The ultrasonics humidifiers use a piezoelectric cristal when works atomize water in little drops(make like fog). the cristal ever be cover by water in the first pics they use a porous material (white) to absorve some water to up side of cristal.
Other factor is the shape of outflow more or less narrow to adjust the plume.
Switch on off the current do the pulses effect. The usb humidifiers works to 5v. adjust the circuit and with some more power enhance the effect.