56,57 the junction pressure is proportional to the blood ow rate (P j $ Q b ). Thus, the results exhibited consistent trends in relation to the blood ow rate.…”

“…The two fluids (blood and diluent) were quantified by calculating the junction pressure ( P j ) and pressure-induced work ( W p ) using the temporal variation of β . By referring to a previous study, 56 the analytical expression of junction pressure in blood flow was derived analytically using discrete fluidic circuit elements, as shown in Fig. 2A.…”

“…, P r = R r × Q r ). The analytical formula of the junction pressure of the reference fluid ( P r ) was then derived as According to a previous study, 56 the normalized difference between the analytical formula and numerical simulation was less than 15%, where the interface was positioned between β = 0.1 to β = 0.9. The previous results confirmed that the junction pressure obtained in the coflowing channel could be employed to evaluate change in blood flows with sufficient consistency.…”

“…Analytical expression of uidic resistance was derived as R r ¼ 12  m r  l ð1 À bÞ Â w  h 3 : The junction pressure (P r ) was then obtained by multiplying uidic resistance (R r ) by ow rate (Q r ) (i.e., P r ¼ R r  Q r ). The analytical formula of the junction pressure of the reference uid (P r ) was then derived as P r ¼ 12m r  l ð1 À bÞ Â w  h 3  Q r : According to a previous study, 56 the normalized difference between the analytical formula and numerical simulation was less than 15%, where the interface was positioned between b ¼ 0.1 to b ¼ 0.9. The previous results conrmed that the junction pressure obtained in the coowing channel could be employed to evaluate change in blood ows with sufficient consistency.…”