Micro-particle emission device for generating highly viscous picolitre-sized droplets

Abstract An inkjet device for emitting picolitre-sized droplets of liquid materials with viscosities up to 1 Pa s, approximately 1000 times greater than that of pure water, was developed in this study. The device consists of a glass capillary tube with a micro-sized aperture and a thin metal rod driven by a piezoelectric actuator to push out the sample liquid contained in the glass nozzle from its aperture. The precise control of the driving voltage of the actuator enables the generation of picolitre-sized droplets from various liquid types. In this study, we discuss the challenges of applying inkjet technology to high-viscosity liquids and measuring liquid properties by observing the flight of emitted microdroplets. Furthermore, we demonstrated the ejection behavior of Newtonian and non-Newtonian liquids over a wide viscosity range, including liquid food and paint.