Somatosensory actuator based on stretchable conductive photothermally responsive hydrogel

2021 ◽  
Vol 6 (53) ◽  
pp. eabd5483
Author(s):  
Yusen Zhao ◽  
Chiao-Yueh Lo ◽  
Lecheng Ruan ◽  
Chen-Huan Pi ◽  
Cheolgyu Kim ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Artificial Muscle ◽  
Material Design ◽  
Self Monitoring ◽  
Step Motion ◽  
Thermal Actuation ◽  
Neuromuscular Systems ◽  
Porous Microstructure ◽  
Loop Feedback ◽  
Liquid Crystal Elastomers

Mimicking biological neuromuscular systems’ sensory motion requires the unification of sensing and actuation in a singular artificial muscle material, which must not only actuate but also sense their own motions. These functionalities would be of great value for soft robotics that seek to achieve multifunctionality and local sensing capabilities approaching natural organisms. Here, we report a soft somatosensitive actuating material using an electrically conductive and photothermally responsive hydrogel, which combines the functions of piezoresistive strain/pressure sensing and photo/thermal actuation into a single material. Synthesized through an unconventional ice-templated ultraviolet–cryo-polymerization technique, the homogenous tough conductive hydrogel exhibited a densified conducting network and highly porous microstructure, achieving a unique combination of ultrahigh conductivity (36.8 milisiemens per centimeter, 103-fold enhancement) and mechanical robustness, featuring high stretchability (170%), large volume shrinkage (49%), and 30-fold faster response than conventional hydrogels. With the unique compositional homogeneity of the monolithic material, our hydrogels overcame a limitation of conventional physically integrated sensory actuator systems with interface constraints and predefined functions. The two-in-one functional hydrogel demonstrated both exteroception to perceive the environment and proprioception to kinesthetically sense its deformations in real time, while actuating with near-infinite degrees of freedom. We have demonstrated a variety of light-driven locomotion including contraction, bending, shape recognition, object grasping, and transporting with simultaneous self-monitoring. When connected to a control circuit, the muscle-like material achieved closed-loop feedback controlled, reversible step motion. This material design can also be applied to liquid crystal elastomers.

scholarly journals Kraken: A wirelessly controlled octopus-like hybrid robot utilizing stepper motors and fishing line artificial muscle for grasping underwater

2021 ◽  
Author(s):  
Yara Almubarak ◽  
Michelle Schmutz ◽  
Miguel Perez ◽  
Shrey Shah ◽  
Yonas Tadesse
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
Arm Movement ◽  
Artificial Muscle ◽  
Aquatic Life ◽  
Stepper Motors ◽  
3D Printed ◽  
Arm Motion ◽  
Hybrid Actuation ◽  
Underwater Exploration

Abstract Underwater exploration or inspection requires suitable robotic systems capable of maneuvering, manipulating objects, and operating untethered in complex environmental conditions. Traditional robots have been used to perform many tasks underwater. However, they have limited degrees of freedom, manipulation capabilities, portability, and have disruptive interactions with aquatic life. Research in soft robotics seeks to incorporate ideas of the natural flexibility and agility of aquatic species into man-made technologies to improve the current capabilities of robots using biomimetics. In this paper, we present a novel design, fabrication, and testing results of an underwater robot known as Kraken that has tentacles to mimic the arm movement of an octopus. To control the arm motion, Kraken utilizes a hybrid actuation technology consisting of stepper motors and twisted and a coiled fishing line polymer muscle (TCP FL ). TCPs are becoming one of the promising actuation technologies due to their high actuation stroke, high force, light weight, and low cost. We have studied different arm stiffness configurations of the tentacles tailored to operate in different modalities (curling, twisting, and bending), to control the shape of the tentacles and grasp irregular objects delicately. Kraken uses an onboard battery, a wireless programmable joystick, a buoyancy system for depth control, all housed in a three-layer 3D printed dome-like structure. Here, we present Kraken fully functioning underwater in an Olympic-size swimming pool using its servo actuated tentacles and other test results on the TCP FL actuated tentacles in a laboratory setting. This is the first time that an embedded TCP FL actuator within elastomer has been proposed for the tentacles of an octopus-like robot along with the performance of the structures. Further, as a case study, we showed the functionality of the robot in grasping objects underwater for field robotics applications.

