Inkjet printing is a widely known technology to generate small droplets for accurate patterning of functional materials. The droplet generation is a complex interaction of the internal pump dimensions, the piezo electric driving conditions and the liquid properties. Standard drop formation is executed in the so-called slosh mode, all fluid in the pump moves against the surface tension spring. This slosh mode produces droplets with a diameter that is of the order of the nozzle diameter. As there is a need for smaller and smaller patterns, especially for non-graphical applications, while still maintaining a robust printing process, i.e. without clogging of the nozzle, it is very interesting to generate smaller size droplets than are made with the slosh model. In this paper it is shown theoretically and experimentally that such droplets can be made via higher order meniscus modes. In such a mode the fluid motion is confined to the very close environment of the meniscus. When the print head and pulse are designed such that an overtone of the waveguide coincides with a symmetric resonance mode of the meniscus it is possible to make stable droplets that are more than an order of magnitude smaller than the standard droplet.
|Title||Ultra small droplet generation in inkjet printing by higher order meniscus oscillations|
Philips Personal Health, Technical Expert Group, Drachten, The Netherlands
|Session||21. Bubbles and droplets IV|
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