Mallorie, C. | Search bioRxiv

bioRxiv2025

Optimization of Injection-Molded Thermoplastic Microfluidic Chip Design with Numerical Modeling and Two-Photon Polymerization 3D Printing

Precise microfluidic geometries are critical for particle dynamics studies but challenging to fabricate repeatably and rigidly. This study aims to experimentally validate computational fluid dynamics predictions of particle trajectories in cross-slot junctions, overcoming previous manufacturing limitations. We developed a novel fabrication process combining precisely bonded injection-molded chips with integrated two-photon polymerization 3D-printed junction geometries. Using this approach, experimental measurements of microsphere trajectories via the Cytovale system successfully validated predictions, confirming the influence of stenosis and outlet widths. This work establishes a robust methodology for optimizing microfluidic designs by synergizing advanced manufacturing and simulation, enabling precise experimental investigations.

bioengineering↗

bioRxiv2023

Numerical analysis of flow anisotropy in rotated-square deterministic lateral displacement devices at moderate Reynolds number

Deterministic lateral displacement (DLD) is a microfluidic method for accurately separating particles by size or deformability. Recent efforts to operate DLD devices in the inertial, rather than in the Stokes, flow regime have been hindered by a loss of separation efficiency and difficulty predicting the separation behaviour. One factor contributing to these problems is the onset of inertia-induced flow anisotropy where the average flow direction does not align with the direction of the pressure gradient in the device. We use the lattice-Boltzmann method to simulate two-dimensional flow through a rotated-square DLD geometry with circular pillars at Reynolds number up to 100 for different gap sizes and rotation angles. We find that anisotropy in this geometry is a non-monotonous function of Reynolds number and can be positive or negative. This finding is in contradiction to the naive expectation that inertia would always drive flow along principal direction of the pillar array. Anisotropy tends to increase in magnitude with gap size and rotation angle. By analysing the traction distribution along the pillar surface, we explain how the change of the flow field upon increasing inertia leads to the observed trends of anisotropy. Our work contributes to a better understanding of the inertial flow behaviour in ordered cylindrical porous media, and might contribute to improved DLD designs for operation in the inertial regime.

bioengineering↗