scholarly journals Multimodal Hybrid Piezoelectric-Electromagnetic Insole Energy Harvester Using PVDF Generators

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 635 ◽  
Author(s):  
Muhammad Iqbal ◽  
Malik Muhammad Nauman ◽  
Farid Ullah Khan ◽  
Pg Emeroylariffion Abas ◽  
Quentin Cheok ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Degrees Of Freedom ◽  
Energy Harvester ◽  
Wearable Sensors ◽  
Hand Movement ◽  
Low Frequency ◽  
Open Circuit ◽  
Wearable Electronics ◽  
Mobile Source ◽  
Step Motion

Harvesting biomechanical energy is a viable solution to sustainably powering wearable electronics for continuous health monitoring, remote sensing, and motion tracking. A hybrid insole energy harvester (HIEH), capable of harvesting energy from low-frequency walking step motion, to supply power to wearable sensors, has been reported in this paper. The multimodal and multi-degrees-of-freedom low frequency walking energy harvester has a lightweight of 33.2 g and occupies a small volume of 44.1 cm3. Experimentally, the HIEH exhibits six resonant frequencies, corresponding to the resonances of the intermediate square spiral planar spring at 9.7, 41 Hz, 50 Hz, and 55 Hz, the Polyvinylidene fluoride (PVDF) beam-I at 16.5 Hz and PVDF beam-II at 25 Hz. The upper and lower electromagnetic (EM) generators are capable of delivering peak powers of 58 µW and 51 µW under 0.6 g, by EM induction at 9.7 Hz, across optimum load resistances of 13.5 Ω and 16.5 Ω, respectively. Moreover, PVDF-I and PVDF-II generate root mean square (RMS) voltages of 3.34 V and 3.83 V across 9 MΩ load resistance, under 0.6 g base acceleration. As compared to individual harvesting units, the hybrid harvester performed much better, generated about 7 V open-circuit voltage and charged a 100 µF capacitor up to 2.9 V using a hand movement for about eight minutes, which is 30% more voltage than the standalone piezoelectric unit in the same amount of time. The designed HIEH can be a potential mobile source to sustainably power wearable electronics and wireless body sensors.

scholarly journals Designing next-generation negative compressibility materials.

2014 ◽  
Vol 70 (a1) ◽  
pp. C262-C262 ◽  
Author(s):  
Andrew Cairns ◽  
Andrew Goodwin
Keyword(s):  
Crystal Structure ◽  
Transition Metal Oxides ◽  
Artificial Muscle ◽  
Material Design ◽  
Negative Response ◽  
Next Generation ◽  
Diverse Range ◽  
Challenges And Opportunities ◽  
Metal Organic ◽  
Underlying Mechanisms

Negative compressibility is a rare but desirable property whereby a material's crystal structure actually expands in one (negative linear compressibility, NLC) or two (negative area compressibility, NAC) principal directions against application of increasing hydrostatic pressure. The performance of such materials–for use in, for e.g., sensitive interferometric or ferroelectric pressure sensing devices, advanced actuators, or prototype artificial muscle–critically depends on the magnitude of intrinsic negative response. NLC and NAC have been previously reported in a diverse range of materials: from the elemental forms of selenium and tellurium, to transition metal oxides, halides and chalcogenides [1], to more recent reports of NLC in molecular materials, and metal–organic and metal–cyanide frameworks. We explore, using examples from our work [2,3] as well as that of others, how understanding known NLC and NAC materials can inform material design, and how the versatile chemistry of molecular frameworks–the connecting of cationic metal nodes with anionic molecular linkers in one or more dimensions–allows for the targeting, enhancing and coupling of functionalities. By analysis of the negative response across all known NLC and NAC materials we develop new understanding into the underlying mechanisms of these unusual responses. Structural motifs identified point towards strategies for designing the next-generation of these materials, including the simple "wine-rack," "honeycomb" and "spring" mechanisms, where hinging about nodes requires volume reduction by simultaneous expansion and contraction in perpendicular directions (Figure 1). We discuss the first report of "giant" NLC in zinc(II) dicyanoaurate(I), Zn[Au(CN)2]2, where the crystal structure expands >10% over 1.8 GPa [2], the unprecedented prolonged NAC in silver (I) tricyanomethanide, Ag(C4N3) [3], and conclude with our perspective on the challenges and opportunities that remain in the quest for even more extreme responses.

