Soft robotics

If you polymerize and lightly crosslink a nematic liquid crystal, in a uniformly aligned state, into a rubber, you make an amazing material called a liquid crystal elastomer (LCE). They have the extraordinary ability to contract along the nematic director and expand in the two perpendicular dimensions as a result of a phase transition from the nematic to the isotropic state. This transition can be induced by heating or, with appropriate additives, by light irradiation. The shape change can be up to several 100%, so an LCE can be a very useful artificial muscle. This is all the more so since it is soft: it is, after all, a rubber.

Together with the organic macromolecular chemistry group of Prof. Rudolf Zentel, Johannes-Gutenberg University Mainz, Germany, we recently demonstrated that LCE shells, made using a microfluidic production technique, exhibit a quite unusual actuation mode, which gives them the function of micropumps [1]. We are now working on developing this concept to LCE actuators with a variety of shapes, and the target is to employ them in soft active components for robots. Either small, entirely soft robotic elements with limited but unique function, or as a soft actuator playing a particular role within a more complex robot with hard and soft components. To this end we are collaborating with Mathew Schwarz and Prof. Jaeheung Park at the Digital Human Research Center at Seoul National University/Advanced Institutes of Convergence Technology, South Korea.


[1] One-piece micropumps from liquid crystalline core-shell particles Eva-Kristina Fleischmann, Hsin-Ling Liang, Nadia Kapernaum, Frank Giesselmann, Jan P.F. Lagerwall, and Rudolf Zentel Nat. Commun., 8, (2012), DOI: 10.1038/ncomms2193
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