Low-cost sheath-less microfluidic impedance cytometry for point-of-care applications

The present study introduces a microfluidic device that employs impedance measurement to accurately enumerate cells in suspension. Prior to the development of this device, impedance cytometry microfluidic chips necessitated the use of planar electrodes and sheath fluids, which complicated the system, or utilized small constricted regions that impeded cell movement and reduced operational efficiency. This newly developed device is capable of sensitive and rapid cell enumeration without the need for sheath fluid or planar electrodes, making it suitable for point-of-care applications. Instead of thin-film electrodes, the same needles used for liquid injection were implemented for impedance measurement, thus simplifying the device. The physical parameters of the device were designed using analytical and computer-aided simulations to determine the maximum dimensions required for sensitive detection of human cells. Simulations were also employed to investigate the effects of flow rates, cell shape, and injection method on device performance, and results were compared with experimental findings. Finally, this novel device was tested for its ability to count MCF7 cells at various flow rates and concentrations, with a limit of detection of 32.3 cells per μL being achieved in 1 mL/hr flow rate.