HbA1c ratio detection using the microfluidic biosensor based on developed sandwich immunoassay and impedance measurement

The proposed microfluidic biosensor successfully detected the impedance signals of the various hemoglobin (Hb) and glycated hemoglobin (HbA1c) concentrations to obtain the HbA1c ratio. HbA1c develops when the glucose molecules attach to the hemoglobin in blood cells under higher blood glucose levels, so HbA1c ratio is primarily used in diabetes care to identify the average plasma glucose concentration over three months. This paper presents a microfluidic biosensor into which the gold nanoparticles (AuNPs) were introduced through the specific binding of antibodies to change the impedance signals of various concentrations. The impedance variation can be easily measured with any commercial LCR meter, and we observed an obvious difference in impedance signals after 8 min. The detection range of the HbA1c concentration was from 0.1 to 100 ng/ml, and the detection range of the Hb concentration was from 10 to 500 ng/ml. Finally, the HbA1c ratio was calculated from 2 to 10%. Therefore, the microfluidic biosensor has advantages including small sample volumes (10 μL) and rapid quantitative measurement, and works with wider detection range of concentration in clinical diagnosis.