Formation of liquid cone jet dependent on rise time of driving voltage

• Drop-on-demand operation of electrospray is required higher repetition rate.
• Difference in rise time of applied voltage has been neglected thus far.
• Formation time of Taylor-cone was observed in three kinds of rise times.
• Tiny difference in rise time made much larger difference in formation time.
• Optimization of rise time may enable drastic improvement of repetition rate.

This paper reports on transient dynamics of electrospray driven by high step voltage and its dependence on voltage rise time. Three rise times (50 ns, 1.8 μs, and 400 μs) were used to compare influence on liquid dynamics. It was found that, when the applied voltage exceeds a certain level, minute differences in voltage rise time significantly affect jet formation time. A rise time of 50 ns accelerates the jet ejection by about 20% compared with other rise times. These results indicate that optimization of rise time may enable drastic improvement of controllability of drop-on-demand electrospray.