Harnessing Soft Elasticity of Liquid Crystal Elastomers to Achieve Low Voltage Driven Actuation

Abstract

Dielectric elastomers (DE) are soft electromechanical transducers that can generate large, rapid, and reversible deformation under an electric field. Despite being one of the leading candidates for soft actuators, the widespread applications of dielectric elastomers are restricted by the high voltage requirement (1–10 kV) for thin film DEs, which increases the system complexity and pose a potential safety threat for humans. In this work, a new class of dielectric elastomer actuators using liquid crystal elastomers (DLCEs) is reported. Soft elasticity of DLCEs and the high dielectric constant are utilized to reduce the actuation voltage. Freestanding DLCE thin film actuators (≈20 µm) are fabricated, which can generate large actuation strains (≈88%) at 400 V, an input voltage almost one order of magnitude lower compared to typical dielectric elastomers actuators. This allows to develop a soft tunable bilayer DE lens, which can achieve a 21% focal length variation at 500 V.

Electrically Driven Crosslinked Liquid Crystal Polymers†

“…Reproduced with permission. [ 52 ] Copyright 2023 Wiley Online Library. (f) Schematics of LCE film and its transformation in shape upon the application of voltage.…”

“…To improve the electromechanical performance of the DLCE, Cai et al . [ 52 ] developed a novel DLCE actuator using a two‐step polymerization method. DLCE materials possess soft elasticity and a high dielectric constant, owing to which they can operate at relatively low driving voltages compared with traditional dielectric elastomers.…”

Electrostatically Powered Multimode Liquid Crystalline Elastomer Actuators

“…39 −41 Recently, such type of LCE has shown low voltage actuation (∼300 V). 42 However, the degree of freedom and response rate are limited due to the tethered electrodes and sandwich structures; thus, the mechanical property of the electrode always should be considered. More importantly, shape-changing directions can only morph configurations with predetermined molecular patterns in LCEs.…”

“…Typically, heat triggers (e.g., thermal, photothermal, and electrothermal) are used for reversible shape morphing in the LCEs by disrupting the anisotropic molecular order. ,− For instance, LCE actuators are fabricated by embedding stretchable serpentine heating wires to control the spatial distribution of heat for multimode actuation . However, these types of actuators may not achieve fast cyclic speed for robotic applications in an environment, where the temperature increase is limited. , Instead, the electrically driven actuation of LCEs shows a rapid response enabled by facile integration of unit actuator elements for complex, high degree-of-freedom motions that are more suitable for robotic applications. − Several studies have demonstrated electromechanical actuation of LCEs similar to dielectric actuators to drive Maxwell stress-introduced strain. − Recently, such type of LCE has shown low voltage actuation (∼300 V) . However, the degree of freedom and response rate are limited due to the tethered electrodes and sandwich structures; thus, the mechanical property of the electrode always should be considered.…”

Ultra Rate‐Dependent Pressure Sensitive Adhesives Enabled by Soft Elasticity of Liquid Crystal Elastomers

“…[11][12][13] The unique actuation properties of LCE have been explored in various studies for applications in soft robotics, biomedical devices, etc. [14][15][16][17][18] On the other hand, soft elasticity is observed in the uniaxial tension of LCE, as a plateau of constant low stress for a large deformation arising from the rotation of liquid crystal mesogens with little increase in the elastic energy. [8,[19][20][21] Hence compared to a routine elastomer, LCEs show enhanced viscoelastic dissipation emerging from the inter-mesogen interaction in addition to the friction of typical polymer networks.…”