Soft Robotic Patterning of Liquids

Patterning of two or more liquids, either homogeneous in each phase or mixed with particles (including biological matter, such as cells and proteins), by controlling their fow dynamics, is relevant to several applications. Examples include dynamic spatial confnement of liquids in microfuidic systems (such as lab-on-a-chip and organ-on-a-chip devices) or structuring of polymers to modulate various properties (such as strength, conductivity, transparency and surface fnishing). State-ofthe-art strategies use various technologies, including positioners, shakers and acoustic actuators, which often combine limited versatility of mixing with signifcant inefciency, energy consumption, and noise, as well as tendency to increase the temperature of the liquids. Here, we describe a new kind of robotic mixers of liquids, based on electro-responsive smart materials (dielectric elastomer actuators). We show for the frst time how an efcient soft robotic device can be used to produce, via combinations of rotations and translations, various spatial patterns in liquids and maintain them stable for a few minutes. Moreover, we show that, as compared to a conventional orbital shaker, the new type of robotic device can mix liquids with a higher efcacy (~94% relative to~ 80%, after 8 min of mixing) and with a signifcantly lower increase of the liquids’ temperature (+1 °C relative to+ 5 °C, after 6 h of mixing). This is especially benefcial when mixing should occur according to controllable spatial features and should involve temperature-sensitive matter (such as biological cells, proteins, pre-polymers and other thermolabile molecules).