The nozzle-less structure of the ultrasonic inkjet system is advantageous leading to printability of inks of a wide range of viscosities without clogging. In the ultrasonic inkjet head, dot placement accuracy of high-viscosity ink was as same as that of standard viscosity ink. The shape of meniscus changes as the viscosity increases. Using the printability of high-viscosity inks, the ultrasonic inkjet printing was applied for LED packaging by depositing silicone resin and fabrication of solution-processed organic thin-film transistors by printing high-viscosity organic conducting ink, PEDOT:PSS.