Label-free electrical discrimination of cells at normal, apoptotic and necrotic status with a microfluidic device.

As a label-free alternative of conventional flow cytometry, chip-based impedance measurement for single cell analysis has attracted increasing attentions in recent years. In this paper, we designed a T-shape microchannel and fabricated a pair of gold electrodes located horizontally on each side of the microchannel using a transfer printing method. Instant electric signals of flowing-through single cells were then detected by connecting the electrodes to a Keithley resistance and capacitance measurement system. Experimental results based on the simultaneous measurement of resistance and capacitance demonstrated that HL-60 and SMMC-7721 cells could be differentiated effectively. Moreover, SMMC-7721 cells at normal, apoptotic and necrotic status can also be discriminated in the flow. We discussed the possible mechanism for the discrimination of cell size and cell status by electrical analysis, and it is believed that the improvement of detection with our design results from more uniform distribution of the electric field. This microfluidic design may potentially become a promising approach for the label-free cell sorting and screening.