Dual-Size Particle (1 μm and 4 μm) Separation and Concentration in a High Throughput Double-Layer Microfluidic Channel

Size-based micro-particle separation is widely used in biomedical, environmental, and food-analysis applications, and inertial microfluidics offers a label-free, highthroughput platform suitable for such tasks. This study presents a novel double-layer inertial microfluidic device capable of separating and concentrating$1 \mu \mathrm{m}$particles without external fields. Compared with existing$1 \mu \mathrm{m}$targeted device, the proposed channel produces a substantially narrower focusing stream located closer to the channel wall, achieving a separation efficiency of 99.3 %. Experiments using bacteria and white blood cells (WBCs) further validated the separation performance, yielding efficiencies of 95 % for WBCs and 87 % for bacteria.