Label-Free Multitarget Separation of Particles and Cells under Flow Using Acoustic, Electrophoretic, and Hydrodynamic Forces

Multiplex separation of mixed biological samples is essential in a considerable portion of biomedical research and clinical applications. An automated and operator-independent process for the separation of samples is highly sought after. There is a significant unmet need for methods that can perform fractionation of small volumes of multicomponent mixtures. Herein, we design an integrated chip that combines acoustic and electric fields to enable efficient and label-free separation of multiple different cells and particles under flow. To facilitate the connection of multiple sorting mechanisms in tandem, we investigate the electroosmosis (EO)-induced deterministic lateral displacement (DLD) separation in a combined pressure- and DC field-driven flow and exploit the combination of the bipolar electrode (BPE) focusing and surface acoustic wave (SAW) sorting modules. We successfully integrate four sequential microfluidic modules for multitarget separation within a single platform: (i) sorting particles and cells relying on the size and surface charge by adjusting the flow rate and electric field using a DLD array; (ii) alignment of cells or particles within a microfluidic channel by a bipolar electrode; (iii) separation of particles based on compressibility and density by the acoustic force; and (iv) separation of viable and nonviable cells using dielectric properties via the dielectrophoresis (DEP) force. As a proof of principle, we demonstrate the sorting of multiple cell and particle types (polystyrene (PS) particles, oil droplets, and viable and nonviable yeast cells) with high efficiency. This integrated microfluidic platform combines multiple functional components and, with its ability to noninvasively sort multiple targeted cells in a label-free manner relying on different properties, is compatible with high-definition imaging, showing great potential in diverse diagnostic and analysis applications.