Micro-Actuators:  When Artificial Muscles Made of Nematic Liquid Crystal Elastomers Meet Soft Lithography

2006 ◽  
Vol 128 (4) ◽  
pp. 1088-1089 ◽  
Author(s):  
Axel Buguin ◽  
Min-Hui Li ◽  
Pascal Silberzan ◽  
Benoit Ladoux ◽  
Patrick Keller
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Soft Lithography ◽  
Artificial Muscles ◽  
Micro Actuators ◽  
Liquid Crystal Elastomers

scholarly journals Better Actuation Through Chemistry: Using Surface Coatings to Create Uniform Director Fields in Nematic Liquid Crystal Elastomers

2016 ◽  
Vol 8 (19) ◽  
pp. 12466-12472 ◽  
Author(s):  
Yu Xia ◽  
Elaine Lee ◽  
Hao Hu ◽  
Mohamed Amine Gharbi ◽  
Daniel A. Beller ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Surface Coatings ◽  
Liquid Crystal Elastomers

scholarly journals Digital light processing of liquid crystal elastomers for self-sensing artificial muscles

2021 ◽  
Vol 7 (30) ◽  
pp. eabg3677
Author(s):  
Shuo Li ◽  
Hedan Bai ◽  
Zheng Liu ◽  
Xinyue Zhang ◽  
Chuqi Huang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Optical Transition ◽  
Orientational Order ◽  
Weight Ratio ◽  
Great Promise ◽  
Artificial Muscles ◽  
Specific Work ◽  
Digital Light Processing ◽  
Stimuli Responsive Polymers ◽  
Liquid Crystal Elastomers

Artificial muscles based on stimuli-responsive polymers usually exhibit mechanical compliance, versatility, and high power-to-weight ratio, showing great promise to potentially replace conventional rigid motors for next-generation soft robots, wearable electronics, and biomedical devices. In particular, thermomechanical liquid crystal elastomers (LCEs) constitute artificial muscle-like actuators that can be remotely triggered for large stroke, fast response, and highly repeatable actuations. Here, we introduce a digital light processing (DLP)–based additive manufacturing approach that automatically shear aligns mesogenic oligomers, layer-by-layer, to achieve high orientational order in the photocrosslinked structures; this ordering yields high specific work capacity (63 J kg−1) and energy density (0.18 MJ m−3). We demonstrate actuators composed of these DLP printed LCEs’ applications in soft robotics, such as reversible grasping, untethered crawling, and weightlifting. Furthermore, we present an LCE self-sensing system that exploits thermally induced optical transition as an intrinsic option toward feedback control.

scholarly journals Impact damping and vibration attenuation in nematic liquid crystal elastomers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mohand O. Saed ◽  
Waiel Elmadih ◽  
Andrew Terentjev ◽  
Dimitrios Chronopoulos ◽  
David Williamson ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Vibration Isolation ◽  
Surface Adhesion ◽  
Damping Material ◽  
Liquid Crystal Elastomers ◽  
The Impact ◽  
Deformation Modes ◽  
Enhanced Surface ◽  
Impact Damping

AbstractNematic liquid crystal elastomers (LCE) exhibit unique mechanical properties, placing them in a category distinct from other viscoelastic systems. One of their most celebrated properties is the ‘soft elasticity’, leading to a wide plateau of low, nearly-constant stress upon stretching, a characteristically slow stress relaxation, enhanced surface adhesion, and other remarkable effects. The dynamic soft response of LCE to shear deformations leads to the extremely large loss behaviour with the loss factor tanδ approaching unity over a wide temperature and frequency ranges, with clear implications for damping applications. Here we investigate this effect of anomalous damping, optimising the impact and vibration geometries to reach the greatest benefits in vibration isolation and impact damping by accessing internal shear deformation modes. We compare impact energy dissipation in shaped samples and projectiles, with elastic wave transmission and resonance, finding a good correlation between the results of such diverse tests. By comparing with ordinary elastomers used for industrial damping, we demonstrate that the nematic LCE is an exceptional damping material and propose directions that should be explored for further improvements in practical damping applications.

