Microfluidic-Based Novel Optical Quantification of Red Blood Cell Concentration in Blood Flow

Yudong Wang, Bharath Babu Nunna, Niladri Talukder, Eon Soo Lee (2022/06)

Volume 9 (6), Page 247, Bioengineering



The optical quantification of hematocrit (volumetric percentage of red blood cells) in blood
flow in microfluidic systems provides enormous help in designing microfluidic biosensing platforms
with enhanced sensitivity. Although several existing methods, such as centrifugation, complete blood
cell count, etc., have been developed to measure the hematocrit of the blood at the sample preparation
stage, these methods are impractical to measure the hematocrit in dynamic microfluidic blood flow
cases. An easy-to-access optical method has emerged as a hematocrit quantification technique to
address this limitation, especially for the microfluidic-based biosensing platform. A novel optical
quantification method is demonstrated in this study, which can measure the hematocrit of the blood
flow at a targeted location in a microchannel at any given instant. The images of the blood flow
were shot using a high-speed camera through an inverted transmission microscope at various light
source intensities, and the grayscale of the images was measured using an image processing code.
By measuring the average grayscale of the images of blood flow at different luminous exposures,
a relationship between hematocrit and grayscale has been developed. The quantification of the
hematocrit in the microfluidic system can be instant and easy with this method. The innovative
proposed technique has been evaluated with porcine blood samples with hematocrit ranging from
5% to 70%, flowing through 1000 μm wide and 100 μm deep microchannels. The experimental
results obtained strongly supported the proposed optical technique of hematocrit measurement in
microfluidic systems