On-chip single-cell lysis for extracting intracellular material

A newly designed microfluidic chip with a pinched-channel structure and two pairs of electrodes has been developed to enable easier single-cell capture and lysis. The function of the chip was evaluated by introducing zucchini protoplast cells into the channel. In the first experiment, we attempted to break a cell using the through force of a triangular pinched structure via electroosmotic flow generated by outer electrodes. The pinched structure appeared to break the cell without applying the electric field to the cell directly; however, in this case, the breakable size of the cell was limited by the width of the pinched structure. The next attempt was to break cells regardless of their sizes using a pair of inner electrodes located under the pinched structure. The inner electrodes generated a gradient electric field around the captured cell by applying an alternative voltage to the electrodes. Captured cells with a diameter from 40 to 85 mu m could be broken using the inner electrodes with a trapezoidal pinched structure, and the cells were successfully broken at 10 V-pp or less at a frequency of 1 MHz.