Experimental Studies of Thermo-Induced Mechanical Effects in the Main-Chain Liquid Crystal Elastomers

2014 ◽  
Vol 896 ◽  
pp. 322-326 ◽  
Author(s):  
Supardi ◽  
Harsojo ◽  
Yusril Yusuf
Keyword(s):  
Liquid Crystal ◽  
Critical Temperature ◽  
Main Chain ◽  
Experimental Studies ◽  
Artificial Muscles ◽  
Direction Parallel ◽  
Mechanical Effects ◽  
Liquid Crystal Elastomers ◽  
Heating Up ◽  
Contraction And Expansion

Liquid crystal elastomers (LCEs), either side-chain LCEs (SCLCEs) or main-chain LCEs (MCLCEs), possess a combination of LC and elastic properties, and are expected to be used as artificial muscles. We experimentally investigated the thermo-induced mechanical effects showed by MCLCEs with four different crosslinker concentrations, i.e., 8%, 12%, 14% and 16%. The samples were heated up to the critical temperature and the images were recorded. The samples made the contraction in direction parallel to the director and the expansion in direction perpendicular to the director. Drastic changes occured when approaching the critical temperature, the greater the crosslinkers concentration the bigger the maximum contraction and expansion. The shape anisotropy expression showed that heating up to the critical temperature caused the system no longer in anisotropic state.

Fundamental Research on Development of Micro-Actuator Driven by Liquid Crystal

2012 ◽  
Vol 490-495 ◽  
pp. 3150-3154 ◽  
Author(s):  
Zhan Zhe Zhang ◽  
Gang Li
Keyword(s):  
Liquid Crystal ◽  
Constitutive Equation ◽  
Nematic Liquid Crystal ◽  
Applied Voltage ◽  
Liquid Crystalline ◽  
Parallel Plates ◽  
Micro Actuator ◽  
Fundamental Research ◽  
Micro Actuators

For the purpose of developing liquid crystalline micro-actuators, the transient behaviors of a nematic liquid crystal between two parallel plates have been computed for various parameters such as applied voltage, the gap between the plates, and the twist and tilt angles at the plates. The Leslie–Ericksen theory has been selected as a constitutive equation. As conclusion of this study, we can develop micro-actuators with arbitrary characteristics by suitably controlling the applied voltage, the size of the actuators, and the director anchoring conditions.

Nonlocal model for nematic liquid-crystal elastomers

2006 ◽  
Vol 74 (6) ◽  
Author(s):  
R. Ennis ◽  
L. C. Malacarne ◽  
P. Palffy-Muhoray ◽  
M. Shelley
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Nonlocal Model ◽  
Liquid Crystal Elastomers

Artificial muscles based on liquid crystal elastomers

2006 ◽  
Vol 364 (1847) ◽  
pp. 2763-2777 ◽  
Author(s):  
Min-Hui Li ◽  
Patrick Keller
Keyword(s):  
Liquid Crystal ◽  
Main Chain ◽  
Uv Light ◽  
Shape Change ◽  
Artificial Muscle ◽  
Isotropic Phase ◽  
Artificial Muscles ◽  
Stimuli Responsive ◽  
Liquid Crystal Elastomers ◽  
The Individual

This paper presents our results on liquid crystal (LC) elastomers as artificial muscle, based on the ideas proposed by de Gennes. In the theoretical model, the material consists of a repeated series of main-chain nematic LC polymer blocks, N, and conventional rubber blocks, R, based on the lamellar phase of a triblock copolymer RNR. The motor for the contraction is the reversible macromolecular shape change of the chain, from stretched to spherical, that occurs at the nematic-to-isotropic phase transition in the main-chain nematic LC polymers. We first developed a new kind of muscle-like material based on a network of side-on nematic LC homopolymers. Side-on LC polymers were used instead of main-chain LC polymers for synthetic reasons. The first example of these materials was thermo-responsive, with a typical contraction of around 35–45% and a generated force of around 210 kPa. Subsequently, a photo-responsive material was developed, with a fast photochemically induced contraction of around 20%, triggered by UV light. We then succeeded in preparing a thermo-responsive artificial muscle, RNR, with lamellar structure, using a side-on nematic LC polymer as N block. Micrometre-sized artificial muscles were also prepared. This paper illustrates the bottom-up design of stimuli-responsive materials, in which the overall material response reflects the individual macromolecular response, using LC polymer as building block.

Effect of molecular parameters on thermomechanical behavior of side-on nematic liquid crystal elastomers

Polymer ◽  
2013 ◽  
Vol 54 (20) ◽  
pp. 5321-5329 ◽  
Author(s):  
Renbo Wei ◽  
Lingyun Zhou ◽  
Yaning He ◽  
Xiaogong Wang ◽  
Patrick Keller
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Thermomechanical Behavior ◽  
Molecular Parameters ◽  
Liquid Crystal Elastomers
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