University of Cambridge research could help solve inkjet paradox

The University of Cambridge has announced the publication of research into droplet formation that could help solve the so-called inkjet paradox of creating tiny droplets from viscous fluids.

Scientists from the University's Department of Engineering and Institute for Manufacturing have developed a method for predicting whether a filament of fluid will condense along its length to form a single droplet, or collapse into multiple droplets.

The research, which was co-authored by Dr Alfonso Pita and Dr Rafa Pita and published in the journal Physical Review Letters last Friday (17 February), could aid in designing future generations of inkjet printheads.

A large-scale, fully controlled model of a printhead was developed to recreate the process of droplet generation, which was recorded using ultrafast imaging technologies to observe droplet formation within a simple fluid solution of water and glycerine.

The scientists observed how, when the solution was sufficiently viscous, long threads, or filaments (rather than drops), were formed several centimeters long and one tenth of a millimeter thick. These long filaments would slowly contract to form a single large drop, rather than breaking up into several smaller drops.

Professor Ian Hutchings, who led the University of Cambridge team, said: "Our regime diagram can predict whether or not a certain liquid can be broken into useful droplets; it is, in simple words, a rule of thumb to determine whether a liquid can be used to produce a droplet or not."

Dr Alfonso Pita added: "For the first time in an experimental and quantitative way, the ultimate behaviour of a filament under nothing but the action of viscous and surface tension forces has been explored."

Barney Cox, senior consultant at Infotrends, said that the research showed promise to help improve current inkjet technologies, both heads and fluids.

"Hopefully, it will enable the development of printing systems that overcome current limitations in speed, cost, reliability and application," he added. "Ultimately, these developments should help printing remain competitive in the current graphical and information markets it addresses, as well making it suitable for other industries and manufacturing processes."