Ejection of a single cell in a single droplet using piezoelectric inkjet head

The inkjet ejection technology used in printers has been adopted and research has been conducted on manufacturing artificial tissue through micronozzle ejection of small droplets containing multiple cells by patterning them. However, stable injection of cells has proven difficult, owing to the frequent occurrence of nozzle clogging. Almost no research has been conducted on a method for driving inkjet heads for the purpose of stably ejecting cells. In the present research, a glass capillary that enabled viewing of the nozzle section was used, and a piezoelectric inkjet head was developed, the movement of cells ejected from the nozzle tip was analyzed, and a method for stably ejecting cells was verified. In addition, the pull-push method was compared with the push-pull method for the voltage waveform applied to the piezoelectric element of the head when the cells were ejected. The push-pull method was found to be more suitable for their stable ejection. Further, a state where one droplet of ejected fluid contained only one cell was realized by detecting the position of the cell in the nozzle section and utilizing these position data. Thus, a method for more precise patterning at targeted positions was established.