A portable rotating disc as blood rheometer

Abstract

Abnormalities in biophysical properties of blood are often strong indicators of life threatening infections. However, there is no existing device that integrates the sensing of blood hematocrit (or equivalently, packed cell volume), viscosity, and erythrocyte sedimentation rate (ESR) in a unified paradigm for point-of-care diagnostics. In an effort to develop a rapid, integrated, accurate, portable, and inexpensive sensing platform to diagnose the corresponding pathophysical parameters, we develop a simple and portable spinning disk capable of yielding these results in a few minutes instead of the traditional duration of hours. The device requires only 40 μl of unprocessed freshly drawn blood treated with an anticoagulant ethylenediaminetetraacetic acid, instead of the traditional requirement of 2 ml of blood for just the ESR measurement and still more for hematocrit determination. In contrast to the sophisticated instrumentation required to determine these parameters by the previously proposed microfluidic devices, our device requires minimal infrastructure. The measurement of hematocrit is accomplished by means of a simple 15 cm ruler. Additionally, a simple measurement of the blood flow rate enables the determination of the ESR value. The rapidity, ease, accuracy, portability, frugality, and possible automation of the overall measurement process of some of the most important parameters of blood under infection pinpoint its utility in extreme point-of-care settings.

Assessment of Rheological Models Applied to Blood Flow in Human Thoracic Aorta

“…Behaving as Newtonian fluids at large shear rates and differing mainly at low shear rates, differences between the rheological models are expected for local shear rates below the order of 100 s −1 . A direct comparison of the contributions of the different models is displayed in terms of I L and I g , Equation (5), and shown in Figure 2a,b. The space averaging of the normalized viscosity (I L ) and the non-Newtonian importance factor enables the assessment of the temporal variations of the rheological models during the cardiac cycle.…”

“…Blood rheology has been the subject of many studies found in the literature. Often, WBV measurements have been carried out using standard (shear) rheometers (cf Cowan et al [4]), implying that the flow is laminar and that the shear rate is well defined and solely dependent on the rotation rate (cf Agarwal et al [5]). Yamamoto et al [6] used a compact-sized falling needle rheometer on fresh blood samples to measure the relationship between the shear stress (τ) and shear rate (γ).…”

Biomechanical Assessment of Red Blood Cells in Pulsatile Blood Flows

“…Microfluidic devices that can provide in vitro biological microenvironments [ 15 , 16 ] or physiological capillary vessel structures [ 17 ] have been extensively adopted to measure rheological properties [ 18 , 19 , 20 ]. Several rheological properties, including viscosity [ 21 , 22 , 23 , 24 , 25 ], viscoelasticity [ 26 ], aggregation (or sedimentation) [ 27 , 28 ], deformability [ 29 ], and hematocrit [ 25 , 30 , 31 ], have been obtained by manipulating blood flows in microfluidic environments [ 32 , 33 ].…”