# Continuous Size-Based Particle Separation Using Inertial Force and Deterministic Lateral Displacement

## TL;DR

This paper introduces a microfluidic device that continuously separates particles by size using inertial forces and a special channel design, without needing labels or external fields.

## Contribution

The novel contribution is a compact microfluidic device combining inertial focusing and DLD for efficient, label-free particle separation.

## Key findings

- The device achieved over 93% separation efficiency for 8 μm and 15 μm glass beads.
- The design is adaptable for various applications like extracellular vesicles and drug-delivery carriers.
- The system operates under laminar flow and is scalable, cost-effective, and passive.

## Abstract

Continuous, label-free particle separation is essential for a broad range of biochemical and biomedical applications. Here, we present a microfluidic device that integrates inertial focusing and deterministic lateral displacement (DLD) within a compact channel architecture to achieve size-based particle sorting under laminar flow conditions. The design combines upstream curved channels for initial lateral positioning with downstream micropillar-embedded curved channels to enhance separation resolution. Theoretical analysis and numerical simulations were performed to optimize channel geometry and micropillar arrangement, predicting size-dependent lateral displacement driven by centrifugal forces and pillar-induced constraints. Experimental validation using glass beads of two distinct sizes (8 μm and 15 μm) demonstrated a separation efficiency exceeding 93% across a range of flow rates and particle concentrations. The device offers a simple, cost-effective, and scalable solution for passive particle sorting without external fields or labeling. The flexibility of the design configuration can be adapted for diverse applications, including extracellular vesicles, barcoded hydrogel particles, and engineered drug-delivery carriers.