Laser-printed microfluidic paper analytical device for rapid separation of whole blood and hematocrit estimation by smartphone readout.

In contrast to the widely used centrifugation and hematocrit method, this report presents a simple-to-fabricate paper microfluidic device (µPAD) for the estimation of RBC and hematocrit using µPAD dimensions, histogram, relative colorimetric intensity, and threshold algorithms. With laser printing (LP) technology, LP-µPAD was fabricated to fractionate freshly collected whole blood from male Wistar rats and human blood samples. Fluid flow on the LP-µPAD was tested to assess the capability of the toner-fortified hydrophobic barrier to confine fluid within designated hydrophilic regions. Taking 30 µl of different percentages of whole blood from rats, the LP-µPAD was evaluated to concentrate RBCs at sample zones to estimate hematocrit levels in rat and human blood samples. The LP-µPAD demonstrated promising capability to confine fluids within the hydrophobic barrier and separate blood samples. Whilst the histogram revealed one peak in whole blood, relative colorimetric intensity methods predicted a critical point (32.00%) useful for determining anemic condition, and the threshold algorithm was employed for the visualization of the captured RBCs at the sample zone. Likewise, with the dimension of the µPAD geometry, hematocrit levels were determined in all the samples on a par with the hematocrit method. Thus, LP-µPAD is a frugal alternative to wax printing and effective for hematocrit estimation at the point of care.