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Graphical abstract Highlights • A polyelectrolyte soft actuator is designed and developed by 3D printing. • The bending of actuator is controlled through electrical stimulus. • A grey-box Multiphysics model is developed for the printed actuator. • Image processing algorithm is developed for tracking the actuator end point. • The uncertain model of soft actuator is dealt with incorporation of fuzzy sliding mode controller. Abstract Introduction of 3-dimensional (3D) printing in fabrication and increasing applications of intriguing products in soft robotics have led to studies on controllable 3D printed soft actuators. Therefore, a demand for a precise and computationally efficient model for bending control of the 3D printed soft actuators has arisen. This study initially used a grey box strategy for dynamic modeling of a 3D printed soft actuator which undergoes large bending deformations. Yet, the primary model estimated results deviated from experimental results due to uncertainties such as hysteresis and time varying characteristics of the soft actuator in presence of electric field. Thus, a robust feedback control needed for more accurate bending control of the 3D printed polyelectrolyte actuator. In this paper a sliding mode control scheme is developed with the incorporation of Takagi–Sugeno (T-S) fuzzy modeling of a class of complex 3D printed soft actuator system. A set of extreme fuzzy subsystems are derived for modeling purpose of the actuator; then, a sliding mode control law is employed to ensure the stability of the closed-loop fuzzy system and deal with model uncertainties. Finally, the proposed approach is verified by experimental results. [ABSTRACT FROM AUTHOR]

Fruit hardness is an indispensable attribute for appraising fruit quality, with notable implications for nondestructive robotic grasping, ripeness determination, and classification. This article introduces an tactile predictive recognition approach that leverages an adaptive capsule network to assess fruit hardness through manual interaction. This methodology serves as the foundation for an all-encompassing robotic system, integrating grasping and tactile acquisition capabilities. Within this framework, a vision module captures images and generates optimal grasping configurations, while an actuator endowed with tactile fingertips applies controlled pressure to collect tactile data from the fruit's surface. It is noteworthy that the capsule model surpasses conventional convolutional neural networks in its adept utilization of temporal information. Additionally, a dedicated fruit grasping dataset is meticulously curated and employed, online grasping experiments performed on representative fruit samples, The empirical results unequivocally establish the superior accuracy of the capsule network model in hardness recognition, surpassing existing Time Series models. Consequently, our proposed scheme holds promise for engendering novel insights into the automation of fruit sorting processes and the advancement of non-destructive fruit picking methodologies. [Display omitted] • Presenting a vision-based guide for assessing fruit firmness using tactile sensors. • A neural network model combining self-attention and capsule networks is presented. • The proposed method achieves good regression performance in experiments. [ABSTRACT FROM AUTHOR]

Highlights • A new small size piezoelectric impact drive actuator is proposed. Dimensions of the actuator are 8 × 8.5 × 5.6 mm and the weight is 1.39 g. • Actuator has novel design and can operate as a self-moving type or to the drive a slider. • Slider is held by the actuator therefore no bearings are needed to move slider. • Saw tooth or rectangular pulse type electric signal can be used for the motor driving. • Actuators achieves a maximum trust force of 0.21 N, the maximum no load velocity of the slider is 40.376 mm/s, the maximum power density is 4175.42 W/m3. Abstract A new small size linear type piezoelectric inertia-friction actuator has been developed. The actuator is self-inertia type and operation principle is based on the impact drive. Piezoelectric actuator has simple design and consists of four rectangular bimorph piezoelectric plates fixed in two metal holders that are connected by the two springs. Actuator can operate as self-moving slider on the clamped carbon fiber reinforced plastic rod or it can be clamped to drive the rod. Size of the actuator is 8 × 8.5 × 5.6 mm. Excitation of the actuator can be carried out by single saw tooth or rectangular pulse type signal. Bidirectional motion of the slider is achieved by changing phase of the saw tooth electrical signal by π or duty ratio of the rectangular pulse signal. Numerical investigation of the piezoelectric actuator was performed to analyze natural frequencies, modal shapes and response of the actuator to the different excitation signals. A prototype piezoelectric actuator was made and operating principle of the actuator was validated. Measurements of electrical and mechanical output characteristics were performed. The maximum no load velocity of the slider reaches 40.376 mm/s with driving voltage of 40 V. Actuator achieves maximum thrust force of 0.21 N with the same input voltage. [ABSTRACT FROM AUTHOR]

