Figure 3. Single-cell printing efficiency was evaluated by printing GFP expressing E. coli cells on glass slides.

Each spot of a 10 × 10 array (A) was classified via bright-field and fluorescent microscopy either as void droplet (B), droplet containing a single cell (C) or droplet containing multiple cells (D). The experiment was performed three times for each of three different dispenser chips. (E) The relative occurrence of events is plotted for each of the three tested dispensing chips. The corresponding CV was calculated based on the standard deviation of three repeated experiments. In total, 845 out of 900 spots produced in 3 × 3 experiments contained a single-cell, resulting in an averaged single-cell printing efficiency of 93%.