Electrochemical hematocrit determination in a direct current microfluidic device

Abstract

Hematocrit (HCT) tests are widely performed to screen blood donors and to diagnose medical conditions. Current HCT test methods include conventional microhematocrit, Coulter counter, CuSO4 specific gravity, and conductivity-based point-of-care (POC) HCT devices, which can be either expensive, environmentally inadvisable, or complicated. In the present work, we introduce a new and simple microfluidic system for a POC HCT determination. HCT was determined by measuring current responses of blood under 100 V DC for 1 min in a microfluidic device containing a single microchannel with dimensions of 180 μm by 70 μm and 10 mm long. Current responses of red blood cell (RBC) suspensions in PBS or separately plasma at HCT concentrations of 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, and 70 vol% were measured to show feasibility of the microfluidic system for HCT determination. Key parameters affecting current responses included electrolysis bubbles and irreversible RBC adsorption; parameters were optimized via addition of nonionic surfactant Triton X-100 into sample solution and carbonizing electrode surfaces. The linear trend line of current responses over a range of RBC concentrations were obtained in both PBS and plasma. This work suggested that a simple microfluidic device could be a promising platform for a new POC HCT device.

Microfluidic-Based Measurement Method of Red Blood Cell Aggregation under Hematocrit Variations

“…For this reason, biochemical analyses, such as biomarkers in cardiovascular diseases and disorders [ 4 ] or DNA [ 5 ], do not show sufficient promise for the early detection of cardiovascular diseases [ 6 ]. Since the associations between coronary heart diseases and blood rheology have been sufficiently investigated [ 3 , 7 , 8 ], several biophysical properties such as the viscosity [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], erythrocyte sedimentation rate (ESR) [ 17 , 18 , 19 , 20 , 21 , 22 ], hematocrit [ 23 , 24 , 25 ], aggregation [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ], and deformability [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ] are employed to detect variations in blood samples. Among them, blood viscosity varies depending on several factors, such as the plasma viscosity, hematocrit, red blood cell (RBC) aggregation, and deformability.…”

Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity

“…Then, by repeating the same PBS and 60% RBC solution measurement cycles, current responses could be restored to 60–63 μA again. These carbonized platinum electrodes demonstrated sufficient activity and stability to reproducibly measure RBC hematocrit to ∼2 vol% resolution .…”

“…Triton X‐100 attenuates electrolysis bubble effects that destabilize current responses by facilitating formation of smaller bubbles. It was shown that 320 μM Triton X‐100 does not compromise RBC membrane integrity .…”

Quantitative Measurement and Evaluation of Red Blood Cell Aggregation in Normal Blood Based on a Modified Hanai Equation

“…Patients with serious CVDs have microcirculatory disorders that are found to be strongly associated with the biophysical properties of blood [2]. Hence, the biophysical properties of blood, such as the viscosity [3,4,5], hematocrit [6,7], RBC deformability [8,9], erythrocyte sedimentation rate (ESR) [10,11], RBC aggregation [12,13,14] and other factors [15,16,17], are widely tested to diagnose the pathological or physiological disorders of CVDs. Among the biophysical properties of blood, RBC aggregation is the major cause of the non-Newton flow properties of whole blood, and it has been popularly utilized to diagnose the inflammatory diseases in clinic, since the level of aggregation rises enormously in association with diabetes [18], sepsis [19], myocardial ischaemia [20] and so on.…”