Flexo-ionic effect of Ionic Liquid Crystal Elastomers for Soft Robotic Applications*

Strain gradient induced electricity (flexoelectricity) has been potential of a wide variety of applications such as bending sensors and micropower generators [1] [2]. Liquid crystals are fascinating materials with long-range molecular orientation, used for various applications  [3] [4] [5]. Liquid crystal elastomers are polymers, which exhibit liquid crystal properties. The first study of the flexo-ionic effect of the recently discovered ionic liquid crystal elastomers (iLCEs) is reported [6].  The measured flexo- ionic coefficients were found to strongly depend on the director alignment of the iLCE films and can be over 200 µC/m [7]. This value is orders of magnitude higher than the flexo-electric coefficient found in insulating liquid crystals and is comparable to the well-developed ionic polymers (iEAPs). The shortest response times, i.e., the largest bandwidth of the flexo-ionic responses, is achieved in planar alignment, when the director is uniformly parallel to the substrates. These results render high potential for iLCE-based devices for applications in soft robotics.