As a new kind of smart materials for fabricating ionic electric actuator, Chitosan Gel Polymer (CGP) known as bionic artificial muscle, has broad application prospects and high academic value with advantages of simple structure, good biocompatibility and large deflection under low driving voltage (≤5 V). In this paper, effects and enhancement mechanism of the heat treating optimization technology on response speed performance of the CGP actuator were mainly investigated. Furthermore, its preparation process including material selection, membrane fabrication and the assembly along with fabrication principle were deeply researched. The CGP actuator consisted of two parts; electric actuating membrane which is sandwiched between non-metallic electrode membranes. On one hand, high viscosity chitosan inside the actuating membrane served as framework which gives access to anions and cations within the electrode membranes. On the other hand, Multi-walled Carbon Nanotube (MCNT) was adopted to modify chitosan in the electrode membrane for obtaining good conductivity and stable chemical character. Moreover, response speed of the CGP actuator that underwent repeated heat treating for a short time, would be continuously improved with the increase of heat treating times. But as the heat treating time prolonged, electromechanical properties of the CGP actuator began to degrade. In addition, since conduction velocity of microscopic ions inside the CGP actuator was presented as macroscopic current magnitude, the experimental results revealed that the changing trend of response speed was almost in accord with the current trend of the CGP actuator. Both of these are fitted in a quadratic function relationship. [ABSTRACT FROM AUTHOR]

This article extends the conventional permittivity change based displacement self-sensing technique for piezoelectric actuators to an impedance change based displacement–force self-sensing technique. The presented methodology evaluates changes in capacitance and resistance at an electrical resonance frequency and uses a third order polynomial fit to estimate displacement and force. Experimental validations show a mean error of 1.8%, and an error standard deviation of 1.9% for displacement and a mean error of 1.7%, and an error standard deviation of 1.8% for force. [ABSTRACT FROM AUTHOR]

By using aligned multi-walled carbon nanotube (MWCNT) reinforced epoxy composites possessing a negative coefficient of thermal expansion (CTE) as well as high Young’s modulus and aluminum foils, novel electrothermal bimorph actuators are fabricated. U-shaped bimorph actuators are formed by cutting out the middle part of the composite/aluminum laminates, where the MWCNT-aligned direction is parallel to the length direction of the U-shaped bimorph actuators. We demonstrate that the bimorph actuators with a free length of 16 mm show a large bending displacement and force output, and their values are 7.6–10.0 mm and 0.8–7.8 mN under a DC voltage of 5.2–6.0 V. Based on these results, the bending displacement and force output of the bimorph actuator are modeled by combining strength-of-materials theories and rule of mixtures (Voigt model and Turner’s model). By using these models, we indicate contributions from two sources toward the increased bending displacement and force output in the bimorph actuator: (i) designing the Young’s modulus and negative CTE of the composite layer by controlling the MWCNT volume fraction and the dimensional parameters (especially thickness) of the bimorph actuator; (ii) selecting materials having a high Young’s modulus as well as a large CTE as the second layer. [ABSTRACT FROM AUTHOR]

