Assessment of multiple hemorheological properties in microfluidic environment

Measuring and monitoring hemorheological properties provide valuable insights into diseases. To effectively detect impaired blood, it is necessary to quantify the multiple hemorheological properties. However, most of the previous methods only provide single blood property. They require bulky and expensive syringe pumps for precise on–off control. In this study, to resolve several issues, a novel method for measuring multiple hemorheological properties (fluidic resistance, blood viscosity, time constant, compliance coefficient, red blood cell [RBC] aggregation index, and RBC sedimentation index) is proposed by analyzing blood images in microfluidic channels, where transient blood flow is induced by a portable air-compression pump. A microfluidic device consists of an inlet, a test chamber joined to a main channel, and a reservoir. The outlet of test chamber is connected to an air damper, which contributes to stopping blood flow promptly. A fluid circuit model of the proposed microfluidic channels is constructed for estimating flow rate and pressure in the main channel. First, the proposed method is used to obtain the rheological properties of glycerin solution (30%). The normalized difference between the proposed method and the reference value is less than 4%. Subsequently, the proposed method is adopted to detect differences in the medium (1× phosphate-buffered saline, dextran solution: 20 mg/ml) and hematocrit (30%–60%). All hemorheological properties exhibit substantial differences with respect to the hematocrit and medium. The proposed method yields comparable results when compared to the previous methods. In conclusion, the proposed method can measure multiple hemorheological properties by analyzing blood flow in microfluidic channels.