Harvard University researchers have developed a new printing method that uses soundwaves to generate droplets from liquids with an unprecedented range of composition and viscosity. This technique could enable the manufacture of many new biopharmaceuticals, cosmetics, and food, and expand the possibilities of optical and conductive materials.
“By harnessing acoustic forces, we have created a new technology that enables myriad materials to be printed in a drop-on-demand manner,” said Jennifer Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences and the senior author of the paper. Lewis is also a core faculty member at the Wyss Institute for Biologically Inspired Engineering and the Jianming Yu Professor of Arts and Sciences at Harvard.
The research is published in Science Advances.
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Liquid droplets are used in many applications, from printing ink on paper to creating microcapsules for drug delivery. Inkjet printing is the most common technique used to pattern liquid droplets, but it’s only suitable for liquids that are roughly 10 times more viscous than water. Yet many fluids of interest to researchers are far more viscous. For example, biopolymer and cell-laden solutions, which are vital for biopharmaceuticals and bioprinting, are at least 100 times more viscous than water. Some sugar-based biopolymers could be as viscous as honey, which is 25,000 times more viscous than water.
The viscosity of these fluids also changes dramatically with temperature and composition, making it ever more difficult to optimize printing parameters to control droplet sizes.