Printing Technology Uses Sound Waves to Control Size of Liquid Droplets

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 ten times more viscous than water. Many fluids of interest to researchers are far more viscous; for example, biopolymer and cell-laden solutions that 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 more difficult to optimize printing parameters to control droplet sizes.