Breakdown of deterministic lateral displacement efficiency for non-dilute suspensions: A numerical study

Area of Science:

• Microfluidics
• Biophysics
• Particle Separation

Background:

• Deterministic lateral displacement (DLD) is a widely used microfluidic technique for particle separation.
• DLD devices are typically designed and optimized for dilute suspensions.
• The performance of DLD devices with dense suspensions, such as blood, remains poorly understood.

Purpose of the Study:

• To investigate the impact of particle volume fraction on the efficiency of deterministic lateral displacement (DLD) devices.
• To determine how dense red blood cell (RBC) suspensions affect DLD-based particle separation.
• To analyze the robustness of different DLD modes under high particle concentrations.

Main Methods:

• Utilized 3D simulations incorporating immersed-boundary, lattice-Boltzmann, and finite-element methods.
• Modeled the flow dynamics of red blood cells (RBCs) within various DLD device geometries.
• Quantified DLD device efficiency using failure probabilities and particle counts at device outlets.

Main Results:

• The displacement mode in DLD devices breaks down significantly with increased RBC volume fraction.
• The zigzag mode of DLD demonstrates relative robustness even at higher particle concentrations.
• Separating larger particles from dense RBCs is more feasible than separating smaller particles.

Conclusions:

• Increased particle volume fraction in suspensions negatively impacts the efficiency of deterministic lateral displacement (DLD) devices.
• Non-deterministic particle collisions in dense suspensions interfere with the predictable operation of DLD devices.
• Dense suspension effects generally hinder efficient particle separation in deterministic microfluidic systems.