A circuit model of human whole blood in a microfluidic dielectric sensor

摘要

Dielectric spectroscopy (DS) is a powerful monitoring technique that can extract important molecular and cellular properties from a variety of biological materials. DS measurements on human whole blood can reveal a wealth of physiologic information, primarily from the dispersion region that arises from interfacial polarization of red blood cells (RBCs) [1]. Specifically, the use of DS to monitor the blood coagulation process (i.e., dielectric coagulometry) enables rapid and comprehensive assessment of patients' blood coagulation status at the point-of-care (POC) [2]. However, the ratio of RBC volume to total blood volume, or hematocrit (Hct) value, is a confounding parameter in dielectric coagulometry and thus important to analyze using DS. Comprehensive DS analysis on human whole blood has thus far been limited to bulk-solution measurements using ~mL sample volumes [1]. On the other hand, DS analysis on a single drop of blood (~10μL) in a microfluidic dielectric sensor presents challenges due to the increased effect of the capacitive double-layer (CDL) formed at electrode surfaces (electrode polarization) due to the scaling of electrode dimensions.