Microfluidic-driven mechanica l actuation opens new possibilities for positioning and manipulating delicate small components. However, existing microfluidic actuation methods are not well-suited to positioning with high resolution. This paper reports a method for precise, open-loop control of droplet position in finite steps by varying the duty cycle of the input signal in electrowetting actuation. When wetted to a solid object, both the droplet and the solid can be actuated. Unlike conventional electrowetting actuation methods, positioning resolution in our proposed method can be much smaller than the size of the underlying electrodes without requiring closed loop feedback control system. Using a leaky dielectric coating, the electrode/electrolyte combination in our device acts as a simple diode by blocking current in one direction and conducting in the other. Each duty cycle of the applied AC square wave corresponds to a unique position on the electrode. The position – duty cycle relationship is found to be nonlinear but symmetric about the center of the electrodes. This approach provides a method for improving open-loop positioning resolution without adding more electrodes. Positioning is within 0.2 mm (<2.5% of the droplet diameter) of the idealized model and repeatability is <0.07 mm (<0.8% of the droplet diameter). [ABSTRACT FROM AUTHOR]

This paper presents an illustrative experiment-based comparison between different approaches for hysteresis compensation in piezoelectric actuators ( X and Y axes). The focus is on 3D piezoactuation on some lab-made nanopositioning device, based on tunneling current phenomenon ( Z axis). The experimental validation is done for two formerly developed methods – operator-based Modified Prandtl-Ishlinskii (MPI) inversion on the one hand and disturbance observer (DOB) affine hysteresis approximation on the other hand, as well as for the one corresponding to DOB based on MPI hysteresis approximation. It is shown that the modeling error introduced by MPI model is bounded and the MPI compensator in a forward path of the considered system can improve the performance of DOB. The results are given for tracking spiral patterns recently used in Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM). [ABSTRACT FROM AUTHOR]

This paper describes three-dimensional (3D) digital microfluidics based on an alternating current electrowetting-on-dielectric (AC-EWOD) principle. To achieve 3D manipulation of a droplet between two parallel plates, the horizontal and vertical actuation of a droplet is investigated separately. The dynamic behavior of a water droplet actuated by AC-EWOD in various conditions is studied using high-speed imaging. Optimum actuation parameters such as applied frequency, switching time, and the gap between the top and bottom plates are obtained. For horizontal actuation, a high frequency (1 kHz) is used for small-droplet deformation; on the other hand, for vertical actuation, a low frequency (44 Hz) is used for large-droplet deformation. Finally, as a proof of concept, 3D manipulation of a droplet with two parallel plates is demonstrated by the combination of horizontal and vertical AC-EWOD actuation, resulting in increased space for digital microfluidics. [ABSTRACT FROM AUTHOR]

Scanning fiber tips provides the most convenient way for forward-viewing fiber-optic microendoscopy. In this paper, a distal fiber scanning method based on a large-displacement MEMS actuator is presented. A single-mode fiber is glued on the micro-platform of an electrothermal MEMS stage to realize large range non-resonant scanning. The micro-platform has a large piston scan range of up to 800 μm at only 6 V. The tip deflection of the fiber can be further amplified by placing the MEMS stage at a proper location along the fiber. A quasi-static model of the fiber-MEMS assembly has been developed and validated experimentally. The frequency response has also been studied and measured. A fiber tip deflection of up to 1650 μm for the 45 mm-long movable fiber portion has been achieved when the MEMS electrothermal stage was placed 25 mm away from the free end. The electrothermally-actuated MEMS stage shows a great potential for forward viewing fiber scanning and optical applications. [ABSTRACT FROM AUTHOR]

A dual-mounted actuator structure is widely used to reduce the inertial force from high-speed actuators and to alleviate the vibration of the base in a scanning probe microscope. However, the inertial force resulting from an unbalanced weight should be considered and is conventionally performed by adding a dummy mass to balance the weight. In this paper, the inertial force resulting from an unbalanced weight is balanced by adjusting the amplitude ratio of the voltages applied to two actuators in a dual-mounted actuator structure. The experimental results show that the base vibration is well suppressed even if an unbalanced weight exists. The vibration suppression effect of the proposed approach is comparable to the effect generated when using the traditional method. [ABSTRACT FROM AUTHOR]

