Inertial Microfluidics Enabling Clinical Research

Abstract

Fast and accurate interrogation of complex samples containing diseased cells or pathogens is important to make informed decisions on clinical and public health issues. Inertial microfluidics has been increasingly employed for such investigations to isolate target bioparticles from liquid samples with size and/or deformability-based manipulation. This phenomenon is especially useful for the clinic, owing to its rapid, label-free nature of target enrichment that enables further downstream assays. Inertial microfluidics leverages the principle of inertial focusing, which relies on the balance of inertial and viscous forces on particles to align them into size-dependent laminar streamlines. Several distinct microfluidic channel geometries (e.g., straight, curved, spiral, contraction-expansion array) have been optimized to achieve inertial focusing for a variety of purposes, including particle purification and enrichment, solution exchange, and particle alignment for on-chip assays. In this review, we will discuss how inertial microfluidics technology has contributed to improving accuracy of various assays to provide clinically relevant information. This comprehensive review expands upon studies examining both endogenous and exogenous targets from real-world samples, highlights notable hybrid devices with dual functions, and comments on the evolving outlook of the field.

Microfluidic-Based Technologies for CTC Isolation: A Review of 10 Years of Intense Efforts towards Liquid Biopsy

“…Another hydrodynamic size separation technology utilizes inertial focusing to create size-dependent equilibrium positions within the channel. This phenomenon relies on the balance of lift forces arising from the curvature of the velocity profile (the shear gradient lift) and the interaction between the cell and the channel wall (the wall effect lift) for Reynold number of the order of 1 or greater [61]. It results in a lateral ordering of cells according to their size: larger cells migrate to the channel centerline.…”

Advances and enabling technologies for phase-specific cell cycle synchronisation

“…121,122 Moreover, the microchannel dimensions in these devices are comparably larger than the cell's size that eliminate the problem of clogging within the channels. [123][124][125] Cell cycle synchronisation by inertial microfluidics has been achieved using a spiral microfluidic device by combining the effects of inertial forces and Dean drag forces. Warkiani and colleagues used inertial and Dean drag forces in spiral microchannels to perform high throughput, large scale cell synchronisation of CHO and hMSCs.…”

Low‐cost polymer‐film spiral inertial microfluidic device for label‐free separation of malignant tumor cells

“…In passive devices, separation is commonly based on the difference in the dynamic equilibrium positions. Classical technologies for passive separation include inertial microfluidics [21][22][23], viscoelastic microfluidics [24][25][26], deterministic lateral displacement [27,28], and hydrodynamic filtration [29]. As a passive technology, inertial microfluidics [21-23, 30, 31] has attracted increasing interest due to its advantages of label-free and sheath-free operation, simple channel structure, and passive working principle.…”