Gel Actuator Research Articles

Creation of 3D Print Gel Actuator

United Nations set the goal to maintain the richness of the sea in SDGs. In Japan, they are aiming for broad spectrum and real time of ocean information collection. Various kinds of underwater exploration techniques have been developed. For instance, submersible research vehicles and autonomous underwater vehicle (AUV) have been used for observation of underwater conditions, in addition to the technique of fixed-point observation. However, such research vehicles and conventional AUV are difficult to control, are expensive, and are usually made with non-biodegradable materials such as metals. For this problem, we came up with the robot composed by only organic material. This idea realizes the recycling society. Jellyfish is the most efficient swimmers, traveling for long distance with saving energy by drifting in the ocean, its body can be decomposed after death, and safe for surrounding creatures. Therefore, we are developing the jellyfish-mimic AUV using a hydrogel. For designing a Jellyfish-mimic AUV robot, it is preferable to introduce a soft actuator driven by water pressure, as it requires low electric power and it is eco-friendly. Here, we report a 3D printing hydrogel hydraulically-driven soft actuator that can make a bending motion of umbrella-shaped bell of artificial Jellyfish. We utilized the Pneunets Bending Actuator for designing the actuator, and the detailed information of this actuator is shown in the website of Soft Robotics Toolkit (see https://softroboticstoolkit.com/book/pneunets-bending-actuator). We changed the parameters of 3D print speed and UV light power gel concentration when we make some gel actuators. In addition, we measured and evaluated these performances. Finally, we are making the robot to use it and be composed by only organic materials so that we can release many robots at the same time.

High-performance polyvinyl chloride gel artificial muscle actuator with graphene oxide and plasticizer

A transparent and electroactive plasticized polyvinyl chloride (PVC) gel was investigated to use as a soft actuator for artificial muscle applications. PVC gels were prepared with varying plasticizer (dibutyl adipate, DBA) content. The prepared PVC gels were characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and dynamic mechanical analysis. The DBA content in the PVC gel was shown to have an inverse relationship with both the storage and loss modulus. The electromechanical performance of PVC gels was demonstrated for both single-layer and stacked multi-layer actuators. When voltage was applied to a single-layer actuator and then increased, the maximum displacement of PVC gels (for PVC/DBA ratios of 1:4, 1:6, and 1:8) was increased from 105.19, 123.67, and 135.55 µm (at 0.5 kV) to 140.93, 157.13, and 172.94 µm (at 1.0 kV) to 145.03, 191.34, and 212.84 µm (at 1.5 kV), respectively. The effects of graphene oxide (GO) addition in the PVC gel were also investigated. The inclusion of GO (0.1 wt.%) provided an approximate 20% enhancement of displacement and 41% increase in force production, and a 36% increase in power output for the PVC/GO gel over traditional plasticizer only PVC gel. The proposed PVC/GO gel actuator may have promising applications in artificial muscle, small mechanical devices, optics, and various opto-electro-mechanical devices due to its low-profile, transparency, and electrical response characteristics.

Basic Study of Heating Response Measurement for Nanosheet Particle/Polymer Composite Gel Actuator with Anisotropic Contraction

A soft actuator is expected to be applied in the next generation of robotics. This study focuses on soft gel actuators hybridized with nanosheet liquid crystals. The resulting soft actuator has a highly hydrophilic property, and is suitable for underwater use. When the gel in water is heated to more than the transition temperature, the gel contracts; conversely, it swells when it is cooled. This gel actuator remarkably has an anisotropic contraction characteristic because the orientation of the nanosheets is uniformly arranged. However, little is known about its dynamic characteristics of the thermal contraction. As a basic analysis, this paper investigates the heating step response through experiments, and reveals the variation of the time constant against the dimensions.

