Relationships between hematocrit and sample flows on Lab-on-a-Chip

Abstract

In this work, the reusable Lab-on-a-Chip or LOC was fabricated and developed to reduce its investment cost and to ease its operations. A sandwiched acrylic set was chosen to assemble the PDMS LOC which was aimed to investigate biological samples, especially the samples from animals. Chicken and sheep blood were chosen as the samples to implement two-phase flows with different red-blood-cell shapes. The chicken blood flow represented the viscous twophase flow with the oval shape particles while the sheep blood flow represented the inadhesive samples with the round particles. The LOC electrodes from different materials as the sputtered nickel plate, the aluminium foil, the copper plate, and the gold foil were examined. Ratios between the anticoagulant solution and the biological samples were studied to find their effects on sample velocities and to find the best image to characterize the RBC flow behaviors. Since it was hard to characterize the particle flow in the inadhesive flows, the result pictures were analyzed and presented in terms of color intensities per unit area by using a computer program called "ImageJ". The sheep-blood-flow results were validated with the hematology results which were the hematocrits to find their relationships between the hematocrits and the RBC flows. Among different LOC electrodes, the sputtered nickel electrodes were the most suitable electrodes in this current application. We found that the suitable anticoagulant-sample ratios for chicken and sheep samples were 5:1 and 1:1 by volume, respectively. The normal-health-condition sheep with the standard hematocrits higher than 28% showed the averagedifferent- color intensities per unit area between cathode and anode at 39.485 pixels per unit area while the lower standard hematocrit samples, the hematocrits were lower than 28%, showed the average-different-color intensities at 14.641 pixels per unit area, the lower intensity the lower hematocrit. So the LOC coupled with "ImageJ" exhibited their capabilities to investigate the sheep blood conditions, especially, this coupled technique consumed less time than the traditional hematology process. Copyright © 2013 by ASME.