In this study, a novel linear impact-resonant actuator was proposed for mobile device applications. The most significant issue in mobile haptic actuators is the ability to provide various vibrotactile and alert functions despite their size and power consumption limitations. This study aimed to achieve fast and strong impact vibrations over a wide frequency range, including the resonant frequency, which decoupled the intensity and frequency of the vibration to achieve both fruitful vibrotactile feedback and strong alarming vibration. To accomplish this, a new mechanism was proposed that can amplify the impact force at the end of the stroke and increase the speed of the response. The magnetic flux path was optimized using an equivalent magnetic circuit model to maximize the electromagnetic force. The performance of a prototype actuator (11 mm × 9 mm × 3.2 mm) was evaluated in terms of the response time and vibration acceleration amplitude under an input power of 0.3 W. The experimental results clearly showed that the proposed actuator could create a vibration acceleration that was greater than 2 g over a frequency range of 1–210 Hz with a fast response of 4 ms and extremely short residual vibration. In addition, a stronger impact force of around 3 g could be generated near the resonant frequency of 190 Hz. [ABSTRACT FROM AUTHOR]

High quality factors are preferable for resonating microcantilever sensors in order to improve sensitivity and resolution. In this paper we investigate the performance of microcantilevers in different resonant modes vibrating in infinite gaseous environments. Aluminum nitride based piezoelectric microcantilevers are fabricated and tested under controlled pressure from high vacuum to atmospheric pressure in N 2 environment, using a custom-built vacuum chamber. From the experiment results it can be seen that the torsional modes exhibit larger quality factors than those of the flexural and lateral ones, and the lateral modes have the lowest Q factors, which are limited mainly by the high intrinsic damping. Finally, analytical models for the fluidic damping characteristics of beam-shaped resonators at different resonant modes are derived and show good agreement with experimental results in the higher pressure regime. [ABSTRACT FROM AUTHOR]

Abstract: Pull-in instability as an inherently nonlinear and crucial effect continues to become increasingly important for the design of electrostatic MEMS and NEMS devices and ever more interesting scientifically. This review reports not only the overview of the pull-in phenomenon in electrostatically actuated MEMS and NEMS devices, but also the physical principles that have enabled fundamental insights into the pull-in instability as well as pull-in induced failures. Pull-in governing equations and conditions to characterize and predict the static, dynamic and resonant pull-in behaviors are summarized. Specifically, we have described and discussed on various state-of-the-art approaches for extending the travel range, controlling the pull-in instability and further enhancing the performance of MEMS and NEMS devices with electrostatic actuation and sensing. A number of recent activities and achievements methods for control of torsional electrostatic micromirrors are introduced. The on-going development in pull-in applications that are being used to develop a fundamental understanding of pull-in instability from negative to positive influences is included and highlighted. Future research trends and challenges are further outlined. [Copyright &y& Elsevier]

Highlights: [•] A new all organic composite based on ferroelectric relaxor polymer matrix and bis (2-ethylhexyl) phthalate (DEHP) has been elaborated and characterized. [•] P(VDF-TrFE-CFE) composite doped with DEHP shows a 28-fold increase of the longitudinal electrostrictive strain and a 235-fold increase of the mechanical energy density. [•] This easy and low cost modification allows a 6 times reduction of the electric field compared to the neat terpolymer. [•] Experimental results have been compared to classical models and the increase attributed to large interfacial effects caused by charges trapped at the structural heterogeneities of the polymer. [Copyright &y& Elsevier]

This paper studies the influence of the mass of carboxymethyl cellulose on the SCIA sample of the sodium alginate biogel ion electric actuator. An experimental platform is built to study its deflection displacement and output force characteristics. The internal structure of the ion electric actuator was observed by a scanning electron microscope. Further test SCIA samples with infrared and electrochemical workstation. Studies have shown that when the mass of CMC is 0.25 g, the comprehensive performance of the SCIA sample is the best, the output force performance is good, the ion channel is the largest, and the response speed is fast. The maximum output force is 2.675 mN, the maximum deflection displacement is 17.137 mm, the maximum response speed is 0.176 mm/s, and the maximum specific capacitance in electrochemical performance is 96.95 mF/g. However, with the increase of CMC and excessive cross-linking, the performance of SCIA samples decreased. [Display omitted] • The output force performance and electrochemical performance are greatly improved. • The internal skeleton structure is improved. • The ion channel migration rate is increased. • The maximum output force is 2.675 mN, and the maximum deflection displacement is 17.137 mm. [ABSTRACT FROM AUTHOR]

