Numerical investigation of microfluidic sorting of microtissues

We characterize through simulation a microfluidic-based particle sorting approach instrumental in flow cytometry for quantifying microtissue features. The microtissues are represented herein as rigid spheres. The numerical solution employed draws on a Lagrangian–Lagrangian (LL), Smoothed Particle Hydrodynamics (SPH) approach for the simulation of the coupled fluid–rigid-body dynamics. The study sets out to first quantify the influence of the discretization resolution, numerical integration step size, and SPH marker spacing on the accuracy of the numerical solution. By considering the particle motion through the microfluidic device, we report particle surface stresses in the range of σ=[0.1,1.0]Pa; i.e., significantly lower than the critical value of 100Pa that would affect cell viability. Lift-off of non-neutrally buoyant particles in a rectangular channel flow at the target flow regime is investigated to gauge whether the particle shear stress is magnified as a result of dragging on the wall. Several channel designs are considered to assess the effect of channel shape on the performance of the particle sorting device. Moreover, it is shown that a deviation in flow rate does not influence the focusing of the particles at the channel outlet.