Focusing-free impedimetric differentiation of red blood cells and leukemia cells: A system optimization

•A focusing-free microfluidic impedance flow cytometry is presented based on geometrical optimization of channel design.•The system is able to differentiate similar size cell types at high precision: red blood cells and lymphocytes.•Position-independent impedance signal was obtained by using a shallow channel that generates homogenous field distribution.•The system uses conventional microelectrodes and does not require any complicated fabrication or high-end signal processing units.•The microfluidic device was formed by a reversible sealing technique, hence the channel and the electrodes are reusable. A focusing-free microfluidic impedimetric cell detection system is developed. The effect of the channel dimensions, solution conductivity, excitation voltage, and particle size on impedimetric signal outputs were optimized to increase the sensitivity of the system. Conventional microfabrication techniques were adapted to obtain low height, resealable microchannels. The geometry optimization was performed by a combination of analytical, numerical and experimental approaches. The results demonstrate that reliable impedimetric particle differentiation can be achieved without any labeling or particle focusing. The system parameters were studied and rule-of-thumb design criteria were provided. Finally, using the developed system, red blood cells and leukemia cells were experimentally detected and differentiated. Thanks to its simplicity, the focusing-free cell differentiation system may find applications in several cellular diagnostic uses.