Enhanced particle detection in a spinning helical microchannel

Abstract

The present study is focused on developing a CD4+ T-cell counting device for HIV/AIDS monitoring with the aid of a helical microchannel. Numerical studies were carried out in a stationary and a spinning helical microchannel to compare the effect of pressure drop and flow distribution for a high pressure and varying spinning speed and thereby stable conditions for the experiment was derived out. For the experiment, 10, μm sized particles were used for visualization with a fluorescence microscope system. A sample with the viscosity as that of blood and other samples with different viscosities were also prepared to determine the effect of density and viscosity in aligning the particles. The samples were then injected into the channel and the particles were then traced in stationary and spinning channels. The channels were rotated using a DC motor controlled by an Arduino board with a Bluetooth shield. It was found that when the sample cartridge was made stationary, no particle alignment was achieved for a medium with density lower than that of the particles, but when it was spun at 2000–3000, rpm for 1–4, min, an alignment was obtained at the top of the channel facilitating detection of those particles. Since an alignment of particles was achieved for a medium with density as that of blood plasma, the same approach can be applied for aligning and counting CD4+ T-lymphocytes in whole blood samples collected from patients.