2.2 Flow characterization of the MO–MPS
Flow velocity was measured by the particle tracking velocimetry (PTV) method using fluorescent microbeads with a diameter of 1.17 µm (17687, Polysciences, USA). The fluorescent microbeads were suspended in ultra-pure water with Tween20 (103168, MP Biomedicals, USA). After filling the microchannels, the suspension was perfused by the stirrer-based micropump at between 1300 and 2800 rpm. The flowing microbeads in the microchannels were observed by a high-speed camera (MEMRECAM HX-3, nac Image Technology Inc., Japan) installed into a fluorescence microscope (IX71, Olympus, Japan). The flow rates in each organ were calculated from the velocities of the flowing fluorescent bead measured using ImageJ.