Fabrication and Characterization of Highly Deformable Artificial Muscle Fibers Based on Liquid Crystal Elastomers

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Haiqing Lu ◽  
Zhanan Zou ◽  
Xingli Wu ◽  
Chuanqian Shi ◽  
Jianliang Xiao
Keyword(s):  
Liquid Crystal ◽  
Low Cost ◽  
Muscle Fibers ◽  
Artificial Muscle ◽  
Electric Heating ◽  
Heating Time ◽  
Soft Systems ◽  
Screen Printing Technique ◽  
Liquid Crystal Elastomers ◽  
Pulling Force

Abstract Artificial muscles have important applications in areas ranging from robotics to prosthetics and medical devices. In this study, highly deformable artificial muscle fibers that utilize superior actuating properties of liquid crystal elastomers and liquid-like deformability of liquid metal are reported. An effective and low-cost fabrication approach using screen printing technique is developed. The actuating properties of the artificial muscle fibers, including the dependence of temperature, contraction strain, and pulling force of the artificial muscle fiber on electric heating current and heating time, are characterized. The results could provide important guidance to design and for development of soft systems that utilize the actuating mechanisms of liquid crystal elastomers.

Smart artificial muscle actuators: Liquid crystal elastomers with integrated temperature feedback

2015 ◽  
Vol 231 ◽  
pp. 44-51 ◽  
Author(s):  
S. Petsch ◽  
R. Rix ◽  
B. Khatri ◽  
S. Schuhladen ◽  
P. Müller ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Artificial Muscle ◽  
Temperature Feedback ◽  
Liquid Crystal Elastomers ◽  
Muscle Actuators

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.

scholarly journals Perfunctionalized Dodecaborate Clusters as Stable Metal-Free Active Materials for Charge Storage

2018 ◽  
Author(s):  
John L. Barton ◽  
Alex I. Wixtrom ◽  
Jeffrey A. Kowalski ◽  
Fikile Brushett ◽  
Alexander Spokoyny
Keyword(s):  
Degrees Of Freedom ◽  
Material Design ◽  
Active Species ◽  
High Concentration ◽  
Boron Clusters ◽  
System A ◽  
Energy Conversion And Storage ◽  
Electrochemical Cycling ◽  
Exceptional Stability ◽  
And Storage

We report a class of perfunctionalized dodecaborate clusters that exhibit high stability towards high concentration electrochemical cycling. These boron clusters afford several degrees of freedom in material design to tailor properties including solubility and redox potential. The exceptional stability of these clusters was demonstrated using a symmetric flow cell setup for electrochemical cycling between two oxidation states for 45 days, with post-run analysis showing negligible decomposition of the active species (<0.1%). To further probe the limits of this system, a prototype redox flow battery with two different cluster materials was used to determine mutual compatibility. This work effectively illustrates the potential of bespoke boron clusters as robust material platform for electrochemical energy conversion and storage.

scholarly journals Perfunctionalized Dodecaborate Clusters as Stable Metal-Free Active Materials for Charge Storage

