Flowing cells in a wavy microchannel for effective size-based cell sorting

Currently cancer is becoming one of the leading causes of human death. One of the major difficulties towards achieving radical cure in cancer is due to malignant metastasis, which directly causes overwhelming obstacles in therapeutic management and early diagnosis. The ability to isolate rare circulating tumor cells (CTCs), the seeds for cancer metastasis, enables much less invasive approach for cancer diagnosis and prognosis. New microfluidic technologies for high throughput, high accuracy cell sorting of complex biological samples are highly sought after to address the challenge in rare cell isolation.

In this research, Dr Ai's team presented a novel inertial focusing and sorting device with a series of reverse wavy channel structures consisting of semi-circular sections that generate a periodically reversed hydrodynamic flow perpendicular to the main flow direction. The balance between two kinds of hydrodynamic forces resulted in a size-dependent lateral particle movement across the channel, which finally achieved size-based separation of target cells from non-target cells. The principal investigator, SUTD's Dr Ai said: "Compared to active methods, the passive inertial focusing with the use of hydrodynamic forces exhibit the merits of a simplified setup, high-throughput and low-energy consumption. Moreover, the linear array of these repeated wavy channel units also facilitates easy horizontal (2D) and vertical (3D) parallelization of multiple channels, which provides great potential for high-throughput cell sorting in practical biomedical applications." The team has applied the developed sorting technology for high-throughput isolation of cancer cells from whole blood samples.