An approach to design and fabrication of a piezo-actuated microdroplet generator

In this research, a piezo-actuated microdroplet printing device for drop on demand (DOD) is studied. Microdroplet devices are used in applications such as inkjet printing, rapid prototyping, and production of metal powder. An experimental device is designed and manufactured, in which the fluctuation of a flexible diaphragm-by a piezoelectric element-pushes the liquid out of the nozzle and produces droplets. The deflection of diaphragm due to different voltages is investigated by analytical and experimental study. In experiments, beside deflection voltage, the effect of suction and compression time and nozzle diameter on droplet size, droplet velocity, satellite droplets, and cutoff length is also investigated. High-speed camera is used to take photo of the formation of droplets. In order to calculate droplet diameter and velocity, outputs of high-speed camera are processed by MATLAB R2008a. Results obtained by analytical and experimental are in good agreement with each other and could be used to control droplet properties. It is shown that the device is able to produce droplet of diameter from 450 to 1,000 mu m. Velocity of droplet can be also controlled in a range of about 0.2 to 1.4 m/s. The repeatability is investigated by ink printing on a paper attached to a rotary table.