2018 ◽  
Author(s):  
John L. Barton ◽  
Alex I. Wixtrom ◽  
Jeffrey A. Kowalski ◽  
Fikile Brushett ◽  
Alexander Spokoyny
Keyword(s):  
Degrees Of Freedom ◽  
Material Design ◽  
Active Species ◽  
High Concentration ◽  
Boron Clusters ◽  
System A ◽  
Energy Conversion And Storage ◽  
Electrochemical Cycling ◽  
Exceptional Stability ◽  
And Storage

We report a class of perfunctionalized dodecaborate clusters that exhibit high stability towards high concentration electrochemical cycling. These boron clusters afford several degrees of freedom in material design to tailor properties including solubility and redox potential. The exceptional stability of these clusters was demonstrated using a symmetric flow cell setup for electrochemical cycling between two oxidation states for 45 days, with post-run analysis showing negligible decomposition of the active species (<0.1%). To further probe the limits of this system, a prototype redox flow battery with two different cluster materials was used to determine mutual compatibility. This work effectively illustrates the potential of bespoke boron clusters as robust material platform for electrochemical energy conversion and storage.

Design, Mobility and Kinematics Analysis of a Novel Reconfigurable Continuum Shape Morphing Mechanism

2020 ◽  
Author(s):  
Yinjun Zhao ◽  
Yingzhong Tian ◽  
Long Li ◽  
Guangjie Yuan ◽  
Fengfeng Xi
Keyword(s):  
Degrees Of Freedom ◽  
Compliant Mechanism ◽  
Compact Structure ◽  
Shape Morphing ◽  
Step Motion ◽  
Motion Modes ◽  
Load Carrying ◽  
Kinematic Models ◽  
Variable Geometry Truss Manipulator ◽  
Variable Geometry Truss

Abstract This paper presents a novel design for morphing mechanisms that combine the passive lockable reconfigurable variable geometry truss manipulator (VGTM) and the active parallel compliant mechanism. The structure of the VGTM is in a parallel-serial structure and its shape can be fully controlled just by using two active panels. This mechanism is suitable for the aerospace application due to its light, compact structure, load-carrying ability and can achieve multiple degrees-of-freedom (DOFs) deformation. The mobility and topological configuration of the mechanism are thoroughly analyzed. To make the moving process simple and efficient, a control strategy combining the approximate motion mode and the precise motion modes was proposed. The kinematic models for the multi-step motion are established and all solved analytically. At last, a prototype was fabricated to show the structure and the application on morphing wings.

scholarly journals Monolithic shape-programmable dielectric liquid crystal elastomer actuators

2019 ◽  
Vol 5 (11) ◽  
pp. eaay0855 ◽  
Author(s):  
Zoey S. Davidson ◽  
Hamed Shahsavan ◽  
Amirreza Aghakhani ◽  
Yubing Guo ◽  
Lindsey Hines ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
High Performance ◽  
Degrees Of Freedom ◽  
New Technologies ◽  
Elastic Anisotropy ◽  
Active Material ◽  
Soft Robotics ◽  
Liquid Crystal Elastomer ◽  
Liquid Crystal Elastomers ◽  
Soft Actuators

Soft robotics may enable many new technologies in which humans and robots physically interact, yet the necessary high-performance soft actuators still do not exist. The optimal soft actuators need to be fast and forceful and have programmable shape changes. Furthermore, they should be energy efficient for untethered applications and easy to fabricate. Here, we combine desirable characteristics from two distinct active material systems: fast and highly efficient actuation from dielectric elastomers and directed shape programmability from liquid crystal elastomers. Via a top-down photoalignment method, we program molecular alignment and localized giant elastic anisotropy into the liquid crystal elastomers. The linearly actuated liquid crystal elastomer monoliths achieve strain rates over 120% per second with an energy conversion efficiency of 20% while moving loads over 700 times the elastomer weight. The electric actuation mechanism offers unprecedented opportunities toward miniaturization with shape programmability, efficiency, and more degrees of freedom for applications in soft robotics and beyond.

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