Heat Transfer and Fluid Flow Investigations in PDMS Microchannel Heat Sinks Fabricated by Means of a Low-Cost 3D Printer

Polydimethylsiloxane (PDMS), due to its remarkable properties such as optical transparency and ability to easily mold, is one of the most popular polymers used in micro- and nanofluidics. Furthermore, 3D printing technology due to its low cost and simplicity is also gaining a great interest among the microfluidic community. In this work, the potential of 3D printing is shown to produce microfluidic devices, their ability for studying flows and heat transfer of nanofluids, and their applicability as a heat sink device. The low-cost fused deposition modeling 3D printing technique was combined with a PDMS casting technique for the microfluidic device fabrication. The potential of this technique was experimentally demonstrated by fluid flow and heat transfer investigations using different fluids, such as distilled water-, alumina (Al2O3)-, and iron oxide (Fe3O4)-based nanofluids. The simplicity, low-cost, and unique features of the proposed heat sink device may provide a promising way to investigate nanofluids’ flow and heat transfer phenomena that are not possible to be studied by the current traditional systems

Experimental perspective on the mechanisms for near-wall accumulation of platelet-size particles in pressure-driven red blood cell suspension flows

The root causes for the mechanisms for margination and near-wall platelet accumulation have previously been investigated by numerical simulations and the results pointed to two main contributors. First, the behavior of the red blood cells (RBCs), namely, traveling around the centerline and formation of the cell-free layer (CFL). Second, the multiple interactions between RBCs and platelets. However, these mechanisms remain to be experimentally verified. In this work, we focus on the dynamics of platelet-size particles inside RBC flows through straight-square microchannels. We used rigid particles with nominal diameter of 2.47 μm to mimic platelets. The three-dimensional (3D) coordinates (x, y, z) and velocity components (vx, vy, vz) of the platelet-size particles inside the RBC-suspension flows were measured by means of the general defocusing particle tracking method (GDPT). From the 3D particle trajectories, we were able to investigate the root causes for margination and near-wall particle accumulation. The overall picture points to the RBCs as the dictator of the near-wall particle accumulation and margination. We show that the phenomenon of margination is an irreversible, fast, unpredictable and discontinuous process, and more importantly it can be an opportunity-based event