Accurate profiling of blood components in microliter with position-insensitive coplanar electrodes-based cytometry

Differentiating and counting blood cell subtypes are essential for medical diagnosis. Microfluidic impedance-based cytometry has been discussed in the past decade as cost-effective and label-free cell classification using multi-cellular electrical properties. The coplanar electrode configuration is particularly desirable since it can dramatically reduce the device fabrication complexity and cost. However, very few research demonstrated accurate leukocyte classification with coplanar electrodes due to the in-channel height-dependent sensitivity variation in cell profiling caused by nonuniform electric field. Herein we propose a microfluidic high-throughput (up to 1000 cells/second) impedance cytometry with a unique coplanar electrode configuration to eliminate height-dependent sensitivity variation for accurate electrical cell profiling. The proposed position-insensitive cytometry enables an accurate 3-part leukocyte classification and quantification comparable with fluorescence-based cytometry. In addition, unlike conventional leukocyte classification approaches that require red blood cell lysis to remove noises caused by erythrocytes, the position-insensitive cytometry can distinguish erythrocytes simply based on cell sizes and characterize the mean size and distribution width of erythrocytes with leukocyte classification simultaneously, offering red blood cell indices for diagnosis with reduced test time. The position-insensitive impedance cytometry has the great potential to provide a point-of-care blood analysis for clinical utility in many diseases (i.e., infections, cancers and HIV).