Hydrodynamic focusing through cross-filtration in a parallel microfluidic device

Focusing is a necessary prior step for analysing particles or cells in a fluid flow. Hydrodynamic focusing is the gold-standard method used in traditional flow-cytometer in order to get cells aligned as they pass through the detection/interrogation region. In the recent years, microfluidic devices with different configurations for achieving hydrodynamic focusing have been proposed. However, the micro-channel configurations till now adopted have the main drawback of requiring multiple inlets, and this bring to a high complexity if parallelization has to be introduced into the device. In this work all these limitations are overcome by realizing a parallelized microfluidic device that allows to achieve hydrodynamic focusing by needing of only one inlet. This is obtained by introducing a cross-filter region at each one of the parallel channels. Different filter geometries have been exploited, and the focusing power of each devices has been tested by using both polystyrene beads and leukemic cells.