Geometry-Driven Inertial Focusing and Dielectrophoretic Separation of Blood Microparticles in Serpentine Lab-on-a-Disc Microchannels: A Numerical Study.

Precise, sheathless manipulation of blood microscale components remains a central challenge in microfluidics, particularly for Lab-on-a-Disc (LOD) platforms where inertial, rotational, and electrokinetic effects coexist. This simulation study proposes a two-phase particle-handling strategy that integrates rotation-assisted inertial focusing with high-frequency dielectrophoretic (DEP) sorting inside serpentine microchannels. In phase I, three channel geometries─an asymmetric sinusoidal, symmetric sinusoidal, and rectangular layout─were systematically evaluated to determine their ability to confine 3 μm particles using inertial lift, Dean vortices, and rotation-induced centrifugal and Coriolis forces. The asymmetric sinusoidal design produced the strongest hydrodynamic ordering, achieving focusing efficiencies above 96%, especially when combined with higher inlet velocity, narrow channel width, and increased serpentine turns. Rotational actuation further enhanced focusing, with the combined centrifugal-Coriolis contribution improving performance from ∼34% (no rotation) to ∼64% at 800 rad/s. In phase II, rotation was removed and the prefocused stream was directed into a DEP electrode array for label-free separation of red blood cells (RBCs) and platelets (PLTs). Here, the rectangular geometry─despite being the weakest inertial focuser─outperformed the sinusoidal channels by stabilizing particle trajectories before entering regions of steep ∇|E|2. Under |20| V and 10 GHz actuation, the device achieved ∼95% platelet isolation with concurrent ∼25% RBC diversion, while higher inlet velocities reduced separation due to shorter DEP residence times. The combined findings establish a unified inertial-DEP mechanism for high-precision, pump-free blood component handling on LOD systems and provide design rules for next-generation point-of-care hematology platforms.