Highlights: [•] It is proved that leakage current is mainly determined by the voltage on actuator. [•] A compensation circuit for charge drive is proposed. [•] Displacement drift rate is decreased from 0.9nm/s to lower than 0.033nm/s. [Copyright &y& Elsevier]

• Parametric study of DBD plasma actuators for deicing/ice sensing was presented. • Effect of DBD geometrical scales on thermal and ice sensing behavior was studied. • The influence of dielectric material on thermal and ice sensing was explored. • Deicing of an ice layer and a frost layer with DBD plasma actuator was demonstrated. [Display omitted] In this paper a parametric optimization of the dielectric barrier discharge (DBD) plasma actuator is conducted in order to achieve better ice sensing and deicing performance. For this purpose, different DBD plasma actuators were tested by changing the main geometrical dimension of the DBD plasma actuator and dielectric material. Both the ice sensing and thermal characteristics of the DBD plasma actuator were analyzed and compared. The results reveal that there exists two separate set of optimum parameters that lead to best ice sensing and thermal behavior. For both the sensing and thermal characteristics, the thinnest DBD showed the best performance. Kapton DBD plasma actuator showed the highest surface temperature while PMMA (poly methyl methacrylate) had the best performance for ice sensing. In the end, the deicing performance of a DBD actuator that had in average better thermal and ice sensing performance was tested for deicing an ice layer and a frost layer. The progress of the deicing process and the ice sensing measure on the surface were recorded and analyzed. [ABSTRACT FROM AUTHOR]

• The multi-balloon actuator is designed on the basis of a pneumatic rubber actuator and a DEA. • The fully soft actuator was successfully fabricated by screen printing, rubber casting, and plasma treatment processes. • The multi-balloon actuator's components assembled and interacted with each other and could transport an object linearly. • This design can be applied to portable small-scale robots and annelid robots with high reliability and body compliance. [Display omitted] Recently, various soft actuators with biologically inspired motions have emerged in the field of robotics. The present study focuses on the development of a multi-balloon dielectric elastomer actuator (DEA) to provide a traveling wave motion for the linear transportation of an object. The multi-balloon actuator is designed on the basis of a pneumatic rubber actuator and a DEA, which itself consists of a dielectric membrane mounted on a silicone air chamber. An actuator that is inflated by pre-charged air pressure induces a rapid response speed and large deformations using only electric power; thus, it does not require the bulky external system which is essential for conventional pneumatic actuators. A multi-balloon actuator made of only soft materials was successfully fabricated by screen printing, rubber casting, and plasma treatment processes. Throughout the experiment, the maximum displacements of the balloon actuator with respect to height and width were obtained at an air pressure of 12.2 kPa. Importantly, the multi-balloon actuator's components assembled and interacted with each other and could successfully transport an object linearly via a traveling wave. In the object transfer experiment of this study, the linear velocity reached 0.97 mm/s with an initial air pressure and the applied voltage maintained at 13.3 kPa and 7.5 kV, respectively. The potential applicability of this system as a portable robot is demonstrated by replaying the traveling wave motions using a multi-balloon actuator. In the future, this design can be applied to portable small-scale robots and annelid robots with high reliability and body compliance. [ABSTRACT FROM AUTHOR]

