The experiment illustrates the difference in heat generation when creating the same displacement depending on the driving signal. (a) Thermal images corresponding to the driving period and the number of driven channels under bipolar signal application, (b) temperature graph based on driving period when four channels are operated, (c) temperature graph based on the number of channels when the driving period is 16μs. For unipolar signal application: (d) thermal images based on driving period and number of driven channels, (e) temperature graph based on driving period when four channels are operated, (f) temperature graph based on the number of channels when the driving period is 16μs.

(a) Time-lapse images of the dispensed liquid, (d) optical images of hydrogels printed on untreated substrate (left) and hydrophobic glass (right), (e) printing results with hydrogels at 1mm intervals, 3mm intervals, and 5mm intervals from left to right.