Evaluation of thermal response on microgel aggregate toward micro gel actuators

Evaluation of thermal response on microgel aggregate toward micro gel actuators

"A study on soft mobile robot using gel and shape memory alloy actuator

Animals with soft bodies, such as snail and caterpillars, often exhibit excellent adaptivity to various terrain. For the purpose to clarify their excellence , the authors take a synthetic approach by constructing flexible robots which resemble their motion. In this paper, we develop a soft-bodied mobile robot using gel in which multiple shape memory alloy actuators in V-shaped arrangement. By applying periodic voltage with certain phase difference, we show that a surface wave appears on the robots belly, which results in its forward locomotion.

Gel actuators based on polymeric radicals.

Low-voltage electrochemical actuation of radical polymer gels has been demonstrated in an organic electrolyte. Polymer gels were prepared by post-modification of active-ester precursor gels with an amine-functionalised radical. A combination of few-layer graphene and multiwall carbon nanotubes gave high conductivity and improved actuation in the gels, with 32% linear actuation. The actuator system showed good stability over at least 10 cycles, showing its promise. The cycle time was several hours due to mass-transport limited transport of ions and solvent into the device.

A dynamic self-regulation actuator combined double network gel with gradient structure driven by chemical oscillating reaction.

Self-regulation of the dynamic actuation of a chemical oscillating reaction-based gel was realized by altering the network structure of the gradient double network gel. We demonstrated that the propagation mode of the chemical wave was influenced by the network structure, and consequently determined the dynamic feature of the gel actuator.

Low-voltage planar PVC gel actuator with high performances

In this work, a novel planar actuator based on plasticized poly (vinyl chloride) gel and flexible silicone grease electrodes is proposed to realize a new soft actuator with high performance under low driving voltages. The proposed planar PVC gel actuator (PPGA) can demonstrate a strain of 21%, an output stress of over 0.6 MPa and a respond time of about 90 ms, only at a low driving voltage of 120 V. These performances are comparable to those of the biological muscle and are much better as compared to 10–12% strain and 0.09 MPa stress at 400 V for the traditional stainless electrodes-based multilayered PVC gel actuator (MPGA). In addition, compared to the typical planar dielectric elastomer actuator (DEA) (3 M VHB4905), the operating voltage and response time for the PPGA are reduced by one order of magnitude. A theoretical model is used to discuss the difference between the two types of actuators, finding a good agreement with the experimental results. Furthermore, the PPGA can be continuously actuated for more than 1 million times which shows a good durability. These results demonstrate the feasibility of PPGA as a soft actuator, so a wide application is expected.

Effect of doping nanoparticles on the output force performance of chitosan-based nanocomposite gel actuator

ABSTRACTIn this work, a kind of bio-inspired chitosan-based Nanocomposite Gel Actuator (NGA) was developed whose electrolyte membrane was fabricated by doping multi-walled carbon nanotubes (MCNT). Furthermore, the output force performance of NGA was studied. The results illustrated that doping MCNT particles will play a crosslinking role. The electrolyte membrane with different MCNT doping ratios could significantly reduce its elastic modulus and enhanced its specific capacitance. When the MCNT doping ratio was 2 wt%, the output performance of the electric actuator was the best and the output force density (19.17 mN/g) and strain (0.83 %) were increased by 92% and 17%, respectively.

Fabrication process and enhanced electromechanical properties of the muscle-like gel actuator doped with glycerol

