A simple microfluidic method to select, isolate, and manipulate single-cells in mechanical and biochemical assays

This article describes a simple and low-tech microfluidic method for single-cell experimentation, which permits cell selection without stress, cell manipulation with fine control, and passive self-exclusion of all undesired super-micronic particles. The method requires only conventional soft lithography microfabrication techniques and is applicable to any microfluidic single-cell circuitry. The principle relies on a bypass plugged in parallel with a single-cell assay device and collecting 97% of the flow rate. Cell selection into the single cell device is performed by moving the cell of interest back and forth in the vicinity of the junction between the bypass and the analysis circuitry. Cell navigation is finely controlled by hydrostatic pressure via centimetre-scale actuation of external macroscopic reservoirs connected to the device. We provide successful examples of biomechanical and biochemical assays on living human leukocytes passing through 4 mm wide capillaries. The blebbing process dynamics are monitored by conventional 24 fps videomicroscopy and subcellular cytoskeleton organization is imaged by on-chip immunostaining.