• The dielectric properties of dynamic ion crosslink (DIC) elastomers are evaluated. • The performance when DIC elastomers are used in a dielectric elastomer actuator (DEA) are also evaluated. • The relative permittivity of the DIC elastomers was approx. 3.0 and was constant below 2.70 V/μm at 20 Hz. • The expected large-scale ionic polarization was not observed. • The Young's modulus of DIC elastomer under an electric field was 1.4 times higher than in the absence of an electric field. • The max. blocking stress of the DEA using the DIC elastomer (DIC-DEA) was 22.6 times larger than DEA using VHB 4910. • DIC-DEA self-healed even after the mechanical damage. • DIC-DEA is a sustainable DEA that exhibits no deterioration of the performance. [Display omitted] The dielectric properties of self-healing dynamic ion crosslink (DIC) elastomer and its performance as a dielectric elastomer actuator (DEA) were evaluated. The relative permittivity of the DIC elastomer was approximately 3.0 and it was almost constant in the frequency range of 20–200,000 Hz and in the field strength below 2.70 V/μm at 20 Hz. The expected large-scale ionic polarization of the ionic aggregates was not observed under the electric field examined. The maximum blocking stress of the DEA using the DIC elastomer (DIC-DEA) was much larger (approximately 22.6 times) than that of the DEA using a commercial tape (VHB4910) (VHB-DEA). This is brought by the advantage that the breakdown strength of DIC-DEA is much higher than that of VHB-DEA. The Young's modulus of DIC showed a peculiar behavior; it was higher (1.4 times) under an electric field (3.00 V/μm) than in the absence of an electric field (0.39 ± 0.07 MPa). The maximum blocking stress at 1.0 kV/s was the same as that at 0.2 kV/s. This would reflect the fact that the blocking stress is independent of the Young's modulus as a function of the deformation rate. In addition, cut DIC elastomer reconnected at room temperature, and the blocking stresses at 5.80 V/μm of the self-healed DIC-DEA was the same as that of the prior-to-cut DIC-DEA, regardless of the rate of change of voltage. These results suggest that DIC-DEA is a sustainable DEA that exhibits no deterioration of the performance because of its self-healing behavior even after the mechanical damage. [ABSTRACT FROM AUTHOR]

[Display omitted] • BSEP is UV-curing synthesized with electroactive and thermal shape-memory property. • Ag NWs are embedded in active layer for stable joule-heating. • 3 Paralleled stiff strips are used to direct the actuation. • The soft actuators maintain actuating motion without external stimuli. Soft actuators based on electroactive polymer (EAP) and shape memory polymer (SMP) have drawn increasing attention, whereas EAP and SMP usually are used as independent functional components. In this work, bistable electroactive polymer (BSEP) with tunable modulus that can be actuated by Maxwell pressure was synthesized. The phase-transition points around ambient temperature were tuned by adjusting the ratio of octadecyl acrylate and soft segment. Bilayer structure was adopted by combining BSEP and passive layer to realize out-of-plane actuation. This actuator can maintain actuating shape without continuously applied stimuli when it is at stable states. Ag nanowires network embedded in BSEP was used as heating electrode, along with carbon nanotube network as high-voltage electrode. Finite element analysis and experiment results show that stiff strips parallelly attached to the actuator can effectively control the actuating direction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coupling strategy (thought) of electric explosion and plasma discharge was proposed to increase the launching capacity of electro-explosively actuator. • A mini electro-explosively actuator was designed and fabricated using MEMS technology and PCB technology to verify the coupling thought. • Flyer velocity characterization, electrical characterization and plasma spectrum characterization were conducted to help us know about the process and effect of plasma discharge. • The coupling thought provides a new method for the development of other high- speed flyer loading methods. In this study, a novel high-speed flyer launching strategy based on the principle of the electric explosion of metal bridge foil and plasma discharge coupling was proposed to further improve the capability of conventional electro-explosively actuators. A mini electro-explosively actuator with built-in electrodes in its barrel was drawn up and fabricated using microelectromechanical system (MEMS) and printed circuit board (PCB) technologies to verify the coupling concept. Extra energy was transferred to the plasma produced by the metal foil electric explosion through the metal electrodes embedded in the side wall of the barrel, realizing the energy coupling between electric explosion and plasma discharge and then acquiring higher flyer velocity. Photonic Doppler velocimetry (PDV) was utilized to characterize and compare the flyer velocities of this mini electro-explosively actuator under uncoupled and coupled conditions. Finally, electrical characterization and plasma spectrum tests were performed to further understand the details of plasma discharge. The results confirmed that the proposed idea was conducive to the development of the electro-explosively actuator. [ABSTRACT FROM AUTHOR]