At present the Muscle-like Gel Actuator (MLGA), an emerging ionic Electro Active Polymer (EAP), has advantages of small driving voltage, low cost and good biocompatibility, so it is widely used in bionic engineering, marine equipment and medical science etc. But the small output force and slow response speed still seriously restrict further implementation of the MLGA in engineering applications. In this paper, using glycerol as the plasticizer, Calcium Alginate Hydrogel (CAH) was fabricated as electrically actuating membrane to promote its electromechanical properties, and the complete preparation process was proposed. The MLGA was a double-layer capacitor similar to ‘sandwich’ structure, which consisted of the middle actuating membrane and non-metallic electrode membrane on its bilateral surface, where the electrode membrane was made from Sodium Alginate (SA) blended with Multi-walled Carbon Nanotube (MWCNT). Furthermore, the output force performance of the MLGA doped with various glycerol contents was tested by an experimental platform, to obtain the effect law and optimum doping amount. By the tensile test and Cyclic Voltammetry (CV), elastic modulus and specific capacitance of the actuating membrane were acquired, and then from the microcosmic viewpoint, electrically actuating mechanism of the MLGA was deeply analyzed to further clarify the influencing mechanism. Experiments revealed that with the increase of glycerol amount, the elastic modulus decreased gradually but the specific capacitance increased first and then declined after 2 ml. When 1 ml glycerol was added, the output force reached the maximum and its density was 49.560 mN g−1, which was 1.87 times larger than that of the sample without glycerol. Because the ion channel could be improved in a small amount of glycerol, which resulted in easy pass for internal ions. Instead, owing to the viscosity, large amounts of glycerol would block ion migration, which caused small output force density and poor electromechanical performance.

Electrical properties and electromechanical modeling of plasticized PVC gel actuators

We studied the detailed electrochemical and electromechanical properties of a polyvinyl chloride (PVC) gel with dibutyladipate (DBA) as a plasticizer and developed an electromechanical model based on the electrochemical data. We evaluated the electric deformation of the PVC gel by the bending displacement response of the PVC gel strip when a square-wave voltage is applied. For every electrode, the bending responses were to the anode side and increased with the applied voltage. The bending response of the PVC gel is considered to be due to the electric creep movement on the anode surface. We checked this result by optical microscopy. We studied the electrochemical impedance measurements of the PVC gel under bias voltages and the voltage–current and voltage–displacement measurements in response to a triangle-wave voltage. Based on the above electromechanical and electrochemical experimental results, we developed a deformation model of the PVC gel where the electric bending response is basically due to the electrochemical formation of the solvent-rich layer and its deformation from the Maxwell stress. We estimated the displacements with applied voltages of 200 and 1000 V, and the model results were in good agreement with the experimental results despite the rough estimation.

Dynamic mechanical analysis of bucky gel actuator electrolyte by molecular dynamics simulation

Bucky gel actuator is a kind of ionic electroactive polymer that bends when stimulated by an electric field. The mechanical properties of bucky gel actuator play a crucial role in its performance, determining the amount of displacement and blocking force. Dynamic mechanical analysis is performed by molecular dynamics simulation for the electrolyte layer that contains polyvinylidene fluoride as polymer membrane and 1-ethyl-3-methylimidazolium tetrafluoroborate as ionic liquid to study viscoelastic properties behavior of electrolyte at different strain frequencies. Calculated storage modulus increases and viscosity decreases while strain frequency increases in both tensile and shear modes. This is consistent with experimental result for pure polyvinylidene fluoride. Therefore, the presented molecular dynamics simulation method could be utilized for further studies to understand the ion transportation and bend mechanism of the bucky gel actuator.

Degree of Crystallinity and Phase Fraction of Polyvinylidene Fluoride Nanocomposites Containing Ionic Liquid and Graphene/Carbon Nanotube

Bucky gel actuator (BGA) is a type of electro‐active polymer that bends when stimulated by an electric field. Its operation is affected by a matrix network, which has two opposite effects on ion migration and material strength properties of the actuator. Therefore, designing a BGA with more deflection or more strength demands the study of matrix structural properties. In this paper, polyvinylidene fluoride (PVDF) was used as the polymer matrix in BGA composites, and the degree of crystallinity and the fraction of phase were calculated using X‐ray diffraction and Fourier Transform Infrared spectroscopy respectively to investigate the matrix structural properties. Furthermore, Raman spectroscopy analysis was utilized for phase characterization. Several composite films with various components including electrode and electrolyte layers of BGA were prepared by the drop‐casting method in two different conditions to study the effects of PVDF concentration in dimethylacetamide solvent, drying temperature, and additive materials on the matrix structural properties for the first time. It was observed that low concentrations of PVDF in dimethylacetamide solvent coupled with a high drying temperature in a carbon nanotube‐based BGA in contrast with using a graphene‐based BGA, had the lowest degree of crystallinity and phase fraction. POLYM. COMPOS., 39:E1208–E1215, 2018. © 2018 Society of Plastics Engineers

