A novel method to produce small droplets from large nozzles.

This work presents a new method to generate droplets with diameters significantly smaller than the nozzle from which they emerge. The electrical waveform used to produce the jetting consists of a single square negative pulse. The negative edge of the pressure wave pulls the meniscus in, overturning the surface in such a way that a cavity is created. This cavity is then forced to collapse under the action of the positive edge of the pressure wave. This violent collapse produces a thin jet that eventually breaks up and produces droplets. Four droplet generator prototypes that demonstrate the capabilities of this novel mechanism are described. It is also shown that the proposed mechanism extends the existing limits of the commonly accepted inkjet operating regime.

Future, opportunities and challenges of inkjet technologies

Inkjet printing relies on the formation of small liquid droplets to deliver precise amounts of material to a substrate under digital control. Inkjet technology is becoming relatively mature and is of great industrial interest thanks to its flexibility for graphical printing and its potential use in less conventional applications such as additive manufacturing and the production of printed electronics and other functional devices. Its advantages over traditional methods of printing include the following: it produces little or no waste, it is versatile because several different methods exist, it is noncontact, and it does not require a master template so that printed patterns can be readily modified on demand. However, the technology is in need of further development to become mainstream in emerging applications such as additive manufacturing (3D printing). This review contains a description of conventional and less common inkjet methods and surveys the current applications of inkjet in industry. This is followed by specific examples of the barriers, limitations, and challenges faced by inkjet technology in both graphical printing and manufacturing. © 2013 by Begell House, Inc.

Jetting of complex fluids

Recent results from a number of UK academic inkjet research studies advance the understanding of complex fluid jetting behavior and may be of interest to the wider digital fabrication community for the enhancement of inkjet printing applications. © 2013 Society for Imaging Science and Technology.