• IPAM displays the best output force and response speed at freeze-drying temperatures of −50°C ∼ −70°C. • Crystal grains can conduct mutual diffusion to reinforce the IPAM binding force and mechanical property. • At −50°C ∼ −60°C the IPAM crystallization is fully completed with fine porous structure, ion channel and water retention rate. • The better water retention rate, the smaller tremor frequency and amplitude of the IPAM. Ionic Polymer Artificial Muscle (IPAM), as a new electric actuator, has the advantages of good flexibility, excellent biocompatibility, large deformation and low price, which involves wide application prospects in engineering fields. In this work, effects of freeze-drying temperature on response speed, output force and its tremor characteristics of the IPAM were researched in depth. Experimental results showed that the optimal freeze-drying temperature was from -50°C to -70°C, then IPAM displayed the best output force and response speed, with the maximum of 6.76 mN and 0.166 mN/s respectively, which were 1.7 times and 4.9 times higher than the minimum values. Thereinto, at -60°C freeze-drying temperature, output-force tremor frequency and its amplitude of the IPAM were separately once and 0.4 mN, which were 0.06 times and 0.13 times less than that of the maximum. Furthermore, improvement mechanism of the IPAM was that a high freeze-drying temperature would weaken the crystallinity of water molecules with big and unstable crystal structure during the sublimation, which was easily destroyed by stress inside the IPAM accompanying small diameter of ion channels and thickness. But moderate low freeze-drying temperatures could refine crystal grains of the water molecules, and then their diffusion enhanced mechanical property of the IPAM with fine connectivity and smoothly of the ion channels. [ABSTRACT FROM AUTHOR]

• Design of a robust control strategy for characterization of DEA system. • Proposal of a robust input shaper that eliminates resident vibration and overshoot. • Robust control effects of proposed design under varying applied voltage. Dielectric elastomer actuators (DEAs) are an emerging type of soft actuator. When electrostatically actuated the DEA with a step signal, the inherent vibrations may limit their motion accuracy in practical applications. Moreover, increasing the applied voltage reduces the natural frequency of the dielectric elastomer structure, as the electrostatic stress decreases the tension in the DE device. This paper proposes a robust input shaper for a DEA system to eliminate vibration under various applied voltage. To extend the frequency control range of the shaper, an improved zero distribution method is proposed. The zeros are symmetrically distributed in the radial direction of the designed zero of a distributed zero-vibration (DZV) shaper. Simulations and experiments are performed to explain the robust control effects of the proposed design method. The step responses of the DEA are conducted at 2, 3 and 4 kV, the vibration attenuations of 27.66, 4.867 and 9.803 dB are achieved, respectively. Meanwhile, the overshoots are eliminated from the step responses. The designed method can pave the way to improve the control accuracy of soft material devices under varying operating conditions. [ABSTRACT FROM AUTHOR]

• A helical shaped dielectric barrier discharge actuator is developed as a plasma swirler. • Advantages of the plasma swirl injector with helical shaped actuators are demonstrated. • Actuators with different helical directions and electrode positions are assessed. • A central recirculation zone induced by the plasma actuation is observed. • The central recirculation zone dissipates the azimuthal velocity of the jet flow. In order to enhance the flow control effectiveness of the plasma swirl injector, dielectric barrier discharge (DBD) actuators with helical electrodes are developed and the performance is compared with that of straight actuators through flow field measurement. This new design can adjust the plasma distribution and increase the plasma intensity. More importantly, the design can be used to adjust the axial velocity besides the azimuthal velocity, therefore it can be used to mitigate flame blow-off or flashback. In addition, the plasma-induced flow can be aligned with the direction of flow moving out of the vane swirler accurately, which can reduce the pressure loss from the swirler. The helical shaped actuator is more suitable for working in conjunction with traditional mechanical swirlers, providing more flexibility in flow control. By changing the direction of the helical electrodes and their relative positions, four different plasma swirler configurations for flow control are considered, making flexible combinations with the vane swirler possible and providing more options for combustion control. Results of flow field measurement showed that a central recirculation zone (CRZ) appeared under the plasma actuation. Compared with that of the straight electrode actuation, the size of CRZ is increased and the back flow in CRZ is enhanced by the helical electrode actuation. Effect of CRZ on the azimuthal velocity dissipation is also observed. [ABSTRACT FROM AUTHOR]