Development of Multilayered Structure Type PVC Gel Actuators for Waist Support Wear

Development of Multilayered Structure Type PVC Gel Actuators for Waist Support Wear

Basic Analysis of Response Characteristics of Sheeted Particles / Polymer Composite Gel Actuator with Anisotropic Contraction

Basic Analysis of Response Characteristics of Sheeted Particles / Polymer Composite Gel Actuator with Anisotropic Contraction

Dynamic control of hybrid MEMS gel actuator using thermoresponsive gel

Dynamic control of hybrid MEMS gel actuator using thermoresponsive gel

Stimuli-responsive gel actuator containing single walled carbon nanotubes driven by infrared light

Stimuli-responsive gel actuator containing single walled carbon nanotubes driven by infrared light

Understanding the electro-stimulated deformation of PVC gel by in situ Raman spectroscopy

Electro-responsive materials are of promising applications in microdevices. A dioctyl terephthalate (DOTP) plasticized polyvinyl chloride (PVC) gel actuator driven by unilateral electrodes was proposed, with which the dynamical creeping deformation of the gel around the anode by electro-stimulation was investigated by in situ Raman spectroscopy. The obtained results reveal that the intensity of the band at 1612 cm−1 was linearly correlated to the ratio of DOTP in PVC gel. The plasticizer concentration evolved after an external electro-stimulation was applied, which indicates the migration of plasticizer around the anode. The migration of the plasticizers to the two sides of the anode consequently drives the deformation of the PVC gel. The memory effect of deformation is due to the residuals of the plasticizers out of their original positions after the removal of electro-stimulation. The understanding of the dynamical deformation of PVC gel in response to electro-stimulations may be helpful for the designing of novel electric actuators.

PVC gel soft actuator-based wearable assist wear for hip joint support during walking

Plasticized polyvinyl chloride (PVC) gel and mesh electrode-based soft actuators have considerable potential to provide new types of artificial muscle, exhibiting similar responsiveness to biological muscle in air, >10% deformation, >90 kPa output stress, variable stiffness, long cycle life (>5 million cycles), and low power consumption. We have designed and fabricated a prototype of walking assist wear using the PVC gel actuator in previous study. The system has several advantages compared with traditional motor-based exoskeletons, including lower weight and power consumption, and no requirement for rigid external structures that constrain the wearer’s joints. In this study, we designed and established a control and power system to making the whole system portable and wearable outdoors. And we designed two control strategies based on the characteristics of the assist wear and the biological kinematics. In a preliminary experimental evaluation, a hemiparetic stroke patient performed a 10 m to-and-fro straight line walking task with and without assist wear on the affected side. We found that the assist wear enabled natural movement, increasing step length and decreasing muscular activity during straight line walking. We demonstrated that the assistance effect could be adjusted by controlling the on-off time of the PVC gel soft actuators. The results show the effectiveness of the proposed system and suggest the feasibility of PVC gel soft actuators for developing practical soft wearable assistive devices, informing the development of future wearable robots and the other soft actuator technologies for human movement assistance and rehabilitation.

A comprehensive review of select smart polymeric and gel actuators for soft mechatronics and robotics applications: fundamentals, freeform fabrication, and motion control

ABSTRACTSmart polymeric and gel actuators change shape or size in response to stimuli like electricity, heat, or light. These smart polymeric- and gel-based actuators are compliant and well suited for development of soft mechatronic and robotic devices. This paper provides a thorough review of select smart polymeric and gel actuator materials where an automated and freeform fabrication process, like 3D printing, is exploited to create custom shaped monolithic devices. In particular, the advantages and limitations, examples of applications, manufacturing and fabrication techniques, and methods for actuator control are discussed. Finally, a rigorous comparison and analysis of some of the advantages and limitations, as well as manufacturing processes, for these materials, are presented.