Development of microfluidic platform capable of characterizing cytoplasmic viscosity, cytoplasmic conductivity and specific membrane capacitance of single cells

This paper presents a microfluidic platform capable of characterizing cytoplasmic viscosity mu(cy), cytoplasmic conductivity sigma(cy) and specific membrane capacitance C-sm of single cells continuously. A travelling cell is forced to squeeze through a major microfluidic constriction channel and aspirated into a side microfluidic constriction channel with cell aspiration length and impedance variations captured and translated into intrinsic markers of mu(cy), sigma(cy) and C-sm based on an equivalent biophysical model. As a demonstration, mu(cy), sigma(cy) and C-sm of hundreds of HL-60 cells that were native or treated by Cytochalasin D (CD for cytoskeleton modulation) or Concanavalin A (ConA for membrane regulation) were quantified where high success rates of cell type classification were found, which were 88.0% for HL-60 cells vs. HL-60 + CD cells and 75.6% for HL-60 cells vs. HL-60 + ConA cells. Furthermore, the microfluidic system was used to process granulocytes from two healthy donors where comparable distributions of mu(cy), sigma(cy) and C-sm and low success rates of cell type classification (< 60%) were found, indicating that there may exist ranges of mu(cy) (10-20 Pa center dot s), sigma(cy) (0.4-0.6 S/m) and C-sm (2.0-3.0 mu F/cm(2)) for normal granulocytes. In summary, the developed microfluidic system can collect cytoplasmic viscosity, cytoplasmic conductivity and specific membrane capacitance from hundreds of single cells simultaneously and may provide new perspective for future developments of hematology analyzers.