Polyvinyl Chloride Gel Actuators Research Articles

Soft lenses with large focal length tuning range based on stacked PVC gel actuators

A novel tunable lens with large focal length change and driven by stacked polyvinyl chloride (PVC) gel actuators is designed and characterized in this study. The lens rigid parts are 3D-printed and commercially available, whereas the PVC gel membrane is in volume production. Under electrical actuation, the lens attains focal length ranges from 30 to 217 mm within 400 V. A manual regulating mechanism is proposed for the finished lens that dexterously adjusts the initial focus and focal length ranges. In the compound actuation mode, large focus variation over 950% is achieved within 250 V. Under 250 V step input, the lens exhibits practical response time around 291 ms. Focal length tuning ability of the lens is also demonstrated by capturing the images of objects placed in different positions. This tunable lens is promising for various smart optics.

Deformation theory and nonlinear dynamic behavior of PVC gel actuators

Polyvinyl chloride (PVC) gel generates complex nonlinear vibration behavior under an alternating current voltage excitation, which has potential application as a dynamic electromechanical actuator. However, there are few studies on the deformation theory of PVC gel actuators, especially the dynamic nonlinear response theory. In this paper, a complex dynamic model is established according to the electrodeformation mechanism of PVC film, and the nonlinear dynamic behavior of the actuator is numerically studied by a differential equation. The effects of applied voltage amplitude, voltage frequency, dibutyl adipate content, mechanical tension, and bias voltage on the dynamic properties of PVC film were analyzed under the condition of equal biaxial tension. The variation of amplitude and the generation and disappearance of the beat frequency during vibration are analyzed by using time-domain characteristics. The degree of PVC actuator nonlinearity as well as vibration stability and periodicity is also reflected based on the phase path and Poincare map. Finally, the law of influence of external condition parameters on the dynamic response of the PVC actuator is obtained.

Enhanced performance of electro-responsive PVC gel actuators prepared by advanced rapid thermal melting technique

Polyvinyl chloride (PVC) gel actuators exhibit a contraction-relaxation movement characterized by large strain and rapid response when electrically stimulated, comparable to that of biological muscles, making them attractive for artificial muscles and other actuation purposes. However, the standard fabrication of PVC gel by so-called solution casting has been found to be time-consuming (i.e., typically taking 4–7 days), cost-ineffective, and prone to skin/eyes irritation hazards, limiting its application potential. In this study, a thermal melting method using non-toxic and low-cost stabilizer was proposed to fabricate PVC gel in approximately 10 min. Experimental results show that under the fabrication conditions optimized by Taguchi orthogonal array, the actuation performance of PVC gel is improved, with a contraction strain of 20.62%, an output force of 0.43 N, and a recovery response time of 1.416 s, all of which are superior to that prepared by traditional method. These results open a doorway for fast, affordable, and easily accessible fabrication technology of PVC gel actuators.

Polyvinyl chloride gel based electro-active switchable bio-inspired adhesive

Controlled attachment and detachment mechanisms of geckos have been the focus of attention for decades. Although great progress has been made in the fabrication of biomimetic adhesive materials, dynamically switchable adhesion is still challenging. In this work, inspired by the active muscular locomotion of gecko toes, a novel switchable electro-active adhesive based on polyvinyl chloride (PVC) gel was successfully prepared, including PVC gel active backing layer and a passive PVC fibrillar adhesive layer.The performance of PVC gel actuator, adhesive, and electro-active adhesive are stable. Due to the active backing layer and adhesive layer are all made by PVC gel, the strong bonding between two layers was achieved. Compared with reported reversible adhesive, it exhibited greater adhesion force and response speed.Furthermore, a flexible gripper was made, and the grasping test was successfully carried out.This work provides a new technology for micro/nano manipulation, transfer printing, and climbing robot applications.

Nonlinear Modeling and Control of Polyvinyl Chloride (PVC) Gel Actuators

Polyvinyl chloride (PVC) gels represent a novel type of electroactive polymer actuators with a number of appealing characteristics, including low cost, high compliance, large strain, medium-to-high stress output, fast response, and thermal stability. Despite their vast potential in a variety of applications, modeling and control of nonlinear dynamics of PVC actuators has received little attention. In this article, we first present a data-driven approach to modeling nonlinear dynamics of PVC gel actuators. A Hammerstein model, consisting of a nonlinear module cascaded with linear dynamics, is proposed to capture the pronounced dependence of the voltage input–displacement output frequency response on the input amplitude and bias. A control scheme is then designed based on the model, where an inverse compensator for the nonlinear element is combined with a PID feedback controller. A disturbance observer is further introduced for the estimation and rejection of the influences from imperfect inverse compensation and model uncertainties. Experimental results are presented to support the efficacy of the proposed modeling and control approach. In particular, for a number of reference trajectories, the proposed control scheme results in over 80% reduction of tracking error in comparison with a well-tuned PID controller.

Design of fishtail structure based on oscillating mechanisms using PVC gel actuators

Bionic robot fish, as a kind of underwater robots, has already demonstrated great potential in the ocean. Developing soft actuators for the bionic robot fish has become a key issue. This paper proposed a novel robot fishtail consisting of oscillating mechanisms and the stacked soft polyvinyl chloride (PVC) gel actuators. Based on the fish body wave curve used to control the kinematics of fish swimming, a bionic fishtail skeleton with six joints was developed. A stacked PVC gel actuator was fabricated and its mechanical properties and frequency response characteristics were analyzed. On this basis, a fishtail prototype was fabricated, assembled and tested, which showed good agreement with the theoretical prediction. In addition, mechanical properties and frequency response characteristics of the prototype were also studied. The results showed that the swing amplitude of the fishtail could generate a peak value at about 1.5 Hz (2 Hz on land) due to the resonance effect, which was conducive to the swing of the bionic robot fish. And the underwater tests have demonstrated that the fishtail structure can still generate propulsion and move in the water. The conclusion can provide guidance for the design of bionic robot fish in practical application.

