PolyJet 3D-printed microfluidic device that integrates hydrodynamic focusing of red blood cells and detection of ATP release.

In this paper, a PolyJet 3D printed microfluidic device was designed and fabricated (using a print-pause-print technique with liquid support) to hydrodynamically focus and deform red blood cells (RBCs) and also quantitate the release of adenosine triphosphate (ATP) as a function of the deformation forces. Average focusing widths of 70 µm and 28 µm were achieved by constricting the RBCs into well-defined narrow streams at flow rates of 10 µL min-1 and 30 µL min-1, respectively. Near real-time measurements of ATP release after focusing were carried out via a chemiluminescence reaction by introducing luciferin/luciferase mixture into the sheath flow side channels, mixing with any released ATP, and the resulting emitted light was captured with a PMT under the device. The dimensions of the 3D printed focusing/mixing channel were optimized downstream to increase the residence time of the RBCs over the PMT, leading to improvements in calibration sensitivity and the limit of detection for both flow rates. The optimized device was used to detect the ATP release from RBCs as a function of differing focusing widths. Finally, the effect of inhibiting ATP release from RBCs was also determined using diamide and glibenclamide. This PolyJet 3D printing approach clearly provides a method to modulate deformation forces on RBCs and measure the subsequent ATP release in near real-time.