SUMMARY

Inkjet printing is a method of fluid ejection utilized when fine control of droplet generation and placement are required. These devices exhibit excellent controllability and repeatability in the atomization of low viscosity fluids. However, at viscosities greater than approximately 10 mPa∙s, atomization with inkjets can produce undesirable behavior, such as the creation of satellite droplets, or cease fluid ejection completely. Horn-based ultrasonic atomization is a new method for fluid ejection that employs a resonant acoustic field that is focused by a horn structure connected to the fluid cavity and terminating at the ejection nozzle. The acoustics and fluid mechanics of horn-based ultrasonic atomizers have been previously characterized for low viscosity Newtonian fluids. Achieving controlled ejection of highly viscous fluids and minimizing the unwanted effects of atomization requires an in-depth understanding of inkjet acoustics, including prediction of the pressure distribution in the ejector fluid cavity and fluid-transducer interactions. This proposal seeks to develop a fundamental understanding of the acoustics and piezoelectric transducer coupling underlying the operation of inkjets and horn-based ultrasonic atomizers focusing on ejection of highly viscous fluids. The understanding gained by this work will be applied to explore new concepts of piezoelectric transducer-driven fluid atomizers aiming to achieve ejection of high viscosity fluids.