• Designing two types of exploding foil overpressure actuators for multiple point synchronous initiation and Mach reflection studies at small laboratory scale. • Mass production and integrated fabrication of exploding foil overpressure actuators realized by MEMS technology. • Developing these actuators as a versatile tool for dynamic high-pressure loading and hypervelocity impacting experiments. • Establishing Lagrange hydrodynamic one-dimensional simulation to numerically simulate the impact loading process of flyers In this paper, two new forms (series-parallel and serial) of exploding foil overpressure actuators (EFOA) have been designed for the Mach reflection pressure studies and initiation of insensitive explosives at a small laboratory scale. These actuators, prepared with microelectromechanical system (MEMS) technique, can be in-situ integrated and mass-produced to reduce manufacturing cost. Electrical characterizations were carried out to obtained some important parameters, such as peak current and voltage, burst time and deposited energy, and the results revealed that the bridge foil of serial-type actuator has an earlier burst time and lower deposited energy than that of series-parallel one. Using an in-house built photon Doppler velocimetry (PDV), each flyer velocity history was measured separately, and the results indicated that the flyer speed of series-parallel actuator is higher, and its exit velocity consistency and time synchronicity are better than that of the serial ones. The flyers of two actuators exhibited a high level of integrity through the ultra-high-speed camera shooting. Based on the Lagrange hydrodynamic equation group, one-dimensional simulation was conducted by introducing the equation of state, discharging circuit equation and Joule heat equation to numerically simulate the whole process of actuator action. The simulation results are well agreed with the experimental ones both in electrical parameters of bridge foil and flyer velocity. Finally, the multipoint synchronous initiation of HNS-IV explosives was successfully achieved with the actuator. All the efforts demonstrated that the actuators are feasible and attractive. [ABSTRACT FROM AUTHOR]

• The investigations showed that the use of FLG significantly improves the properties of composites. • Effects of particle size, structure, and aspect ratio of the FLG on the properties of composites were studied. • Applications of composites such as piezo-electric actuating were demonstrated. • It was experimentally found that the FLG with Type-B rubber shows the largest mechanical displacement. Three-dimensional (3-D) sp2 hybridized few-layer graphene (FLG) is studied due to high properties. Thus, FLG was used as a filler work to reinforce different types of room-temperature-vulcanized (RTV) silicone rubber to improve its properties. The FLG was characterized by a medium surface area of 123 m2/g, low lamella thickness index (LTI) of 18–22 (which is identical to the number of graphene layers stacked), and carbon purity of 99.85 %. The LTI was calculated by dividing the surface area of FLG by the surface area of single-layer graphene (SLG). Composites were prepared by mixing FLG with different types of RTV silicone rubber by solution mixing. The tensile modulus was 0.78 MPa (Type-A) and 0.51 MPa (Type-B). The electrical properties shows that electric resistance fell to 6760 MΩ (Type-A) and 3300 MΩ (Type-B) at 20 phr of FLG. These improved properties were tested for application in a piezo-electric actuator. From 2 to 14 kV, the displacement increased by 600 % for Type-A silicone rubber and 540 % for Type-B silicone rubber at 15 phr of FLG in the electrode. A series of experiments demonstrate the dependency of the properties and piezo-electric actuation on the FLG loading and type of silicone rubber. [ABSTRACT FROM AUTHOR]