A study of electroactive polyvinyl chloride (PVC) gel actuators through the use of the electric modulus formalism and cyclic linear voltage sweeps

The conductivity and dielectric properties are integral to the function of polyvinyl chloride (PVC) gel actuators. The frequency-dependent properties of PVC gel actuators are investigated here in terms of their impedance, permittivity, and for the first time, electric modulus. The data shows that PVC gels’ conductive properties are just as, if not more, important as their dielectric properties in electromechanical transduction applications. The electrode polarization (EP) and its impact on the impedance and dielectric spectra of PVC gels, as well as the developed asymmetric space charge at the anode, are discussed. The electric modulus and tan spectra are used for the fitting of Cole-Cole (CC) and Debye relaxation models for gels of varying plasticizer content. The electrostatic adhesive force for PVC gels of varying plasticizer is also measured, indicating large electrostatic adhesion (>2 N cm−2). A cyclic linear voltage sweep is used to clarify the dynamics of space charge within the gels. The peak current (associated with space charge development) is seen to be concurrent with the onset of mechanical deformation, showing the asymmetric charge as the origin of electromechanical transduction. Additionally, the maximum charge transferred (as measured by the integration of current over time) before space charge development is found to correlate with the electrostatic adhesive force measured for the gels, pointing to a new method of characterizing PVC gels for actuation.

Effect of ionic liquids as additives for improving the performance of plasticized PVC gel actuators

Dielectric gels are low-density materials that exhibit a mechanical reaction to electric stimuli. They have recently attracted attention for their potential applications in actuators for wearable robotics. In order to lower the driving voltages of actuators consisting of polyvinyl chloride (PVC) gels (PVC gels with a plasticizer), we studied the generated strain of PVC gel actuators with four types of ionic liquids (ILs) additives: trihexyltetradecyl phosphonium chloride (THTDPCl), tetradodecylammonium chloride (TDACl ), tributylmethyl ammonium chloride (TBMACl), and 1-Butyl-3-mthylimidazolium hexafluorophosphate (BMIMPF6). We found that the actuator responses for PVC gels with additives of 0.01 wt% THTDPCl and TDACl were almost two times larger than those for PVC gels without ILs at low applied voltages ranging from 200 to 600 V. Conversely, the displacement responses of PVC gels with the same IL content but of TBMACl and BMIMPF6 were lower than those of gels without ILs. We studied the electrochemical properties of PVC gels with ILs and proposed an improved electromechanical model based on one proposed in a previous study. Based on the proposed electromechanical model, the effect of the IL additives for lowering the driving voltage can be clearly described.

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.

3A1-M04 ナノファイバー技術を用いたPVCゲルアクチュエータの開発(機能性材料と応用の新展開)

This study shows a new PVC (polyvinyl chloride) gel actuator. PVC gel consists of PVC, dibutyl adipate (DBA) and tetrahydrofuran (THF) and it shows electroactive response. Its characteristic is used for the PVC gel actuator. The PVC gel actuator has two gel sheets including cathode (foil electrode), and one anode (mesh electrode) sandwiched between them. While, a new PVC gel actuator consists of two foil electrodes and one gel non-woven. We named this a PVC gel non-woven actuator, and investigated its characteristic.

2A1-K01 伸縮型PVCゲルアクチュエータの積層数と駆動特性(バイオロボティクス)

A poly vinyl chloride (PVC) gel actuator shows great potential for use as a new soft actuator because of such positive characteristics as movement in the air, large deformation, lower power consumption and being lightweight. We have developed a contraction and expansion type actuator by using the PVC gel and mesh type electrodes in the previous study. In this study, in order to developing a kind of high-performance actuators for practical application, we investigated the relationship between the stacked layers and characteristics of the PVC gel actuator.

Characteristics of the creep-induced bending deformation of a PVC gel actuator by an electric field

The influence of plasticizer (Dibutyl adipate) content on characteristics of creep-induced bending deformation of polyvinyl chloride (PVC) gel actuator was investigated in an electric field. The PVC gel bent to the anode side during the first electric field application. However, the gel quickly bent, and the bending deformation gradually increased to a stable state during the succeeding application of electric field. The measurement of space charge showed that a negative space charge gradually accumulated near the anode during the succeeding application of electric field. The dielectric constant of the gel also showed the above similarities. Such similarities suggest that PVC gel can memorize electrically induced deformation. On the other hand, the bending deformation, and the memory effect of the gel depended on the contents of plasticizer. Strong memory effect was obtained for lower content of plasticizer which indicated an influence of the density of the PVC chains and the alignment of PVC dipoles for orientation conformation in the gel network on the characteristics of creep-induced bending actuation and the memory effect of the PVC gel actuator in an electric field.

Development of a Negative Type Polymer Brake Using a Contraction Type PVC Gel Actuator

A poly vinyl chloride (PVC) gel actuator shows great potential because of such positive characteristics as movement in the air, large deformation, and being lightweight. We have developed a contraction type actuator [2]–[6]. In this study, we propose an application of the PVC gel actuator to negative actuated brakes. We made an experimental apparatus which consisted of a motor with an encoder, a torque sensor and a brake using the PVC gel actuator. We measured the characteristics of the polymer brake by using the experimental apparatus. The followings are the results that we found from the experiments. The static brake torque is more than 70[mNm], and the response rate is about 0.04[s]. Based on the results, we showed that the proposed brake was useful for small motors.