Extended Data Fig. 7: Spiral-shaped inertial microfluidic channel for cell focusing and imaging.
From: Epistasis regulates genetic control of cardiac hypertrophy
a, Schematic of an inertial microfluidic cell focusing device. Cell suspensions and fresh medium were introduced into the microfluidic device through the cell and sheath flow inlets, respectively, using a syringe pump and flowed down the 5-loop spiral microchannel with the same flow rate (1.2 mL/min). Inserted microscopy images show that randomly dispersed cells were separated by size and bifurcated into the top (large cells) or bottom (small cells) outlets. Scale bar, 10 μm. Outlet channels are connected to straight observation channels where flowing cells were further focused in the channel height direction and imaged using a high-speed camera for morphological feature extraction (Fig. 6c). b, Schematic of the cell focusing principle. The spiral microchannel has a cross-section with a slanted ceiling, resulting in different depths at the inner and outer side of the microchannel. This geometry induces strong Dean vortices (counter rotating vortices in the plane perpendicular to the main flow direction) in the outer half of the microchannel cross-section. The interplay between drag forces (FD) induced by Dean vortices and lift forces (FL) due to shear gradient and the channel wall drives cell transverse migration towards equilibrium positions where the net force is zero. As a result, large cells in a heterogeneous population progressively migrate closer to the inner channel wall, while smaller cells move towards the outer channel wall. Details about microchannel dimensions can be found in Methods.
